X-box binding protein 1-mediated COL4A1s secretion regulates communication between vascular smooth muscle and stem/progenitor cells

Angshumonik Angbohang, Lei Huang, Yi Li, Yue Zhao, Yijie Gong, Yi Fu, Chenfeng Mao, Jose Morales, Peiyi Luo, Mazdak Ehteramyan, Yingtang Gao, Andriana Margariti, Wenduo Gu, Min Zhang, Alberto Smith, Ajay M Shah, Tong Li, Wei Kong, Lingfang Zeng

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Abstract

Vascular smooth muscle cells (VSMCs) contribute to the deposition of extracellular matrix proteins (ECMs), including Type IV collagen, in the vessel wall. ECMs coordinate communication among different cell types, but mechanisms underlying this communication remain unclear. Our previous studies have demonstrated that X-box binding protein 1 (XBP1) is activated and contributes to VSMC phenotypic transition in response to vascular injury. In this study, we investigated the participation of XBP1 in the communication between VSMCs and vascular progenitor cells (VPCs). Immunofluorescence and immunohistology staining revealed that Xbp1 gene was essential for COL4A1 expression during mouse embryonic development and vessel wall ECM deposition and stem cell antigen 1-positive (Sca1 )-VPC recruitment in response to vascular injury. Western blot analysis elucidated an Xbp1 gene dose-dependent effect on COL4A1 expression and that the spliced XBP1 protein (XBP1s) increased protease-mediated COL4A1 degradation as revealed by Zymography. RT-PCR analysis revealed that XBP1s in VSMCs not only upregulated COL4A1/2 transcription but also induced the occurrence of a novel transcript variant, COL4A1s, in which the front part of exon 4 is joined with the rear part of exon 42. Chromatin-immunoprecipitation, DNA/protein pulldown and in vitro transcription demonstrated that XBP1s binds to exon 4 and exon 42, directing the transcription from exon 4 to exon 42. This leads to transcription complex bypassing the internal sequences, producing a shortened soluble COL4A1s protein that increased Sca1 -VPC migration. Taken together, these results suggest that activated VSMCs may recruit Sca1 -VPCs via XBP1s-mediated COL4A1s secretion, leading to vascular injury repair or neointima formation.
Original languageEnglish
Article number100541
Number of pages13
JournalThe Journal of biological chemistry
Volume296
Early online date15 Mar 2021
DOIs
Publication statusEarly online date - 15 Mar 2021

Keywords

  • X-box binding protein-1
  • adventitia
  • alternative splicing
  • cell movement
  • intron bypass transcription
  • neointima
  • type Ⅳ collagen
  • vascular progenitor cell
  • vascular remodeling
  • vascular smooth muscle cell

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