Reversal of TGF-β1 stimulation of α-smooth muscle actin and extracellular matrix components by cyclic AMP in Dupuytren's - derived fibroblasts

Transforming growth factor-β1 (TGF-β1) is known to induce epithelial-mesenchymal transition in the kidney, a process involved in tubulointerstitial fibrosis. We hypothesized that a coactivator of the serum response factor (SRF), megakaryoblastic leukemia factor-1 (MKL1), stimulates α-smooth muscle actin (α-SMA) transcription in primary cultures of renal tubular epithelial cells (RTC), which convert into myofibroblasts on treatment with TGF-β1. Herein, we study the effect of MKL1 expression on α-SMA in these cells. We demonstrate that TGF-β1 stimulation of α-SMA transcription is mediated through CC(A/T)6-rich GG elements known to bind to SRF. These elements also mediate the MKL1 effect that dramatically activates α-SMA transcription in serum-free media. MKL1 fused to green fluorescent protein localizes to the nucleus and induces α-SMA expression regardless of treatment with TGF-β1. Using proteasome inhibitors, we also demonstrate that the proteolytic ubiquitin pathway regulates MKL1 expression. These data indicate that MKL1 overexpression is sufficient to induce α-SMA expression. Inhibition of endogenous expression of MKL1 by small interfering RNA abolishes TGF-β1 stimulation of α-SMA expression. Therefore, MKL1 is also absolutely required for TGF-β1 stimulation of α-SMA expression. Western blot and immunofluorescence analysis show that overexpressed and endogenous MKL1 are located in the nucleus in non-stimulated RTC. Chromatin immunoprecipitation assay demonstrates that TGF-β1 induces binding of endogenous SRF and MKL1 to the α-SMA promoter in chromatin. Since MKL1 constitutes a potent factor regulating α-SMA expression, modulation of endogenous MKL1 expression or activity may have a profound effect on myofibroblast formation and function in the kidney.

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Expression of alpha-smooth muscle actin, TGF-β1 and TGF-β type II receptor during connective tissue contraction

In Vitro Cellular & Developmental Biology - Animal ◽

10.1007/s11626-997-0112-4 ◽

1997 ◽

Vol 33 (8) ◽

pp. 622-627 ◽

Cited By ~ 6

Author(s):

M. Reza Ghassemifar ◽

Roy W. Tarnuzzer ◽

Nasser Chegini ◽

Erkki Tarpila ◽

Gregory S. Schultz ◽

...

Keyword(s):

Smooth Muscle ◽

Connective Tissue ◽

Smooth Muscle Actin ◽

Type Ii ◽

Muscle Actin ◽

Alpha Smooth Muscle Actin ◽

Tissue Contraction ◽

Tgf Β1

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The Improvement Effect of Sodium Ferulate on the Formation of Pulmonary Fibrosis in Silicosis Mice Through the Neutrophil Alkaline Phosphatase 3 (NALP3)/Transforming Growth Factor-β1 (TGF-β1)/α-Smooth Muscle Actin (α-SMA) Pathway

Medical Science Monitor ◽

10.12659/msm.927978 ◽

2021 ◽

Vol 27 ◽

Author(s):

Jingyin Han ◽

Yangmin Jia ◽

Shujuan Wang ◽

Xiaoyu Gan

Keyword(s):

Alkaline Phosphatase ◽

Smooth Muscle ◽

Growth Factor ◽

Transforming Growth Factor ◽

Smooth Muscle Actin ◽

Transforming Growth Factor Β1 ◽

Muscle Actin ◽

Improvement Effect ◽

Neutrophil Alkaline Phosphatase ◽

Tgf Β1

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Extracellular matrix components and regulators in the airway smooth muscle in asthma

European Respiratory Journal ◽

10.1183/09031936.00147807 ◽

2008 ◽

Vol 32 (1) ◽

pp. 61-69 ◽

Cited By ~ 109

Author(s):

B. B. Araujo ◽

M. Dolhnikoff ◽

L. F. F. Silva ◽

J. Elliot ◽

J. H. N. Lindeman ◽

...

Keyword(s):

Extracellular Matrix ◽

Smooth Muscle ◽

Airway Smooth Muscle ◽

Extracellular Matrix Components ◽

Matrix Components

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Evaluation of myofibroblasts and its association with TGF-β and IFN-γ in lesions of patients with american tegumentary leishmaniasis

Anais Brasileiros de Dermatologia ◽

10.1590/s0365-05962012000400004 ◽

2012 ◽

Vol 87 (4) ◽

pp. 545-549 ◽

Cited By ~ 2

Author(s):

Agostinho Gonçalves Viana ◽

Carlos Alberto de Carvalho Fraga ◽

Paulo Rogério Ferreti Bonan

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Actin ◽

Healing Process ◽

Sand Fly ◽

Muscle Actin ◽

Alpha Smooth Muscle Actin ◽

Tegumentary Leishmaniasis ◽

American Tegumentary Leishmaniasis ◽

Ifn Γ ◽

Tgf Β1

BACKGROUND: Leishmaniasis is caused by protozoa of Leishmania spp. genus. It is transmitted by the bite of the sand fly insect. It is believed that 12 million people are infected with this disease and that its annual incidence is 2 million; this number is increasing. OBJECTIVES: The present study aimed to evaluate the expression of myofibroblasts through alpha smooth muscle actin labeling, and to analyze their relationship with the expression of the cytokines Interferon gama (IFN-γ) and Transforming growth factor beta (TGF-β1) in lesions of American tegumentary leishmaniasis (ATL). METHODS: For this retrospective study, we gathered 28 patients diagnosed with ATL between 2002 and 2006. We verified α-SMA positivity and performed IFN-γ and TGF-β1 immunolabeling to identify the profile of these cytokines in both positive and negative cases for myofibroblasts, via immunohistochemistry, in order to assess the presence of myofibroblasts,. RESULTS: We observed that out of the 28 cases, 17 (60.71%) were positive for alpha smooth muscle actin, while 11 (39.29%) were negative, and IFN-γ was more expressed than TGF-β1 (p=0.007). The mean percentages of expression of IFN-γ and TGF-β1 in the group negative for alpha smooth muscle actin were different, with an increased expression of IFN-γ (p=0.047). However, in the group positive for alpha smooth muscle actin, there was no difference in cytokine labeling (p>0.05). CONCLUSION: We verified the presence of positive α-SMA stromal cells in the majority of the cases of ATL, indicating the presence of myofibroblasts. In cases negative for alpha smooth muscle actin, an increased expression of IFN-γ compared to TGF-β1 was observed, revealing an inflammatory phase progressing to a healing process.

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