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1.  Altered Mitochondrial Function and Metabolic Inflexibility Associated with Loss of Caveolin-1 
Cell Metabolism  2012;15(2):171-185.
Caveolin-1 is a major structural component of raft structures within the plasma membrane and has been implicated as a regulator of cellular signal transduction with prominent expression in adipocytes. Here, we embarked on a comprehensive characterization of the metabolic pathways dysregulated in caveolin-1 null mice. We found that these mice display decreased circulating levels of total and high molecular weight adiponectin and a reduced ability to change substrate use in response to feeding/fasting conditions. Caveolin-1 null mice are extremely lean, but retain muscle mass despite lipodystrophy and massive metabolic dysfunction. Hepatic gluconeogenesis is chronically elevated, while hepatic steatosis is reduced. Our data suggest that the complex phenotype of the caveolin-1 null mouse is caused by altered metabolic and mitochondrial function in adipose tissue with a subsequent compensatory response driven mostly by the liver. This mouse model highlights the central contributions of adipose tissue for system-wide preservation of metabolic flexibility.
doi:10.1016/j.cmet.2012.01.004
PMCID: PMC3278712  PMID: 22326219
2.  Transplanted progenitors generate functional enteric neurons in the postnatal colon 
The Journal of Clinical Investigation  2013;123(3):1182-1191.
Cell therapy has the potential to treat gastrointestinal motility disorders caused by diseases of the enteric nervous system. Many studies have demonstrated that various stem/progenitor cells can give rise to functional neurons in the embryonic gut; however, it is not yet known whether transplanted neural progenitor cells can migrate, proliferate, and generate functional neurons in the postnatal bowel in vivo. We transplanted neurospheres generated from fetal and postnatal intestinal neural crest–derived cells into the colon of postnatal mice. The neurosphere-derived cells migrated, proliferated, and generated neurons and glial cells that formed ganglion-like clusters within the recipient colon. Graft-derived neurons exhibited morphological, neurochemical, and electrophysiological characteristics similar to those of enteric neurons; they received synaptic inputs; and their neurites projected to muscle layers and the enteric ganglia of the recipient mice. These findings show that transplanted enteric neural progenitor cells can generate functional enteric neurons in the postnatal bowel and advances the notion that cell therapy is a promising strategy for enteric neuropathies.
doi:10.1172/JCI65963
PMCID: PMC3582137  PMID: 23454768
3.  Phosphoinositide Signaling Regulates the Exocyst Complex and Polarized Integrin Trafficking in Directionally Migrating Cells 
Developmental Cell  2012;22(1):116-130.
Summary
Polarized delivery of signaling and adhesion molecules to the leading edge is required for directional migration of cells. Here, we describe a role for the PIP2 synthesizing enzyme, PIPKIγi2, in regulation of exocyst complex control of cell polarity and polarized integrin trafficking during migration. Loss of PIPKIγi2 impaired directional migration, formation of cell polarity, and integrin trafficking to the leading edge. Upon initiation of directional migration PIPKIγi2 via PIP2 generation controls the integration of the exocyst complex into an integrin-containing trafficking compartment(s) that requires the talin-binding ability of PIPKIγi2, and talin for integrin recruitment to the leading edge. A PIP2 requirement is further emphasized by inhibition of PIPKIγi2-regulated directional migration by an Exo70 mutant deficient in PIP2 binding. These results reveal how phosphoinositide generation orchestrates polarized trafficking of integrin in coordination with talin that links integrins to the actin cytoskeleton, processes that are required for directional migration.
doi:10.1016/j.devcel.2011.10.030
PMCID: PMC3266520  PMID: 22264730
Cell Migration; Phosphatidylinositol-4; 5-biphosphate; Cell Polarity; Integrin; Exocyst
4.  Perinatal germ cell development and differentiation in the male marmoset (Callithrix jacchus): similarities with the human and differences from the rat 
STUDY QUESTION
Is perinatal germ cell (GC) differentiation in the marmoset similar to that in the human?
SUMMARY ANSWER
In a process comparable with the human, marmoset GC differentiate rapidly after birth, losing OCT4 expression after 5–7 weeks of age during mini-puberty.
WHAT IS KNOWN ALREADY
Most of our understanding about perinatal GC development derives from rodents, in which all gonocytes (undifferentiated GC) co-ordinately lose expression of the pluripotency factor OCT4 and stop proliferating in late gestation. Then after birth these differentiated GC migrate to the basal lamina and resume proliferation prior to the onset of spermatogenesis. In humans, fetal GC differentiation occurs gradually and asynchronously and OCT4+ GC persist into perinatal life. Failure to switch off OCT4 in GC perinatally can lead to development of carcinoma in situ (CIS), the precursor of testicular germ cell cancer (TGCC), for which there is no animal model. Marmosets show similarities to the human, but systematic evaluation of perinatal GC development in this species is lacking. Similarity, especially for loss of OCT4 expression, would support use of the marmoset as a model for the human and for studying CIS origins.
STUDY DESIGN, SIZE AND DURATION
Testis tissues were obtained from marmosets (n = 4–10 per age) at 12–17 weeks' gestation and post-natal weeks 0.5, 2.5, 5–7, 14 and 22 weeks, humans at 15–18 weeks' gestation (n = 5) and 4–5 weeks of age (n = 4) and rats at embryonic day 21.5 (e21.5) (n = 3) and post-natal days 4, 6 and 8 (n = 4 each).
PARTICIPANTS/MATERIALS, SETTING AND METHODS
Testis sections from fetal and post-natal marmosets, humans and rats were collected and immunostained for OCT4 and VASA to identify undifferentiated and differentiated GC, respectively, and for Ki67, to identify proliferating GC. Stereological quantification of GC numbers, differentiation (% OCT4+ GC) and proliferation were performed in perinatal marmosets and humans. Quantification of GC position within seminiferous cords was performed in marmosets, humans and rats.
MAIN RESULTS AND ROLE OF CHANCE
The total GC number increased 17-fold from birth to 22 post-natal weeks in marmosets; OCT4+ and VASA+ GC proliferated equally in late gestation and early post-natal life. The percentage of OCT4+ GC fell from 54% in late fetal life to <0.5% at 2.5 weeks of age and none were detected after 5–7 weeks in marmosets. In humans, the percentage of OCT4+ GC also declined markedly during the equivalent period. In marmosets, GC had begun migrating to the base of seminiferous cords at ∼22 weeks of age, after the loss of GC OCT4 expression.
LIMITATIONS, REASONS FOR CAUTION
There is considerable individual variation between marmosets. Although GC development in marmosets and humans was similar, there are differences with respect to proliferation during fetal life. The number of human samples was limited.
WIDER IMPLICATIONS OF THE FINDINGS
The similarities in testicular GC differentiation between marmosets and humans during the perinatal period, and their differences from rodents, suggest that the marmoset may be a useful model for studying the origins of CIS, with relevance for the study of TGCC.
STUDY FUNDING/COMPETING INTERESTS
This work was supported by Grant G33253 from the Medical Research Council, UK. No external funding was sought and there are no competing interests.
doi:10.1093/humrep/des465
PMCID: PMC3600838  PMID: 23321215
testis; fetal; post-natal; germ cell; differentiation
5.  Star-PAP Control of BIK Expression and Apoptosis Is Regulated by Nuclear PIPKIα and PKCδ Signaling 
Molecular Cell  2012;45(1):25-37.
SUMMARY
BIK protein is an initiator of mitochondrial apoptosis and BIK expression is induced by pro-apoptotic signals including DNA damage. Here we demonstrate that 3′-end processing and expression of BIK mRNA are controlled by the nuclear PI4,5P2-regulated poly(A) polymerase Star-PAP downstream of DNA damage. Nuclear PKCδ is a key mediator of apoptosis and DNA damage stimulates PKCδ association with the Star-PAP complex where PKCδ is required for Star-PAP-dependent BIK expression. PKCδ binds the PI4,5P2-generating enzyme PIPKIα, which is essential for PKCδ interaction with the Star-PAP complex and PKCδ activity is directly stimulated by PI4,5P2. Features in the BIK 3′-UTR uniquely define Star-PAP specificity and may block canonical PAP activity toward BIK mRNA. This reveals a nuclear phosphoinositide signaling nexus where PIPKIα, PI4,5P2 and PKCδ regulate Star-PAP control of BIK expression and induction of apoptosis. This pathway is distinct from the Star-PAP-mediated oxidative stress pathway indicating signal-specific regulation of mRNA 3′-end processing.
doi:10.1016/j.molcel.2011.11.017
PMCID: PMC3268557  PMID: 22244330
6.  Profound tumor-specific Th2 bias in patients with malignant glioma 
BMC Cancer  2012;12:561.
Background
Vaccination against tumor-associated antigens is one promising approach to immunotherapy against malignant gliomas. While previous vaccine efforts have focused exclusively on HLA class I-restricted peptides, class II-restricted peptides are necessary to induce CD4+ helper T cells and sustain effective anti-tumor immunity. In this report we investigated the ability of five candidate peptide epitopes derived from glioma-associated antigens MAGE and IL-13 receptor α2 to detect and characterize CD4+ helper T cell responses in the peripheral blood of patients with malignant gliomas.
Methods
Primary T cell responses were determined by stimulating freshly isolated PBMCs from patients with primary glioblastoma (GBM) (n = 8), recurrent GBM (n = 5), meningioma (n = 7), and healthy controls (n = 6) with each candidate peptide, as well as anti-CD3 monoclonal antibody (mAb) and an immunodominant peptide epitope derived from myelin basic protein (MBP) serving as positive and negative controls, respectively. ELISA was used to measure IFN-γ and IL-5 levels, and the ratio of IFN-γ/IL-5 was used to determine whether the response had a predominant Th1 or Th2 bias.
Results
We demonstrate that novel HLA Class-II restricted MAGE-A3 and IL-13Rα2 peptides can detect T cell responses in patients with GBMs as well as in healthy subjects. Stimulation with a variety of peptide antigens over-expressed by gliomas is associated with a profound reduction in the IFN-γ/IL-5 ratio in GBM patients relative to healthy subjects. This bias is more pronounced in patients with recurrent GBMs.
Conclusions
Therapeutic vaccine strategies to shift tumor antigen-specific T cell response to a more immunostimulatory Th1 bias may be needed for immunotherapeutic trials to be more successful clinically.
doi:10.1186/1471-2407-12-561
PMCID: PMC3537750  PMID: 23186108
7.  Correlation between three assay systems for anti-Müllerian hormone (AMH) determination 
Purpose
Analysis of anti-Müllerian hormone (AMH) is becoming of recognized importance in reproductive medicine, but assays are not standardized. We have evaluated the correlation between the new Gen II ELISA kit (Beckman-Coutler) and the older ELISA kits by Immunotech (IOT) and Diagnostic Systems Laboratories (DSL).
Methods
A total of 56 archived serum samples from patients with subfertility or reproductive endocrine disorders were retrieved and assayed in duplicate using the three AMH ELISA kits . The samples covered a wide range of AMH concentrations (1.9 to 142.5 pmol/L).
Results
We observed good correlations between the new (AMH Gen II) and old AMH assay kits by IOT and DSL (R2 = 0.971 and 0.930 respectively). The regression equations were AMH (Gen II) = 1.353 × AMH (IOT) + 0.051 and AMH (Gen II) = 1.223 × AMH (DSL) – 1.270 respectively.
Conclusions
AMH concentrations using the Gen II kit are slightly higher than those from the IOT and DSL kits. Standardization of assay results worldwide is urgently required but this analysis facilitates the interpretation of values obtained historically and in future studies using any of the 3 assays available. Meanwhile, adapting clinical cut-offs from previously published work by direct conversion is not recommended.
doi:10.1007/s10815-012-9880-1
PMCID: PMC3528883  PMID: 23117477
Anti-Mullerian hormone; ELISA kit
8.  All you need is light 
Virulence  2011;2(6):509-520.
The story of prevention and control of infectious diseases remains open and a series of highly virulent pathogens are emerging both in and beyond the hospital setting. Antibiotics were an absolute success story for a previous era. The academic and industrial biomedical communities have now come together to formulate consensus beliefs regarding the pursuit of novel and effective alternative anti-infective countermeasures. Photodynamic therapy was established and remains a successful modality for malignancies but photodynamic inactivation has been transformed recently to an antimicrobial discovery and development platform. The concept of photodynamic inactivation is quite straightforward and requires microbial exposure to light energy, typically wavelengths in the visible region, that causes the excitation of photosensitizer molecules (either exogenous or endogenous), which results in the production of singlet oxygen and other reactive oxygen species that react with intracellular components, and consequently produce cell inactivation. It is an area of increasing interest, as research is advancing (1) to identify the photochemical and photophysical mechanisms involved in inactivation, (2) to develop potent and clinically compatible photosensitizer, (3) to understand how photoinactivation is affected by key microbial phenotypic elements (multidrug resistance and efflux, virulence and pathogenesis determinants, biofilms), (4) to explore novel delivery platforms inspired by current trends in pharmacology and nanotechnology and (5) to identify photoinactivation applications beyond the clinical setting such as environmental disinfectants.
doi:10.4161/viru.2.6.17889
PMCID: PMC3260545  PMID: 21971183
photodynamic inactivation and therapy; photosensitizer; reactive oxygen species; permeability barrier; multidrug efflux systems; biofilms; drug delivery; nanomedicine; antimicrobial resistance; clinical applications
9.  PIP2 signaling, an integrator of cell polarity and vesicle trafficking in directionally migrating cells 
Cell Adhesion & Migration  2012;6(5):409-412.
Cell migration is a fundamental cellular process required for embryonic development to wound healing and also plays a key role in tumor metastasis and atherosclerosis. Migration is regulated at multiple strata, from cytoskeletal reorganization to vesicle trafficking. In migrating cells, signaling pathways are integrated with vesicle trafficking machineries in a highly coordinated fashion to accomplish the recruitment and trafficking of the trans-membrane proteins toward the leading edge. Different signaling molecules regulate cell migration in different physio-pathological contexts, among them, phosphatidylinositol-4,5-biphosphate (PIP2) is an integral component of the plasma membrane and pleiotropic lipid signaling molecule modulating diverse biological processes, including actin cytoskeletal dynamics and vesicle trafficking required for cell migration. In this commentary, we provide a brief overview of our current understandings on the phosphoinositide signaling and its implication in regulation of cell polarity and vesicle trafficking in migrating cells. In addition, we highlight the coordinated role of PIPKIγi2, a focal adhesion-targeted enzyme that synthesizes PIP2, and the exocyst complex, a PIP2-effector, in the trafficking of E-cadherin in epithelial cells and integrins in migrating cancer cells.
doi:10.4161/cam.21192
PMCID: PMC3496677  PMID: 23076053
phosphoinositides; integrins; exocyst complex; cell migration
10.  Stromal Expression of Decorin, Semaphorin6D, SPARC, Sprouty1 and Tsukushi in Developing Prostate and Decreased Levels of Decorin in Prostate Cancer 
PLoS ONE  2012;7(8):e42516.
Background and Aim
During prostate development, mesenchymal-epithelial interactions regulate organ growth and differentiation. In adult prostate, stromal-epithelial interactions are important for tissue homeostasis and also play a significant role in prostate cancer. In this study we have identified molecules that show a mesenchymal expression pattern in the developing prostate, and one of these showed reduced expression in prostate cancer stroma.
Methodology and Principal Findings
Five candidate molecules identified by transcript profiling of developmental prostate mesenchyme were selected using a wholemount in situ hybridisation screen and studied Decorin (Dcn), Semaphorin6D (Sema6D), SPARC/Osteonectin (SPARC), Sprouty1 (Spry-1) and Tsukushi (Tsku). Expression in rat tissues was evaluated using wholemount in situ hybridisation (postnatal day (P) 0.5) and immunohistochemistry (embryonic day (E) E17.5, E19.5; P0.5; P6; 28 & adult). Four candidates (Decorin, SPARC, Spry-1, Tsukushi) were immunolocalised in human foetal prostate (weeks 14, 16, 19) and expression of Decorin was evaluated on a human prostate cancer tissue microarray. In embryonic and perinatal rats Decorin, Semaphorin6D, SPARC, Spry-1 and Tsukushi were expressed with varying distribution patterns throughout the mesenchyme at E17.5, E19.5, P0.5 and P6.5. In P28 and adult prostates there was either a decrease in the expression (Semaphorin6D) or a switch to epithelial expression of SPARC, and Spry-1, whereas Decorin and Tsukushi were specific to mesenchyme/stroma at all ages. Expression of Decorin, SPARC, Spry-1 and Tsukushi in human foetal prostates paralleled that in rat. Decorin showed mesenchymal and stromal-specific expression at all ages and was further examined in prostate cancer, where stromal expression was significantly reduced compared with non-malignant prostate.
Conclusion and Significance
We describe the spatio-temporal expression of Decorin, Semaphorin6D, SPARC, Spry-1 and Tsukushi in developing prostate and observed similar mesenchymal expression patterns in rat and human. Additionally, Decorin showed reduced expression in prostate cancer stroma compared to non-malignant prostate stroma.
doi:10.1371/journal.pone.0042516
PMCID: PMC3411755  PMID: 22880013
11.  Highly potent human hematopoietic stem cells first emerge in the intraembryonic aorta-gonad-mesonephros region 
The Journal of Experimental Medicine  2011;208(12):2417-2427.
Human HSCs appear first in the embryonic dorsal aorta, and only later in the yolk sac, liver, and placenta; a single human AGM region HSC can generate at least 300 daughter HSCs that are retransplantable into secondary recipient mice.
Hematopoietic stem cells (HSCs) emerge during embryogenesis and maintain hematopoiesis in the adult organism. Little is known about the embryonic development of human HSCs. We demonstrate that human HSCs emerge first in the aorta-gonad-mesonephros (AGM) region, specifically in the dorsal aorta, and only later appear in the yolk sac, liver, and placenta. AGM region cells transplanted into immunodeficient mice provide long-term high level multilineage hematopoietic repopulation. Human AGM region HSCs, although present in low numbers, exhibit a very high self-renewal potential. A single HSC derived from the AGM region generates at least 300 daughter HSCs in primary recipients, which disseminate throughout the entire recipient bone marrow and are retransplantable. These findings highlight the vast regenerative potential of the earliest human HSCs and set a new standard for in vitro generation of HSCs from pluripotent stem cells for the purpose of regenerative medicine.
doi:10.1084/jem.20111688
PMCID: PMC3256972  PMID: 22042975
12.  Proposed Role for COUP-TFII in Regulating Fetal Leydig Cell Steroidogenesis, Perturbation of Which Leads to Masculinization Disorders in Rodents 
PLoS ONE  2012;7(5):e37064.
Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal ‘masculinization programming window’. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased ∼3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3β-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders.
doi:10.1371/journal.pone.0037064
PMCID: PMC3355148  PMID: 22615892
13.  Caveolin targeting to late endosome/lysosomal membranes is induced by perturbations of lysosomal pH and cholesterol content 
Molecular Biology of the Cell  2012;23(5):864-880.
Caveolin-1 traffics to late endosomal/lysosomal membranes in response to manipulations of the cholesterol content of cells, suggesting that caveolin functions in the egress of cholesterol from this organelle. Cavicles associate with the periphery of the lysosome as they do with caveosomes, but these are separate organelles.
Caveolin-1 is an integral membrane protein of plasma membrane caveolae. Here we report that caveolin-1 collects at the cytosolic surface of lysosomal membranes when cells are serum starved. This is due to an elevation of the intralysosomal pH, since ionophores and proton pump inhibitors that dissipate the lysosomal pH gradient also trapped caveolin-1 on late endosome/lysosomes. Accumulation is both saturable and reversible. At least a portion of the caveolin-1 goes to the plasma membrane upon reversal. Several studies suggest that caveolin-1 is involved in cholesterol transport within the cell. Strikingly, we find that blocking cholesterol export from lysosomes with progesterone or U18666A or treating cells with low concentrations of cyclodextrin also caused caveolin-1 to accumulate on late endosome/lysosomal membranes. Under these conditions, however, live-cell imaging shows cavicles actively docking with lysosomes, suggesting that these structures might be involved in delivering caveolin-1. Targeting of caveolin-1 to late endosome/lysosomes is not observed normally, and the degradation rate of caveolin-1 is not altered by any of these conditions, indicating that caveolin-1 accumulation is not a consequence of blocked degradation. We conclude that caveolin-1 normally traffics to and from the cytoplasmic surface of lysosomes during intracellular cholesterol trafficking.
doi:10.1091/mbc.E11-07-0598
PMCID: PMC3290645  PMID: 22238363
14.  Cognitive and functional status after vein of Galen aneurysmal malformation endovascular occlusion 
World Journal of Radiology  2012;4(3):83-89.
AIM: To study the clinical outcomes of treating vein of Galen aneurysmal malformations (VGAM), we assessed our patient cohort using standardized cognitive and functional measures.
METHODS: A retrospective review of patients with VGAM treated by a single practitioner between 2003 and 2009 was performed for this study. In addition to routine clinical assessment, all patients were evaluated for cognitive and functional impairment using validated measures including the Neurobehavioral Rating Scale-Revised, the Bicêtre outcome score, and the Barthel index.
RESULTS: Five patients underwent combined transarterial and transvenous embolization of their VGAM during the study period. VGAMs were classified based on angioarchitecture as either choroidal (1/5) or mural (4/5) according to the classification scheme of Lasjaunias. In total, 13 embolization procedures were performed consisting of 1 to 3 treatment stages per patient. Complete or near complete occlusion was achieved in 4 patients, while subtotal occlusion was achieved in 1 patient. During follow-up (median 62.6 mo), all patients were either unchanged or cognitively and neurologically intact.
CONCLUSION: VGAM can be safely and effectively treated by staged transarterial and transvenous embolization. Using this strategy, excellent long-term cognitive and functional outcomes can be achieved.
doi:10.4329/wjr.v4.i3.83
PMCID: PMC3314932  PMID: 22468188
Cognition; Embolization; Endovascular; Hemorrhage; Interventional neuroradiology; Neurological development; Outcomes; Vein of Galen aneurysmal malformation
15.  An association between type Iγ PI4P 5-kinase and Exo70 directs E-cadherin clustering and epithelial polarization 
Molecular Biology of the Cell  2012;23(1):87-98.
Type Iγ phosphatidylinositol-4-phosphate 5-kinase and Exo70 cooperate in the directed targeting of E-cadherin on the plasma membrane to newly formed adherens junctions. This promotes the regional accumulation of E-cadherin, expansion and maturation of adherens junctions, and differentiation of the lateral membrane domain.
E-Cadherin–mediated formation of adherens junctions (AJs) is essential for the morphogenesis of epithelial cells. However, the mechanisms underlying E-cadherin clustering and AJ maturation are not fully understood. Here we report that type Iγ phosphatidylinositol-4-phosphate 5-kinase (PIPKIγ) associates with the exocyst via a direct interaction with Exo70, the exocyst subunit that guides the polarized targeting of exocyst to the plasma membrane. By means of this interaction, PIPKIγ mediates the association between E-cadherin and Exo70 and determines the targeting of Exo70 to AJs. Further investigation revealed that Exo70 is necessary for clustering of E-cadherin on the plasma membrane and extension of nascent E-cadherin adhesions, which are critical for the maturation of cohesive AJs. In addition, we observed phosphatidylinositol-4,5-bisphosphate (PI4,5P2) accumulation at E-cadherin clusters during the assembly of E-cadherin adhesions. PIPKIγ-generated PI4,5P2 is required for recruiting Exo70 to newly formed E-cadherin junctions and facilitates the assembly and maturation of AJs. These results support a model in which PIPKIγ and PIPKIγ-generated PI4,5P2 pools at nascent E-cadherin contacts cue Exo70 targeting and orient the tethering of exocyst-associated E-cadherin. This could be an important mechanism that regulates E-cadherin clustering and AJ maturation, which is essential for the establishment of solid, polarized epithelial structures.
doi:10.1091/mbc.E11-05-0449
PMCID: PMC3248907  PMID: 22049025
17.  PIPKIγ regulates β-catenin transcriptional activity in mesenchymal-like cells downstream of growth factor receptor activation 
Cancer research  2011;71(4):1282-1291.
Increased β-catenin transcriptional activity downstream of the Wnt/Wingless signaling pathway has been observed in many human tumors, most notably colorectal carcinomas. However, β-catenin activation is also observed in many human malignancies with no observable Wnt activity. Wnt-independent pathways that activate β-catenin remain undefined, yet have the potential to play a significant role during tumorigenesis. Here, we report that PIPKIγ, an enzyme that generates the messenger phosphatidylinositol 4,5-bisphosphate, can increase β-catenin activity downstream of growth factor stimulation. In addition to enhancing β-catenin accumulation in the nucleus, PIPKIγ-mediated generation of phosphoinositides increase β-catenin phosphorylation and enhance its transcriptional activity. PIPKIγ expression correlates with a decreased survival in breast cancer patients, an observation that requires β-catenin. Lastly, we show that β-catenin is required for PIPKIγ-dependent increased cell proliferation. These results reveal a novel mechanism where PIPKIγ generation of phosphoinositides enhances β-catenin nuclear translocation and expression of its target genes to promote tumorigenesis.
doi:10.1158/0008-5472.CAN-10-2480
PMCID: PMC3066690  PMID: 21303971
PIPKIγ; β-catenin; phosphoinositide; growth factor; breast cancer
18.  LIN28 Is Selectively Expressed by Primordial and Pre-Meiotic Germ Cells in the Human Fetal Ovary 
Stem Cells and Development  2012;21(13):2343-2349.
Germ cell development requires timely transition from primordial germ cell (PGC) self-renewal to meiotic differentiation. This is associated with widespread changes in gene expression, including downregulation of stem cell–associated genes, such as OCT4 and KIT, and upregulation of markers of germ cell differentiation and meiosis, such as VASA, STRA8, and SYCP3. The stem cell–expressed RNA-binding protein Lin28 has recently been demonstrated to be essential for PGC specification in mice, and LIN28 is expressed in human germ cell tumors with phenotypic similarities to human fetal germ cells. We have therefore examined the expression of LIN28 during normal germ cell development in the human fetal ovary, from the PGC stage, through meiosis to the initiation of follicle formation. LIN28 transcript levels were highest when the gonad contained only PGCs, and decreased significantly with increasing gestation, coincident with the onset of germ cell differentiation. Immunohistochemistry revealed LIN28 protein expression to be germ cell–specific at all stages examined. All PGCs expressed LIN28, but at later gestations expression was restricted to a subpopulation of germ cells, which we demonstrate to be primordial and premeiotic germ cells based on immunofluorescent colocalization of LIN28 and OCT4, and absence of overlap with the meiosis marker SYCP3. We also demonstrate the expression of the LIN28 target precursor pri-microRNA transcripts pri-LET7a/f/d and pri-LET-7g in the human fetal ovary, and that expression of these is highest at the PGC stage, mirroring that of LIN28. The spatial and temporal restriction of LIN28 expression and coincident peaks of expression of LIN28 and target pri-microRNAs suggest important roles for this protein in the maintenance of the germline stem cell state and the regulation of microRNA activity in the developing human ovary.
doi:10.1089/scd.2011.0730
PMCID: PMC3424972  PMID: 22296229
19.  Genetic interactions and modifier genes in Hirschsprung's disease 
Hirschsprung’s disease is a congenital disorder that occurs in 1:5000 live births. It is characterised by an absence of enteric neurons along a variable region of the gastrointestinal tract. Hirschsprung’s disease is classified as a multigenic disorder, because the same phenotype is associated with mutations in multiple distinct genes. Furthermore, the genetics of Hirschsprung’s disease are highly complex and not strictly Mendelian. The phenotypic variability and incomplete penetrance observed in Hirschsprung’s disease also suggests the involvement of modifier genes. Here, we summarise the current knowledge of the genetics underlying Hirschsprung’s disease based on human and animal studies, focusing on the principal causative genes, their interactions, and the role of modifier genes.
doi:10.3748/wjg.v17.i45.4937
PMCID: PMC3236992  PMID: 22174542
Neural crest; Enteric nervous system; Hirschsprung’s disease; Aganglionosis; Modifier genes
20.  E-Cadherin Antagonizes Transforming Growth Factor β1 Gene Induction in Hepatic Stellate Cells by Inhibiting RhoA–Dependent Smad3 Phosphorylation 
Hepatology (Baltimore, Md.)  2010;52(6):2053-2064.
Cadherins mediate cell-cell adhesion and catenin (ctn)-related signaling pathways. Liver fibrosis is accompanied by the loss of E-cadherin (ECAD), which promotes the process of epithelial-mesenchymal transition. Currently, no information is available about the inhibitory role of ECAD in hepatic stellate cell activation. Because of ECAD’s potential for inhibiting the induction of transforming growth factor β1 (TGFβ1), we investigated whether ECAD overexpression prevents TGFβ1 gene induction; we also examined what the molecular basis could be. Forced expression of ECAD decreased α-smooth muscle actin and vimentin levels and caused decreases in the constitutive and inducible expression of the TGFβ1 gene and its downstream genes. ECAD overexpression decreased Smad3 phosphorylation, weakly decreased Smad2 phosphorylation, and thus inhibited Smad reporter activity induced by either treatment with TGFβ1 or Smad3 overexpression. Overexpression of a dominant negative mutant of ras homolog gene family A (RhoA) diminished the ability of TGFβ1 to elicit its own gene induction. Consistently, transfection with a constitutively active mutant of RhoA reversed the inhibition of TGFβ1-inducible or Smad3-inducible reporter activity by ECAD. Studies using the mutant constructs of ECAD revealed that the p120-ctn binding domain of ECAD was responsible for TGFβ1 repression. Consistently, ECAD was capable of binding p120-ctn, which recruited RhoA; this prevented TGFβ1 from increasing RhoA-mediated Smad3 phosphorylation. In the liver samples of patients with mild or severe fibrosis, ECAD expression reciprocally correlated with the severity of fibrosis.
Conclusion
Our results demonstrate that ECAD inhibits Smad3/2 phosphorylation by recruiting RhoA to p120-ctn at the p120-ctn binding domain, whereas the loss of ECAD due to cadherin switching promotes the up-regulation of TGFβ1 and its target genes, and facilitates liver fibrosis.
doi:10.1002/hep.23931
PMCID: PMC3086490  PMID: 20890948
21.  A Validated Model of Serum Anti-Müllerian Hormone from Conception to Menopause 
PLoS ONE  2011;6(7):e22024.
Background
Anti-Müllerian hormone (AMH) is a product of growing ovarian follicles. The concentration of AMH in blood may also reflect the non-growing follicle (NGF) population, i.e. the ovarian reserve, and be of value in predicting reproductive lifespan. A full description of AMH production up to the menopause has not been previously reported.
Methodology/Principal Findings
By searching the published literature for AMH concentrations in healthy pre-menopausal females, and using our own data (combined ) we have generated and robustly validated the first model of AMH concentration from conception to menopause. This model shows that 34% of the variation in AMH is due to age alone. We have shown that AMH peaks at age 24.5 years, followed by a decline to the menopause. We have also shown that there is a neonatal peak and a potential pre-pubertal peak. Our model allows us to generate normative data at all ages.
Conclusions/Significance
These data highlight key inflection points in ovarian follicle dynamics. This first validated model of circulating AMH in healthy females describes a transition period in early adulthood, after which AMH reflects the progressive loss of the NGF pool. The existence of a neonatal increase in gonadal activity is confirmed for females. An improved understanding of the relationship between circulating AMH and age will lead to more accurate assessment of ovarian reserve for the individual woman.
doi:10.1371/journal.pone.0022024
PMCID: PMC3137624  PMID: 21789206
22.  CKI isoforms α and ε regulate Star–PAP target messages by controlling Star–PAP poly(A) polymerase activity and phosphoinositide stimulation 
Nucleic Acids Research  2011;39(18):7961-7973.
Star–PAP is a non-canonical, nuclear poly(A) polymerase (PAP) that is regulated by the lipid signaling molecule phosphatidylinositol 4,5 bisphosphate (PI4,5P2), and is required for the expression of a select set of mRNAs. It was previously reported that a PI4,5P2 sensitive CKI isoform, CKIα associates with and phosphorylates Star–PAP in its catalytic domain. Here, we show that the oxidative stress-induced by tBHQ treatment stimulates the CKI mediated phosphorylation of Star–PAP, which is critical for both its polyadenylation activity and stimulation by PI4,5P2. CKI activity was required for the expression and efficient 3′-end processing of its target mRNAs in vivo as well as the polyadenylation activity of Star–PAP in vitro. Specific CKI activity inhibitors (IC261 and CKI7) block in vivo Star–PAP activity, but the knockdown of CKIα did not equivalently inhibit the expression of Star–PAP targets. We show that in addition to CKIα, Star–PAP associates with another CKI isoform, CKIε in the Star–PAP complex that phosphorylates Star–PAP and complements the loss of CKIα. Knockdown of both CKI isoforms (α and ε) resulted in the loss of expression and the 3′-end processing of Star–PAP targets similar to the CKI activity inhibitors. Our results demonstrate that CKI isoforms α and ε modulate Star–PAP activity and regulates Star–PAP target messages.
doi:10.1093/nar/gkr549
PMCID: PMC3185439  PMID: 21729869
23.  Retinoic Acid Signalling and the Control of Meiotic Entry in the Human Fetal Gonad 
PLoS ONE  2011;6(6):e20249.
The development of mammalian fetal germ cells along oogenic or spermatogenic fate trajectories is dictated by signals from the surrounding gonadal environment. Germ cells in the fetal testis enter mitotic arrest, whilst those in the fetal ovary undergo sex-specific entry into meiosis, the initiation of which is thought to be mediated by selective exposure of fetal ovarian germ cells to mesonephros-derived retinoic acid (RA). Aspects of this model are hard to reconcile with the spatiotemporal pattern of germ cell differentiation in the human fetal ovary, however. We have therefore examined the expression of components of the RA synthesis, metabolism and signalling pathways, and their downstream effectors and inhibitors in germ cells around the time of the initiation of meiosis in the human fetal gonad. Expression of the three RA-synthesising enzymes, ALDH1A1, 2 and 3 in the fetal ovary and testis was equal to or greater than that in the mesonephros at 8–9 weeks gestation, indicating an intrinsic capacity within the gonad to synthesise RA. Using immunohistochemistry to detect RA receptors RARα, β and RXRα, we find germ cells to be the predominant target of RA signalling in the fetal human ovary, but also reveal widespread receptor nuclear localization indicative of signalling in the testis, suggesting that human fetal testicular germ cells are not efficiently shielded from RA by the action of the RA-metabolising enzyme CYP26B1. Consistent with this, expression of CYP26B1 was greater in the human fetal ovary than testis, although the sexually-dimorphic expression patterns of the germ cell-intrinsic regulators of meiotic initiation, STRA8 and NANOS2, appear conserved. Finally, we demonstrate that RA induces a two-fold increase in STRA8 expression in cultures of human fetal testis, but is not sufficient to cause widespread meiosis-associated gene expression. Together, these data indicate that while local production of RA within the fetal ovary may be important in regulating the onset of meiosis in the human fetal ovary, mechanisms other than CYP26B1-mediated metabolism of RA may exist to inhibit the entry of germ cells into meiosis in the human fetal testis.
doi:10.1371/journal.pone.0020249
PMCID: PMC3108594  PMID: 21674038
24.  Cinnamon: Potential Role in the Prevention of Insulin Resistance, Metabolic Syndrome, and Type 2 Diabetes 
Metabolic syndrome is associated with insulin resistance, elevated glucose and lipids, inflammation, decreased antioxidant activity, increased weight gain, and increased glycation of proteins. Cinnamon has been shown to improve all of these variables in in vitro, animal, and/or human studies. In addition, cinnamon has been shown to alleviate factors associated with Alzheimer's disease by blocking and reversing tau formation in vitro and in ischemic stroke by blocking cell swelling. In vitro studies also show that components of cinnamon control angiogenesis associated with the proliferation of cancer cells. Human studies involving control subjects and subjects with metabolic syndrome, type 2 diabetes mellitus, and polycystic ovary syndrome all show beneficial effects of whole cinnamon and/or aqueous extracts of cinnamon on glucose, insulin, insulin sensitivity, lipids, antioxidant status, blood pressure, lean body mass, and gastric emptying. However, not all studies have shown positive effects of cinnamon, and type and amount of cinnamon, as well as the type of subjects and drugs subjects are taking, are likely to affect the response to cinnamon. In summary, components of cinnamon may be important in the alleviation and prevention of the signs and symptoms of metabolic syndrome, type 2 diabetes, and cardiovascular and related diseases.
PMCID: PMC2901047  PMID: 20513336
cardiovascular diseases; cinnamon; diabetes; insulin sensitivity; metabolic syndrome
25.  Novel angiogenesis inhibitory activity in cinnamon extract blocks VEGFR2 kinase and downstream signaling 
Carcinogenesis  2009;31(3):481-488.
As a critical factor in the induction of angiogenesis, vascular endothelial growth factor (VEGF) has become an attractive target for anti-angiogenesis treatment. However, the side effects associated with most anti-VEGF agents limit their chronic use. Identification of naturally occurring VEGF inhibitors derived from diet is a potential alternative approach, with the advantage of known safety. To isolate natural inhibitors of VEGF, we established an in vitro tyrosine kinase assay to screen for diet-based agents that suppress VEGFR2 kinase activity. We found that a water-based extract from cinnamon (cinnamon extract, CE), one of the oldest and most popular spices, was a potent inhibitor of VEGFR2 kinase activity, directly inhibiting kinase activity of purified VEGFR2 as well as mitogen-activated protein kinase- and Stat3-mediated signaling pathway in endothelial cells. As a result, CE inhibited VEGF-induced endothelial cell proliferation, migration and tube formation in vitro, sprout formation from aortic ring ex vivo and tumor-induced blood vessel formation in vivo. Depletion of polyphenol from CE with polyvinylpyrrolidone abolished its anti-angiogenesis activity. While cinnamaldehyde, a component responsible for CE aroma, had little effect on VEGFR2 kinase activity, high-performance liquid chromatography-purified components of CE, procyanidin type A trimer (molecular weight, 864) and a tetramer (molecular weight, 1152) were found to inhibit kinase activity of purified VEGFR2 and VEGFR2 signaling, implicating procyanidin oligomers as active components in CE that inhibit angiogenesis. Our data revealed a novel activity in cinnamon and identified a natural VEGF inhibitor that could potentially be useful in cancer prevention and/or treatment.
doi:10.1093/carcin/bgp292
PMCID: PMC3105590  PMID: 19969552

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