Project description:Inflammatory bowel disease (IBD) is a complex and relapsing inflammatory disease, and patients with IBD exhibit a higher risk of developing colorectal cancer (CRC). Epithelial barrier disruption is one of the major causes of inflammatory bowel disease (IBD) in which epigenetic modulations are pivotal elements. However, the epigenetic mechanisms underlying the epithelial barrier integrity regulation remain largely unexplored. Here, we investigated how SETD2, a histone H3K36 trimethyltransferase, maintains intestinal epithelial homeostasis under inflammatory conditions. GEO public database and IBD tissues were used to investigate the clinical relevance of SetD2 in IBD. To define the role of SetD2 in the colitis, we generated mice with epithelial-specific deletion of Setd2 (Setd2Vil-KO mice). Acute colitis was induced by 2% dextran sodium sulfate (DSS), and colitis-associated CRC was induced by injecting azoxymethane (AOM), followed by three cycles of 2% DSS treatments. Colon tissues were collected from mice and analyzed by histology, immunohistochemistry and immunoblots. Organoids were generated from Setd2Vil-KO and control mice, and were stained with 7-AAD to detect apoptosis. We isolated intestinal epithelial cells (IECs), performed RNA-seq and H3K36me3 ChIP-seq analysis to uncover the mechanism. Results were validated in functional rescue experiments by N-acetyl-l-cysteine (NAC) treatment and transgenes expression in IECs. SETD2 expression was decreased in IBD patients and DSS-treated colitis mice. Setd2Vil-KO mice had abnormal loss of mucosa-producing goblet cells and antimicrobial peptide (AMP)-producing Paneth cells, and promoted early intestinal inflammation development. Consistent with the reduced SETD2 expression in IBD patients, Setd2Vil-KO mice exhibited increased susceptibility to DSS-induced colitis, accompanied by more severe epithelial barrier disruption. Intestinal permeability was markedly increased in Setd2Vil-KO mice. Setd2 ablation drived inﬂammation-associated CRC. Deletion of Setd2 resulted in excess reactive oxygen species (ROS), which led to cellular apoptosis and the defects in barrier integrity. N-acetyl-l-cysteine (NAC) treatment in Setd2Vil-KO mice rescued epithelial barrier injury and apoptosis. Moreover, overexpression of antioxidase PRDX6 in Setd2Vil-KO IECs largely alleviated the overproductions of ROS and improved the cellular survival. Deficiency of Setd2 specifically in the intestine aggravates epithelial barrier disruption and inflammatory response in colitis via a mechanism dependent on oxidative stress. More importantly, we show that Setd2 depletion results in excess ROS by directly down-regulating PRDX6, an antioxidant protein that inhibit excess ROS. Thus, our results highlight an epigenetic mechanism by which Setd2 mediates oxidative stress to modulate intestinal epithelial homeostasis.

Project description:Histone-Lysine N-methyltransferase SETD2 is an evolutionarily conserved histone methyltransferase that associates with RNA Polymerase II (RNAPII) and catalyzes trimethylation of histone H3 lysine 36 (H3K36me3) in transcribed regions. Interestingly, SETD2 is frequently mutated in cancers. Clear cell renal cell carcinomas (ccRCCs) have extensive mutation of SETD2, implicating SETD2 as a tumor suppressor. ccRCCs are known for early driving events where the 3p chromosomal arm is lost, deleting one copy of SETD2, resulting in haploinsufficiency. While the role of SETD2 mediated H3K36me3 and interaction of RNAPII has been the focus of many studies, haploinsufficient SETD2 tumors retain H3K36me3, yet have drastic genome stability defects. The C-terminus of SETD2 is required for H3K36me3 while the N-terminus of SETD2 remains poorly characterized compared to the C-terminus. The N-terminus is highly disordered and has recently been shown to contribute to SETD2 stability, implicating regulatory functions. To better understand how SETD2 contributes to chromatin biology, we first sought to identify SETD2 protein interactors. A stable, immortalized normal human kidney epithelial cell (HKC) line with a dox inducible SETD2-APEX2 construct was used for a proximity-based biotinylation assay. Initial analysis yielded 2083 biotinylated proteins with significant enrichment (log2 fold change > 2 p-value < 0.05) in SETD2-APEX2 compared to control. Gene Ontology analysis of these interactors revealed enrichment of proteins involved in nuclear envelope functions, including lamin A/C, lamin B1, lamin B2 and emerin. These interactions were confirmed via western and reciprocal immunoprecipitation (IP). To determine effect of SETD2 depletion on lamin A/C and lamin B1 phosphorylation, we performed lamin A/C or lamin B1 IP from control or SETD2-knockdown (KD) cells and interrogated via LC-MS/MS. Mass spectrometry analysis revealed a significant decrease in lamin A/C S22 phosphorylation, and modest decrease in S390 phosphorylation, in SETD2 depleted cells compared to controls. While lamin B1 S23 phosphorylation was detected in control cells, we did not detect it in SETD2-KD cells, indicating a significant reduction in S23 phosphorylation upon SETD2 depletion. Next, we sought to identify the effect of SETD2 N-terminal deletion on the SETD2 protein interactome. We compared the protein interactors of dox inducible WT-SETD2 APEX2 fusion to an N-terminal deletion mutant of SETD2 (tSETD2-APEX2). Deletion of the N-terminus resulted in loss of lamin B1 and emerin interaction. Intriguingly, tSETD2 selectively associated with lamin C, whereas WT SETD2 interacted with both lamin A and C. These data together reveal an interaction with SETD2 and nuclear lamins. Further experiments revealed a role for the SETD2 N-terminus in facilitating the association of lamins with CDK1, thereby promoting lamin phosphorylation and depolymerization required for nuclear envelope disassembly during mitosis. Together, the data reveal a non-catalytic role of SETD2 during mitosis.

			Action	DRS
	DIANN_output_Co-IP.zip	Other
	DIANN_output_Mouse.zip	Other
	DIANN_output_Ribosome.zip	Other
	DIANN_output_Subcellular_Fraction.zip	Other
	HA_dia_90min_Slot1-49_1_7238.d.zip	Other

Dataset Information

Proteomics analysis on SETD2 deficient intestinal epithelial cells

Dataset's files

Publications

Ribosome Homeostasis Regulated by SETD2 Preserves Intestinal Epithelial Barrier.

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