TRIM28 Regulates Dlk1 Expression in Adipogenesis

Abstract

The tripartite motif-containing protein 28 (TRIM28) is a transcription corepressor, interacting with histone deacetylase and methyltransferase complexes. TRIM28 is a crucial regulator in development and differentiation. We would like to investigate its function and regulation in adipogenesis. Knockdown of Trim28 by transducing lentivirus-carrying shRNAs impairs the differentiation of 3T3-L1 preadipocytes, demonstrated by morphological observation and gene expression analysis. To understand the molecular mechanism of Trim28-mediated adipogenesis, the RNA-seq was performed to find out the possible Trim28-regulated genes. Dlk1 (delta-like homolog 1) was increased in Trim28 knockdown 3T3-L1 cells both untreated and induced to differentiation. Dlk1 is an imprinted gene and known as an inhibitor of adipogenesis. Further knockdown of Dlk1 in Trim28 knockdown 3T3-L1 would rescue cell differentiation. The epigenetic analysis showed that DNA methylation of Dlk1 promoter and differentially methylated regions (DMRs) was not altered significantly in Trim28 knockdown cells. However, compared to control cells, the histone methylation on the Dlk1 promoter was increased at H3K4 and decreased at H3K27 in Trim28 knockdown cells. Finally, we found Trim28 might be recruited by transcription factor E2f1 to regulate Dlk1 expression. The results imply Trim28-Dlk1 axis is critical for adipogenesis.

Genome-wide DNA methylation, imprinting, and gene expression in human placentas derived from Assisted Reproductive Technology

“…5). However, we did not observe significantly decreased DNAm in the ART placentas compared to controls, which indicated that the ICR hypomethylation is not the only mechanism which affects the complex DLK1 regulation 59,60 .…”

Role of the tripartite motif‐containing (TRIM) family of proteins in insulin resistance and related disorders

“…First, it inhibits NLRP3 inflammasome activation and reduces reactive oxygen species production when overexpressed. 32 Second, TRIM30α, an isoform, can inhibit inflammatory responses by promoting the degradation of transforming growth factor-β-activated kinase 1 (TAK1)-binding protein 2 (TAB2) and TAB3, as well as a feedback loop of NF-κB activation, through the Toll-like receptor signalling pathway. 36 Overall, these two TRIM proteins can affect adipocyte formation and insulin sensitivity through regulation of target proteins, transcription factor expression, and epigenetics.…”

“…TRIM28 is a transcriptional regulator in adipocytes associated with increased fat mass 90 . It can be recruited by the transcription factor E2f1 to regulate the histone methylation of the delta‐like noncanonical notch ligand 1 (Dlk1; an adipogenic inhibitor) promoter, negatively regulating Dlk1 expression and promoting adipocyte differentiation 32 . TRIM28 also reduces the expression of Krüppel‐like factor (KLF) transcription factor 14, a well‐defined gender‐specific regulator, which in turn alters adiposity and body weight 91 .…”

“…TRIM30 inhibits inflammatory responses through two distinct pathways. First, it inhibits NLRP3 inflammasome activation and reduces reactive oxygen species production when overexpressed 32 . Second, TRIM30α, an isoform, can inhibit inflammatory responses by promoting the degradation of transforming growth factor‐β‐activated kinase 1 (TAK1)‐binding protein 2 (TAB2) and TAB3, as well as a feedback loop of NF‐κB activation, through the Toll‐like receptor signalling pathway 36 .…”

Pituitary Tumor-Transforming Gene 1/Delta like Non-Canonical Notch Ligand 1 Signaling in Chronic Liver Diseases

“…It has been reported that KLF6 binding with histone deacetylase 3 to the DLK1 promoter (between −78 and −53 bp upstream of the transcriptional start site) results in DLK1 repression [47]. Contrarily, the E2F Transcription Factor 1 has been shown to activate the DLK1 promoter, and its activity is inhibited by a tripartite motif-containing protein 28 [48]. Finally, at the proximal 5 enhancer region, the DLK1 gene includes three putative hypoxia responsive elements at −758, −402, and −248 bp, and consequently its expression is induced by hypoxia inducible factor 1α (HIF-1α) and HIF-2α [49].…”