The Chd4 subunit of the NuRD complex regulates Pdx1-controlled genes involved in β-cell function

Abstract

Type 2 diabetes (T2D) is associated with loss of transcription factors (TFs) from a subset of failing β-cells. Among these TFs is Pdx1, which controls the expression of numerous genes involved in maintaining β-cell function and identity. Pdx1 activity is modulated by transcriptional coregulators and has recently been shown, through an unbiased screen, to interact with the Chd4 ATPase subunit of the Nucleosome Remodeling and Deacetylase complex. Chd4 contributes to the maintenance of cellular identity and functional status of numerous different cell types. Here, we demonstrate Pdx1 dynamically interacts with Chd4 under physiological and stimulatory conditions within islet β-cells. We establish a fundamental role for Chd4 in regulating insulin secretion and modulating numerous Pdx1 bound genes in vitro, including the MafA TF, where we discovered Chd4 is bound at the MafA Region 3 enhancer. Furthermore, we found that Pdx1:Chd4 interactions are significantly compromised in islet β-cells under metabolically-induced stress in vivo and in human donor tissues with T2D. Our findings establish a fundamental role for Chd4 in regulating insulin secretion and modulating Pdx1-bound genes in vitro, and disruption of Pdx1:Chd4 interactions coincides with β-cell dysfunction associated with T2D.

Dynamic regulation of pancreatic β cell function and gene expression by the SND1 coregulator in vitro

“…Rodent and human β cell lines: mouse βTC3 cells, mouse insulinoma 6 (MIN6) cells, rat INS-1 832/13 and human EndoC-βH1 cells (passage number 65–70 used) were cultured using protocols as previously described 23 .…”

“…Cas9-expressing MIN6 cells were generated as previously described 23 . To generate lentivirus expressing Snd1 specific gRNAs, we transfected HEK2 93T cells with packaging plasmids pVSV-G, psPAX2 and puromycin-resistant single guide gRNA transfer vectors (Addgene clones: 138479, 12260 and 52,963 (used as backbone for cloning gRNAs)) ( Table 1 ) in Opti-MEM using Lipofectamine 2000.…”

Regulation of Pdx1 by oxidative stress and Nrf2 in pancreatic beta-cells

“…Apart from affecting PDX1 abundance, conditions associated with increased ROS can affect PDX1 transcriptional activity by targeting coactivator complexes associated with PDX1 ( 97 ). For example, decreased interaction between PDX1 and the chromodomain helicase DNA-binding 4 (CHD4) ATPase subunit of the NuRD complex is observed in both islets of type-2 donors and in mice fed on HFD ( 83 ). Similarly, in human type-2 diabetic beta-cells, there is a significant reduction in PDX1 binding to the ATP-dependent SWI/SNF chromatin remodeling complex, a complex that is needed for pancreas development and beta-cell identity ( 87 , 98 ).…”

Citrus flavanone metabolites protect pancreatic β-cells against cholesterol stress through a multi-proteomic mechanism

“…8 These results are in agreement with another study in which flavonoids classes such as flavanones, flavanols, and anthocyanidin were shown to reduce insulin resistance by regulating the insulin signaling pathway. 39 Previous studies suggest that the decrease in Cell Division Cycle 42 (CDC42), Actin Related Protein 2/3 complex (ARP 2/ 3), 40 proto-oncogene tyrosine-protein kinase (YES), 41 and Chromodomain Helicase DNA Binding Protein 4 (CHD4) proteins, 42 is implicated in pancreatic β-cell function, insulin resistance, insulin secretion and, consequently, TD2. 40,42 In our study, H7G and PA promoted the upregulation of these proteins (Table S1 †), and these proteins present high proteinprotein interaction.…”

“…39 Previous studies suggest that the decrease in Cell Division Cycle 42 (CDC42), Actin Related Protein 2/3 complex (ARP 2/ 3), 40 proto-oncogene tyrosine-protein kinase (YES), 41 and Chromodomain Helicase DNA Binding Protein 4 (CHD4) proteins, 42 is implicated in pancreatic β-cell function, insulin resistance, insulin secretion and, consequently, TD2. 40,42 In our study, H7G and PA promoted the upregulation of these proteins (Table S1 †), and these proteins present high proteinprotein interaction. Corroborating our findings, it was previously suggested that resveratrol together with the glucan complex promotes an increase in the expression of CDC42.…”