Dataset Information

E3 ligase substrate adaptor SPOP fine tunes the UPR of pancreatic beta cells

ABSTRACT: The Cullin 3 E3 ligase adaptor protein, SPOP, targets proteins for ubiquitination and proteasomal degradation. We previously established the β cell transcription factor (TF) and human diabetes gene PDX1 as an SPOP substrate, suggesting a functional role for SPOP in the β cell. Here, we generated a β cell specific Spop deletion mouse strain (SpopβKO) and found that Spop is necessary to prevent aberrant basal insulin secretion and for maintaining glucose- stimulated insulin secretion (GSIS) through impacts on glycolysis and glucose-stimulated calcium flux. Integration of proteomic, TF-regulatory gene network and biochemical analyses identified XBP1 as a functionally important SPOP substrate in pancreatic β cells.Further, loss of SPOP strengthened the IRE1α-XBP1 axis of unfolded protein response (UPR) signaling. ER stress promoted proteasomal degradation of SPOP, supporting a model whereby SPOP fine-tunes XBP1 activation during the UPR. These results position SPOP as a regulatorof β cell function and proper UPR activation.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Pancreatic Islet Cell

SUBMITTER: Hossein Fazelinia

LAB HEAD: Doris A.

PROVIDER: PXD052527 | Pride | 2024-11-12

REPOSITORIES: Pride

ACCESS DATA

Dataset's files

Source:

			Action	DRS
	20221116_174852_DS1736_SL_DIA.sne	Other
	checksum.txt	Txt
	x221108_DS1736_DIA_01.raw	Raw
	x221108_DS1736_DIA_02.raw	Raw
	x221108_DS1736_DIA_03.raw	Raw

Items per page:

1 - 5 of 17

Similar Datasets

Project description:BACKGROUND AND AIM: We previously established that endoplasmic reticulum stress leads to unfolded protein response (UPR) that promotes liver fibrosis by activating hepatic stellate cell (HSC). We aimed to determine the role of X-box binding protein 1 (XBP1), one of three UPR effector pathways, in the fibrogenic HSC activation. METHODS: XBP1 expression was measured by qPCR in tunicamycin-treated human HSC lines (TWNT4 and LX2) and culture-activated human primary HSCs. XBP1 was overexpressed in primary human HSCs and the HSC lines, and fibrogenic genes (COL1A1, ACTA2, PDGFRB, MMP2, TIMP1) and encoded proteins were assessed by qPCR and Western blotting, respectively. Autophagy was inhibited by knockdown of ATG7. Genome-wide transcriptome profiling was performed to determine modulated molecular pathway by XBP1. In vivo XBP1 activation was assessed in transcriptome datasets of fibrotic mouse models and immunohistochemistry of human liver tissues. RESULTS: XBP1 overexpression accompanied both tunicamycin- and culture-based HSC activation. Ectopic overexpression of XBP1 induced fibrogenic gene expression in the HSC lines, which was inhibited by knockdown of ATG7. UPR pathway together with PDGFRB pathway, a hallmark of HSC activation, were induced in transcriptome profiles of XBP1-transduced HSC lines. Some known fibrogenic pathways such as transforming growth factor (TGF)-beta pathway were not induced, suggesting partial contribution of XBP1 to the entire fibrogenic HSC activation machinery. XBP1 target gene signature defined in our XBP1-overexpressing HSC lines was significantly induced in liver tissue transcriptome profiles of carbon tetrachloride-treated or bile duct-ligated mouse models, and XBP1 and alpha-smooth muscle actin (encoded by ACTA2, another hallmark of HSC activation) were co-localized in human fibrotic liver tissues, collectively supporting involvement of XBP1 in HSC activation and fibrogesis in vivo. CONCLUSIONS: XBP1-mediated UPR is at least partially responsible for fibrogenic HSC activation via autophagy.

Dataset Information

E3 ligase substrate adaptor SPOP fine tunes the UPR of pancreatic beta cells

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets