Transforming Growth Factor-β1 Specifically Induce Proteins Involved in the Myofibroblast Contractile Apparatus

Abstract

Transforming growth factor-␤ 1 (TGF-␤ 1 ) induces ␣-smooth muscle actin (␣-SMA) and collagen synthesis in fibroblast both in vivo and in vitro and plays a significant role in tissue repair and the development of fibrosis. During these processes the fibroblasts differentiate into activated fibroblasts (so called myofibroblasts), characterized by increased ␣-SMA expression. Because TGF-␤ 1 is considered the main inducer of the myofibroblast phenotype and cytoskeletal changes accompany this differentiation, the main objective of this investigation was to study how TGF-␤ 1 alters protein expression of cytoskeletal-associated proteins. Metabolic labeling of cell cultures by [ 35 S]methionine, followed by protein separation on twodimensional gel electrophoresis, displayed ϳ2500 proteins in the pI interval of 3-10. Treatment of TGF-␤ 1 led to specific spot pattern changes that were identified by mass spectrometry and represent specific induction of several members of the contractile apparatus such as calgizzarin, cofilin, and profilin. These proteins have not previously been shown to be regulated by TGF-␤ 1 , and the functional role of these proteins is to participate in the depolymerization and stabilization of the microfilaments. These results show that TGF-␤ 1 induces not only ␣-SMA but a whole set of actin-associated proteins that may contribute to the increased contractile properties of the myofibroblast. These proteins accompany the induced expression of ␣-SMA and may participate in the formation of stress fibers, cell contractility, and cell spreading characterizing the myofibroblasts phenotype.

Transforming Growth Factor-β Signaling in Prostate Stromal Cells Supports Prostate Carcinoma Growth by Up-regulating Stromal Genes Related to Tissue Remodeling

“…A characteristic of myofibroblasts in tissue remodeling is their contractile property (30), which is induced by TGFh (31). Several genes involved in cytoskeletal contraction and motility were found to be up-regulated by TGFh in PrSC.…”

Decorin-transforming Growth Factor-β Interaction Regulates Matrix Organization and Mechanical Characteristics of Three-dimensional Collagen Matrices

“…The application or enhanced expression of TGF-␤ has been linked to increased cell proliferation and migration (47,48), increased collagen synthesis (49,50), and suppressed collagenase activity (51,52) by fibroblasts cultured from various tissues. TGF-␤ causes fibroblasts to differentiate into myofibroblasts, resulting in their greater expression of SMA (33,53) and ␣ 2 ␤ 1 integrins (54), which as shown here would cause greater contraction of the collagen matrix. Similarly, many of the effects of TGF-␤, such as cell migration (55,56), hyaluronan synthesis (56,57), proteoglycan synthesis (58), and cell proliferation have been shown to be dependent upon cell density, that is, greater response is observed for lower cell density.…”

Myofibroblasts Exhibit Enhanced Fibronectin Assembly That Is Intrinsic to Their Contractile Phenotype

“…Idiopathic pulmonary fibrosis is characterized by the elaboration of abundant extracellular matrix (ECM) 3 driven by myofibroblasts, specially modified fibroblasts characterized by increased contractile gene expression (1)(2)(3). A key step in the formation of new ECM is the assembly of a fibrillar fibronectin (FN) matrix, which serves as a scaffold for the binding of collagens and other extracellular matrix proteins (4 -6).…”