Profiling of G-Protein Coupled Receptors in Adipose Tissue and Differentiating Adipocytes Offers a Translational Resource for Obesity/Metabolic Research

Abundance of dopamine and its receptors in the brain and adipose tissue following diet-induced obesity or caloric restriction

While obesity and type 2 diabetes (T2D) are associated with altered dopaminergic activity in the central nervous system and in adipose tissue (AT), the directions and underlying mechanisms remain inconclusive. Therefore, we characterized changes in the abundance of dopamine, its metabolites, and receptors DRD1 and DRD2 in the brain and AT upon dietary intervention or obesity. Male Wistar rats were fed either a standard pellet diet, a cafeteria diet inducing obesity and insulin resistance, or a calorie-restricted diet for 12 weeks. Abundance of dopamine and its receptors DRD1 and DRD2 were examined in brain regions relevant for feeding behavior and energy homeostasis. Furthermore, DRD1 and DRD2 protein levels were analyzed in rat inguinal and epidydimal AT and in human subcutaneous and omental AT from individuals with or without obesity. Rats with diet-induced obesity displayed higher dopamine levels, as well as DRD1 or DRD2 receptor levels in the caudate putamen and the nucleus accumbens core. Surprisingly, caloric restriction induced similar changes in DRD1 and DRD2, but not in dopamine levels, in the brain. Both diets reduced DRD1 abundance in inguinal and epidydimal AT, but upregulated DRD2 levels in inguinal AT. Furthermore, in human obesity, DRD1 protein levels were elevated only in omental AT, while DRD2 was upregulated in both omental and subcutaneous AT. These findings highlight dopaminergic responses to changes in energy balance, occurring both in the brain and AT. We propose that dopaminergic pathways are involved in tissue crosstalk during the development of obesity and T2D.

Breaking barriers in obesity research: 3D models of dysfunctional adipose tissue

Obesity is a global health crisis characterised by excessive accumulation of adipose tissue (AT). Under obesogenic conditions, this metabolically active tissue undergoes fibrosis and inflammation, leading to obesity-linked comorbidities. Modelling AT is essential for understanding its pathophysiology and developing treatments to protect against metabolic complications. 3D in vitro AT models are promising tools that address the limitations of traditional 2D in vitro models and in vivo animal models, providing enhanced biomimetic and human-relevant platforms. 3D models facilitate the study of AT pathophysiology and therapeutic screening. This review discusses the crucial role of AT in obesity-linked comorbidities, its dynamicity and complexity, and recent advances in engineering 3D scaffold-based in vitro dysfunctional AT models, highlighting potential breakthroughs in metabolic research and beyond.

Single-cell transcriptomics of clinical grade adipose-derived regenerative cells reveals consistency between donors independent of gender and BMI

Adipose-derived regenerative cells (ADRCs) also referred to as the stromal vascular fraction, provide an ample source of stem cells with widespread regenerative therapeutic use. Being heterogenous in nature, possibly affecting the clinical outcome after stem cell treatment, the ADRC- donor, -BMI, and -gender may have a large impact on ADRC composition and quality but this remains largely unexplored. Herein, we provide a comprehensive single-cell RNA sequencing ADRC mapping across two cell trial intervention studies but found no gender- or BMI-related variations, except for a minor female increase in PI16/CD55-expressing stem cells. Indeed, ADRC heterogeneity was surprisingly minimal between donors. This provides important decision-making support on adipose stem cell donor selection for stem cell treatments, and suggest that donor, gender and BMI should be regarded as less influential.

G protein-coupled receptor 146: new insights from genetics and model systems

PURPOSE OF REVIEW

Atherosclerotic cardiovascular diseases continue to be a significant global cause of death. Despite the availability of efficient treatments, there is an ongoing need for innovative strategies to lower lipid levels, especially for individuals experiencing refractory dyslipidemias or intolerable adverse effects. Based on human genetic findings and on mouse studies, the G protein-coupled receptor 146 (GPR146) emerges as a promising target against hypercholesterolemia and atherosclerosis. The present review aims at providing a thorough summary of the latest information acquired regarding GPR146, encompassing genetic evidence, functional insights, and its broader implications for cardiometabolic health.

RECENT FINDINGS

Human genetic studies uncovered associations between GPR146 variants, plasma lipid levels and metabolic parameters. Additionally, GPR146's influence extends beyond lipid regulation, impacting adipocyte differentiation, lipolysis, and inflammation pathways. Despite GPR146's orphan status, ongoing efforts to deorphanize it, suggest a potential ligand with downstream effects involving Gαi coupling.

SUMMARY

Here, we outline and deliberate on recent progress focused on: enhancing comprehension of the effects of inhibiting GPR146 in humans through genetic instruments, evaluating the extra-hepatic functions of GPR146, and discovering its natural ligand(s). Grasping these biological parameters and mechanisms is crucial in the exploration of GPR146 as a prospective therapeutic target.

Genome-wide association study (GWAS) identified PCOS susceptibility variants and replicates reported risk variants

BACKGROUND

Genetic predisposition and environmental factors are considered risk factors for polycystic ovary syndrome (PCOS). Genome-wide association studies (GWAS) have been reported from various subpopulations to evaluate SNPs associated with PCOS risk. No PCOS-associated GWAS study has been reported from India so far.

PURPOSE

The current study was conducted to identify the PCOS-susceptible loci among the North Indian population and to validate the significant loci reported by previous GWAS studies.

METHODS

A total of 272 participants with 134 PCOS patients and 138 age-matched healthy controls were recruited. Genomic DNA was isolated and genotyped by using Infinium Global Screening Array v3.0 microchip considering HWE 10e-5 statistically significant.

RESULTS

A total of fifteen markers have been identified as candidate PCOS risk factors. Only two SNPs, namely rs17186366 and rs11171739 have been identified through replication analysis while comparing the previously reported PCOS GWAS data. In-silico analysis was performed to study the functional impact of identified significant genes for gene ontology, pathways related to gene set, and cluster analysis to determine protein-protein interaction among genes or gene products.

CONCLUSION

The study suggests that multiple variants play an important role in PCOS pathogenesis and emphasizes the importance of further genetic studies among Indian subpopulations. The study also validates two previously reported SNPs in the Indian population. What this study adds to clinical work Study summarizes the importance of candidate gene markers validated by replication and in-silico functional study, significantly involved in PCOS pathogenesis in the studied population. These markers can be used in the future as diagnostic markers for clinical phenotype identification.

Brown adipose tissue-derived metabolites and their role in regulating metabolism

The discovery and rejuvenation of metabolically active brown adipose tissue (BAT) in adult humans have offered a new approach to treat obesity and metabolic diseases. Beyond its accomplished role in adaptive thermogenesis, BAT secretes signaling molecules known as "batokines", which are instrumental in regulating whole-body metabolism via autocrine, paracrine, and endocrine action. In addition to the intrinsic BAT metabolite-oxidizing activity, the endocrine functions of these molecules may help to explain the association between BAT activity and a healthy systemic metabolic profile. Herein, we review the evidence that underscores the significance of BAT-derived metabolites, especially highlighting their role in controlling physiological and metabolic processes involving thermogenesis, substrate metabolism, and other essential biological processes. The conversation extends to their capacity to enhance energy expenditure and mitigate features of obesity and its related metabolic complications. Thus, metabolites derived from BAT may provide new avenues for the discovery of metabolic health-promoting drugs with far-reaching impacts. This review aims to dissect the complexities of the secretory role of BAT in modulating local and systemic metabolism in metabolic health and disease.

Transcriptomic and Proteomic Analysis Reveals the Potential Role of RBMS1 in Adipogenesis and Adipocyte Metabolism

Adipocytes play a critical role in maintaining a healthy systemic metabolism by storing and releasing energy in the form of fat and helping to regulate glucose and lipid levels in the body. Adipogenesis is the process through which pre-adipocytes are differentiated into mature adipocytes. It is a complex process involving various transcription factors and signaling pathways. The dysregulation of adipogenesis has been implicated in the development of obesity and metabolic disorders. Therefore, understanding the mechanisms that regulate adipogenesis and the factors that contribute to its dysregulation may provide insights into the prevention and treatment of these conditions. RNA-binding motif single-stranded interacting protein 1 (RBMS1) is a protein that binds to RNA and plays a critical role in various cellular processes such as alternative splicing, mRNA stability, and translation. RBMS1 polymorphism has been shown to be associated with obesity and type 2 diabetes, but the role of RBMS1 in adipose metabolism and adipogenesis is not known. We show that RBMS1 is highly expressed during the early phase of the differentiation of the murine adipocyte cell line 3T3-L1 and is significantly upregulated in the adipose tissue depots and adipocytes of high-fat-fed mice, implying a possible role in adipogenesis and adipose metabolism. Knockdown of RBMS1 in pre-adipocytes impacted the differentiation process and reduced the expression of some of the key adipogenic markers. Transcriptomic and proteomic analysis indicated that RBMS1 depletion affected the expression of several genes involved in major metabolic processes, including carbohydrate and lipid metabolism. Our findings imply that RBMS1 plays an important role in adipocyte metabolism and may offer novel therapeutic opportunity for metabolic disorders such as obesity and type 2 diabetes.