A nucleus-targeted alternately spliced Nix/Bnip3L protein isoform modifies nuclear factor κB (NFκB)-mediated cardiac transcription

Yun Chen, Keith F. Decker, Dali Zheng, Scot J. Matkovich, Li Jia, Gerald W. Dorn

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Several Bcl2 family proteins are expressed both as mitochondrial-targeted full-length and as cytosolic truncated alternately spliced isoforms. Recombinantly expressed shorter Bcl2 family isoforms can heterotypically bind to and prevent mitochondrial localization of their full-length analogs, thus suppressing their activity by sequestration. This "sponge" role requires 1:1 expression stoichiometry; absent this an alternate role is suggested. Here, RNA sequencing revealed coordinate regulation of BH3-only protein Nix/Bnip3L (Nix) and its alternately spliced soluble form (sNix) in hearts, but relative sNix/Nix expression of ∼1:10. Accordingly, we examined other putative functions of sNix. Although Nix expressed in H9c2 rat myoblasts localized to mitochondria, sNix showed variable cytoplasmic and nuclear distribution. Tumor necrosis factor α (TNFα) induced rapid and complete sNix nucleoplasmic translocation concomitant with nuclear translocation of the p65/RelA subunit of NFκB. sNix co-localized and co-precipitated with p65/RelA after TNFα stimulation; TNFα-induced sNix nuclear translocation did not occur in p65/RelA null murine embryonic fibroblasts. ChIP sequencing of TNFα-stimulated H9c2 cells revealed sNix suppression of p65/RelA binding to a subset of weaker DNA binding sites, accounting for its ability to alter gene expression in cultured cells and in vivo mouse hearts. These findings reveal TNFα-stimulated cytoplasmic-nuclear shuttling of the alternately spliced non-mitochondrial Nix isoform and uncover a role for sNix as a modulator of TNFα/NFκB-stimulated cardiac gene expression. Transcriptional co-regulation of sNix and Nix, combined with sNix posttranslational regulation by TNFα, comprises a previously unknown mechanism for molecular cross-talk between extrinsic death receptor and intrinsic mitochondrial apoptosis pathways.

Original languageEnglish (US)
Pages (from-to)15455-15465
Number of pages11
JournalJournal of Biological Chemistry
Volume288
Issue number22
DOIs
StatePublished - May 31 2013
Externally publishedYes

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Transcription
Protein Isoforms
Tumor Necrosis Factor-alpha
Gene expression
RNA Sequence Analysis
Gene Expression
Death Domain Receptors
Mitochondria
Myoblasts
Porifera
Fibroblasts
Stoichiometry
Modulators
Rats
Cultured Cells
Proteins
Binding Sites
Cells
RNA
Apoptosis

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

A nucleus-targeted alternately spliced Nix/Bnip3L protein isoform modifies nuclear factor κB (NFκB)-mediated cardiac transcription. / Chen, Yun; Decker, Keith F.; Zheng, Dali; Matkovich, Scot J.; Jia, Li; Dorn, Gerald W.

In: Journal of Biological Chemistry, Vol. 288, No. 22, 31.05.2013, p. 15455-15465.

Research output: Contribution to journalArticle

Chen, Yun ; Decker, Keith F. ; Zheng, Dali ; Matkovich, Scot J. ; Jia, Li ; Dorn, Gerald W. / A nucleus-targeted alternately spliced Nix/Bnip3L protein isoform modifies nuclear factor κB (NFκB)-mediated cardiac transcription. In: Journal of Biological Chemistry. 2013 ; Vol. 288, No. 22. pp. 15455-15465.
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