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Myocardin regulates exon usage in smooth muscle cells through induction of splicing regulatory factors

Liu, Li LU ; Kryvokhyzha, Dmytro LU ; Rippe, Catarina LU ; Jacob, Aishwarya ; Borreguero-Muñoz, Andrea LU ; Stenkula, Karin G. LU ; Hansson, Ola LU orcid ; Smith, Christopher W.J. ; Fisher, Steven A. and Swärd, Karl LU (2022) In Cellular and Molecular Life Sciences 79(8).
Abstract

Differentiation of smooth muscle cells (SMCs) depends on serum response factor (SRF) and its co-activator myocardin (MYOCD). The role of MYOCD for the SMC program of gene transcription is well established. In contrast, the role of MYOCD in control of SMC-specific alternative exon usage, including exon splicing, has not been explored. In the current work we identified four splicing factors (MBNL1, RBPMS, RBPMS2, and RBFOX2) that correlate with MYOCD across human SMC tissues. Forced expression of MYOCD family members in human coronary artery SMCs in vitro upregulated expression of these splicing factors. For global profiling of transcript diversity, we performed RNA-sequencing after MYOCD transduction. We analyzed alternative transcripts... (More)

Differentiation of smooth muscle cells (SMCs) depends on serum response factor (SRF) and its co-activator myocardin (MYOCD). The role of MYOCD for the SMC program of gene transcription is well established. In contrast, the role of MYOCD in control of SMC-specific alternative exon usage, including exon splicing, has not been explored. In the current work we identified four splicing factors (MBNL1, RBPMS, RBPMS2, and RBFOX2) that correlate with MYOCD across human SMC tissues. Forced expression of MYOCD family members in human coronary artery SMCs in vitro upregulated expression of these splicing factors. For global profiling of transcript diversity, we performed RNA-sequencing after MYOCD transduction. We analyzed alternative transcripts with three different methods. Exon-based analysis identified 1637 features with differential exon usage. For example, usage of 3´ exons in MYLK that encode telokin increased relative to 5´ exons, as did the 17 kDa telokin to 130 kDa MYLK protein ratio. Dedicated event-based analysis identified 239 MYOCD-driven splicing events. Events involving MBNL1, MCAM, and ACTN1 were among the most prominent, and this was confirmed using variant-specific PCR analyses. In support of a role for RBPMS and RBFOX2 in MYOCD-driven splicing we found enrichment of their binding motifs around differentially spliced exons. Moreover, knockdown of either RBPMS or RBFOX2 antagonized splicing events stimulated by MYOCD, including those involving ACTN1, VCL, and MBNL1. Supporting an in vivo role of MYOCD-SRF-driven splicing, we demonstrate altered Rbpms expression and splicing in inducible and SMC-specific Srf knockout mice. We conclude that MYOCD-SRF, in part via RBPMS and RBFOX2, induce a program of differential exon usage and alternative splicing as part of the broader program of SMC differentiation.

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author
; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Actin-binding, Differentiation, Focal adhesion, Heart, Splicing code
in
Cellular and Molecular Life Sciences
volume
79
issue
8
article number
459
publisher
Birkhäuser
external identifiers
  • pmid:35913515
  • scopus:85135269684
ISSN
1420-682X
DOI
10.1007/s00018-022-04497-7
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2022, The Author(s).
id
01b9ae37-b9d0-4c28-a7a8-6fac9b0dc941
date added to LUP
2022-09-29 08:16:09
date last changed
2024-11-01 10:22:13
@article{01b9ae37-b9d0-4c28-a7a8-6fac9b0dc941,
  abstract     = {{<p>Differentiation of smooth muscle cells (SMCs) depends on serum response factor (SRF) and its co-activator myocardin (MYOCD). The role of MYOCD for the SMC program of gene transcription is well established. In contrast, the role of MYOCD in control of SMC-specific alternative exon usage, including exon splicing, has not been explored. In the current work we identified four splicing factors (MBNL1, RBPMS, RBPMS2, and RBFOX2) that correlate with MYOCD across human SMC tissues. Forced expression of MYOCD family members in human coronary artery SMCs in vitro upregulated expression of these splicing factors. For global profiling of transcript diversity, we performed RNA-sequencing after MYOCD transduction. We analyzed alternative transcripts with three different methods. Exon-based analysis identified 1637 features with differential exon usage. For example, usage of 3´ exons in MYLK that encode telokin increased relative to 5´ exons, as did the 17 kDa telokin to 130 kDa MYLK protein ratio. Dedicated event-based analysis identified 239 MYOCD-driven splicing events. Events involving MBNL1, MCAM, and ACTN1 were among the most prominent, and this was confirmed using variant-specific PCR analyses. In support of a role for RBPMS and RBFOX2 in MYOCD-driven splicing we found enrichment of their binding motifs around differentially spliced exons. Moreover, knockdown of either RBPMS or RBFOX2 antagonized splicing events stimulated by MYOCD, including those involving ACTN1, VCL, and MBNL1. Supporting an in vivo role of MYOCD-SRF-driven splicing, we demonstrate altered Rbpms expression and splicing in inducible and SMC-specific Srf knockout mice. We conclude that MYOCD-SRF, in part via RBPMS and RBFOX2, induce a program of differential exon usage and alternative splicing as part of the broader program of SMC differentiation.</p>}},
  author       = {{Liu, Li and Kryvokhyzha, Dmytro and Rippe, Catarina and Jacob, Aishwarya and Borreguero-Muñoz, Andrea and Stenkula, Karin G. and Hansson, Ola and Smith, Christopher W.J. and Fisher, Steven A. and Swärd, Karl}},
  issn         = {{1420-682X}},
  keywords     = {{Actin-binding; Differentiation; Focal adhesion; Heart; Splicing code}},
  language     = {{eng}},
  number       = {{8}},
  publisher    = {{Birkhäuser}},
  series       = {{Cellular and Molecular Life Sciences}},
  title        = {{Myocardin regulates exon usage in smooth muscle cells through induction of splicing regulatory factors}},
  url          = {{http://dx.doi.org/10.1007/s00018-022-04497-7}},
  doi          = {{10.1007/s00018-022-04497-7}},
  volume       = {{79}},
  year         = {{2022}},
}