scholarly journals Expression of Connective Tissue Growth Factor in Human Renal Fibroblasts: Regulatory Roles of RhoA and cAMP

2001 ◽  
Vol 12 (9) ◽  
pp. 1853-1861 ◽  
Author(s):  
JULIANE HEUSINGER-RIBEIRO ◽  
MICHAEL EBERLEIN ◽  
NADIA ABDEL WAHAB ◽  
MARGARETE GOPPELT-STRUEBE
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Connective Tissue ◽  
Protein Kinase A ◽  
Connective Tissue Growth Factor ◽  
Tissue Growth ◽  
Cytochalasin D ◽  
Small Gtpase ◽  
General Role ◽  
Kinase A

Abstract. The induction of connective tissue growth factor (CTGF) was investigated in a human renal fibroblast cell line that exhibited many characteristics of primary human renal fibroblasts. Induction of CTGF mRNA was observed after treatment of the cells with transforming growth factor-β (TGF-β) or, even more prominently, lysophosphatidic acid (LPA). LPA induced a rapid transient increase in CTGF mRNA expression, with maximal levels being observed after 1 to 2 h. This increase was accompanied by CTGF protein synthesis. Induction of CTGF was insensitive to pertussis toxin and was not dependent on the activation of p42/44 mitogen-activated protein kinases. Inhibition of the proteins of the Rho family with toxin B from Clostridium difficile abrogated basal and LPA-mediated induction of CTGF. Specific targeting of RhoA with C3 exotoxin or of the Rho kinases with the inhibitor Y-27632 similarly prevented induction of CTGF, implicating RhoA as a signaling module downstream of LPA. Inhibition of RhoA depolymerized the actin cytoskeleton, as did treatment with cytochalasin D. Preincubation of the human renal fibroblasts with cytochalasin D prevented induction of CTGF by LPA, indicating a strong contribution of an intact cytoskeleton. Interference with RhoA signaling similarly inhibited the induction of CTGF by TGF-β. Elevation of intracellular levels of cAMP and thus activation of protein kinase A prevented induction of CTGF expression. The cytoskeletal effects of cAMP, however, were reversed by LPA. These data indicate complex interactions involving LPA-mediated activation of RhoA- and protein kinase A-dependent signaling pathways. The data thus demonstrate the regulatory functions of the small GTPase RhoA and of an intact cytoskeleton in the expression of CTGF after stimulation with LPA or TGF-β. Analogous signal transduction pathways were previously demonstrated in rat mesangial cells, suggesting a more general role for RhoA in the regulation of CTGF expression.

scholarly journals CCN2 (Connective Tissue Growth Factor) Promotes Fibroblast Adhesion to Fibronectin

2004 ◽  
Vol 15 (12) ◽  
pp. 5635-5646 ◽  
Author(s):  
Yunliang Chen ◽  
David J. Abraham ◽  
Xu Shi-wen ◽  
Jeremy D. Pearson ◽  
Carol M. Black ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Growth Factor ◽  
Protein Kinase ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Tissue Growth ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Fibroblast Adhesion

In vivo, CCN2 (connective tissue growth factor) promotes angiogenesis, osteogenesis, tissue repair, and fibrosis, through largely unknown mechanisms. In vitro, CCN2 promotes cell adhesion in a variety of systems via integrins and heparin sulfate proteoglycans (HSPGs). However, the physiological relevance of CCN2-mediated cell adhesion is unknown. Here, we find that HSPGs and the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase cascade are required for adult human dermal fibroblasts to adhere to CCN2. Endogenous CCN2 directly binds fibronectin and the fibronectin receptors integrins α4 β1 and α5 and syndecan 4. Using Ccn2-/- mouse embryonic fibroblasts, we show that loss of endogenous CCN2 results in impaired spreading on fibronectin, delayed α-smooth muscle actin stress fiber formation, and reduced ERK and focal adhesion kinase phosphorylation. These results suggest that a physiological role of CCN2 is to potentiate the ability of fibroblasts to spread on fibronectin, which may be important in modulating fibroblast adhesion to the provisional matrix during tissue development and wound healing. These results are consistent with the notion that a principal function of CCN2 is to modulate receptor/ligand interactions in vivo.

scholarly journals Effect of Connective Tissue Growth Factor on Protein Kinase Expression and Activity in Human Corneal Fibroblasts

2012 ◽  
Vol 53 (13) ◽  
pp. 8076 ◽  
Author(s):  
Siva S. Radhakrishnan ◽  
Timothy D. Blalock ◽  
Paulette M. Robinson ◽  
Genevieve Secker ◽  
Julie Daniels ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Tissue Growth ◽  
Corneal Fibroblasts ◽  
Kinase Expression ◽  
Expression And Activity

Dual Role of Cytochalasin D in the Regulation of Connective Tissue Growth Factor

2002 ◽  
Vol 973 (1) ◽  
pp. 57-59 ◽  
Author(s):  
MARGARETE GOPPELT-STRUEBE ◽  
JULIANE HEUSINGER-RIBEIRO ◽  
BARBARA FISCHER
Keyword(s):  
Growth Factor ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Tissue Growth ◽  
Cytochalasin D ◽  
Dual Role

Actin-dependent regulation of connective tissue growth factor

2007 ◽  
Vol 292 (5) ◽  
pp. C1732-C1738 ◽  
Author(s):  
Susanne Muehlich ◽  
Iwona Cicha ◽  
Christoph D. Garlichs ◽  
Bettina Krueger ◽  
Guido Posern ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Connective Tissue ◽  
Connective Tissue Growth Factor ◽  
Actin Polymerization ◽  
Tissue Growth ◽  
Small Gtpase ◽  
Fiber Formation ◽  
Microvascular Endothelial Cell ◽  
Microvascular Endothelial

Expression of connective tissue growth factor (CTGF) in endothelial cells is modulated by shear stress affecting the organization of the cytoskeleton. The molecular connection between alterations of actin and CTGF expression was investigated in human umbilical vein endothelial cells (HUVEC) and a microvascular endothelial cell line. Overexpression of nonpolymerizable monomeric actin R62D interfered with stress fiber formation in HUVEC and concomitantly reduced immunoreactive CTGF. In microvascular endothelial cells, flow-dependent upregulation of CTGF was prevented by this actin mutant. In contrast, overexpression of actin S14C strengthened filamentous actin and increased CTGF expression. These data indicated an inverse relationship between CTGF expression and monomeric actin. Coexpression of the mutant actins and different CTGF promoter constructs revealed an actin-sensitive site between 3 and 4.5 kb of the CTGF promoter. A CArG-like box at −3791 bp was responsible for actin-dependent CTGF induction as shown by mutagenesis. Overexpression of actin S14C activated the nonmutated promoter significantly more strongly than the mutated promoter. Actin polymerization is regulated by the small GTPase RhoA and activation of serum response factor (SRF). Overexpression of constitutively active RhoA or SRF significantly increased CTGF protein synthesis. The 4.5-kb promoter construct, but not the construct with a mutation in the CArG box, was activated by SRF or RhoA, providing evidence for a functional role of this site in CTGF induction. These findings provide novel evidence that monomeric actin is the connecting link between alterations in the cytoskeleton and CTGF gene expression and demonstrate the importance of SRF in regulating CTGF transcription.

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