Transforming growth factor-  as a differentiating factor for cultured smooth muscle cells

Abstract

The aim of the present study was to determine whether the development of supercontractile smooth muscle cells, contributing to the nonspecific hyperreactivity of airways in asthmatic patients, is due to transforming growth factor (TGF)-b.In cultured smooth muscle cells starved by removal of 10% foetal bovine serum for 7 days, growth arrest was seen; 30% became elongated and demonstrated super contractility. Study of conditioned medium suggested that the differentiating factor was TGF-b. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was carried out on conditioned medium from the arrested cells. Two protein bands were identified as matrix metalloproteinase (MMP)-2 and TGF-b1. To determine second messenger signalling by SMAD2, Western blotting and confocal microscopy were employed.Conditioned medium from arrested cultures showed the presence of MMP-2 and TGF-b1, as revealed by SDS-PAGE; 68-and 25-kDa bands were seen. Differentiation was confirmed by upregulation of marker proteins, smooth muscle type myosin heavy chain and myosin light chain kinase. Confirmation was obtained by downregulating these proteins with decorin treatment, which reduces the levels of active TGF-b and an adenoviral dominant-negative vector coding for a mutated type II TGF-b-receptor. Activation of second messenger signalling was demonstrated immunocytochemically by the presence of phosphorylated SMAD2 and SMAD4.Transforming growth factor-b is likely to be the differentiating factor responsible for the development of these supercontractile smooth muscle cells. The development of such cells in vivo after cessation of an asthmatic attack could contribute to the nonspecific hyperreactivity of airways seen in patients.

Embryonic stem cell differentiation into smooth muscle cells is mediated by Nox4-produced H2O2

“…It has been previously reported that TGF-␤ 1 is a regulator for SMC differentiation (12,26). Recent report indicates that TGF-␤ 1 acts as a differentiating factor for cultured SMCs (12).…”

“…Recent report indicates that TGF-␤ 1 acts as a differentiating factor for cultured SMCs (12). TGF-␤ 1 is also a key inducer for stem/progenitor cell differentiation toward myofibroblast (7) and SMCs (4,17,26).…”

Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link?

“…Studies suggest that NOX4-mediated ROS production may mediate TGF-b1 signaling or may activate latent TGF-b1 in an autocrine fashion (115,116). In addition, increased cellular ROS may influence E-C coupling by acting on Ca 21 signaling pathways or by modifying the phosphorylation of kinases in the contractile pathway (117). Indeed, the inhibition of NOX4 decreases agonistinduced contractility in HASM (114), suggesting a role for NOX4-mediated ROS in TGF-b1-induced AHR.…”

“…In addition to facilitating structural cell remodeling, TGF-b1 may participate in airway narrowing by increasing ASM contractile protein expression (21). Conversely, the act of ASM shortening alone activates TGF-b1 signaling.…”

“…Although the role of TGF-b1 in mediating classic E-C coupling remains unclear, TGF-b1 modulates Ca 21 homeostasis in a variety of cell types. TGF-b1 treatment induces an immediate and transient Ca 21 release in human osteoblasts (102). In human pulmonary fibroblasts, both acute and overnight TGF-b1 treatment evokes Ca 21 transients (103).…”