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1.  Selective Augmentation of Stem Cell Populations in Structural Fat Grafts for Maxillofacial Surgery 
PLoS ONE  2014;9(11):e110796.
Structural fat grafting utilizes the centrifugation of liposuction aspirates to create a graded density of adipose tissue. This study was performed to qualitatively investigate the effects of centrifugation on stem cells present in adipose tissue. Liposuction aspirates were obtained from healthy donors and either not centrifuged or centrifuged at 1,800 rpm for 3 minutes. The obtained fat volumes were divided into three layers and then analyzed. The results demonstrate that centrifugation induces a different distribution of stem cells in the three layers. The high-density layer displays the highest expression of mesenchymal stem cell and endothelial markers. The low-density layer exhibits an enrichment of multipotent stem cells. We conclude that appropriate centrifugation concentrates stem cells. This finding may influence the clinical practice of liposuction aspirate centrifugation and enhance graft uptake.
PMCID: PMC4222876  PMID: 25375632
2.  Differential expression of microRNA501-5p affects the aggressiveness of clear cell renal carcinoma 
FEBS Open Bio  2014;4:952-965.
•Low expression of miR501-5p correlates with good prognosis for patients with ccRCC.•miRNA501-5p downregulation stimulates apoptosis by p53 activation.•miR501-5p upregulation promotes cell proliferation and survival.•Increased cell growth occurs by activation of mTOR kinase and MDM2 expression.•This miRNA modulates apoptosis/cell growth, making it a prognostic biomarker for ccRCC.
Renal cell carcinoma is a common neoplasia of the adult kidney that accounts for about 3% of adult malignancies. Clear cell renal carcinoma is the most frequent subtype of kidney cancer and 20–40% of patients develop metastases. The absence of appropriate biomarkers complicates diagnosis and prognosis of this disease. In this regard, small noncoding RNAs (microRNAs), which are mutated in several neoplastic diseases including kidney carcinoma, may be optimal candidates as biomarkers for diagnosis and prognosis of this kind of cancer. Here we show that patients with clear cell kidney carcinoma that express low levels of miR501-5p exhibited a good prognosis compared with patients with unchanged or high levels of this microRNA. Consistently, in kidney carcinoma cells the downregulation of miR501-5p induced an increased caspase-3 activity, p53 expression as well as decreased mTOR activation, leading to stimulation of the apoptotic pathway. Conversely, miR501-5p upregulation enhanced the activity of mTOR and promoted both cell proliferation and survival. These biological processes occurred through p53 inactivation by proteasome degradation in a mechanism involving MDM2-mediated p53 ubiquitination. Our results support a role for miR501-5p in balancing apoptosis and cell survival in clear cell renal carcinoma. In particular, the downregulation of microRNA501-5p promotes a good prognosis, while its upregulation contributes to a poor prognosis, in particular, if associated with p53 and MDM2 overexpression and mTOR activation. Thus, the expression of miR501-5p is a possible biomarker for the prognosis of clear cell renal carcinoma.
PMCID: PMC4241533  PMID: 25426415
ccRCC, clear cell renal cell carcinoma; MDM2, mouse double minute 2 homolog; mTOR, mammalian target of rapamycin; pRCC, papillary renal cell carcinoma; MicroRNA501-5p; mTOR signaling; p53; Apoptosis; Cell survival
3.  PLCB3 is a key modulator of IL-8 expression in cystic fibrosis bronchial epithelial cells 
Respiratory insufficiency is the major cause of morbidity and mortality in patients affected by cystic fibrosis. An excessive neutrophilic inflammation, mainly orchestrated by the release of IL-8 from bronchial epithelial cells and amplified by chronic bacterial infection with Pseudomonas aeruginosa, leads to progressive tissue destruction. The anti-inflammatory drugs presently utilized in cystic fibrosis patients have several limitations, indicating the need for identifying novel molecular targets. To address this issue, we preliminarily studied the association of 721 single-nucleotide polymorphisms from 135 genes potentially involved in signal transduction implicated in neutrophil recruitment in a cohort of F508del homozygous cystic fibrosis patients with either severe or mild progression of lung disease. The top ranking association was found for a nonsynonymous polymorphism of the phospholipase C beta 3 (PLCB3) gene. Studies in bronchial epithelial cells exposed to P.aeruginosa revealed that PLCB3 is implicated in extra cellular nucleotide–dependent intracellular calcium signaling, leading to activation of the protein kinase C alpha and beta and of the nuclear transcription factor NF-κB p65. The pro-inflammatory pathway regulated by PLCB3 acts by potentiating the Toll-like Receptors’ signaling cascade and represents an interesting molecular target to attenuate the excessive recruitment of neutrophils without completely abolishing the inflammatory response.
PMCID: PMC4166552  PMID: 21411730
4.  STAT3 Activities and Energy Metabolism: Dangerous Liaisons 
Cancers  2014;6(3):1579-1596.
STAT3 mediates cytokine and growth factor receptor signalling, becoming transcriptionally active upon tyrosine 705 phosphorylation (Y-P). Constitutively Y-P STAT3 is observed in many tumors that become addicted to its activity, and STAT3 transcriptional activation is required for tumor transformation downstream of several oncogenes. We have recently demonstrated that constitutively active STAT3 drives a metabolic switch towards aerobic glycolysis through the transcriptional induction of Hif-1α and the down-regulation of mitochondrial activity, in both MEF cells expressing constitutively active STAT3 (Stat3C/C) and STAT3-addicted tumor cells. This novel metabolic function is likely involved in mediating pre-oncogenic features in the primary Stat3C/C MEFs such as resistance to apoptosis and senescence and rapid proliferation. Moreover, it strongly contributes to the ability of primary Stat3C/C MEFs to undergo malignant transformation upon spontaneous immortalization, a feature that may explain the well known causative link between STAT3 constitutive activity and tumor transformation under chronic inflammatory conditions. Taken together with the recently uncovered role of STAT3 in regulating energy metabolism from within the mitochondrion when phosphorylated on Ser 727, these data place STAT3 at the center of a hub regulating energy metabolism under different conditions, in most cases promoting cell survival, proliferation and malignant transformation even though with distinct mechanisms.
PMCID: PMC4190557  PMID: 25089666
STAT3; metabolism; Warburg effect; aerobic glycolysis; cellular transformation; mitochondrial activity
5.  The mitochondrial permeability transition pore is a dispensable element for mitochondrial calcium efflux 
Cell Calcium  2014;56(1):1-13.
Graphical abstract
The mitochondrial permeability transition pore (mPTP) has long been known to have a role in mitochondrial calcium (Ca2+) homeostasis under pathological conditions as a mediator of the mitochondrial permeability transition and the activation of the consequent cell death mechanism. However, its role in the context of mitochondrial Ca2+ homeostasis is not yet clear. Several studies that were based on PPIF inhibition or knock out suggested that mPTP is involved in the Ca2+ efflux mechanism, while other observations have revealed the opposite result.
The c subunit of the mitochondrial F1/FO ATP synthase has been recently found to be a fundamental component of the mPTP. In this work, we focused on the contribution of the mPTP in the Ca2+ efflux mechanism by modulating the expression of the c subunit. We observed that forcing mPTP opening or closing did not impair mitochondrial Ca2+ efflux. Therefore, our results strongly suggest that the mPTP does not participate in mitochondrial Ca2+ homeostasis in a physiological context in HeLa cells.
PMCID: PMC4074345  PMID: 24755650
ANT, adenine nucleotide translocase; [Ca2+]c, cytosolic calcium concentration; [Ca2+]m, mitochondrial calcium concentration; CsA, cyclosporine A; HK, hexokinase II; H2O2, hydrogen peroxide; IB, intracellular milieu; MCU, mitochondrial Ca2+ uniporter; NCLX, mitochondrial Na+/Ca2+ antiporter; MPT, mitochondrial permeability transition; mPTP, mitochondrial permeability transition pore; PiC, inorganic phosphate carrier; PPIF, peptidyl prolyl isomerase; siRNAs, small-interfering RNAs; TSPO, peripheral benzodiazepine receptor; RuR, ruthenium red; VDAC, voltage-dependent anion channel; ATP5G1; Calcium (Ca2+); Cyclophilin F; Cyclosporine A (CsA); Mitochondria; Permeability transition pore (PTP); Peptidyl prolyl isomerase F (PPIF)
6.  Role of the c subunit of the FO ATP synthase in mitochondrial permeability transition 
Cell Cycle  2013;12(4):674-683.
The term “mitochondrial permeability transition” (MPT) refers to an abrupt increase in the permeability of the inner mitochondrial membrane to low molecular weight solutes. Due to osmotic forces, MPT is paralleled by a massive influx of water into the mitochondrial matrix, eventually leading to the structural collapse of the organelle. Thus, MPT can initiate mitochondrial outer membrane permeabilization (MOMP), promoting the activation of the apoptotic caspase cascade as well as of caspase-independent cell death mechanisms. MPT appears to be mediated by the opening of the so-called “permeability transition pore complex” (PTPC), a poorly characterized and versatile supramolecular entity assembled at the junctions between the inner and outer mitochondrial membranes. In spite of considerable experimental efforts, the precise molecular composition of the PTPC remains obscure and only one of its constituents, cyclophilin D (CYPD), has been ascribed with a crucial role in the regulation of cell death. Conversely, the results of genetic experiments indicate that other major components of the PTPC, such as voltage-dependent anion channel (VDAC) and adenine nucleotide translocase (ANT), are dispensable for MPT-driven MOMP. Here, we demonstrate that the c subunit of the FO ATP synthase is required for MPT, mitochondrial fragmentation and cell death as induced by cytosolic calcium overload and oxidative stress in both glycolytic and respiratory cell models. Our results strongly suggest that, similar to CYPD, the c subunit of the FO ATP synthase constitutes a critical component of the PTPC.
PMCID: PMC3594268  PMID: 23343770
ATP5G1; apoptosis; caspases; cytochrome c; mitochondrial respiratory chain; p53; permeability transition pore (PTP)
8.  The Mitochondrial Permeability Transition Pore and Cancer: Molecular Mechanisms Involved in Cell Death 
Frontiers in Oncology  2014;4:302.
Since its discovery in the 1970s, the mitochondrial permeability transition (MPT) has been proposed to be a strategic regulator of cell death. Intense research efforts have focused on elucidating the molecular components of the MPT because this knowledge may help to better understand and treat various pathologies ranging from neurodegenerative and cardiac diseases to cancer. In the case of cancer, several studies have revealed alterations in the activity of the mitochondrial permeability transition pore (mPTP) and have determined its regulatory mechanism; these studies have also suggested that suppression of the activity of the mPTP, rather than its inactivation, commonly occurs in solid neoplasms. This review focuses on the most recent advances in understanding mPTP regulation in cancer and highlights the ability of the mPTP to impede the mechanisms of cell death.
PMCID: PMC4235083  PMID: 25478322
apoptosis; cancer; necrosis; permeability transition pore; ATP synthase; ROS; tumors; PTP
9.  Transglutaminase 2 Contributes to Apoptosis Induction in Jurkat T Cells by Modulating Ca2+ Homeostasis via Cross-Linking RAP1GDS1 
PLoS ONE  2013;8(12):e81516.
Transglutaminase 2 (TG2) is a protein cross-linking enzyme known to be associated with the in vivo apoptosis program of T cells. However, its role in the T cell apoptosis program was not investigated yet.
Here we report that timed overexpression of both the wild type (wt) and the cross-linking mutant of TG2 induced apoptosis in Jurkat T cells, the wt being more effective. Part of TG2 colocalised with mitochondria. WtTG2-induced apoptosis was characterized by enhanced mitochondrial Ca2+ uptake. Ca2+-activated wtTG2 cross-linked RAP1, GTP-GDP dissociation stimulator 1, an unusual guanine exchange factor acting on various small GTPases, to induce a yet uncharacterized signaling pathway that was able to promote the Ca2+ release from the endoplasmic reticulum via both Ins3P and ryanodine sensitive receptors leading to a consequently enhanced mitochondrial Ca2+uptake.
Our data indicate that TG2 might act as a Ca2+ sensor to amplify endoplasmic reticulum-derived Ca2+ signals to enhance mitochondria Ca2+ uptake. Since enhanced mitochondrial Ca2+ levels were previously shown to sensitize mitochondria for various apoptotic signals, our data demonstrate a novel mechanism through which TG2 can contribute to the induction of apoptosis in certain cell types. Since, as compared to knock out cells, physiological levels of TG2 affected Ca2+ signals in mouse embryonic fibroblasts similar to Jurkat cells, our data might indicate a more general role of TG2 in the regulation of mitochondrial Ca2+ homeostasis.
PMCID: PMC3859493  PMID: 24349085
10.  17β-Estradiol Enhances Signalling Mediated by VEGF-A-Delta-Like Ligand 4-Notch1 Axis in Human Endothelial Cells 
PLoS ONE  2013;8(8):e71440.
Estrogens play a protective role in coronary artery disease. The mechanisms of action are still poorly understood, although a role for estrogens in stimulation of angiogenesis has been suggested. In several cell types, estrogens modulate the Notch pathway, which is involved in controlling angiogenesis downstream of vascular endothelial growth factor A (VEGF-A). The goal of our study was to establish whether estrogens modulate Notch activity in endothelial cells and the possible consequences on angiogenesis. Human umbilical vein endothelial cells (HUVECs) were treated with 17β-estradiol (E2) and the effects on Notch signalling were evaluated. E2 increased Notch1 processing as indicated by i) decreased levels of Notch1 transmembrane subunit ii) increased amount of Notch1 in nuclei iii) unaffected level of mRNA. Similarly, E2 increased the levels of the active form of Notch4 without altering Notch4 mRNA. Conversely, protein and mRNA levels of Notch2 were both reduced suggesting transcriptional repression of Notch2 by E2. Under conditions where Notch was activated by upregulation of Delta-like ligand 4 (Dll4) following VEGF-A treatment, E2 caused a further increase of the active form of Notch1, of the number of cells with nuclear Notch1 and of Hey2 mRNA. Estrogen receptor antagonist ICI 182.780 antagonized these effects suggesting that E2 modulation of Notch1 is mediated by estrogen receptors. E2 treatment abolished the increase in endothelial cells sprouting caused by Notch inhibition in a tube formation assay on 3D Matrigel and in mouse aortic ring explants. In conclusion, E2 affects several Notch pathway components in HUVECs, leading to an activation of the VEGF-A-Dll4-Notch1 axis and to a modulation of vascular branching when Notch signalling is inhibited. These results contribute to our understanding of the molecular mechanisms of cardiovascular protection exerted by estrogens by uncovering a novel role of E2 in the Notch signalling-mediated modulation of angiogenesis.
PMCID: PMC3742772  PMID: 23967210
11.  Mitochondrial calcium uniporter, MiRNA and cancer 
Mitochondria receive calcium (Ca2+) signals from endoplasmic reticulum (ER) and decode them into pro-apoptotic inputs, which lead to cell death. Therefore, mitochondrial Ca2+ overload is considered a fundamental trigger of the apoptotic process, and several oncogenes and tumor suppressors modify the activity of protein involved in Ca2+ homeostasis to control apoptosis. The identification of the channel responsible for mitochondrial Ca2+ entry, the Mitochondrial Ca2+Uniporter (MCU), together with its regulatory components, MICU1 and MCUR1, provides new molecular tools to investigate this process. Recent data have also shown that miR-25 decreases mitochondrial Ca2+ uptake through selective MCU downregulation, conferring resistance to apoptotic challenges. MCU appears to be downregulated in human colon cancer samples, and accordingly, miR-25 is aberrantly expressed, indicating the importance of mitochondrial Ca2+ regulation in cancer cell survival.
PMCID: PMC3656015  PMID: 23713134
mitochondria; calcium (Ca2+); Mitochondrial Calcium Uniporter (MCU); MicroRNAs (MiRNA); apoptosis; cell death; cancer
12.  Systemic elevation of PTEN induces a tumor suppressive metabolic state 
Cell  2012;149(1):49-62.
Decremental loss of PTEN results in cancer susceptibility and tumor progression. In turn this raises the possibility that PTEN elevation might be an attractive option for cancer prevention and therapy. We have generated several transgenic mouse lines with variably elevated PTEN expression levels, taking advantage of BAC (Bacterial Artificial Chromosome)-mediated transgenesis. Super-PTEN mutants are viable and show reduced body size due to decreased cell number, with no effect on cell size. Unexpectedly, PTEN elevation at the organism level results in healthy metabolism characterized by increased energy expenditure and reduced body fat accumulation. Cells derived from these mice show reduced glucose and glutamine uptake, increased mitochondrial oxidative phosphorylation, and are resistant to oncogenic transformation. Mechanistically we find that PTEN elevation orchestrates this metabolic switch by regulating PI3K-dependent and independent pathways, and negatively impacts two of the most pronounced metabolic features of tumor cells: glutaminolysis and the Warburg effect.
PMCID: PMC3319228  PMID: 22401813
13.  Oxidative Stress in Cardiovascular Diseases and Obesity: Role of p66Shc and Protein Kinase C 
Reactive oxygen species (ROS) are a byproduct of the normal metabolism of oxygen and have important roles in cell signalling and homeostasis. An imbalance between ROS production and the cellular antioxidant defence system leads to oxidative stress. Environmental factors and genetic interactions play key roles in oxidative stress mediated pathologies. In this paper, we focus on cardiovascular diseases and obesity, disorders strongly related to each other; in which oxidative stress plays a fundamental role. We provide evidence of the key role played by p66Shc protein and protein kinase C (PKC) in these pathologies by their intracellular regulation of redox balance and oxidative stress levels. Additionally, we discuss possible therapeutic strategies aimed at attenuating the oxidative damage in these diseases.
PMCID: PMC3625561  PMID: 23606925
14.  The selective inhibition of nuclear PKCζ restores the effectiveness of chemotherapeutic agents in chemoresistant cells 
Cell Cycle  2012;11(5):1040-1048.
The atypical protein kinase C (PKC) isoform zeta (PKCζ) has been implicated in the intracellular transduction of mitogenic and apoptotic signals by acting on different signaling pathways. The key role of these processes in tumorigenesis suggests a possible involvement of PKCζ in this event. PKCζ is activated by cytotoxic treatments, inhibits apoptotic cell death and reduces the sensitivity of cancer cells to chemotherapeutic agents. Here, using pharmacological and DNA recombinant approaches, we show that oxidative stress triggers nuclear translocation of PKCζ and induces resistance to apoptotic agents. Accordingly, chemoresistant cells show accumulation of PKCζ within the nucleus, and a nuclear-targeted PKCζ transfected in tumor cells decreases sensitivity to apoptosis. We thus developed a novel recombinant protein capable of selectively inhibiting the nuclear fraction of PKCζ that restored the susceptibility to apoptosis in cells in which PKCζ was enriched in the nuclear fraction, including chemoresistant cells. These findings establish the importance of PKCζ as a possible target to increase the effectiveness of anticancer therapies and highlight potential sites of intervention.
PMCID: PMC3323800  PMID: 22333579
protein kinase C; chemoresistance; oxidative stress; nuclear translocation; apoptosis
15.  Hyaluronic Acid Induces Activation of the κ-Opioid Receptor 
PLoS ONE  2013;8(1):e55510.
Nociceptive pain is one of the most common types of pain that originates from an injury involving nociceptors. Approximately 60% of the knee joint innervations are classified as nociceptive. The specific biological mechanism underlying the regulation of nociceptors is relevant for the treatment of symptoms affecting the knee joint. Intra-articular administration of exogenous hyaluronic acid (HA) in patients with osteoarthritis (OA) appears to be particularly effective in reducing pain and improving patient function.
We performed an in vitro study conducted in CHO cells that expressed a panel of opioid receptors and in primary rat dorsal root ganglion (DRG) neurons to determine if HA induces the activation of opioid peptide receptors (OPr) using both aequorin and the fluorescent dye Fura-2/AM.
Selective agonists and antagonists for each OPr expressed on CHO cells were used to test the efficacy of our in vitro model followed by stimulation with HA. The results showed that HA induces stimulatory effects on the κ receptor (KOP). These effects of HA were also confirmed in rat DRG neurons, which express endogenously the OPr.
HA activates the KOP receptor in a concentration dependent manner, with a pEC50 value of 7.57.
PMCID: PMC3557250  PMID: 23383210
16.  Downregulation of the Mitochondrial Calcium Uniporter by Cancer-Related miR-25 
Current Biology  2013;23(1):58-63.
The recently discovered mitochondrial calcium uniporter (MCU) promotes Ca2+ accumulation into the mitochondrial matrix [1, 2]. We identified in silico miR-25 as a cancer-related MCU-targeting microRNA family and demonstrate that its overexpression in HeLa cells drastically reduces MCU levels and mitochondrial Ca2+ uptake, while leaving other mitochondrial parameters and cytosolic Ca2+ signals unaffected. In human colon cancers and cancer-derived cells, miR-25 is overexpressed and MCU accordingly silenced. miR-25-dependent reduction of mitochondrial Ca2+ uptake correlates with resistance to apoptotic challenges and can be reversed by anti-miR-25 overexpression. Overall, the data demonstrate that microRNA targeting of mitochondrial Ca2+ signaling favors cancer cell survival, thus providing mechanistic insight into the role of mitochondria in tumorigenesis and identifying a novel therapeutic target in neoplasia.
► miR-25 regulates intracellular calcium homeostasis ► Mitochondrial calcium uniporter (MCU) is a target of miR-25 ► MCU plays a critical role in apoptosis and tumorigenesis ► MCU is downregulated in different cancer cell lines and in human colonic adenocarcinoma
PMCID: PMC3540261  PMID: 23246404
17.  Chemoresistance and Cancer-Related Inflammation: Two Hallmarks of Cancer Connected by an Atypical Link, PKCζ 
Frontiers in Oncology  2013;3:232.
Atypical protein kinase C isoforms are serine threonine kinases involved in various pathological conditions. In recent years, the PKCζ isoform has emerged as an important regulator of multiple cellular processes operating in cancer. In this review, we will focus on the PKCζ isoform as an oxidative-sensing kinase involved in cancer-related inflammation and chemoresistance. We will discuss its nuclear localization and its possible pivotal role in connecting inflammation with drug resistance.
PMCID: PMC3770915  PMID: 24062985
atypical PKC; PKCζ; cancer; chemoresistance; inflammation; nucleus; apoptosis
18.  Donor Age-Related Biological Properties of Human Dental Pulp Stem Cells Change in Nanostructured Scaffolds 
PLoS ONE  2012;7(11):e49146.
The aim of the present work is to study how biological properties, such as proliferation and commitment ability, of human adult dental pulp stem cells (DPSCs) relate to the age of the donor. Human dental pulps were extracted from molars of healthy adult subjects aged 16 to >66 years. DPSCs were isolated and cultured in the presence of osteogenic, neurogenic, or vasculogenic differentiation medium. Proliferation ability was evaluated by determining doubling time, and commitment ability was evaluated by gene expression and morphological analyses for tissue-specific markers. The results confirm a well-defined proliferative ability for each donor age group at an early in vitro passage (p2). DPSCs from younger donors (up to 35 years) maintain this ability in long-term cultures (p8). Stem cells of all age donor groups maintain their commitment ability during in vitro culture. In vivo tests on the critical size defect repair process confirmed that DPSCs of all donor ages are a potent tool for bone tissue regeneration when mixed with 3D nanostructured scaffolds.
PMCID: PMC3509126  PMID: 23209565
19.  The mitochondrial heme exporter FLVCR1b mediates erythroid differentiation 
The Journal of Clinical Investigation  2012;122(12):4569-4579.
Feline leukemia virus subgroup C receptor 1 (FLVCR1) is a cell membrane heme exporter that maintains the balance between heme levels and globin synthesis in erythroid precursors. It was previously shown that Flvcr1-null mice died in utero due to a failure of erythropoiesis. Here, we identify Flvcr1b, a mitochondrial Flvcr1 isoform that promotes heme efflux into the cytoplasm. Flvcr1b overexpression promoted heme synthesis and in vitro erythroid differentiation, whereas silencing of Flvcr1b caused mitochondrial heme accumulation and termination of erythroid differentiation. Furthermore, mice lacking the plasma membrane isoform (Flvcr1a) but expressing Flvcr1b had normal erythropoiesis, but exhibited hemorrhages, edema, and skeletal abnormalities. Thus, FLVCR1b regulates erythropoiesis by controlling mitochondrial heme efflux, whereas FLVCR1a expression is required to prevent hemorrhages and edema. The aberrant expression of Flvcr1 isoforms may play a role in the pathogenesis of disorders characterized by an imbalance between heme and globin synthesis.
PMCID: PMC3533534  PMID: 23187127
20.  ATP synthesis and storage 
Purinergic Signalling  2012;8(3):343-357.
Since 1929, when it was discovered that ATP is a substrate for muscle contraction, the knowledge about this purine nucleotide has been greatly expanded. Many aspects of cell metabolism revolve around ATP production and consumption. It is important to understand the concepts of glucose and oxygen consumption in aerobic and anaerobic life and to link bioenergetics with the vast amount of reactions occurring within cells. ATP is universally seen as the energy exchange factor that connects anabolism and catabolism but also fuels processes such as motile contraction, phosphorylations, and active transport. It is also a signalling molecule in the purinergic signalling mechanisms. In this review, we will discuss all the main mechanisms of ATP production linked to ADP phosphorylation as well the regulation of these mechanisms during stress conditions and in connection with calcium signalling events. Recent advances regarding ATP storage and its special significance for purinergic signalling will also be reviewed.
PMCID: PMC3360099  PMID: 22528680
ATP synthesis; ATP storage; Mitochondria; Calcium
21.  Adipose Tissue Regeneration: A State of the Art 
Adipose tissue pathologies and defects have always represented a reconstructive challenge for plastic surgeons. In more recent years, several allogenic and alloplastic materials have been developed and used as fillers for soft tissue defects. However, their clinical use has been limited by further documented complications, such as foreign-body reactions potentially affecting function, degradation over time, and the risk for immunogenicity. Tissue-engineering strategies are thus being investigated to develop methods for generating adipose tissue. This paper will discuss the current state of the art in adipose tissue engineering techniques, exploring the biomaterials used, stem cells application, culture strategies, and current regulatory framework that are in use are here described and discussed.
PMCID: PMC3488420  PMID: 23193362
22.  Mitochondrial Ca2+ and apoptosis 
Cell Calcium  2012;52(1):36-43.
Mitochondria are key decoding stations of the apoptotic process. In support of this view, a large body of experimental evidence has unambiguously revealed that, in addition to the well-established function of producing most of the cellular ATP, mitochondria play a fundamental role in triggering apoptotic cell death.
Various apoptotic stimuli cause the release of specific mitochondrial pro-apoptotic factors into the cytosol. The molecular mechanism of this release is still controversial, but there is no doubt that mitochondrial calcium (Ca2+) overload is one of the pro-apoptotic ways to induce the swelling of mitochondria, with perturbation or rupture of the outer membrane, and in turn the release of mitochondrial apoptotic factors into the cytosol.
Here, we review as different proteins that participate in mitochondrial Ca2+ homeostasis and in turn modulate the effectiveness of Ca2+-dependent apoptotic stimuli. Strikingly, the final outcome at the cellular level is similar, albeit through completely different molecular mechanisms: a reduced mitochondrial Ca2+ overload upon pro-apoptotic stimuli that dramatically blunts the apoptotic response.
PMCID: PMC3396846  PMID: 22480931
Calcium; Mitochondria; Apoptosis; Cell death; Endoplasmic reticulum; MAM
24.  Mitochondrial calcium homeostasis as potential target for mitochondrial medicine 
Mitochondrion  2012;12(1):77-85.
Mitochondria are crucial in different intracellular pathways of signal transduction. Mitochondria are capable of decoding a variety of extracellular stimuli into markedly different intracellular actions, ranging from energy production to cell death. The fine modulation of mitochondrial calcium (Ca2+) homeostasis plays a fundamental role in many of the processes involving this organelle. When mitochondrial Ca2+ homeostasis is compromised, different pathological conditions can occur, depending on the cell type involved. Recent data have shed light on the molecular identity of the main proteins involved in the handling of mitochondrial Ca2+ traffic, opening fascinating and ambitious new avenues for mitochondria-based pharmacological strategies.
PMCID: PMC3281195  PMID: 21798374
Mitochondria; Calcium; Aging; Neurodegeneration; Diabetes; Cardiovascular and mitochondrial disorders
25.  PML Regulates Apoptosis at Endoplasmic Reticulum by Modulating Calcium Release 
Science (New York, N.Y.)  2010;330(6008):1247-1251.
The promyelocytic leukemia (PML) tumor suppressor is a pleiotropic modulator of apoptosis. However, the molecular basis for such a diverse proapoptotic role is currently unknown. We show that extranuclear Pml was specifically enriched at the endoplasmic reticulum (ER) and at the mitochondria-associated membranes, signaling domains involved in ER-to-mitochondria calcium ion (Ca2+) transport and in induction of apoptosis. We found Pml in complexes of large molecular size with the inositol 1,4,5-trisphosphate receptor (IP3R), protein kinase Akt, and protein phosphatase 2a (PP2a). Pml was essential for Akt- and PP2a-dependent modulation of IP3R phosphorylation and in turn for IP3R-mediated Ca2+ release from ER. Our findings provide a mechanistic explanation for the pleiotropic role of Pml in apoptosis and identify a pharmacological target for the modulation of Ca2+ signals.
PMCID: PMC3017677  PMID: 21030605

Results 1-25 (53)