Identification of the intermediate filament protein synemin/SYNM as a target of myocardin family coactivators

Myocardin (MYOCD) is a critical regulator of smooth muscle cell (SMC) differentiation, but its transcriptional targets remain to be exhaustively characterized, especially at the protein level. Here we leveraged human RNA and protein expression data to identify novel potential MYOCD targets. Using correlation analyses we found several targets that we could confirm at the protein level, including SORBS1, SLMAP, SYNM, and MCAM. We focused on SYNM, which encodes the intermediate filament protein synemin. SYNM rivalled smooth muscle myosin (MYH11) for SMC specificity and was controlled at the mRNA and protein levels by all myocardin-related transcription factors (MRTFs: MYOCD, MRTF-A/MKL1, and MRTF-B/MKL2). MRTF activity is regulated by the ratio of filamentous to globular actin, and SYNM was accordingly reduced by interventions that depolymerize actin, such as latrunculin treatment and overexpression of constitutively active cofilin. Many MRTF target genes depend on serum response factor (SRF), but SYNM lacked SRF-binding motifs in its proximal promoter, which was not directly regulated by MYOCD. Furthermore, SYNM resisted SRF silencing, yet the time course of induction closely paralleled that of the SRF-dependent target gene ACTA2. SYNM was repressed by the ternary complex factor (TCF) FLI1 and was increased in mouse embryonic fibroblasts lacking three classical TCFs (ELK1, ELK3, and ELK4). Imaging showed colocalization of SYNM with the intermediate filament proteins desmin and vimentin, and MRTF-A/MKL1 increased SYNM-containing intermediate filaments in SMCs. These studies identify SYNM as a novel SRF-independent target of myocardin that is abundantly expressed in all SMCs.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:317

Enthalten in:

American journal of physiology. Cell physiology - 317(2019), 6 vom: 01. Dez., Seite C1128-C1142

Sprache:

Englisch

Beteiligte Personen:

Swärd, Karl [VerfasserIn]
Krawczyk, Katarzyna K [VerfasserIn]
Morén, Björn [VerfasserIn]
Zhu, Baoyi [VerfasserIn]
Matic, Ljubica [VerfasserIn]
Holmberg, Johan [VerfasserIn]
Hedin, Ulf [VerfasserIn]
Uvelius, Bengt [VerfasserIn]
Stenkula, Karin [VerfasserIn]
Rippe, Catarina [VerfasserIn]

Links:

Volltext

Themen:

ACTA2 protein, human
Actin dynamics
Actins
Bridged Bicyclo Compounds, Heterocyclic
CD146 Antigen
CFL2
CFL2 protein, human
Cofilin 2
DSTN
Desmin
Desmuslin
EC 3.6.4.1
FLI1 protein, human
Intermediate Filament Proteins
Journal Article
Latrunculin A
Lineage markers
MCAM protein, human
MRTFA protein, human
MRTFB protein, human
MYH11 protein, human
Membrane Proteins
Microfilament Proteins
Myocardin
Myosin Heavy Chains
Nuclear Proteins
Phenotypic modulation
Proto-Oncogene Protein c-fli-1
Research Support, Non-U.S. Gov't
SLMAP protein, human
SORBS1 protein, human
SRF protein, human
SRQ9WWM084
Serum Response Factor
Thiazolidines
Trans-Activators
Transcription Factors
VIM protein, human
Vimentin

Anmerkungen:

Date Completed 07.04.2020

Date Revised 30.09.2020

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1152/ajpcell.00047.2019

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM30070819X