Regulation of α-smooth muscle actin gene expression in myofibroblast differentiation from rat lung fibroblasts

Myofibroblasts are implicated in pathological stromal responses associated with lung fibrosis. One prominent phenotypic marker of fully differentiated myofibroblasts is the polymerized, thick cytoplasmic filaments containing newly synthesized α-smooth muscle actin (α-SMA). These α-SMA-containing cytoplasmic filaments are important for myofibroblast contractility during tissue remodeling. However, the molecular mechanisms regulating the formation and maturation of α-SMA-containing filaments have not been defined. This study demonstrates a critical role for neuronal Wiskott-Aldrich syndrome protein (N-WASP) in regulating the formation of α-SMA-containing cytoplasmic filaments during myofibroblast differentiation and in myofibroblast contractility. Focal adhesion kinase (FAK) is activated by transforming growth factor-β1 (TGF-β1) and is required for phosphorylation of tyrosine residue 256 (Y256) of N-WASP. Phosphorylation of Y256 of N-WASP is essential for TGF-β1-induced formation of α-SMA-containing cytoplasmic filaments in primary human lung fibroblasts. In addition, we demonstrate that actin-related protein (Arp) 2/3 complex is downstream of N-WASP and mediates the maturation of α-SMA-containing cytoplasmic filaments. Together, this study supports a critical role of N-WASP in integrating FAK and Arp2/3 signaling to mediate formation of α-SMA-containing cytoplasmic filaments during myofibroblast differentiation and maturation.

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AHindIII DNA polymorphism in the human entric type smooth muscle actin gene (ACTSG)

Nucleic Acids Research ◽

10.1093/nar/19.2.411 ◽

1991 ◽

Vol 19 (2) ◽

pp. 411-411 ◽

Cited By ~ 1

Author(s):

H. Ueyama

Keyword(s):

Smooth Muscle ◽

Dna Polymorphism ◽

Smooth Muscle Actin ◽

Actin Gene ◽

Muscle Actin ◽

Muscle Actin Gene

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A 29-nucleotide DNA segment containing an evolutionarily conserved motif is required in cis for cell-type-restricted repression of the chicken alpha-smooth muscle actin gene core promoter.

Molecular and Cellular Biology ◽

10.1128/mcb.8.1.241 ◽

1988 ◽

Vol 8 (1) ◽

pp. 241-250 ◽

Cited By ~ 53

Author(s):

S L Carroll ◽

D J Bergsma ◽

R J Schwartz

Keyword(s):

Smooth Muscle ◽

Core Promoter ◽

Smooth Muscle Actin ◽

Gene Promoter ◽

Actin Gene ◽

Muscle Actin ◽

Alpha Smooth Muscle Actin ◽

Actin Genes ◽

Muscle Actin Gene ◽

Ccaat Box

A series of 5' deletion mutations of the upstream flanking sequences of the chicken alpha-smooth muscle (aortic) actin gene was prepared and inserted into the chloramphenicol acetyltransferase expression vector pSV0CAT. Deletion recombinants were transfected into fibroblasts, which actively express the alpha-smooth muscle actin gene, and primary myoblast cultures, which accumulate much lower quantities of alpha-smooth muscle actin mRNAs. The first 122 nucleotides of 5'-flanking DNA were found to contain a "core" promoter capable of accurately directing high levels of transcription in both fibroblasts and myotubes. The activity of this core promoter is modulated in fibroblasts by a "governor" element(s) located at least in part between nucleotides -257 and -123. This region contains sequences potentially conserved between mammalian and avian alpha-smooth muscle actin genes as well as one of a pair of 16-base-pair inverted CCAAT box-associated repeats which are conserved among all chordate muscle actin genes examined to date. A smaller DNA segment (-151 to -123) containing these upstream CCAAT box-associated repeats was sufficient to suppress expression of the core promoter in muscle cultures, suggesting that the upstream CCAAT box-associated repeats play a negative role in the alpha-smooth muscle actin gene promoter.

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A 29-nucleotide DNA segment containing an evolutionarily conserved motif is required in cis for cell-type-restricted repression of the chicken alpha-smooth muscle actin gene core promoter

Molecular and Cellular Biology ◽

10.1128/mcb.8.1.241-250.1988 ◽

1988 ◽

Vol 8 (1) ◽

pp. 241-250

Author(s):

S L Carroll ◽

D J Bergsma ◽

R J Schwartz

Keyword(s):

Smooth Muscle ◽

Core Promoter ◽

Smooth Muscle Actin ◽

Gene Promoter ◽

Actin Gene ◽

Muscle Actin ◽

Alpha Smooth Muscle Actin ◽

Actin Genes ◽

Muscle Actin Gene ◽

Ccaat Box

A series of 5' deletion mutations of the upstream flanking sequences of the chicken alpha-smooth muscle (aortic) actin gene was prepared and inserted into the chloramphenicol acetyltransferase expression vector pSV0CAT. Deletion recombinants were transfected into fibroblasts, which actively express the alpha-smooth muscle actin gene, and primary myoblast cultures, which accumulate much lower quantities of alpha-smooth muscle actin mRNAs. The first 122 nucleotides of 5'-flanking DNA were found to contain a "core" promoter capable of accurately directing high levels of transcription in both fibroblasts and myotubes. The activity of this core promoter is modulated in fibroblasts by a "governor" element(s) located at least in part between nucleotides -257 and -123. This region contains sequences potentially conserved between mammalian and avian alpha-smooth muscle actin genes as well as one of a pair of 16-base-pair inverted CCAAT box-associated repeats which are conserved among all chordate muscle actin genes examined to date. A smaller DNA segment (-151 to -123) containing these upstream CCAAT box-associated repeats was sufficient to suppress expression of the core promoter in muscle cultures, suggesting that the upstream CCAAT box-associated repeats play a negative role in the alpha-smooth muscle actin gene promoter.

Download Full-text