Adipose Tissue Hyperplasia and Hypertrophy in Common and Syndromic Obesity—The Case of BBS Obesity

Abstract

Obesity is a metabolic state generated by the expansion of adipose tissue. Adipose tissue expansion depends on the interplay between hyperplasia and hypertrophy, and is mainly regulated by a complex interaction between genetics and excess energy intake. However, the genetic regulation of adipose tissue expansion is yet to be fully understood. Obesity can be divided into common multifactorial/polygenic obesity and monogenic obesity, non-syndromic and syndromic. Several genes related to obesity were found through studies of monogenic non-syndromic obesity models. However, syndromic obesity, characterized by additional features other than obesity, suggesting a more global role of the mutant genes related to the syndrome and, thus, an additional peripheral influence on the development of obesity, were hardly studied to date in this regard. This review summarizes present knowledge regarding the hyperplasia and hypertrophy of adipocytes in common obesity. Additionally, we highlight the scarce research on syndromic obesity as a model for studying adipocyte hyperplasia and hypertrophy, focusing on Bardet–Biedl syndrome (BBS). BBS obesity involves central and peripheral mechanisms, with molecular and mechanistic alternation in adipocyte hyperplasia and hypertrophy. Thus, we argue that using syndromic obesity models, such as BBS, can further advance our knowledge regarding peripheral adipocyte regulation in obesity.

Clinically Effective Molecules of Natural Origin for Obesity Prevention or Treatment

“…Mature adipocytes can store a large number of triglycerides, increasing their volume up to 20 times through hypertrophy [ 39 ]. Furthermore, this excessive growth favors adipocyte hypoxia, the release of reactive oxygen species (ROS), and inflammatory cytokines that activates adipogenesis (adipocyte hyperplasia), another mechanism to increase storage capacity [ 43 ].…”

“…Adipogenesis develops from multipotent mesenchymal stem cells related to preadipocytes, which remain available in the vascular stroma of adipose tissue and undergo mitotic clonal expansion and differentiation of adipocytes to white adipose tissue that has triglyceride storage functions, or to brown adipose tissue with thermogenesis functions [ 44 ]. The CCAAT/enhancer-binding protein β (C/EBP)β and C/EBP δ, which are highly sensitive to adipogenic stimuli, increase from the initial stages [ 43 , 45 , 46 ] and stimulate the expression of the C/EBPα, sterol regulatory element-binding binding protein 1 (SREBP-1) and the expression of the peroxisome proliferator-activated receptor γ ( PPARγ ), which has an essential role in the final phases of adipogenesis [ 46 ] and regulates the increase in adipogenic factors, including C/EBPα expression itself, in a positive feedback mechanism [ 43 ]. Because adipose tissue is not a passive storage space but rather a tissue with endocrine, paracrine, and autocrine functions, new mature adipocytes are capable of not only increasing storage capacity but also releasing adipocytokines, some of which function as neurotransmitters and participate in the neuroendocrine regulatory complex [ 47 ].…”

Unraveling Adipose Tissue Dysfunction: Molecular Mechanisms, Novel Biomarkers, and Therapeutic Targets for Liver Fat Deposition

“…Adipocytes in scWAT are generally larger and have a greater lipid storage capacity than those in visWAT. The expansion of scWAT occurs primarily through adipocyte hypertrophy, whereas visWAT expansion involves both hypertrophy and hyperplasia [ 42 ].…”

The Varied Impacts of Vascular Endothelial Growth Factor-a (VEGF-a) on Vasculature in Ovarian Hyper Stimulation Syndrome (OHSS) and Obesity

“…Moreover, WAT works as an endocrine organ, secreting some hormones such as gerlin and leptin, which are called adipokines. Nevertheless, BAT is specialized for thermogenesis in addition to energy expenditure due to mitochondria function which exist in this sort of adipocytes at high concentrated levels plus high density vasculature [38,54,[61][62][63]. Overall, adipose tissue has the capability to get expanded by some triggering situations which include fasting and excess food intake.…”