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Lipodystrophy is a rare disorder which can be life-threatening. Here individuals fail to develop or maintain appropriate adipose tissue stores. This typically causes severe metabolic complications, including hepatic steatosis and lipoatrophic diabetes. There is no cure for lipodystrophy, and treatment options remain very limited. Here we evaluate whether tissue-selective adeno-associated virus (AAV) vectors can provide a targeted form of gene therapy for lipodystrophy, using a preclinical lipodystrophic mouse model of Bscl2 deficiency. We designed AAV vectors containing the mini/aP2 or thyroxine-binding globulin promoter to selectively target adipose or liver respectively. The AAV-aP2 vectors also contained the liver-specific microRNA-122 target sequence, restricting hepatic transgene expression. Systemic delivery of AAV-aP2 vectors overexpressing human BSCL2 restored adipose tissue development and metabolic health in lipodystrophic mice without detectable expression in the liver. High doses (1 × 1012 GCs) of liver-selective vectors led to off target expression and adipose tissue development, whilst low doses (1 × 1010 GCs) expressed selectively and robustly in the liver but did not improve metabolic health. This reveals that adipose tissue-selective, but not liver directed, AAV-mediated gene therapy is sufficient to substantially recover metabolic health in generalised lipodystrophy. This provides an exciting potential new avenue for an effective, targeted, and thereby safer therapeutic intervention.
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Tecido Adiposo , Dependovirus , Terapia Genética , Vetores Genéticos , Lipodistrofia Generalizada Congênita , Fígado , Animais , Terapia Genética/métodos , Camundongos , Dependovirus/genética , Vetores Genéticos/genética , Vetores Genéticos/administração & dosagem , Fígado/metabolismo , Humanos , Lipodistrofia Generalizada Congênita/terapia , Lipodistrofia Generalizada Congênita/genética , Lipodistrofia Generalizada Congênita/metabolismo , Tecido Adiposo/metabolismo , Modelos Animais de Doenças , Subunidades gama da Proteína de Ligação ao GTP/genética , Subunidades gama da Proteína de Ligação ao GTP/metabolismoRESUMO
OBJECTIVE: Obesity increases osteoarthritis (OA) risk due to adipose tissue dysfunction with associated metabolic syndrome and excess weight. Lipodystrophy syndromes exhibit systemic metabolic and inflammatory abnormalities similar to obesity without biomechanical overloading. Here, we used lipodystrophy mouse models to investigate the effects of systemic versus intra-articular adipose tissue dysfunction on the knee. METHODS: Intra-articular adipose tissue development was studied using reporter mice. Mice with selective lipodystrophy of intra-articular adipose tissue were generated by conditional knockout (cKO) of Bscl2 in Gdf5-lineage cells, and compared with whole-body Bscl2 knockout (KO) mice with generalised lipodystrophy and associated systemic metabolic dysfunction. OA was induced by surgically destabilising the medial meniscus (DMM) and obesity by high-fat diet (HFD). Gene expression was analysed by quantitative RT-PCR and tissues were analysed histologically. RESULTS: The infrapatellar fat pad (IFP), in contrast to overlying subcutaneous adipose tissue, developed from a template established from the Gdf5-expressing joint interzone during late embryogenesis, and was populated shortly after birth by adipocytes stochastically arising from Pdgfrα-expressing Gdf5-lineage progenitors. While female Bscl2 KO mice with generalised lipodystrophy developed spontaneous knee cartilage damage, Bscl2 cKO mice with intra-articular lipodystrophy did not, despite the presence of synovial hyperplasia and inflammation of the residual IFP. Furthermore, male Bscl2 cKO mice showed no worse cartilage damage after DMM. However, female Bscl2 cKO mice showed increased susceptibility to the cartilage-damaging effects of HFD-induced obesity. CONCLUSION: Our findings emphasise the prevalent role of systemic metabolic and inflammatory effects in impairing cartilage homeostasis, with a modulatory role for intra-articular adipose tissue.
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AIMS: Lipodystrophy is a rare disorder characterised by abnormal or deficient adipose tissue formation and distribution. It poses significant challenges to affected individuals, including the development of severe metabolic complications like diabetes and fatty liver disease. These conditions are often chronic, debilitating and life-threatening, with limited treatment options and a lack of specialised expertise. This review aims to raise awareness of lipodystrophy disorders and highlights therapeutic strategies to restore adipose tissue functionality. METHODS: Extensive research has been conducted, including both historical and recent advances. We have examined and summarised the literature to provide an overview of potential strategies to restore adipose tissue functionality and treat/reverse metabolic complications in lipodystrophy disorders. RESULTS: A wealth of basic and clinical research has investigated various therapeutic approaches for lipodystrophy. These include ground-breaking methods such as adipose tissue transplantation, innovative leptin replacement therapy, targeted inhibition of lipolysis and cutting-edge gene and cell therapies. Each approach shows great potential in addressing the complex challenges posed by lipodystrophy. CONCLUSIONS: Lipodystrophy disorders require urgent attention and innovative treatments. Through rigorous basic and clinical research, several promising therapeutic strategies have emerged that could restore adipose tissue functionality and reverse the severe metabolic complications associated with this condition. However, further research and collaboration between academics, clinicians, patient advocacy groups and pharmaceutical companies will be crucial in transforming these scientific breakthroughs into effective and viable treatment options for individuals and families affected by lipodystrophy. Fostering such interdisciplinary partnerships could pave the way for a brighter future for those battling this debilitating disorder.
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Lipodistrofia , Hepatopatia Gordurosa não Alcoólica , Humanos , Tecido Adiposo/metabolismo , Leptina/metabolismo , Lipodistrofia/terapia , Lipólise , Hepatopatia Gordurosa não Alcoólica/complicaçõesRESUMO
Objective: The ß-site APP-cleaving enzyme 1 (BACE1) is a rate-limiting step in ß-amyloid (Aß) production in Alzheimer's disease (AD) brains, but recent evidence suggests that BACE1 is also involved in metabolic regulation. Here, we aimed to assess the effects of highfat diet (HFD) on metabolic and cognitive phenotypes in the diabetic BACE1 knock-in mice (PLB4) and WT controls; we additionally examined whether these phenotypes can be normalized with a synthetic retinoid (Fenretinide, Fen) targeting weight loss.Methods: Five-month old male WT and PLB4 mice were fed either (1) control chow diet, (2) 45%-saturated fat diet (HFD), (3) HFD with 0.04% Fen (HFD + Fen) or (4) control chow diet with 0.04% Fen (Fen) for 10 weeks. We assessed basic metabolic parameters, circadian rhythmicity, spatial habituation (Phenotyper) and working memory (Y-maze). Hypothalami, forebrain and liver tissues were assessed using Western blots, qPCR and ELISAs.Results: HFD feeding drastically worsened metabolism and induced early mortality (-40%) in otherwise viable PLB4 mice. This was ameliorated by Fen, despite no effects on glucose intolerance. In HFD-fed WT mice, Fen reduced weight gain, glucose intolerance and hepatic steatosis. The physiological changes induced in WT and PLB4 mice by HFD (+/-Fen) were accompanied by enhanced cerebral astrogliosis, elevated PTP1B, phopsho-eIF2α and altered hypothalamic transcription of Bace1, Pomc and Mc4r. Behaviourally, HFD feeding exacerbated spatial memory deficits in PLB4 mice, which was prevented by Fen and linked with increased full-length APP, normalized brain Aß*56 oligomerization and astrogliosis.Conclusions: HFD induces early mortality and worsened cognition in the Alzheimer's-like BACE1 mice- partial prevention was achieved with Fenretinide, without improvements in glucose homeostasis.
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Doença de Alzheimer , Fenretinida , Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Ácido Aspártico Endopeptidases/genética , Ácido Aspártico Endopeptidases/metabolismo , Cognição , Dieta Hiperlipídica/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
Aims: Individuals with lipodystrophies typically suffer from metabolic disease linked to adipose tissue dysfunction including lipoatrophic diabetes. In the most severe forms of lipodystrophy, congenital generalised lipodystrophy, adipose tissue may be almost entirely absent. Better therapies for affected individuals are urgently needed. Here we performed the first detailed investigation of the effects of a glucagon like peptide-1 receptor (GLP-1R) agonist in lipoatrophic diabetes, using mice with generalised lipodystrophy. Methods: Lipodystrophic insulin resistant and glucose intolerant seipin knockout mice were treated with the GLP-1R agonist liraglutide either acutely preceding analyses of insulin and glucose tolerance or chronically prior to metabolic phenotyping and ex vivo studies. Results: Acute liraglutide treatment significantly improved insulin, glucose and pyruvate tolerance. Once daily injection of seipin knockout mice with liraglutide for 14 days led to significant improvements in hepatomegaly associated with steatosis and reduced markers of liver fibrosis. Moreover, liraglutide enhanced insulin secretion in response to glucose challenge with concomitantly improved glucose control. Conclusions: GLP-1R agonist liraglutide significantly improved lipoatrophic diabetes and hepatic steatosis in mice with generalised lipodystrophy. This provides important insights regarding the benefits of GLP-1R agonists for treating lipodystrophy, informing more widespread use to improve the health of individuals with this condition.
Assuntos
Receptor do Peptídeo Semelhante ao Glucagon 1 , Lipodistrofia , Liraglutida , Animais , Masculino , Camundongos , Glicemia/metabolismo , Modelos Animais de Doenças , Receptor do Peptídeo Semelhante ao Glucagon 1/agonistas , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Hipoglicemiantes/farmacologia , Hipoglicemiantes/uso terapêutico , Insulina/metabolismo , Resistência à Insulina , Lipodistrofia/tratamento farmacológico , Lipodistrofia/metabolismo , Liraglutida/farmacologia , Liraglutida/uso terapêutico , Doenças Metabólicas/tratamento farmacológico , Doenças Metabólicas/metabolismo , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
Lipodystrophy syndromes are rare diseases primarily affecting the development or maintenance of the adipose tissue but are also distressing indirectly multiple organs and tissues, often leading to reduced life expectancy and quality of life. Lipodystrophy syndromes are multifaceted disorders caused by genetic mutations or autoimmunity in the vast majority of cases. While many subtypes are now recognized and classified, the disease remains remarkably underdiagnosed. The European Consortium of Lipodystrophies (ECLip) was founded in 2014 as a non-profit network of European centers of excellence working in the field of lipodystrophies aiming at promoting international collaborations to increase basic scientific understanding and clinical management of these syndromes. The network has developed a European Patient Registry as a collaborative research platform for consortium members. ECLip and ECLip registry activities involve patient advocacy groups to increase public awareness and to seek advice on research activities relevant from the patients perspective. The annual ECLip congress provides updates on the research results of various network groups members.
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Lipodistrofia , Humanos , Europa (Continente) , Itália , Lipodistrofia/terapia , Lipodistrofia/diagnósticoRESUMO
Congenital generalized lipodystrophy type 2 is a serious multisystem disorder with limited treatment options. It is caused by mutations affecting the BSCL2 gene, which encodes the protein seipin. Patients with congenital generalized lipodystrophy type 2 lack both metabolic and mechanical adipose tissue and develop severe metabolic complications including hepatic steatosis, lipoatrophic diabetes, and cardiovascular disease. Gene therapies are becoming viable treatments, helping to alleviate inherited and acquired human disorders. We aimed to determine whether gene therapy could offer an effective form of medical intervention for lipodystrophy. We examined whether systemic adeno-associated virus delivery of human BSCL2 could reverse metabolic disease in seipin knockout mice, where white adipose tissue is absent. We reveal that adeno-associated virus gene therapy targets adipose progenitor cells in vivo and substantially restores white adipose tissue development in adult seipin knockout mice. This resulted in both rapid and prolonged beneficial effects to metabolic health in this pre-clinical mouse model of congenital generalized lipodystrophy type 2. Hyperglycemia was normalized within 2 weeks post-treatment together with normalization of severe insulin resistance. We propose that gene therapy offers great potential as a therapeutic strategy to correct multiple metabolic complications in patients with congenital lipodystrophy.
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Congenital Generalized Lipodystrophy type 2 (CGL2) is the most severe form of lipodystrophy and is caused by mutations in the BSCL2 gene. Affected patients exhibit a near complete lack of adipose tissue and suffer severe metabolic disease. A recent study identified infection as a major cause of death in CGL2 patients, leading us to examine whether Bscl2 loss could directly affect the innate immune response. We generated a novel mouse model selectively lacking Bscl2 in the myeloid lineage (LysM-B2KO) and also examined the function of bone-marrow-derived macrophages (BMDM) isolated from global Bscl2 knockout (SKO) mice. LysM-B2KO mice failed to develop lipodystrophy and metabolic disease, providing a model to study the direct role of Bscl2 in myeloid lineage cells. Lipopolysaccharide-mediated stimulation of inflammatory cytokines was not impaired in LysM-B2KO mice or in BMDM isolated from either LysM-B2KO or SKO mice. Additionally, intracellular fate and clearance of bacteria in SKO BMDM challenged with Staphylococcus aureus was indistinguishable from that in BMDM isolated from littermate controls. Overall, our findings reveal that selective Bscl2 deficiency in macrophages does not critically impact the innate immune response to infection. Instead, an increased susceptibility to infection in CGL2 patients is likely to result from severe metabolic disease.
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Mutations affecting the BSCL2 gene cause the most severe form of congenital generalised lipodystrophy (CGL). Affected individuals develop severe metabolic complications including diabetes and hepatic steatosis. Bscl2-deficient mice almost entirely reproduce the CGL phenotype. Adipose tissue-specific loss of Bscl2 is also sufficient to cause early-onset generalised lipodystrophy in mice. However, these mice do not show severe metabolic dysfunction, even when challenged with a high-fat diet. Germline Bscl2 loss in mice and BSCL2 disruption in humans causes severe hepatic steatosis, and the encoded protein, seipin, has acknowledged roles in lipid accumulation. Given the critical role of the liver in glucose regulation, we speculated that intact hepatic Bscl2 expression may protect adipose tissue-specific Bscl2-deficient mice from metabolic disease. To investigate this, we generated a novel mouse model in which Bscl2 has been deleted in both adipose tissue and hepatocytes simultaneously using an adeno-associated viral vector. Despite achieving efficient disruption of Bscl2 in the liver, hepatic lipid accumulation and metabolic homeostasis was unaffected in mice fed a high-fat diet for 4 weeks. We also investigated the consequences of BSCL2 ablation in the human hepatocyte HepG2 cell line using CRISPR/Cas9 genome editing. No significant increases in lipid accumulation were observed in BSCL2 knockout cell lines. Overall, we reveal that Bscl2/BSCL2 does not appear to play a cell-autonomous role in the regulation of lipid accumulation in the liver. Loss of hepatic BSCL2 is therefore unlikely to contribute significantly to the development of hepatic steatosis or metabolic dysfunction in this form of CGL.
Assuntos
Subunidades gama da Proteína de Ligação ao GTP/fisiologia , Hepatócitos/metabolismo , Metabolismo dos Lipídeos , Lipodistrofia Generalizada Congênita/metabolismo , Tecido Adiposo/metabolismo , Animais , Feminino , Células Hep G2 , Humanos , Masculino , CamundongosRESUMO
Seipin deficiency causes severe congenital generalized lipodystrophy (CGL) and metabolic disease. However, how seipin regulates adipocyte development and function remains incompletely understood. We previously showed that seipin acts as a scaffold protein for AGPAT2, whose disruption also causes CGL. More recently, seipin has been reported to promote adipogenesis by directly inhibiting GPAT3, leading to the suggestion that GPAT inhibitors could offer novel treatments for CGL. Here we investigated the interactions between seipin, GPAT3 and AGPAT2. We reveal that seipin and GPAT3 associate via direct interaction and that seipin can simultaneously bind GPAT3 and AGPAT2. Inhibiting the expression of seipin, AGPAT2 or GPAT3 led to impaired induction of early markers of adipocyte differentiation in cultured cells. However, consistent with normal adipose mass in GPAT3-null mice, GPAT3 inhibition did not prevent the formation of mature adipocytes. Nonetheless, loss of GPAT3 in seipin-deficient preadipocytes exacerbated the failure of adipogenesis in these cells. Thus, our data indicate that GPAT3 plays a modest positive role in adipogenesis and argue against the potential of GPAT inhibitors to rescue white adipose tissue mass in CGL2. Overall, our study reveals novel mechanistic insights regarding the molecular pathogenesis of severe lipodystrophy caused by mutations in either seipin or AGPAT2.
Assuntos
1-Acilglicerol-3-Fosfato O-Aciltransferase/metabolismo , Aciltransferases/metabolismo , Adipócitos/citologia , Subunidades gama da Proteína de Ligação ao GTP/metabolismo , Células 3T3-L1 , Adipogenia , Tecido Adiposo/patologia , Animais , Diferenciação Celular , Diabetes Mellitus Tipo 2/metabolismo , Regulação da Expressão Gênica , Células HEK293 , Humanos , Metabolismo dos Lipídeos , Camundongos , Camundongos Endogâmicos C3H , Microscopia de Força Atômica , MutaçãoRESUMO
Mutations affecting the BSCL2 gene cause the most severe form of congenital generalised lipodystrophy. Affected individuals almost completely lack adipose tissue and suffer from severe diabetes and metabolic complications. Likewise, mice lacking Bscl2 in all tissues have dramatically reduced adipose mass, glucose intolerance and hyperinsulinaemia. However, male adipose tissue-specific Bscl2 knockout mice fail to develop the metabolic dysfunction observed in Bscl2 null mice and BSCL2 deficient patients, despite a similar generalised lack of adipose tissues. Clinical reports indicate gender differences frequently exist in cases of lipodystrophy, with female patients more adversely affected than male patients. We therefore generated and characterised female mice lacking Bscl2 specifically in adipose tissue (Ad-B2(-/-)). We show that female Ad-B2(-/-) mice also develop early-onset lipodystrophy when fed a chow diet and are maintained under standard housing conditions (21 °C) or thermoneutrality (30 °C). Despite this, female Ad-B2(-/-) mice fail to develop severe metabolic dysfunction. Only when female Ad-B2(-/-) mice are maintained at thermoneutrality and fed a high-fat diet do subtle alterations to metabolic homeostasis manifest. This is despite a striking inability to expand adipose mass. Our findings provide further evidence that loss of Bscl2 in non-adipose tissues may contribute to the severity of metabolic dysfunction in this condition.
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Tecido Adiposo/patologia , Dieta Hiperlipídica , Proteínas Heterotriméricas de Ligação ao GTP/deficiência , Lipodistrofia/patologia , Temperatura , Animais , Feminino , Subunidades gama da Proteína de Ligação ao GTP , Intolerância à Glucose/patologia , Hiperinsulinismo/patologia , Camundongos KnockoutRESUMO
OBJECTIVE: Mutations to the BSCL2 gene disrupt the protein seipin and cause the most severe form of congenital generalised lipodystrophy (CGL). Affected individuals exhibit a near complete loss of white adipose tissue (WAT) and suffer from metabolic disease. Seipin is critical for adipocyte development in culture and mice with germline disruption to Bscl2 recapitulate the effects of BSCL2 disruption in humans. Here we examined whether loss of Bscl2 specifically in developing adipocytes in vivo is sufficient to prevent adipose tissue development and cause all features observed with congenital BSCL2 disruption. METHODS: We generated and characterised a novel mouse model of Bscl2 deficiency in developing adipocytes (Ad-B2(-/-)) using the adipose-specific Adiponectin-Cre line. RESULTS: We demonstrate that Ad-B2(-/-) mice display early onset lipodystrophy, in common with congenital Bscl2 null mice and CGL2 patients. However, glucose intolerance, insulin resistance, and severe hepatic steatosis are not apparent. Food intake and energy expenditure are unchanged, but Ad-B2(-/-) mice exhibit significantly altered substrate utilisation. We also find differential effects of seipin loss between specific adipose depots revealing new insights regarding their varied characteristics. When fed a high-fat diet, Ad-B2(-/-) mice entirely fail to expand adipose mass but remain glucose tolerant. CONCLUSIONS: Our findings demonstrate that disruption of Bscl2 specifically in developing adipocytes is sufficient to cause the early-onset generalised lipodystrophy observed in patients with mutations in BSCL2. However, this significant reduction in adipose mass does not cause the overt metabolic dysfunction seen in Bscl2 knockout mice, even following a high-fat diet challenge.
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Adipócitos/metabolismo , Adipogenia , Metabolismo Energético , Proteínas Heterotriméricas de Ligação ao GTP/genética , Lipodistrofia/genética , Adipócitos/citologia , Animais , Subunidades gama da Proteína de Ligação ao GTP , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Lipodistrofia/metabolismo , Lipodistrofia/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Fibroblast growth factor 21 (FGF21) has emerged as an important beneficial regulator of glucose and lipid homeostasis but its levels are also abnormally increased in insulin-resistant states in rodents and humans. The synthetic retinoid Fenretinide inhibits obesity and improves glucose homeostasis in mice and has pleotropic effects on cellular pathways. To identify Fenretinide target genes, we performed unbiased RNA-seq analysis in liver from mice fed high-fat diet ± Fenretinide. Strikingly, Fgf21 was the most downregulated hepatic gene. Fenretinide normalised elevated levels of FGF21 in both high-fat diet-induced obese mice and in genetically obese-diabetic Leprdbmice. Moreover, Fenretinide-mediated suppression of FGF21 was independent of body weight loss or improved hepatic insulin sensitivity and importantly does not induce unhealthy metabolic complications. In mice which have substantially decreased endogenous retinoic acid biosynthesis, Fgf21 expression was increased, whereas acute pharmacological retinoid treatment decreased FGF21 levels. The repression of FGF21 levels by Fenretinide occurs by reduced binding of RARα and Pol-II at the Fgf21 promoter. We therefore establish Fgf21 as a novel gene target of Fenretinide signalling via a retinoid-dependent mechanism. These results may be of nutritional and therapeutic importance for the treatment of obesity and type-2 diabetes.
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Fenretinida/farmacologia , Fatores de Crescimento de Fibroblastos/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Resistência à Insulina/genética , Obesidade/genética , Tecido Adiposo Branco/efeitos dos fármacos , Tecido Adiposo Branco/metabolismo , Animais , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica , Fatores de Crescimento de Fibroblastos/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Obesidade/metabolismo , Regiões Promotoras Genéticas/genéticaRESUMO
Fenretinide (FEN) is a synthetic retinoid that inhibits obesity and insulin resistance in high-fat diet (HFD)-fed mice and completely prevents 3T3-L1 pre-adipocyte differentiation. The aim of this study was to determine the mechanism(s) of FEN action in 3T3-L1 adipocytes and in mice. We used the 3T3-L1 model of adipogenesis, fully differentiated 3T3-L1 adipocytes and adipose tissue from HFD-induced obese mice to investigate the mechanisms of FEN action. We measured expression of adipogenic and retinoid genes by qPCR and activation of nutrient-signalling pathways by western blotting. Global lipid and metabolite analysis was performed and specific ceramide lipid species measured by liquid chromatography-mass spectrometry. We provide direct evidence that FEN inhibits 3T3-L1 adipogenesis via RA-receptor (RAR)-dependent signaling. However, RARα antagonism did not prevent FEN-induced decreases in lipid levels in mature 3T3-L1 adipocytes, suggesting an RAR-independent mechanism. Lipidomics analysis revealed that FEN increased dihydroceramide lipid species 5- to 16-fold in adipocytes, indicating an inhibition of the final step of ceramide biosynthesis. A similar blockade in adipose tissue from FEN-treated obese mice was associated with a complete normalisation of impaired mitochondrial ß-oxidation and tricarboxylic acid cycle flux. The FEN catabolite, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-OXO), also decreased lipid accumulation without affecting adipogenesis. FEN and 4-OXO (but not RA) treatment additionally led to the activation of p38-MAPK, peIF2α and autophagy markers in adipocytes. Overall our data reveals FEN utilises both RAR-dependent and -independent pathways to regulate adipocyte biology, both of which may be required for FEN to prevent obesity and insulin resistance in vivo.
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Adipócitos/metabolismo , Adipogenia/fisiologia , Ceramidas/biossíntese , Fenretinida/farmacologia , Lipogênese/fisiologia , Mitocôndrias/metabolismo , Receptores do Ácido Retinoico/fisiologia , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipogenia/efeitos dos fármacos , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Animais , Ceramidas/antagonistas & inibidores , Dieta Hiperlipídica/efeitos adversos , Lipogênese/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Mitocôndrias/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologiaRESUMO
OBJECTIVE: The synthetic retinoid fenretinide (FEN) inhibits adiposity in male mice fed a high-fat diet (HFD) in association with alterations in retinoic acid (RA) signaling. Young female mice are protected from obesity via estrogen signaling. We, therefore, investigated whether FEN also influences adiposity in aged female mice differing in parity and whether such effects are mediated by retinoid and estrogen signaling. METHODS: Aged nulliparous and parous female mice were maintained on HFD ± FEN, and adiposity was assessed. Quantitative polymerase chain reaction was performed on white adipose tissue (WAT), liver, and 3T3-L1 adipocytes treated with RA or FEN ± estrogen. RESULTS: Parous females were more obese than nulliparous mice independent of age. FEN-HFD prevented the HFD-induced increase in adiposity and leptin levels independently of parity. FEN-HFD induced retinoid-responsive genes in WAT and liver. Parous females had reduced expression of hepatic estrogen-responsive genes, but FEN-HFD up-regulated WAT Cyp19a1 and Esr2 in parous mice. Estrogen and RA acted synergistically to increase RA receptor-mediated gene expression in 3T3-L1 adipocytes. FEN increased Cyp19a1 and Esr2, similar to our findings in vivo. CONCLUSIONS: The prevention of adiposity by FEN in response to HFD in female mice seems to involve increased retinoid signaling in association with induction of local estrogen production and estrogen signaling in WAT.
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Adiposidade/efeitos dos fármacos , Estrogênios/farmacologia , Fenretinida/uso terapêutico , Obesidade/tratamento farmacológico , Retinoides/farmacologia , Animais , Dieta Hiperlipídica , Feminino , Fenretinida/análise , Leptina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Fenretinide remains the most investigated retinoid compound for the prevention of cancer. Its clinical use remains a genuine possibility due to a favourable toxicological profile and accumulation in fatty tissues. Like other well-characterised pharmacological therapies, Fenretinide has been shown to affect multiple signalling pathways. Recent findings have discovered additional beneficial properties the synthetic retinoid was not intentionally designed for, including the prevention of high-fat diet-induced obesity and insulin resistance. These preclinical findings in rodents are timely since obesity has reached pandemic proportions and safe effective therapeutics are severely lacking. Recent investigations have proposed various mechanisms of action for the beneficial effects of Fenretinide. This review covers the current knowledge about Fenretinide's use as a therapy for cancer and potential to treat obesity, insulin resistance and glucose intolerance. An overview of the signalling pathways manipulated by Fenretinide including retinoid homeostasis, reactive oxygen species generation and inhibition of ceramide synthesis will be presented and insights into apoptosis and/or autophagy induction by Fenretinide will also be discussed. The largely unexplored area of Fenretinide metabolites as alternative therapeutic options and how these may be relevant will also be presented. Fenretinide shows great promise, but unfortunately evidence is lacking from clinical trials on Fenretinide's effectiveness in humans. Finally we identify what action can be taken to further progress the investigation of this extremely important retinoid.
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Antineoplásicos/farmacologia , Diabetes Mellitus Tipo 2/prevenção & controle , Fenretinida/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Obesidade/prevenção & controle , Animais , Autofagia/efeitos dos fármacos , Ensaios Clínicos como Assunto , Sistema Enzimático do Citocromo P-450/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Fenretinida/uso terapêutico , Humanos , Espécies Reativas de Oxigênio/metabolismo , Ácido Retinoico 4 Hidroxilase , Proteínas Plasmáticas de Ligação ao Retinol/metabolismo , Transdução de Sinais/efeitos dos fármacos , Vitamina A/sangue , Vitamina A/metabolismoRESUMO
The synthetic retinoid, Fenretinide (FEN), inhibits obesity and insulin resistance in mice and is in early clinical trials for treatment of insulin resistance in obese humans. We aimed to determine whether alterations in retinoic acid (RA)-responsive genes contribute to the beneficial effects of FEN. We examined the effect of FEN on 3T3-L1 adipocyte differentiation and alterations in gene expression in C57Bl/6 and retinaldehyde dehydrogenase (RALDH) 1 knockout (KO) mice fed a high-fat (HF) diet. FEN completely inhibited adipocyte differentiation by blocking CCAAT/enhancer-binding protein (C/EBP) α/peroxisome proliferator-activated receptor (PPAR) γ-mediated induction of downstream genes and upregulating RA-responsive genes like cellular retinol-binding protein-1. In mice fed an HF diet, RA-responsive genes were markedly increased in adipose, liver, and hypothalamus, with short-term and long-term FEN treatment. In adipose, FEN inhibited the downregulation of PPARγ and improved insulin sensitivity and the levels of adiponectin, resistin, and serum RBP (RBP4). FEN inhibited hyperleptinemia in vivo and leptin expression in adipocytes. Surprisingly, hypothalamic neuropeptide Y expression was completely suppressed, suggesting a central effect of FEN to normalize hyperglycemia. Moreover, FEN induced RA-responsive genes in RALDH1 KO mice, demonstrating that FEN can augment RA signaling when RA synthesis is impaired. We show that FEN-mediated beneficial effects are through alterations in retinoid homeostasis genes, and these are strong candidates as therapeutic targets for the treatment of obesity and insulin resistance.
Assuntos
Tecido Adiposo/efeitos dos fármacos , Fármacos Antiobesidade/uso terapêutico , Fenretinida/uso terapêutico , Hipotálamo/efeitos dos fármacos , Fígado/efeitos dos fármacos , Obesidade/prevenção & controle , Retinoides/metabolismo , Células 3T3-L1 , Adipogenia/efeitos dos fármacos , Tecido Adiposo/citologia , Tecido Adiposo/metabolismo , Família Aldeído Desidrogenase 1 , Animais , Fármacos Antiobesidade/farmacologia , Dieta Hiperlipídica/efeitos adversos , Fenretinida/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hipotálamo/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/etiologia , Obesidade/metabolismo , PPAR gama/genética , PPAR gama/metabolismo , RNA Mensageiro/metabolismo , Distribuição Aleatória , Elementos de Resposta/efeitos dos fármacos , Retinal Desidrogenase/genética , Retinal Desidrogenase/metabolismo , Proteínas Plasmáticas de Ligação ao Retinol/genética , Proteínas Plasmáticas de Ligação ao Retinol/metabolismoRESUMO
Protein tyrosine phosphatase 1B (PTP1B), a key negative regulator of leptin and insulin signaling, is positively correlated with adiposity and contributes to insulin resistance. Global PTP1B deletion improves diet-induced obesity and glucose homeostasis via enhanced leptin signaling in the brain and increased insulin signaling in liver and muscle. However, the role of PTP1B in adipocytes is unclear, with studies demonstrating beneficial, detrimental or no effect(s) of adipose-PTP1B-deficiency on body mass and insulin resistance. To definitively establish the role of adipocyte-PTP1B in body mass regulation and glucose homeostasis, adipocyte-specific-PTP1B knockout mice (adip-crePTP1B(-/-)) were generated using the adiponectin-promoter to drive Cre-recombinase expression. Chow-fed adip-crePTP1B(-/-) mice display enlarged adipocytes, despite having similar body weight/adiposity and glucose homeostasis compared to controls. High-fat diet (HFD)-fed adip-crePTP1B(-/-) mice display no differences in body weight/adiposity but exhibit larger adipocytes, increased circulating glucose and leptin levels, reduced leptin sensitivity and increased basal lipogenesis compared to controls. This is associated with decreased insulin receptor (IR) and Akt/PKB phosphorylation, increased lipogenic gene expression and increased hypoxia-induced factor-1-alpha (Hif-1α) expression. Adipocyte-specific PTP1B deletion does not beneficially manipulate signaling pathways regulating glucose homeostasis, lipid metabolism or adipokine secretion in adipocytes. Moreover, PTP1B does not appear to be the major negative regulator of the IR in adipocytes.