Endocrine Abstracts

Adipogenesis is a highly organized series of events that facilitates the healthy expansion of adipose tissue, beginning during embryogenesis and continuing throughout life. White adipogenesis protects against lipotoxicity, influencing insulin resistance and obesity-related comorbidities, while brown adipogenesis increases energy expenditure, counteracting weight gain. Recently, there has been a significant increase in interest regarding adipocyte differentiation, particularly focusing on the interplay between microRNAs (miRNAs) and the transcriptional cascade that governs adipogenesis and metabolic dysfunction. This study aims to identify miRNAs regulating white and brown adipocyte differentiation and define miRNA action in a stem cell model of adipogenesis. Small RNAseq analysis of primary mouse brown and white adipocytes (WAs) identified miR-10b to be upregulated in mature brown adipocytes (BAs). We generated two model systems: 1) immortalized brown pre-adipocytes treated with miRNA inhibitors and 2) CRISPR/Cas9 KO of miR-10b in E14 mouse embryonic stem cells (ES). Both cell models were differentiated to mature adipocytes. To unravel the pathways that are affected by miR-10b depletion, a transcriptomic analysis was performed at key time points. Both cell models demonstrated that miR-10b depletion severely compromised differentiation into mature adipocytes, evidenced by a lack of lipid droplet accumulation and decreased adipogenic gene expression. We hypothesize that miR-10b-5p directs ES towards the mesoderm lineage, facilitating commitment to pre-adipocytes by controlling GATA6 and its downstream target BMP2. Notably, this mechanism appears unaffected in BA. RNA sequencing revealed a significant increase in genes related to G Protein signalling associated with elevated Tubby (Tub). Consistent with transcriptomic findings, Tub mRNA and protein levels increased with miR-10b-5p inhibition in BA and decreased with miR-10b-5p upregulation in WA. Our research highlights the pleiotropic regulatory role of miR-10b-5p during adipogenesis. Understanding the miR-10b-mediated mechanism in adipocyte commitment and differentiation may aid in developing adipose tissue-engineering strategies for cellular therapies for lipodystrophy and obesity.