RESUMO
Nonalcoholic fatty liver disease is a chronic liver disease which is associated with obesity and insulin resistance. We investigated the implication of REDD1 (Regulated in development and DNA damage response-1), a stress-induced protein in the development of hepatic steatosis. REDD1 expression was increased in the liver of obese mice and morbidly obese patients, and its expression correlated with hepatic steatosis and insulin resistance in obese patients. REDD1 deficiency protected mice from the development of hepatic steatosis induced by high-fat diet (HFD) without affecting body weight gain and glucose intolerance. This protection was associated with a decrease in the expression of lipogenic genes, SREBP1c, FASN, and SCD-1 in liver of HFD-fed REDD1-KO mice. Healthy mitochondria are crucial for the adequate control of lipid metabolism and failure to remove damaged mitochondria is correlated with liver steatosis. Expression of markers of autophagy and mitophagy, Beclin, LC3-II, Parkin, BNIP3L, was enhanced in liver of HFD-fed REDD1-KO mice. The number of mitochondria showing colocalization between LAMP2 and AIF was increased in liver of HFD-fed REDD1-KO mice. Moreover, mitochondria in liver of REDD1-KO mice were smaller than in WT. These results are correlated with an increase in PGC-1α and CPT-1 expression, involved in fatty acid oxidation. In conclusion, loss of REDD1 protects mice from the development of hepatic steatosis.
Assuntos
Hepatopatia Gordurosa não Alcoólica/genética , Fatores de Transcrição/deficiência , Adulto , Animais , Autofagia , Carnitina O-Palmitoiltransferase/genética , Carnitina O-Palmitoiltransferase/metabolismo , Células Cultivadas , Dieta Hiperlipídica/efeitos adversos , Ácido Graxo Sintase Tipo I/genética , Ácido Graxo Sintase Tipo I/metabolismo , Feminino , Deleção de Genes , Humanos , Masculino , Camundongos , Mitofagia , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Estearoil-CoA Dessaturase/genética , Estearoil-CoA Dessaturase/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The primary cilium is an organelle present in most of the cells of the organism. Ciliopathies are genetic disorders of the primary cilium and can be associated with obesity. We have studied the primary cilium during adipocyte differentiation of human adipose stem cells (hASC). We show here that the size of the primary cilium follows several modifications during adipocyte differentiation. It is absent in growing cells and appears in confluent cells. Interestingly, during the first days of differentiation, the cilium undergoes a dramatic elongation that can be mimicked by dexamethasone alone. Thereafter, its size decreases. It can still be detected in cells that begin to accumulate lipids but is absent in cells that are filled with lipids. The cilium elongation does not seem to affect the localization of proteins associated with the cilium such as Kif3-A or Smoothened. However, Hedgehog signaling, an anti-adipogenic pathway dependent on the primary cilium, is inhibited after three days of differentiation, concomitantly with the cilium size increase. Together, these results shed new light on the primary cilium and could provide us with new information on adipocyte differentiation under normal and pathological conditions.
Assuntos
Adipócitos/citologia , Adipócitos/metabolismo , Diferenciação Celular , Adipogenia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Cílios/metabolismo , Dexametasona/farmacologia , Proteínas Hedgehog/metabolismo , Humanos , Cinesinas/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Receptor SmoothenedRESUMO
Metformin and IACS-010759 are two distinct antimetabolic agents. Metformin, an established antidiabetic drug, mildly inhibits mitochondrial complex I, while IACS-010759 is a new potent mitochondrial complex I inhibitor. Mitochondria is pivotal in the energy metabolism of cells by providing adenosine triphosphate through oxidative phosphorylation (OXPHOS). Hence, mitochondrial metabolism and OXPHOS become a vulnerability when targeted in cancer cells. Both drugs have promising antitumoral effects in diverse cancers, supported by preclinical in vitro and in vivo studies. We present evidence of their direct impact on cancer cells and their immunomodulatory effects. In clinical studies, while observational epidemiologic studies on metformin were encouraging, actual trial results were not as expected. However, IACS-01075 exhibited major adverse effects, thereby causing a metabolic shift to glycolysis and elevated lactic acid concentrations. Therefore, the future outlook for these two drugs depends on preventive clinical trials for metformin and investigations into the plausible toxic effects on normal cells for IACS-01075.
Assuntos
Complexo I de Transporte de Elétrons , Metformina , Neoplasias , Metformina/uso terapêutico , Metformina/farmacologia , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/imunologia , Complexo I de Transporte de Elétrons/metabolismo , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Animais , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , Fosforilação Oxidativa/efeitos dos fármacosRESUMO
Breast adipose tissue (AT) participates in the physiological evolution and remodeling of the mammary gland due to its high plasticity. It is also a favorable microenvironment for breast cancer progression. However, information on the properties of human breast adipose progenitor cells (APCs) involved in breast physiology or pathology is scant. We performed differential enzymatic dissociation of human breast AT lobules. We isolated and characterized two populations of APCs. Here we report that these distinct breast APC populations selectively expressed markers suitable for characterization. The population preferentially expressing ALPL (MSCA1) showed higher adipogenic potential. The population expressing higher levels of INHBA and CD142 acquired myofibroblast characteristics upon TGF-ß treatment and a myo-cancer-associated fibroblast profile in the presence of breast cancer cells. This population expressed the immune checkpoint CD274 (PD-L1) and facilitated the expansion of breast cancer mammospheres compared with the adipogenic population. Indeed, the breast, as with other fat depots, contains distinct types of APCs with differences in their ability to specialize. This indicates that they were differentially involved in breast remodeling. Their interactions with breast cancer cells revealed differences in the potential for tumor dissemination and estrogen receptor expression, and these differences might be relevant to improve therapies targeting the tumor microenvironment.
RESUMO
Adipose tissue resides in specific depots scattered in peripheral or deeper locations all over the body and it enwraps most of the organs. This tissue is always in a dynamic evolution as it must adapt to the metabolic demand and constraints. It exhibits also endocrine functions important to regulate energy homeostasis. This complex organ is composed of depots able to produce opposite functions to monitor energy: the so called white adipose tissue acts to store energy as triglycerides preventing ectopic fat deposition while the brown adipose depots dissipate it. It is composed of many cell types. Different types of adipocytes constitute the mature cells specialized to store or burn energy. Immature adipose progenitors (AP) presenting stem cells properties contribute not only to the maintenance but also to the expansion of this tissue as observed in overweight or obese individuals. They display a high regeneration potential offering a great interest for cell therapy. In this review, we will depict the attributes of the distinct types of adipocytes and their contribution to the function and metabolic features of adipose tissue. We will examine the specific role and properties of distinct depots according to their location. We will consider their cellular heterogeneity to present an updated picture of this sophisticated tissue. We will also introduce new trends pointing out a rational targeting of adipose tissue for medical applications.
RESUMO
Fibrosis is a deleterious invasion of tissues associated with many pathological conditions, such as Duchenne muscular dystrophy (DMD) for which no cure is at present available for its prevention or its treatment. Fibro-adipogenic progenitors (FAPs) are resident cells in the human skeletal muscle and can differentiate into myofibroblasts, which represent the key cell population responsible for fibrosis. In this study, we delineated the pool of microRNAs (miRNAs) that are specifically modulated by TGFß1 in FAPs versus myogenic progenitors (MPs) by a global miRNome analysis. A subset of candidates, including several "FibromiRs", was found differentially expressed between FAPs and MPs and was also deregulated in DMD versus healthy biopsies. Among them, the expression of the TGFß1-induced miR-199a~214 cluster was strongly correlated with the fibrotic score in DMD biopsies. Loss-of-function experiments in FAPs indicated that a miR-214-3p inhibitor efficiently blocked expression of fibrogenic markers in both basal conditions and following TGFß1 stimulation. We found that FGFR1 is a functional target of miR-214-3p, preventing the signaling of the anti-fibrotic FGF2 pathway during FAP fibrogenesis. Overall, our work demonstrates that the « FibromiR ¼ miR-214-3p is a key activator of FAP fibrogenesis by modulating the FGF2/FGFR1/TGFß axis, opening new avenues for the treatment of DMD.
Assuntos
Fator 2 de Crescimento de Fibroblastos/genética , MicroRNAs/genética , Distrofia Muscular de Duchenne/genética , Miofibroblastos/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Células-Tronco/metabolismo , Fator de Crescimento Transformador beta1/genética , Adipócitos/metabolismo , Adipócitos/patologia , Adipogenia/genética , Adolescente , Adulto , Sequência de Bases , Diferenciação Celular , Criança , Feminino , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fibrose , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Humanos , Masculino , MicroRNAs/metabolismo , Pessoa de Meia-Idade , Desenvolvimento Muscular/genética , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/patologia , Miofibroblastos/patologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Transdução de Sinais , Células-Tronco/patologia , Fator de Crescimento Transformador beta1/metabolismoRESUMO
Mesenchymal stem cells within the bone are responsible for the generation of osteoblasts, chondrocytes, and adipocytes. In rodents, Indian hedgehog has been shown to play a role in osteoblast differentiation. However, evidence for a direct function of hedgehog (Hh) in human osteoblastic differentiation is missing. Using different models of human mesenchymal stem cells we show that Hh signaling decreases during osteoblast differentiation. This is associated with a decrease in Smoothened expression, a key partner that triggers Hh signaling, and in the number of cells displaying a primary cilium, an organelle necessary for Hh signaling. Remarkably, treatment of human mesenchymal stem cells with sonic hedgehog or two molecules able to activate Hh signaling inhibits osteoblast differentiation. This inhibition is visualized through a decrease in mineralization and in the expression of osteoblastic genes. In particular, activation of Hh signaling induces a decrease in Runx2 expression, a key transcriptional factor controlling the early stage of osteoblast differentiation. Consistently, the activation of Hh signaling during the first days of differentiation is sufficient to inhibit osteoblast differentiation, whereas differentiated osteoblasts are not affected by Hh signaling. In summary, we show here, using various inducers of Hh signaling and mesenchymal stem cells of two different origins, that Hh signaling inhibits human osteoblast differentiation, in sharp contrast to what has been described in rodent cells. This species difference should be taken into account for screening for pro-osteogenic molecules.
Assuntos
Diferenciação Celular/fisiologia , Proteínas Hedgehog/metabolismo , Células-Tronco Mesenquimais/citologia , Transdução de Sinais/fisiologia , Fosfatase Alcalina/metabolismo , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Linhagem Celular , Células Cultivadas , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Meios de Cultivo Condicionados/farmacologia , Regulação da Expressão Gênica , Humanos , Hidroxicolesteróis/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Morfolinas/farmacologia , Células T Matadoras Naturais , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Purinas/farmacologia , Transdução de Sinais/efeitos dos fármacosRESUMO
Cancer associated fibroblasts (CAFs) are central elements of the microenvironment that control tumor development. In breast cancer, CAFs can originate from adipose progenitors (APs). We, and others, have shown that the primary cilium, an antenna-shaped organelle, controls several aspects of APs' biology. We studied the conversion of human APs into CAFs by breast cancer cell lines (BCCs). Deletion of the cilium of APs by a pharmacological inhibitor, or by siRNA, allow us to demonstrate that the cilium is necessary for the differentiation of APs into CAFs. BCCs increase production of TGF-ß1 by APs, which is a known inducer of CAFs. Pharmacological inhibition of TGF-ß1 signaling in APs prevents their conversion into CAFs. Since we previously showed that deletion of the APs' cilium inhibits TGF-ß1 signaling, we propose that BCCs induce TGF-ß1 production in Aps, which binds to the primary cilium of Aps and leads to their differentiation into CAFs. Inhibition of APs conversion into CAFs induces a loss in some of the biological effects of CAFs since deletion of the cilium of APs decreases their effect on the migration of BCCs. This is the first observation of a function of the cilium of APs in their conversion into CAFs, and its consequences on BCCs.
Assuntos
Fibroblastos Associados a Câncer/metabolismo , Cílios/metabolismo , Células-Tronco Mesenquimais/metabolismo , Tecido Adiposo/metabolismo , Neoplasias da Mama/metabolismo , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Cílios/fisiologia , Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Células MCF-7 , Células-Tronco Mesenquimais/fisiologia , Transdução de Sinais/efeitos dos fármacos , Células-Tronco/metabolismo , Células-Tronco/fisiologia , Fator de Crescimento Transformador beta1/genética , Microambiente Tumoral/fisiologiaRESUMO
HIV-protease inhibitors (PIs) markedly decreased mortality of HIV-infected patients. However, their use has been associated with occurence of metabolic abnormalities the causes of which are not well understood. We report here that lopinavir, one of the most prescribed PI, dose-dependently co-induced insulin resistance and ER stress in human adipocytes obtained from differentiation of precursor cells. Insulin resistance was subsequent to IRS1 phosphorylation defects and resulted in a concentration-dependent decrease of glucose uptake. The major ER stress pathway involved was the phosphorylation of eIF2-alpha. Salubrinal, a selective eIF2-alpha dephosphorylation inhibitor, induced insulin resistance by targeting IRS1 phosphorylation at serine 312 and acted synergistically with LPV when both drugs were used in combination. This study points out the key role of eIF2-alpha phosphorylation in the development of PI-associated insulin resistance and ER stress. Thus, this protein represents a promising therapeutic target for development of new PIs devoid of adverse metabolic effects.
Assuntos
Adipócitos/efeitos dos fármacos , Fator de Iniciação 2 em Eucariotos/metabolismo , Inibidores da Protease de HIV/efeitos adversos , Resistência à Insulina , Pirimidinonas/efeitos adversos , Adipócitos/metabolismo , Linhagem Celular , Cinamatos/farmacologia , Retículo Endoplasmático/metabolismo , Inibidores da Protease de HIV/farmacologia , Humanos , Proteínas Substratos do Receptor de Insulina/metabolismo , Lopinavir , Fosforilação , Pirimidinonas/farmacologia , Tioureia/análogos & derivados , Tioureia/farmacologiaRESUMO
Human stem cells are powerful tools by which to investigate molecular mechanisms of cell growth and differentiation under normal and pathological conditions. Hedgehog signaling, the dysregulation of which causes several pathologies, such as congenital defects and cancer, is involved in several cell differentiation processes and interferes with adipocyte differentiation of rodent cells. The present study was aimed at investigating the effect of Hedgehog pathway modulation on adipocyte phenotype using different sources of human mesenchymal cells, such as bone marrow stromal cells and human multipotent adipose-derived stem cells. We bring evidence that Hedgehog signaling decreases during human adipocyte differentiation. Inhibition of this pathway is not sufficient to trigger adipogenesis, but activation of Hedgehog pathway alters adipocyte morphology as well as insulin sensitivity. Analysis of glycerol-3-phosphate dehydrogenase activity and expression of adipocyte marker genes indicate that activation of Hedgehog signaling by purmorphamine impairs adipogenesis. In sharp contrast to reports in rodent cells, the maturation process, but not the early steps of human mesenchymal stem cell differentiation, is affected by Hedgehog activation. Hedgehog interferes with adipocyte differentiation by targeting CCAAT enhancer-binding protein alpha and peroxisome proliferator-activated receptor (PPAR) gamma2 expression, whereas PPARgamma1 level remains unaffected. Although Hedgehog pathway stimulation does not modify the total number of adipocytes, adipogenesis appears dramatically impaired, with reduced lipid accumulation, a decrease in adipocyte-specific markers, and acquisition of an insulin-resistant phenotype. This study indicates that a decrease in Hedgehog signaling is necessary but not sufficient to trigger adipocyte differentiation and unveils a striking difference in the adipocyte differentiation process between rodent and human mesenchymal stem cells.
Assuntos
Adipócitos/fisiologia , Diferenciação Celular/fisiologia , Proteínas Hedgehog/fisiologia , Células-Tronco Mesenquimais/fisiologia , Transdução de Sinais/fisiologia , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Feminino , Proteínas Hedgehog/metabolismo , Humanos , Lactente , Masculino , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Morfolinas/farmacologia , Purinas/farmacologia , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: Multipotent stem cells exist within adipose tissue throughout life. An abnormal recruitment of these adipose precursor cells could participate to hyperplasia of adipose tissue observed in severe obesity or to hypoplasia of adipose tissue observed in lipodystrophy. Therefore, pharmacological molecules that control the pool of stem cells in adipose tissue are of great interest. Glycogen Synthase Kinase (GSK) 3 has been previously described as involved in differentiation of preadipose cells and might be a potential therapeutic target to modulate proliferation and differentiation of adipocyte precursors. However, the impact of GSK3 inhibition on human adipose-derived stem cells remained to be investigated. The aim of this study was to investigate GSK3 as a possible target for pharmacological inhibition of stem cell adipogenesis. To reach this goal, we studied the effects of pharmacological inhibitors of GSK3, i.e. lithium chloride (LiCl) and BIO on proliferation and adipocyte differentiation of multipotent stem cells derived from human adipose tissue. RESULTS: Our results showed that GSK3 inhibitors inhibited proliferation and clonogenicity of human stem cells, strongly suggesting that GSK3 inhibitors could be potent regulators of the pool of adipocyte precursors in adipose tissue. The impact of GSK3 inhibition on differentiation of hMADS cells was also investigated. Adipogenic and osteogenic differentiations were inhibited upon hMADS treatment with BIO. Whereas a chronic treatment was required to inhibit osteogenesis, a treatment that was strictly restricted to the early step of differentiation was sufficient to inhibit adipogenesis. CONCLUSION: These results demonstrated the feasibility of a pharmacological approach to regulate adipose-derived stem cell function and that GSK3 could represent a potential target for controlling adipocyte precursor pool under conditions where fat tissue formation is impaired.
Assuntos
Adipócitos/citologia , Tecido Adiposo/citologia , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Células-Tronco/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Adipogenia/efeitos dos fármacos , Adipogenia/fisiologia , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Pré-Escolar , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Imuno-Histoquímica , Lactente , Cloreto de Lítio/farmacologia , Masculino , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismoRESUMO
Morphogenes, abundantly described during embryogenesis have recently emerged as crucial modulators of cell differentiation processes. Hedgehog signaling, the dysregulation of which causing several pathologies such as congenital defects and cancer, is involved in several cell differentiation processes including adipogenesis. This review presents an overview of the relations between Hedgehog signaling, adipocyte differentiation and fat mass. While the anti-adipogenic role of Hedgehog signaling seems to be established, the effect of Hedgehog inhibition on adipocyte differentiation in vitro remains debated. Finally, Hedgehog potential as a pharmacological target to treat fat mass disorders is discussed.
Assuntos
Adipócitos/citologia , Adipogenia , Proteínas Hedgehog/metabolismo , Obesidade/genética , Adipócitos/metabolismo , Animais , Diferenciação Celular , Proteínas Hedgehog/antagonistas & inibidores , Lipodistrofia/metabolismo , Modelos Biológicos , Obesidade/metabolismo , Transdução de SinaisRESUMO
In response to endotoxemia, the organism triggers an inflammatory response, and the visceral adipose tissue represents a major source of proinflammatory cytokines. The regulation of inflammation response in the adipose tissue is thus of crucial importance. We demonstrated that Regulated in development and DNA damage response-1 (REDD1) is involved in inflammation. REDD1 expression was increased in response to lipopolysaccharide (LPS) in bone marrow derived macrophages (BMDM) and in epidydimal adipose tissue. Loss of REDD1 protected the development of inflammation, since the expression of proinflammatory cytokines (TNFα, IL-6, IL-1ß) was decreased in adipose tissue of REDD1-/- mice injected with LPS compared to wild-type mice. This decrease was associated with an inhibition of the activation of p38MAPK, JNK, NF-κB and NLRP3 inflammasome leading to a reduction of IL-1ß secretion in response to LPS and ATP in REDD1-/- BMDM. Although REDD1 is an inhibitor of mTORC1, loss of REDD1 decreased inflammation independently of mTORC1 activation but more likely through oxidative stress regulation. Absence of REDD1 decreases ROS associated with a dysregulation of Nox-1 and GPx3 expression. Absence of REDD1 in macrophages decreases the development of insulin resistance in adipocyte-macrophage coculture. Altogether, REDD1 appears to be a key player in the control of inflammation.
Assuntos
Endotoxinas/toxicidade , Inflamação/induzido quimicamente , Inflamação/fisiopatologia , Fatores de Transcrição/metabolismo , Tecido Adiposo/patologia , Animais , Citocinas/metabolismo , Epididimo/patologia , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Knockout , Fatores de Transcrição/deficiênciaRESUMO
Autologous fat grafting is a gold standard therapy for soft tissue defects, but is hampered by unpredictable postoperative outcomes. Fat graft enrichment with adipose-derived stromal cell (ASCs) was recently reported to enhance graft survival. Platelet-rich plasma (PRP) has also emerged as a biologic scaffold that promotes fat graft viability. Combined ASC/PRP fat grafting enrichment is thus a promising new regenerative medicine approach. The effects of PRP on ASC proliferation are well documented, but the impact of PRP on ASC differentiation has yet to be investigated in depth to further elucidate the PRP clinical effects. Here we analyzed the human ASC fate upon PRP treatment. PRP was found to sharply reduce the potential of ASCs to undergo differentiation into adipocytes. Interestingly, the PRP anti-adipogenic effect was accompanied by the generation of myofibroblast-like cells. Among the various factors released from PRP, TGFß pathway activators played a critical role in both the anti-adipogenic and pro-myofibroblastic PRP effects. Overall, these data suggest that PRP participates in maintaining a pool of ASCs and in the repair process by promoting ASC differentiation into myofibroblast-like cells. TGFß may provide an important target pathway to improve PRP clinical outcomes.
Assuntos
Adipogenia , Tecido Adiposo/citologia , Diferenciação Celular , Miofibroblastos/citologia , Miofibroblastos/metabolismo , Plasma Rico em Plaquetas/metabolismo , Células Estromais/citologia , Células Estromais/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Adipócitos/citologia , Adipócitos/metabolismo , Idoso , Benzamidas/farmacologia , Células Cultivadas , Dioxóis/farmacologia , Feminino , Humanos , Lactente , Masculino , FenótipoRESUMO
The primary cilium is an organelle present in most of the cells of the organism. Ciliopathies, such as the Bardet Biedl and the Alstrom syndromes are associated with obesity. We, and others, have shown that the primary cilium undergoes size modifications during adipocyte differentiation of human adipose stromal cells. We show here that the levels of acetylated α-tubulin, a constituent of the primary cilium, and the expression of HDAC6, the enzyme that deacetylates α-tubulin and is responsible for the loss of the cilium during mitosis, are modulated during adipogenesis. Moreover, during adipocyte differentiation cells that express higher level of HDAC6 are the first to lose their primary cilium. We have investigated the function of HDAC6 on adipocyte differentiation and on the primary cilium. We observe that inhibition of HDAC6 activity leads to a decrease in adipocyte differentiation. This is associated with an inhibition of the initial elongation of the cilium. Interestingly, overexpression of HDAC6 inhibits adipocyte differentiation and blunts the elongation of the primary cilium. In both situations, inhibition of adipocyte differentiation was not associated with an inhibition of the glucocorticoid receptor activity. This indicates that HDAC6 controls adipogenesis through the levels of acetylated α-tubulin. Moreover, we show that although HDAC6 expression increases during adipocyte differentiation it is not sufficient to provoke the loss of the cilium. This suggests the existence of a novel mechanism for the loss of the cilium. Together, these data indicate that HDAC6, and acetylated α-tubulin, are important regulator of adipocyte differentiation.
Assuntos
Adipócitos/metabolismo , Adipogenia/fisiologia , Diferenciação Celular/fisiologia , Histona Desacetilases/metabolismo , Tubulina (Proteína)/metabolismo , Acetilação , Adipócitos/citologia , Linhagem Celular , Cílios/metabolismo , Desacetilase 6 de Histona , HumanosRESUMO
Human induced pluripotent stem cells (hiPSCs) show great promise for obesity treatment as they represent an unlimited source of brown/brite adipose progenitors (BAPs). However, hiPSC-BAPs display a low adipogenic capacity compared to adult-BAPs when maintained in a traditional adipogenic cocktail. The reasons of this feature are unknown and hamper their use both in cell-based therapy and basic research. Here we show that treatment with TGFß pathway inhibitor SB431542 together with ascorbic acid and EGF were required to promote hiPSCs-BAP differentiation at a level similar to adult-BAP differentiation. hiPSC-BAPs expressed the molecular identity of adult-UCP1 expressing cells (PAX3, CIDEA, DIO2) with both brown (ZIC1) and brite (CD137) adipocyte markers. Altogether, these data highlighted the critical role of TGFß pathway in switching off hiPSC-brown adipogenesis and revealed novel factors to unlock their differentiation. As hiPSC-BAPs display similarities with adult-BAPs, it opens new opportunities to develop alternative strategies to counteract obesity.
Assuntos
Adipócitos Marrons/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Transdução de Sinais/genética , Fator de Crescimento Transformador beta/antagonistas & inibidores , Adipócitos Marrons/citologia , Adipócitos Marrons/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Ácido Ascórbico/farmacologia , Benzamidas/farmacologia , Biomarcadores/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Dioxóis/farmacologia , Fator de Crescimento Epidérmico/farmacologia , Expressão Gênica , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Iodeto Peroxidase/genética , Iodeto Peroxidase/metabolismo , Fator de Transcrição PAX3/genética , Fator de Transcrição PAX3/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo , Membro 9 da Superfamília de Receptores de Fatores de Necrose Tumoral/genética , Membro 9 da Superfamília de Receptores de Fatores de Necrose Tumoral/metabolismo , Iodotironina Desiodinase Tipo IIRESUMO
Defects in insulin secretion, resulting from loss of function or destruction of pancreatic beta-cells, trigger diabetes. Interleukin (IL)-1beta is a proinflammatory cytokine that is involved in type 1 and type 2 diabetes development and impairs beta-cell survival and function. Because effective insulin signaling is required for the optimal beta-cell function, we assessed the effect of IL-1beta on the insulin pathway in a rat pancreatic beta-cell line. We show that IL-1beta decreases insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and insulin receptor substrate (IRS) proteins as well as phosphatidylinositol 3-kinase (PI3K) activation, and that this action is not due to the IL-1beta-dependent nitric oxide (NO) production in RINm5F cells. We next analyzed if suppressor of cytokine signaling (SOCS)-3, which can be induced by multiple cytokines and which we identified as an insulin action inhibitor, was implicated in the IL-1beta inhibitory effect on insulin signaling in these cells. We show that IL-1beta increases SOCS-3 expression and induces SOCS-3/IR complex formation in RINm5F cells. Moreover, we find that ectopically expressed SOCS-3 associates with the IR and reduces insulin-dependent IR autophosphorylation and IRS/PI3K pathway in a way comparable to IL-1beta treatment in RINm5F cells. We propose that IL-1beta decreases insulin action in beta-cells through the induction of SOCS-3 expression, and that this effect potentially alters insulin-induced beta-cell survival.
Assuntos
Insulina/metabolismo , Interleucina-1/farmacologia , Ilhotas Pancreáticas/fisiologia , Proteínas Repressoras/fisiologia , Fatores de Transcrição/fisiologia , Animais , Linhagem Celular Tumoral , Clonagem Molecular , DNA Complementar/genética , Regulação Neoplásica da Expressão Gênica , Secreção de Insulina , Insulinoma , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/imunologia , Neoplasias Pancreáticas , Fosforilação , RNA Mensageiro/genética , Ratos , Proteínas Recombinantes/metabolismo , Proteínas Repressoras/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina , Fatores de Transcrição/genéticaRESUMO
During obesity, a hypoxic state develops within the adipose tissue, resulting in insulin resistance. To understand the underlying mechanism, we analyzed the involvement of caveolae because they play a crucial role in the activation of insulin receptors. In the present study, we demonstrate that in 3T3-L1 adipocytes, hypoxia induces the disappearance of caveolae and inhibits the expression of Cavin-1 and Cavin-2, two proteins necessary for the formation of caveolae. In mice, hypoxia induced by the ligature of the spermatic artery results in the decrease of cavin-1 and cavin-2 expression in the epididymal adipose tissue. Down-regulation of the expression of cavins in response to hypoxia is dependent on hypoxia-inducible factor-1. Indeed, the inhibition of hypoxia-inducible factor-1 restores the expression of cavins and caveolae formation. Expression of cavins regulates insulin signaling because the silencing of cavin-1 and cavin-2 impairs insulin signaling pathway. In human, cavin-1 and cavin-2 are decreased in the sc adipose tissue of obese diabetic patients compared with lean subjects. Moreover, the expression of cavin-2 correlates negatively with the homeostatic model assessment index of insulin resistance and glycated hemoglobin level. In conclusion, we propose a new mechanism in which hypoxia inhibits cavin-1 and cavin-2 expression, resulting in the disappearance of caveolae. This leads to the inhibition of insulin signaling and the establishment of insulin resistance.
Assuntos
Adipócitos/efeitos dos fármacos , Cavéolas/fisiologia , Proteínas de Membrana/metabolismo , Oxigênio/farmacologia , Proteínas de Ligação a RNA/metabolismo , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Regulação para Baixo , Feminino , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Obesidade , Proteínas de Ligação a Fosfato , Interferência de RNA , RNA Interferente Pequeno , Proteínas de Ligação a RNA/genética , Transdução de SinaisRESUMO
Adipose tissue is an alternative source of mesenchymal stem cells and human adipose-derived stem cells (ASCs) display an attractive and substantial therapeutic potential when transplanted in animal models. To this end, an understanding of ASC biology is necessary and the knowledge of mechanisms that maintain ASCs in an undifferentiated state with no loss of differentiation potential during ex vivo expansion represents a crucial step. However, these mechanisms remain to be identified because appropriate human cellular models are scant. In this review we will describe a cellular model isolated from human adipose tissue displaying all the features of stem cells. Then, we will focus on the identification of intrinsic and extrinsic factors regulating the balance between human ASC proliferation and differentiation. We will point out the role of factors secreted by undifferentiated ASCs, such a FGF2, activin A, BMP4, Hedgehog molecules and secreted by adipose tissue macrophages. Finally, we will outline the role of miRNAs in these processes.