Histone Deacetylase 3 Regulates Adipocyte Phenotype at Early Stages of Differentiation

Abstract

Obesity is a condition characterized by uncontrolled expansion of adipose tissue mass resulting in pathological weight gain. Histone deacetylases (HDACs) have emerged as crucial players in epigenetic regulation of adipocyte metabolism. Previously, we demonstrated that selective inhibition of class I HDACs improves white adipocyte functionality and promotes the browning phenotype of murine mesenchymal stem cells (MSCs) C3H/10T1/2 differentiated to adipocytes. These effects were also observed in db/db and diet induced obesity mouse models and in mice with adipose-selective inactivation of HDAC3, a member of class I HDACs. The molecular basis of class I HDACs action in adipose tissue is not deeply characterized and it is not known whether the effects of their inhibition are exerted on adipocyte precursors or mature adipocytes. Therefore, the aim of the present work was to explore the molecular mechanism of class I HDAC action in adipocytes by evaluating the effects of HDAC3-specific silencing at different stages of differentiation. HDAC3 was silenced in C3H/10T1/2 MSCs at different stages of differentiation to adipocytes. shRNA targeting HDAC3 was used to generate the knock-down model. Proper HDAC3 silencing was assessed by measuring both mRNA and protein levels of mouse HDAC3 via qPCR and western blot, respectively. Mitochondrial DNA content and gene expression were quantified via qPCR. HDAC3 silencing at the beginning of differentiation enhanced adipocyte functionality by amplifying the expression of genes regulating differentiation, oxidative metabolism, browning and mitochondrial activity, starting from 72 h after induction of differentiation and silencing. Insulin signaling was enhanced as demonstrated by increased AKT phosphorylation following HDAC3 silencing. Mitochondrial content/density did not change, while the increased expression of the transcriptional co-activator Ppargc1b suggests the observed phenotype was related to enhanced mitochondrial activity, which was confirmed by increased maximal respiration and proton leak linked to reduced coupling efficiency. Moreover, the expression of pro-inflammatory markers increased with HDAC3 early silencing. To the contrary, no differences in terms of gene expression were found when HDAC3 silencing occurred in terminally differentiated adipocyte. Our data demonstrated that early epigenetic events mediated by class I HDAC inhibition/silencing are crucial to commit adipocyte precursors towards the above-mentioned metabolic phenotype. Moreover, our data suggest that these effects are exerted on adipocyte precursors.

Inhibition of histone deacetylases class I improves adipogenic differentiation of human periodontal ligament cells

“…Adipogenesis is the process by which undifferentiated precursor cells differentiate into adipocytes. HDACs and HATs are components in epigenetic regulation; however, there are few reports of HDACs or HAT gene expression in adipocyte differentiation [39]. RT-qPCR assays revealed that HDAC1 and 3 were dynamically downregulated in response to TSA or VPA (Fig.…”

Epigenetic regulation in metabolic diseases: mechanisms and advances in clinical study

“…HDAC3 knockdown could not only regulate adipocyte pro-inflammatory profile, but also promote the expression of transcriptional regulators related to adipogenesis, including Cebpb, Cebpa, Srebf1c, and PPARγ. 193 There is low HDAC6 expression in adipose tissues of humans with obesity and animal models of obesity. HDAC6 could regulate lipid storage by acetylating cell death-inducing DFFA-like effector C (CIDEC), a lipid droplet-binding protein.…”

Environmental Epigenetics and Obesity

“…Each group harbors specific functions, i.e. HDACs class I play a role in adipocyte differentiation as well as in establishing the metabolic characteristics of these cells [39,40].…”