<p dir="ltr">Adipose tissue is characterized by the dominant presence of adipocytes, specialized cells adept at lipid metabolism. These adipocytes act as critical nodes, coordinating the complex processes of energy storage and mobilization according to the body's metabolic requirements. Within the adipocyte population of mammals, there are three main subtypes: white, beige, and brown adipocytes. White adipocytes are primarily dedicated to the sequestration of energy in the form of triglycerides. Conversely, beige and brown adipocytes are distinguished by their capacity for thermogenesis, the process of dissipating nutritional energy as heat. The contemporary challenge of chronic overnutrition has precipitated a global surge in obesity and cardiometabolic diseases. Addressing this issue necessitates the maintenance of white adipocyte homeostasis and the enhancement of the quantity and function of thermogenic adipocytes, which are imperative for mitigating the global obesity epidemics.</p><p dir="ltr">Mitochondrion, a multifunctional organelle, is integral to a broad spectrum of cellular processes, including anabolic and catabolic metabolism, bioenergetics, and signal transduction, all of which are essential for maintaining cellular functions and homeostasis. The efficacy of mitochondrial operations is intrinsically linked to their membrane dynamics. In this study, transmission electron microscopy and mass spectrometry were employed to investigate the proteins implicated in the cold-induced mitochondrial membrane remodeling in brown adipocytes. Through this approach, a poorly characterized protein, Family with Sequence Similarity 210 Member A (FAM210A), was identified as a mitochondrial inner membrane protein that is induced by cold stimulation. Subsequent loss-of-function experiments were conducted to elucidate the role of FAM210A in adipocytes. Mice with adipose-specific deletion of <i>Fam210a</i> (<i>Fam210a</i>^<em>AKO</em>) exhibited compromised mitochondrial cristae structure and a reduced thermogenic capacity in brown adipose tissue (BAT), resulting in an increased susceptibility to lethal hypothermia during acute cold challenge. Moreover, in mice with inducible ablation of <i>Fam210a</i> in adipocytes (<i>Fam210</i>^{<em>iAKO</em>}), mitochondrial alterations in BAT were negligible at thermoneutral conditions; however, they exhibited defective cold-induced mitochondrial cristae remodeling, culminating in a progressive loss of cristae and diminished mitochondrial density. Mechanistically, it was determined that FAM210A interacts with mitochondrial protease YME1L and modulates its activity toward OMA1 and OPA1 cleavage, thus compromising cold-induced mitochondrial remodeling in BAT.</p><p dir="ltr">Additionally, this research delved into the role of FAM210A in adipocytes in response to dietary stress by feeding mice with high-fat diet (HFD). The study found a consistent correlation between FAM210A expression and OPA1 cleavage in adipocytes under HFD challenge. Mice lacking FAM210A in all adipocytes and subjected to HFD exhibited lipoatrophy in white adipose tissue (WAT) and a downregulation of genes associated with adipogenesis and lipid metabolism. In contrast, mice with a brown adipocyte-specific ablation of <i>Fam210a </i>(<i>Fam210a</i>^<em>UKO</em>) displayed no significant change in WAT mass but had enlarged livers. Crucially, both <i>Fam210a</i>^<em>AKO</em> and <i>Fam210a</i>^<em>UKO</em> mice presented increased WAT inflammation, deteriorated glucose tolerance, and exacerbated insulin resistance. These findings underscore the pivotal role of FAM210A in brown adipose tissue (BAT) in the preservation of WAT homeostasis and the regulation of systemic glucose clearance in diet-induced obesity.</p><p dir="ltr">In summary, these studies characterize the mitochondrial dynamics in brown adipocytes in response to cold stress, identify a new cold-induced mitochondrial protein, FAM210A, and uncover its functions in adipocytes under cold and dietary stresses. These findings highlight the importance of mitochondrial remodeling in the adaptive response of adipocytes to evolving metabolic demands. This work establishes FAM210A as a key regulator of mitochondrial cristae remodeling, shedding light on the mechanisms that govern mitochondrial plasticity in adipocytes.</p>

Background and Aims: During positive energy balance, excess lipid storage in subcutaneous adipose tissue (SAT) is associated with increased lipolysis. Elevated circulating fatty acid (FA) concentrations from both SAT lipolysis and dietary fat intake may result in visceral adipose tissue (VAT) accumulation, impairment of glucose metabolism, altogether increasing obesity-associated metabolic risks. We aimed to test the hypothesis that FA composition of red blood cell total phospholipids (RBC-TPL) and SAT is associated with body fat centralisation (VAT/SAT ratio) and insulin sensitivity (SI) in black South African women with obesity. Methods: Participants’ (n = 41) body fat composition and distribution, SI, and RBC-TPL, abdominal and gluteal SAT (gSAT) FA composition (gas-liquid chromatography) were measured. Results: RBC-TPL contained higher proportions of saturated fatty acids (SFAs) than SAT (p < 0.001), which were associated with lower SI (p < 0.05). Mono-unsaturated fatty acids (MUFAs) and stearoyl-CoA desaturase-1 (SCD1)-16 were lower, while poly-unsaturated fatty acids (PUFAs), and delta-5 and delta-6 desaturase indices were higher in RBC-TPL than SAT (p < 0.001). Interestingly, FA profiles differed between SAT depots with higher SFAs and lower MUFAs, SCD1-16 and SCD1-18 indices in abdominal compared to gluteal SAT (p < 0.01). In both SAT depots, higher SFAs and lower PUFAs (n-3 and n-6) correlated with lower VAT/SAT ratio; and lower PUFAs (n-3 and n-6) and higher total MUFA correlated with higher SI. Conclusion: Our findings confirm the relationships between the FA composition of RBC-TPL and SAT and metabolic risk in black women with obesity, which are dependent on both the FA class, and the tissue type/blood compartment in which they are distributed.

No description available.

No description available.

<p>The endoplasmic reticulum (ER) is a specialized organelle that facilitates correct protein folding and maturation. Disruptions in ER homeostasis lead to ER stress and activation of a series of signal transduction cascades known as the unfolded protein response (UPR), which acts to restore ER homeostasis. In recent years, ER stress and UPR dysfunction have been linked to obesity, fatty liver and insulin resistance. Lipid-laden adipocytes, the main cellular component of white adipose tissue (WAT), play a critical role in whole body energy homeostasis as well as lipid and carbohydrate metabolism. Mature adipocytes, which are metabolically active endocrine cells, differentiate from precursor fibroblast-like preadipocytes, through a process called adipogenesis, leading to formation of cells capable of secreting numerous proteins, cytokines and hormones. ER homeostasis and UPR activation are essential to the function/differentiation of highly secretory cells, however, the role of ER stress/UPR activation in adipogenesis had previously not been examined. We hypothesized that<em> adipogenesis may rely on physiological UPR activation to accommodate the demand on the ER for increased folding and secretion of proteins.</em></p> <p>Initial experiments examining UPR activation during 3T3-L1 adipogenesis identified that expression of ER stress/UPR markers was modulated during adipocyte differentiation. Furthermore, inhibition of ER stress/UPR activation by the chemical chaperone, 4-phenyl butyric acid (4-PBA), inhibited adipogenesis and blunted high fat-diet induced weight gain in 4-PBA supplemented mice. These findings suggested that UPR activation modulates adipogenesis and adipose tissue metabolism.</p> <p>Subsequently, we sought to identify novel candidate ER stress/UPR responsive genes that may be involved in adipogenesis and WAT metabolism. The expression of a recently recognized ER stress-responsive gene, T-cell death associated gene 51 (TDAG51) was identified to be differentially regulated during adipogenesis. However, the function of TDAG51 in adipogenesis or energy regulation was not known. Studies from this thesis showed that TDAG51 protein expression is attenuated by ER stress/UPR activation in preadipocytes and declines during adipogenesis. Based on these results, and given the importance of adipogenesis in WAT function and whole body energy metabolism, it was<em> </em>hypothesized that<em> TDAG51 may be a novel regulator of adipogenesis and energy homeostasis.</em> Indeed, as reported here, knock-down or absence of TDAG51 (<em>TDAG51^-/-</em>) in pre-adipocytes increased lipogenesis and lead to earlier and more potent expression of adipogenic markers.</p> <p>Finally, we investigated whether absence of TDAG51 in mice affected adiposity and metabolic outcomes. Consistent with the <em>in vitro </em>results, we found that <em>TDAG51^-/-</em>mice fed a standard chow diet, exhibited an age-associated increase in WAT, developed fatty liver, and exhibited insulin resistance as compared to wild-type mice.</p> <p>Taken together, the findings in this thesis indicate that physiological UPR activation and the UPR-responsive gene TDAG51 play important roles in regulating adipogenesis, lipogenesis and whole-body energy metabolism. Thus, therapeutic approaches aimed at modulating ER folding capacity, UPR activation and/or TDAG51 expression may have great potential in the treatment of obesity and its co-morbidities.</p> / Doctor of Philosophy (PhD)

No description available.

Fettvävnaden är en viktig regulator för ämnesomsättningen och uppvisar en komplex cellulär arkitektur som påverkar olika fysiologiska och patologiska processer. Dess heterogena natur är relativt ostrukturerad och består huvudsakligen av bräckliga feta adipocyter och immunceller. Dessa komplikationer försvårar studier av mikroarkitekturen - som är avgörande för att förstå dess beteende - vilket nyligen har gynnats av teknik med rumslig upplösning, som möjliggör studier av genomiska profiler samtidigt som informationen från vävnaden bevaras. I detta arbete undersöks kromatindynamiken i fettvävnad med hjälp av den nyutvecklade Spatial Assay for Transposase-Accessible Chromatin med sekvensering med hög genomströmning (Spatial ATAC-seq). Med fokus på subkutan vit fettvävnad samlades prover in från en individ som led av fetma före och fem år efter en bariatrisk operation för att studera förändringar i samband med betydande viktnedgång. Studien omfattar detaljer för både experimentella protokoll och avancerade beräkningsverktyg för dataanalys, inklusive användning av en utvecklingsversion av Semla-paketet för att integrera data om rumslig tillgänglighet och kromatintillgänglighet. Analysen visade på en mångsidig cellulär arkitektur och distinkta genomiska egenskaper i vävnaden, vilket framhävde förekomsten av specifika celltyper som AdipoLEP-liknande adipocyter och infiltrerande immunceller. Denna studie visade att det är möjligt att tillämpa Spatial ATAC-seq för att undersöka de molekylära mekanismerna i fettvävnad som ligger till grund för metabol hälsa och sjukdom, särskilt i samband med fetma och viktminskning. / Adipose tissue is a critical regulator of metabolism, exhibiting a complex cellular architecture that influences various physiological and pathological processes. Its heterogeneous nature is relatively unstructured, mainly formed by fragile fatty adipocytes and immune cells. These intricacies complicate the study of its microarchitecture – crucial for understanding its behaviour – which has recently benefitted from spatially resolved technologies, that enable the study of genomic profiles while keeping the information from the tissue. This work explores the chromatin dynamics of adipose tissue using the newly developed Spatial Assay for Transposase-Accessible Chromatin with high throughput sequencing (Spatial ATAC-seq). Focusing on subcutaneous white adipose tissue, samples were collected from an individual suffering from obesity before and five years after bariatric surgery to study changes associated with significant weight loss. The study comprises details for both experimental protocols and advanced computational tools for data analysis, including the use of a development version of Semla package to integrate spatial and chromatin accessibility data. The analysis revealed a diverse cellular architecture and distinct genomic features across the tissue, highlighting the presence of specific cell types such as AdipoLEP-like adipocytes and infiltrating immune cells. This study demonstrated the feasibility of applying Spatial ATAC-seq in investigating the molecular mechanisms of adipose tissue underlying metabolic health and disease, particularly in the context of obesity and weight loss.

INTRODUÇÃO: A Moléstia de Dupuytren (MD) é uma doença crônica progressiva fibroproliferativa caracterizada por contraturas em flexão dos dedos. A origem deste processo está na proliferação de miofibroblastos e na síntese de matriz extracelular. Diversas técnicas já foram descritas no tratamento da MD. A falta de uma técnica capaz de associar altas taxas de sucesso com baixos índices de complicações e recidivas estimulou a procura por novas técnicas. Acredita-se que a propriedade totipotente das células-tronco presentes no tecido adiposo seria capaz de atuar na proliferação e na diferenciação dos fibroblastos em miofibroblastos, interrompendo a formação da fibrose e consequentemente a progressão da deformidade dos dedos. OBJETIVO: O objetivo primário deste estudo foi avaliar o efeito do enxerto de gordura, rico em células-tronco, nos pacientes com MD, submetidos a fasciectomia parcial aberta, por meio de avaliação funcional e goniométrica, e comparar com a técnica convencional (sem adição de enxerto de gordura). MÉTODO: Dois grupos totalizando 45 pacientes (24 pacientes no Grupo Controle e 21 no Grupo com gordura) foram operados pela técnica da fasciectomia parcial aberta. No Grupo controle era realizada apenas a fasciectomia parcial aberta. No Grupo com gordura, era realizada a fasciectomia parcial aberta e injetado, no local da corda ressecada, o enxerto de gordura, após o processamento do lipoaspirado de adipócitos proposto por Coleman (2006). O estudo foi prospectivo, randomizado e terapêutico. Os desfechos foram avaliados pela medida goniométrica do Déficit de Extensão Passiva Total (DEPT) e pelo escore funcional Brief Michigan Hand Questionnaire (BMHQ). As avaliações eram feitas no pré-operatório, com 6 semanas, 6 meses, 1 ano e 2 anos de seguimento. RESULTADOS: Na comparação com 6 semanas de pós-operatório, houve um aumento significativo da dor no Grupo com Gordura [mediana 2 ± 2,82 versus 0 ± 1,86 no grupo Controle (p=0,045)]. Os resultados do DEPT, não mostraram diferença significativa entre os grupos. Observamos piores resultados do escore funcional BMHQ com 6 meses e 1 ano de pós-operatório no Grupo com gordura (p=0,040 e p=0,047, respectivamente). Observamos ainda 9 casos (43%) de complicações no Grupo com gordura e 2 (8%) no Grupo Controle (p=0,019). CONCLUSÃO: O uso do enxerto de gordura associado à fasciectomia parcial aberta promoveu piores resultados funcionais comparado com a fasciectomia parcial aberta convencional, no curto prazo (um ano de seguimento pós-operatório). No entanto, resta a dúvida de qual seriam os resultados a longo prazo e, se as células-tronco, presentes no enxerto de gordura, poderiam interferir na recidiva da doença futuramente / BACKGROUND: Dupuytren\'s disease (DD) is a progressive chronic fibroproliferative disease characterized by flexion contractures of the fingers. The origin of this process is the proliferation of myofibroblasts and extra-cellular matrix synthesis. Several techniques have been described to treat the DD. The lack of a technique capable to associate high success rates with low rates of complications and recurrence stimulated the search for new techniques. It is believed that the totipotent property of the adipose-derived stem cells present in the processed lipoaspirate tissue would be able to inhibit the proliferation and differentiation of fibroblasts in myofibroblasts, interrupting the formation of fibrosis and consequently the progression of finger deformity. The primary objective of this study was to evaluate the effect of adipose-derived stem cells in patients with DD who underwent to open limited fasciectomy and compare with the conventional technique of limited fasciectomy. METHODS: A total of 45 patients were assigned in two groups in a single blind, prospective, randomized, controlled trial. All the patients were treated by the limited fasciectomy technique. In the control group (24 patients), only limited fasciectomy was performed. In the study group (21 patients), after the limited fasciectomy procedure, autologous lipoaspirate was injected at the site of the resected cord. Outcomes were assessed by the Total Passive Extension Deficit (TPED) and by the Brief Michigan Hand Questionnaire (BMHQ) functional score. The evaluations were performed by occupational therapists in the preoperative and at 6 weeks, 6 months, 1 year and 2 years. RESULTS: The study group presented higher rates of pain at 6 weeks postoperative (median 2 ± 2,82 versus 0 ± 1,86 on control group, p=0,045). TPED showed no significant differences between groups. BMHQ score, at 6 months and 1 year after surgery, were significantly inferior in the study group (p=0,040 e p=0,047, respectively). Patients in the study group had higher incidence of complications (9 patients, 43% versus 2, 8% in the control group, p=0,019). CONCLUSIONS: The autologous lipoaspirate associated to limited fasciectomy demonstrates inferior results regarding to functional score and pain compared to conventional limited fasciectomy, in short-term. Further long-term analysis is required to observe the effect of adipose-derived stem cells in the recurrences rates

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Este trabalho teve como objetivo investigar os efeitos da telmisartana (agonista PPAR-gama parcial), losartana (puro bloqueador do receptor AT1 da angiotensina II) e rosiglitazona (agonista PPAR-gama) em modelo experimental de síndrome metabólica. Os alvos do estudo foram a pressão arterial, metabolismo de carboidratos, resistência insulínica, inflamação, tecido adiposo e fígado. Camundongos C57BL/6 (a partir de 3 meses de idade) foram alimentados com dieta padrão (SC, n = 10) ou dieta hiperlipídica rica em sal (HFHS, n = 40) por 12 semanas. Após esse tempo, os animais do grupo HFHS foram subdivididos em 4 grupos (n = 10): HFHS (sem tratamento), ROSI (HFHS tratado com rosiglitazona), TELM (HFHS tratado com telmisartana) e LOS (HFHS tratado com losartana) por 5 semanas. O grupo HFHS apresentou um significante ganho de peso e aumento da pressão arterial sistólica, hiperinsulinemia com resistência insulínica, hiperleptinemia, hipertrofia de adipócitos bem como um quadro de esteatose hepática e níveis aumentados da citocina inflamatória interleucina-6 (IL-6). Os animais tratados com telmisartana chegou ao final do experimento com massa corporal similar ao grupo SC, com reversão do quadro de resistência insulínica, com pressão arterial normal, adipócitos de tamanho normal e sem apresentar esteatose hepática. Além disso, o tratamento com telmisartana aumentou a expressão de PPAR&#947; e adiponectina no tecido adiposo epididimal. A expressão da proteína desacopladora-1 (UCP-1) no tecido adiposo branco (TAB) também foi aumentada. O tratamento com losartana diminuiu a pressão arterial para valores normais, porém com menores efeitos nos parâmetros metabólicos dos animais. O presente modelo experimental de ganho de peso e hipertensão induzidos por dieta mimetiza a síndrome metabólica humana. Neste modelo, a telmisartana aumentou a expressão de UCP-1 no TAB, preveniu o ganho de peso e melhorou a sensibilidade à insulina e a esteatose hepática dos camundongos C57BL/6, provavelmente devido à ativação PPAR-gama. / The study aimed to investigate the effects of telmisartan (a partial PPAR gamma agonist), losartan (a pure angiotensin II receptor blocker) and rosiglitazone (PPAR gamma agonist) in a mice model of metabolic syndrome (MetS). The targets of this study were blood pressure (BP), carbohydrate metabolism, insulin resistance, inflammation, white adipose tissue (WAT) and liver. Male C57BL/6 mice were studied over 17 weeks after being separated into two major groups according to diet: standard chow (SC, 10% fat, n = 10) or high-fat high-salt chow (HFHS, 60% fat, 7% salt, n = 40). In the last 5 weeks of the experiment, the HFHS group was divided into four groups (n = 10): untreated HFHS, ROSI (HFHS plus rosiglitazone), TELM (HFHS plus telmisartan), and LOS (HFHS plus losartan). The HFHS group had significantly greater body mass and BP, in addition to hyperinsulinemia with insulin resistance, hyperleptinemia, adipocyte hypertrophy and hepatic steatosis as well as increased inflammatory cytokine levels. Animals treated with telmisartan had body weights similar to the SC group, in addition to reversed insulin resistance, reduced hypertension, reduced adipocyte hypertrophy, ameliorates hepatic steatosis and decreased IL-6. Telmisartan increased PPAR&#947; and adiponectin expression in white adipose tissue. Interestingly, the expression of UCP-1 in white adipose tissue was also increased by treatment with telmisartan. Losartan decreased BP but had smaller effects on metabolic parameters. The present model of diet-induced weight gain and hypertension in mice mimics human features of MetS. In this model, telmisartan enhances UCP-1 expression in WAT, prevented weight gain and ameliorates insulin sensitivity and hepatic steatosis in C57Bl/6 mice, probably due to PPAR gamma activation.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Este trabalho teve como objetivo investigar os efeitos da telmisartana (agonista PPAR-gama parcial), losartana (puro bloqueador do receptor AT1 da angiotensina II) e rosiglitazona (agonista PPAR-gama) em modelo experimental de síndrome metabólica. Os alvos do estudo foram a pressão arterial, metabolismo de carboidratos, resistência insulínica, inflamação, tecido adiposo e fígado. Camundongos C57BL/6 (a partir de 3 meses de idade) foram alimentados com dieta padrão (SC, n = 10) ou dieta hiperlipídica rica em sal (HFHS, n = 40) por 12 semanas. Após esse tempo, os animais do grupo HFHS foram subdivididos em 4 grupos (n = 10): HFHS (sem tratamento), ROSI (HFHS tratado com rosiglitazona), TELM (HFHS tratado com telmisartana) e LOS (HFHS tratado com losartana) por 5 semanas. O grupo HFHS apresentou um significante ganho de peso e aumento da pressão arterial sistólica, hiperinsulinemia com resistência insulínica, hiperleptinemia, hipertrofia de adipócitos bem como um quadro de esteatose hepática e níveis aumentados da citocina inflamatória interleucina-6 (IL-6). Os animais tratados com telmisartana chegou ao final do experimento com massa corporal similar ao grupo SC, com reversão do quadro de resistência insulínica, com pressão arterial normal, adipócitos de tamanho normal e sem apresentar esteatose hepática. Além disso, o tratamento com telmisartana aumentou a expressão de PPAR&#947; e adiponectina no tecido adiposo epididimal. A expressão da proteína desacopladora-1 (UCP-1) no tecido adiposo branco (TAB) também foi aumentada. O tratamento com losartana diminuiu a pressão arterial para valores normais, porém com menores efeitos nos parâmetros metabólicos dos animais. O presente modelo experimental de ganho de peso e hipertensão induzidos por dieta mimetiza a síndrome metabólica humana. Neste modelo, a telmisartana aumentou a expressão de UCP-1 no TAB, preveniu o ganho de peso e melhorou a sensibilidade à insulina e a esteatose hepática dos camundongos C57BL/6, provavelmente devido à ativação PPAR-gama. / The study aimed to investigate the effects of telmisartan (a partial PPAR gamma agonist), losartan (a pure angiotensin II receptor blocker) and rosiglitazone (PPAR gamma agonist) in a mice model of metabolic syndrome (MetS). The targets of this study were blood pressure (BP), carbohydrate metabolism, insulin resistance, inflammation, white adipose tissue (WAT) and liver. Male C57BL/6 mice were studied over 17 weeks after being separated into two major groups according to diet: standard chow (SC, 10% fat, n = 10) or high-fat high-salt chow (HFHS, 60% fat, 7% salt, n = 40). In the last 5 weeks of the experiment, the HFHS group was divided into four groups (n = 10): untreated HFHS, ROSI (HFHS plus rosiglitazone), TELM (HFHS plus telmisartan), and LOS (HFHS plus losartan). The HFHS group had significantly greater body mass and BP, in addition to hyperinsulinemia with insulin resistance, hyperleptinemia, adipocyte hypertrophy and hepatic steatosis as well as increased inflammatory cytokine levels. Animals treated with telmisartan had body weights similar to the SC group, in addition to reversed insulin resistance, reduced hypertension, reduced adipocyte hypertrophy, ameliorates hepatic steatosis and decreased IL-6. Telmisartan increased PPAR&#947; and adiponectin expression in white adipose tissue. Interestingly, the expression of UCP-1 in white adipose tissue was also increased by treatment with telmisartan. Losartan decreased BP but had smaller effects on metabolic parameters. The present model of diet-induced weight gain and hypertension in mice mimics human features of MetS. In this model, telmisartan enhances UCP-1 expression in WAT, prevented weight gain and ameliorates insulin sensitivity and hepatic steatosis in C57Bl/6 mice, probably due to PPAR gamma activation.