PGC-1α is a transcriptional coactivator induced by exercise that gives muscle many of the best known adaptations to endurance-type exercise, but has no effects on muscle strength or hypertrophy. We have identified a novel form of PGC-1α (PGC-1α4) that results from alternative promoter usage and splicing of the primary transcript. PGC-1α4 is highly expressed in exercised muscle but does not regulate most known PGC-1α targets such as the mitochondrial OXPHOS genes. Rather, it specifically induces IGF1 and represses myostatin, and expression of PGC-1α4 in vitro and in vivo induces robust skeletal muscle hypertrophy. Importantly, mice with skeletal muscle-specific transgenic expression of PGC-1α4 show increased muscle mass and strength, and dramatic resistance to the muscle wasting of cancer cachexia. Expression of PGC-1α4 is preferentially induced in mouse and human muscle during resistance exercise. These studies identify a novel PGC-1α protein that regulates and coordinates factors involved in skeletal muscle hypertrophy.
Skeletal muscle arises from the fusion of precursor myoblasts into multinucleated myofibers1,2. While conserved transcription factors and signaling proteins involved in myogenesis have been identified, upstream regulators are less well understood. Here, we report an unexpected discovery that the membrane protein BAI1, previously linked to recognition of apoptotic cells by phagocytes3, promotes myoblast fusion. Endogenous BAI1 expression increased during myoblast fusion, and BAI1 overexpression enhanced myoblast fusion via signaling through ELMO/Dock180/Rac1 proteins4. During myoblast fusion, a fraction of myoblasts underwent apoptosis and exposed phosphatidylserine (PtdSer), an established ligand for BAI13. Blocking apoptosis potently impaired myoblast fusion, and adding back apoptotic myoblasts restored fusion. Furthermore, primary human myoblasts could be induced to form myotubes by adding apoptotic myoblasts, even under normal growth conditions. In vivo, myofibers from Bai1−/− mice are smaller than wild-type littermates. Muscle regeneration after injury was also impaired in Bai1−/− mice, highlighting a role for BAI1 in mammalian myogenesis. Collectively, these data identify signaling via the phosphatidylserine receptor BAI1 and apoptotic cells as novel promoters of myoblast fusion, with significant implications for muscle development and repair.
Since viruses rely on functional cellular machinery for efficient propagation, apoptosis is an important mechanism to fight viral infections. In this study, we sought to determine the mechanism of cell death caused by Ebola virus (EBOV) infection by assaying for multiple stages of apoptosis and hallmarks of necrosis. Our data indicate that EBOV does not induce apoptosis in infected cells but rather leads to a nonapoptotic form of cell death. Ultrastructural analysis confirmed necrotic cell death of EBOV-infected cells. To investigate if EBOV blocks the induction of apoptosis, infected cells were treated with different apoptosis-inducing agents. Surprisingly, EBOV-infected cells remained sensitive to apoptosis induced by external stimuli. Neither receptor- nor mitochondrion-mediated apoptosis signaling was inhibited in EBOV infection. Although double-stranded RNA (dsRNA)-induced activation of protein kinase R (PKR) was blocked in EBOV-infected cells, induction of apoptosis mediated by dsRNA was not suppressed. When EBOV-infected cells were treated with dsRNA-dependent caspase recruiter (dsCARE), an antiviral protein that selectively induces apoptosis in cells containing dsRNA, virus titers were strongly reduced. These data show that the inability of EBOV to block apoptotic pathways may open up new strategies toward the development of antiviral therapeutics.
A shift from oxidative to glycolytic metabolism has been associated with skeletal muscle insulin resistance in type 2 diabetes1–5. However, whether this metabolic switch is deleterious or adaptive remains controversial6–8, in part due to limited understanding of the regulatory network that directs the metabolic and contractile specification of fast-twitch glycolytic muscle. Here we show that BAF60c, a transcriptional cofactor enriched in fast-twitch muscle, promotes a switch from oxidative to glycolytic myofiber type through Deptor-mediated AKT activation. Muscle-specific transgenic expression of BAF60c activates a program of molecular, metabolic, and contractile changes characteristic of glycolytic muscle. In addition, BAF60c is required for maintaining glycolytic capacity in adult skeletal muscle in vivo. BAF60c expression is significantly decreased in skeletal muscle from obese mice. Unexpectedly, transgenic activation of the glycolytic muscle program by BAF60c protects mice from diet-induced insulin resistance and glucose intolerance. Further mechanistic studies revealed that Deptor is induced by the BAF60c/Six4 transcriptional complex and mediates activation of AKT and glycolytic metabolism by BAF60c in a cell-autonomous manner. This work defines a fundamental mechanism underlying the specification of fast glycolytic muscle and illustrates that the oxidative to glycolytic metabolic shift in skeletal muscle is potentially adaptive and beneficial in the diabetic state.
We tested the hypothesis that low intensity exercise in mdx mice improves plantarflexor muscle contractile function, resistance to fatigue, and mitochondrial adaptations without exacerbating muscular dystrophy.
We subjected mdx mice to 12 wk of voluntary, low-resistance wheel running (Run, n=17) or normal cage activities (sedentary; Sed, n=16) followed by in vivo analyses for plantarflexor torque generation and fatigue resistance, or running capacity on a treadmill. Gastrocnemius muscles were further evaluated for exercise-induced mitochondrial adaptations and fiber type distribution and central nuclei. T-tests were used to determine differences between the Sed and Run groups.
Plantarflexor submaximal isometric torques and maximal isometric torque at multiple ankle joint angles, and resistance to fatigue were greater in Run compared to Sed mdx mice (P<0.05). Citrate synthase and β-HAD enzyme activities and COX IV protein expression in gastrocnemius muscles were greater in Run than Sed mdx mice (P≤0.04), along with a trend of fiber type transformation from type IIb to type 2x fibers. Exercise training in mdx mice did not elevate serum creatine kinase levels, but led to a significant reduction of centrally-nucleated myofibers.
Voluntary, low-resistance wheel running in mdx mice can result in skeletal muscle adaptation, leading to improved contractile function and reduced fatigability, with no indication that exercise was detrimental. This study supports the need for further investigation of low intensity exercise as an early therapeutic intervention in ambulatory boys with DMD.
Duchenne muscular dystrophy; fatigue; mitochondria; physical activity; skeletal muscle; strength
Hyperpolarization-activated currents (Ih) mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels modulate excitability of myelinated A− and Ah-type visceral ganglion neurons (VGN). Whether alterations in Ih underlie the previously reported reduction of excitability of myelinated Ah-type VGNs following ovariectomy (OVX) has remained unclear. Here we used the intact nodose ganglion preparation in conjunction with electrophysiological approaches to examine the role of Ih remodeling in altering Ah-type neuron excitability following ovariectomy in adult rats. Ah-type neurons were identified based on their afferent conduction velocity. Ah-type neurons in nodose ganglia from non-OVX rats exhibited a voltage ‘sag’ as well as ‘rebound’ action potentials immediately following hyperpolarizing current injections, which both were suppressed by the Ih blocker ZD7288. Repetitive spike activity induced afterhyperpolarizations lasting several hundreds of milliseconds (termed post-excitatory membrane hyperpolarizations, PEMHs), which were significantly reduced by ZD7288, suggesting that they resulted from transient deactivation of Ih during the preceding spike trains. Ovariectomy reduced whole-cell Ih density, caused a hyperpolarizing shift of the voltage-dependence of Ih activation, and slowed Ih activation. OVX-induced Ih remodeling was accompanied by a flattening of the stimulus frequency/response curve and loss of PEMHs. Also, HCN1 mRNA levels were reduced by ∼30% in nodose ganglia from OVX rats compared with their non-OVX counterparts. Acute exposure of nodose ganglia to 17beta-estradiol partly restored Ih density and accelerated Ih activation in Ah-type cells. In conclusion, Ih plays a significant role in modulating the excitability of myelinated Ah-type VGNs in adult female rats.
Mitochondria are dynamic organelles in skeletal muscle critical in physical performance and disease. The mitochondrial life cycle spans biogenesis, maintenance, and clearance. Exercise training may promote each of these processes, conferring positive impacts on skeletal muscle contractile and metabolic functions. This review focuses on the regulation of these processes by endurance exercise and discusses potential benefits in health and disease.
Skeletal muscle; exercise-induced adaptation; mitochondrial biogenesis; mitochondrial fission; mitochondrial fusion; autophagy; mitophagy
The transcriptional coactivators PGC-1α and PGC-1β are widely thought to be required for mitochondrial biogenesis and fiber typing in skeletal muscle. We show here that mice lacking both PGC-1s in myocytes do indeed have profoundly deficient mitochondrial respiration, but surprisingly have preserved mitochondrial content, isolated muscle contraction capacity, fiber type composition, in-cage ambulation, and voluntary running capacity. Most of these findings are recapitulated in cell culture, and thus cell-autonomous. Functional electron microscopy reveals normal cristae density with decreased cytochrome oxidase activity. These data lead to the following surprising conclusions: that PGC-1s are in fact dispensable for baseline muscle function, mitochondrial content, and fiber typing; that endurance fatigue at low workloads is not limited by muscle mitochondrial capacity; and that mitochondrial content and cristae density can be dissociated from respiratory capacity.
Growing evidence suggests that Huntington’s disease (HD), a neurodegenerative movement disorder caused by the mutant huntingtin (htt) with an expanded polyglutamine (polyQ) repeat, is associated with the altered intracellular trafficking and synaptic function. GABAA receptors, the key determinant of the strength of synaptic inhibition, have been found to bind to the huntingtin associated protein 1 (HAP1). HAP1 serves as an adaptor linking GABAA receptors to the kinesin family motor protein 5 (KIF5), controlling the transport of GABAA receptors along microtubules in dendrites. In this study, we found that GABAAR-mediated synaptic transmission is significantly impaired in a transgenic mouse model of HD expressing polyQ-htt, which is accompanied by the diminished surface expression of GABAA receptors. Moreover, the GABAAR/HAP1/KIF5 complex is disrupted and dissociated from microtubules in the HD mouse model. These results suggest that GABAAR trafficking and function is impaired in HD, presumably due to the interference of KIF5-mediated microtubule-based transport of GABAA receptors. The diminished inhibitory synaptic efficacy could contribute to the loss of the excitatory/inhibitory balance, leading to increased neuronal excitotoxicity in HD.
huntingtin; GABAA receptor; IPSC; KIF5; microtubule; trafficking
Activation of the transcription factor NF-E2 related factor 2 (Nrf2) by oxidative stress induces the expression of a variety of antioxidant and anti-inflammatory genes. Yet, genetic ablation of Nrf2 was shown to protect mice from high-fat diet (HFD)-induced obesity and insulin resistance. The mechanisms that underlay this seemingly paradoxical finding remain largely unexplored.
Here we examined whether Nrf2 deficiency in myeloid cells contributes to protection against HFD-induced metabolic changes by decreasing adipose tissue inflammation. In vitro, induction of IL-1β by inflammatory stimuli was significantly reduced in Nrf2-deficient macrophages. While, inflammatory gene expression in the stromal vascular fraction was reduced in both global and chimeric Nrf2 KO mice, only global Nrf2-deficient but not bone marrow-transplanted Nrf2 chimeric mice were protected against HFD-induced adipose tissue inflammation. While global Nrf2 deficiency resulted in significantly decreased expression of inflammatory genes and PPARγ2, there was no difference when Nrf2 was absent only in myeloid cells. In vitro co-culture with adipocytes demonstrated that macrophage Nrf2 regulated inflammatory gene expression in macrophages, however, was not required to induce inflammatory gene expression in adipocytes. Finally, in contrast to global Nrf2 knock-out, Nrf2 deficiency in myeloid cells did not protect against HFD-induced insulin resistance.
Together, our data demonstrate a dominant role of nonmyeloid Nrf2 in controlling HFD-induced adipose tissue inflammation and the development of insulin resistance.
Nrf2; inflammation; insulin resistance; bone marrow transplantation; stromal vascular fraction and adipocyte/macrophage co-culture
Chronic stress could trigger maladaptive changes associated with stress-related mental disorders, however, the underlying mechanisms remain elusive. In this study, we found that exposing juvenile male rats to repeated stress significantly impaired the temporal order recognition memory, a cognitive process controlled by prefrontal cortex (PFC). Concomitantly, significantly reduced AMPAR- and NMDAR-mediated synaptic transmission and glutamate receptor expression were found in PFC pyramidal neurons from repeatedly stressed animals. All these effects relied on activation of glucocorticoid receptors and the subsequent enhancement of ubiquitin/proteasome-mediated degradation of GluR1 and NR1 subunits, which was controlled by the E3 ubiquitin ligase Nedd4-1 and Fbx2, respectively. Inhibition of proteasomes or knockdown of Nedd4-1 and Fbx2 in PFC prevented the loss of glutamatergic responses and recognition memory in stressed animals. Our results suggest that repeated stress dampens PFC glutamatergic transmission by facilitating glutamate receptor turnover, which causes the detrimental effect on PFC-dependent cognitive processes.
stress; corticosterone; glucocorticoid receptor; NMDA receptor; AMPA receptor; ubiquitination; degradation; recognition memory
Thymosin alpha 1 (Tα1), which is composed of 28 amino acids, has been commercialized worldwide for its immune-modulatory and antitumor effects. Tα1 can stimulate T cell proliferation and differentiation from bone marrow stem cells, augment cell-mediated immune responses, and regulate homeostasis of immune system. In this study, we developed a novel strategy to produce Tα1 concatemer (Tα1③) in Escherichia coli and compared its activity with chemically synthesized Tα1. Results showed that Tα1③ can more effectively stimulate T cell proliferation and significantly upregulate IL-2 receptor expression. We concluded that the expression system for Tα1 concatemer was constructed successfully, which could serve as an efficient tool for the production of large quantities of the active protein.
To test the hypotheses that obesity due to a very high fat diet induces knee osteoarthritis, and that short-term wheel running exercise protects against obesity-induced knee osteoarthritis by reducing systemic inflammation and metabolic dysregulation.
Male C57BL/6J mice were fed either a control (13.5% kcal fat) or very high fat diet (60% kcal fat) from 12–24 wks of age. From 20–24 wks, half of the animals were housed with running wheels. Knee osteoarthritis severity was determined via histopathology, and serum cytokines were measured using a multiplex bead immunoassay and ELISAs. Body composition was quantified by dual-energy X-ray absorptiometry, and insulin resistance was assessed by glucose tolerance testing.
A very high fat diet increased osteoarthritis scores and serum leptin, adiponectin, KC (mouse analog of IL-8), MIG (monokine induced by interferon-gamma, or CXCL9), and interleukin 1 receptor antagonist (IL-1Ra) levels in proportion to percent body fat, which increased 3-fold compared to controls. Wheel running reduced osteoarthritis progression in the medial femur of obese mice. Exercise disrupted the clustering of cytokine expression and improved glucose tolerance without reducing body fat or cytokine levels.
Obesity induced by a very high-fat diet causes osteoarthritis and systemic inflammation in proportion to body fat. Increased joint loading is not sufficient to explain the increased incidence of knee osteoarthritis with obesity as wheel running is protective rather than damaging. Exercise improves glucose tolerance and disrupts the co-expression of pro-inflammatory cytokines, suggesting that increased aerobic exercise may act independent of weight loss in promoting joint health.
obesity; exercise; knee joint; inflammation; body fat; cartilage; proteoglycan
Accumulation of β-amyloid (Aβ) and cholinergic deficiency are two prominent features of Alzheimer’s disease (AD). To understand how Aβ-induced dysfunction of the nicotinic system may contribute to cognitive impairment in AD, we examined the effect of Aβ on nicotinic regulation of synaptic transmission and neuronal excitability in prefrontal cortex (PFC), a brain region critical for cognitive processes.
We found that activation of nicotinic acetylcholine receptors (nAChRs) with nicotine increased the inhibitory postsynaptic currents recorded in PFC pyramidal neurons, which was associated with the nicotine-induced increase in the excitability of PFC layer I GABAergic interneurons. Both effects of nicotine were disrupted by Aβ. However, Aβ did not impair nicotinic regulation of excitatory neurotransmission in PFC interneurons. The nicotinic effect on synaptic inhibition was also lost in transgenic mice with five familial Alzheimer’s disease mutations. Inhibiting PKC attenuated nicotinic regulation of inhibitory, but not excitatory, neurotransmission.
Our study suggests that Aβ selectively impairs nicotinic regulation of inhibitory inputs to PFC pyramidal neurons, which might be due to its interference with PKC activation. Thus, in the PFC circuits of AD, the balance between inhibition and excitation under the control of nAChRs may be disturbed by Aβ.
Alzheimer’s disease; β-amyloid; Nicotinic acetylcholine receptor; Prefrontal cortex; Interneuron; Pyramidal neuron; Inhibitory postsynaptic current; Firing; Protein kinase C
Nodose ganglia are composed of A-, Ah- and C-type neurons. Despite their important roles in regulating visceral afferent function, including cardiovascular, pulmonary, and gastrointestinal homeostasis, information about subtype-specific expression, molecular identity, and function of individual ion transporting proteins is scarce. Although experiments utilizing the sliced ganglion preparation have provided valuable insights into the electrophysiological properties of nodose ganglion neuron subtypes, detailed characterization of their electrical phenotypes will require measurements in isolated cells. One major unresolved problem, however, is the difficulty to unambiguously identify the subtype of isolated nodose ganglion neurons without current-clamp recording, because the magnitude of conduction velocity in the corresponding afferent fiber, a reliable marker to discriminate subtypes in situ, can no longer be determined. Here, we present data supporting the notion that application of an algorithm regarding to microscopic structural characteristics, such as neuron shape evaluated by the ratio between shortest and longest axis, neuron surface characteristics, like membrane roughness, and axon attachment, enables specific and sensitive subtype identification of acutely dissociated rat nodose ganglion neurons, by which the accuracy of identification is further validated by electrophysiological markers and overall positive predictive rates is 89.26% (90.04%, 76.47%, and 98.21% for A-, Ah, and C-type, respectively). This approach should aid in gaining insight into the molecular correlates underlying phenotypic heterogeneity of nodose ganglia. Additionally, several critical points that help for neuron identification and afferent conduction calibration are also discussed.
visualization; visceral sensory neuron; conduction velocity; whole-cell patch; action potential
Evidence has shown gender differences regarding the critical roles of histamine in the prevalence of asthma, anaphylaxis, and angina pectoris. Histamine depolarizes unmyelinated C-type neurons without any effects on myelinated A-type vagal ganglion neurons (VGNs) in male rats. However, little is known if VGNs from females react to histamine in a similar manner. Membrane depolarization and inward currents were tested in VGNs isolated from adult rats using a whole-cell patch technique. Results from males were consistent with the literature. Surprisingly, histamine-induced depolarization and inward currents were observed in both unmyelinated C-type and myelinated A- and Ah-type VGNs from female rats. In Ah-type neurons, responses to 1.0 μM histamine were stronger in intact females than in males and significantly reduced in ovariectomized (OVX) females. In C-type neurons, histamine-induced events were significantly smaller (pA/pF) in intact females compared with males and this histamine-induced activity was dramatically increased by OVX. Female A-types responded to histamine, which was further increased following ovariectomy. Histamine at 300 nM depolarized Ah-types in females, but not Ah-types in OVX females. In contrast, the sensitivity of A- and C-types to histamine was upregulated by OVX. These data demonstrate gender differences in VGN chemosensitivity to histamine for the first time. Myelinated Ah-types showed the highest sensitivity to histamine across female populations, which was changed by OVX. These novel findings improve the understanding of gender differences in the prevalence of asthma, anaphylaxis, and pain. Changes in sensitivity to histamine by OVX may explain alterations in the prevalence of certain pathophysiological conditions when women reach a postmenopausal age.
chemosensitivity; histamine; vagal afferent neuron; membrane depolarization; inward current; whole-cell patch.
Chronic respiratory inflammation has been associated with lung cancer. Tumor-associated macrophages (TAMs) play a critical role in the formation of inflammation microenvironment. We sought to characterize the role of TAMs in coal tar pitch extract (CTPE)-induced tumorigenic transformation of human bronchial epithelial cells and the underlying mechanisms.
The expression of TAMs-specific CD68 in lung cancer tissues and paired adjacent tissues from cancer patients was determined using immunostaining. Co-culture of human bronchial epithelial cells (BEAS-2B) and macrophage-like THP-1 cells were conducted to evaluate the promotive effect of macrophages on CTPE-induced tumorigenic transformation of BEAS-2B cells. BEAS-2B cells were first treated with 2.4 µg/mL CTPE for 72 hours. After removal of CTPE, the cells were continuously cultured either with or without THP-1 cells and passaged using trypsin-EDTA. Alterations of cell cycle, karyotype, colony formation in soft agar and tumor xenograft growth in nude mice of BEAS-2B cells at passages 10, 20 and 30, indicative of tumorigenecity, were determined, respectively. In addition, mRNA and protein levels of NF-κB in BEAS-2B cells were measured with RT-PCR and western blot, respectively. B(a)P was used as the positive control.
The over-expression of TAMs-specific CD68 around lung tumor tissues was detected and associated with lung cancer progression. The tumorigenic alterations of BEAS-2B cells including increase in cell growth rate, number of cells with aneuploidy, clonogenicity in soft agar, and tumor size in nude mice in vivo occurred at passage 10, becoming significant at passages 20 and 30 of the co-culture following CTPE removal in compared to BEAS-2B cells alone. In addition, the expression levels of NF-κB in BEAS-2B cells were positively correlated to the malignancy of BEAS-2B cells under different conditions of treatment.
The presence of macrophages facilitated CTPE-induced tumorigenic transformation of BEAS-2B cells, which may be mediated by NF-κB.
Parkinson’s disease (PD) is defined by the degeneration of nigral dopaminergic (DA) neurons and can be caused by monogenic mutations of genes such as parkin. The lack of phenotype in parkin knockout mice suggests that human nigral DA neurons have unique vulnerabilities. Through the generation and analyses of induced pluripotent stem cells (iPSCs) from normal subjects and PD patients with parkin mutations, we show here that loss of parkin in human midbrain DA neurons greatly increased the transcription of monoamine oxidases and oxidative stress, significantly reduced DA uptake and increased spontaneous DA release. Lentiviral expression of parkin, but not its PD-linked mutant, rescued all the phenotypes. The results suggest that parkin controls dopamine utilization in human midbrain DA neurons by enhancing the precision of dopaminergic neurotransmission and suppressing dopamine oxidation. Thus, the study provides novel targets and a physiologically relevant screening platform for disease-modifying therapies of PD.
The core protein (HBc) of hepatitis B virus (HBV) has been implicated in the malignant transformation of chronically-infected hepatocytes and displays pleiotropic functions, including RNA- and DNA-binding activities. However, the mechanism by which HBc interacts with the human genome to exert effects on hepatocyte function remains unknown. This study investigated the distribution of HBc binding to promoters in the human genome and evaluated its effects on the related genes’ expression.
Whole-genome chromatin immunoprecipitation microarray (ChIP-on-chip) analysis was used to identify HBc-bound human gene promoters. Gene Ontology and pathway analyses were performed on related genes. The quantitative polymerase chain reaction assay was used to verify ChIP-on-chip results. Five novel genes were selected for luciferase reporter assay evaluation to assess the influence of HBc promoter binding. The HBc antibody immunoprecipitated approximately 3100 human gene promoters. Among these, 1993 are associated with known biological processes, and 2208 regulate genes with defined molecular functions. In total, 1286 of the related genes mediate primary metabolic processes, and 1398 encode proteins with binding activity. Sixty-four of the promoters regulate genes related to the mitogen-activated protein kinase (MAPK) pathways, and 41 regulate Wnt/beta-catenin pathway genes. The reporter gene assay indicated that HBc binding up-regulates proto-oncogene tyrosine-protein kinase (SRC), type 1 insulin-like growth factor receptor (IGF1R), and neurotrophic tyrosine kinase receptor 2 (NTRK2), and down-regulates v-Ha-ras Harvey rat sarcoma viral oncogene (HRAS).
HBc has the ability to bind a large number of human gene promoters, and can disrupt normal host gene expression. Manipulation of the transcriptional profile in HBV-infected hepatocytes may represent a key pathogenic mechanism of HBV infection.
Hepatitis B virus; Hepatitis B core protein; Chromatin immunoprecipitation microarray; ChIP-on-chip; Gene expression; DNA-protein interaction
RACK1 (Receptor for Activated C-Kinase 1), an anchoring protein that shuttles activated PKC to cellular membranes, plays an important role in PKC-mediated signal transduction pathways. A significant loss of RACK1 has been found in the brain of aging animals and Alzheimer’s disease (AD) patients, which implicates the potential involvement of RACK1 in altered PKC activation associated with dementia. Our previous studies have demonstrated that GABAergic inhibition in prefrontal cortex, which is important for cognitive processes like “working memory”, is regulated by muscarinic receptors via a PKC-dependent mechanism, and this effect is impaired by β-amyloid peptide (Aβ). In this study, we found that Aβ oligomers decreased RACK1 distribution in the membrane fraction of cortical neurons. Moreover, overexpression of RACK1 rescued the effect of muscarinic receptors on GABAergic transmission in Aβ-treated cortical cultures in vitro and Aβ-injected cortical neurons in vivo. These results suggest that the Aβ-induced loss of RACK1 distribution in the cell membrane may underlie the Aβ impairment of muscarinic regulation of PKC and GABAergic transmission. Thus, RACK1 provides a potential therapeutic target that can restore some of the impaired cellular processes by Aβ.
Aβ; RACK1; PKC; muscarinic acetylcholine receptors; IPSC; Sindbis virus; stereotaxic injection
Human papillomavirus (HPV) infection causes cervical cancer and premalignant lesions of the cervix. Prevalence of HPV infection and HPV genotypes vary among different regions. However there is no data on the prevalence of HPV infection and HPV genotypes from southwest China. This study was undertaken to determine the prevalence of and risk factors for HR-HPV infection in Qujing of Yunnan province, southwest China to provide comprehensive baseline data for future screening strategies.
A sample of 5936 women was chosen by the multi-stage stratified cluster sampling method with selection probabilities proportional to size (PPS). An epidemiological questionnaire was conducted via a face-to-face interview and cervical specimens were taken for HPV DNA testing by Digene Hybrid Capture 2 (HC2) test. HPV Genotyping Reverse Hybridization Test was used for HPV genotyping. Proportions were compared by Chi-squared tests, and logistic regression was utilized to evaluate risk factors.
The median age was 38 years and the inter-quartile range was from 31 years to 47 years. 97.3% of the study population was Han nationality. Overall prevalence of HR-HPV infection was 8.3% (494/5936) and bimodal age distribution of HPV infection was observed. The five most prevalent HR-HPV genotypes were HPV-16(3.4%), HPV-56(1.7%), HPV-58(1.4%), HPV-33(1.2%) and HPV-52(0.88%). Multiple HPV infections were identified in 50.5% (208/412) of the positive genotyping specimens. Multivariate logistic regression model indicated that parity (OR = 1.35, 95% CI: 1.18-1.53, p < 0.0001) was a risk factor for HR-HPV infection, and age of 50–65 years (OR = 0.60, 95% CI: 0.45-0.80, p = 0.0005), being married or in stable relationship (OR = 0.55, 95% CI: 0.31-0.96, p = 0.035) were protective factors.
This study provided baseline data on HR-HPV prevalence in the general female population in Qujing of Yunnan province, southwest China. The finding of multiple HPV infections and bimodal age distribution revealed that HPV screening is necessary for perimenopausal women in future.
Human papillomavirus; Genotype; Cervix; Epidemiology; China
A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(CoIITAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described. This electrode showed a very attractive performance by combining the advantages of CoIITAPc, MWCNTs, and Nafion. Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode, the electrocatalytic activity of poly(CoIITAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L.
Sulfadiazine; Electrochemical detection; Cobalt tetraaminophthalocyanine; Multi-walled carbon nanotubes
Endurance exercise promotes skeletal muscle adaptation, and exercise-induced peroxisome proliferator-activated receptor γ co-activator-1α (Pgc-1α) gene expression may play a pivotal role in the adaptive processes. Recent applications of mouse genetic models and in vivo imaging in exercise studies started to delineate the signaling-transcription pathways that are involved in the regulation of the Pgc-1α gene. These studies revealed the importance of p38 mitogen-activated protein kinase (MAPK)/activating transcription factor 2 (ATF2) and protein kinase D (PKD)/histone deacetylase 5 (HDAC5) signaling transcription axes in exercise-induced Pgc-1α transcription and metabolic adaptation in skeletal muscle. The signaling/transcription network that is responsible for exercise-induced skeletal muscle adaption remains to be fully elucidated.
exercise; skeletal muscle; fiber type transformation; angiogenesis; mitochondrial biogenesis; signal transduction; transcription; p38 mitogen-activated protein kinase; peroxisome proliferator-activated receptor γ co-activator-1α
To describe the characteristics of modulation transfer function (MTF) of anterior corneal surface, and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior corneal surface in myopes.
Four hundred eyes from 200 patients were examined under SIRIUS corneal topography system. Phoenis analysis software was applied to simulate the MTF curves of anterior corneal surface at vertical and horizontal meridians at the 3, 4, 5, 6, 7mm optical zones of cornea. The MTF values at spatial frequencies of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 cycles/degree (c/d) were selected.
The MTF curve of anterior corneal surface decreased rapidly from low to intermediate frequency (0-15cpd) at various optical zones of cornea, the value decreased to 0 slowly at higher frequency (>15cpd). With the increase of the optical zones of cornea, MTF curve decreased gradually. 3) In the range of 3 mm- 6 mm optical zones of the cornea, the MTF values measured at horizontal meridian were greater than the corresponding values at horizontal meridian of each spatial frequency, the difference was statistically significant (P<0.05). At 7 mm optical zones of cornea, the MTF values measured at horizontal meridian were less than the corresponding values at vertical meridian at 10-60 spatial frequencies(cpd), and the difference was statistically significant in 25, 30, 35, 40, 45, 50 cpd (P<0.05).
MTF can be used to describe the imaging quality of optical systems at anterior corneal surface objectively in detail.
modulation transfer function; optical quality; cornea; point spread function; optical transfer function; phase transfer function
HLA-DRB1 alleles associated with risk of rheumatoid arthritis (RA) encode similar HLA-DRβ(1 sequences referred to as the “shared epitope” (SE). The most common SE sequences are QKRAA and QRRAA. A substantial number of RA patients, nevertheless, lack the SE. Bi-directional fetal-maternal trafficking results in long-term persistence of fetal cells in the mother and maternal cells in her offspring, referred to as microchimerism (Mc). We asked whether RA patients who lack the SE can acquire the SE through Mc.
We developed specific real-time quantitative PCR (qPCR) assays for the SE encoded sequences QKRAA and QRRAA. DNA extracted from peripheral blood mononuclear cells was tested with the SE-specific qPCR assays. A total of 86 subjects who were negative for the SE were studied, 52 women with RA and 34 healthy women.
Mc with the SE was found significantly more often in RA patients than controls, odds ratio 4.1, 95% CI 1.6-10.0, p=0.003. Concentrations of SE Mc were also significantly higher among RA patients than controls, p=0.002. When analyzed separately for SE type, the prevalence of QKRAA Mc in RA vs. healthy women respectively was 17% vs. 3% (9/52 vs. 1/34, p=0.03) and of QRRAA 40% vs. 18% (21/52 vs. 6/34, p=0.04). Mc concentrations were also higher in RA than healthy subjects for QKRAA (p=0.03) and QRRAA (p=0.03).
Results indicate RA patients who genotypically lack the SE can acquire the SE as persistent Mc from maternal-fetal cell exchange and suggest SE-encoding Mc could be a risk factor for RA.
microchimerism; shared epitope; rheumatoid arthritis; HLA