Archiv - September 2009
TGF-b1 Inhibits Cx43 Expression and Formation of Functional Syncytia in Cultured Smooth Muscle Cells from Human Detrusor
Jochen Neuhaus, Marco Heinrich, Thilo Schwalenberg, Jens-Uwe Stolzenburg
Department of Urology, University of Leipzig, Leipzig, Germany
Eur Urol 2009; 55(2): 491-498
Background: Human detrusor smooth muscle cells
coupled by connexin 43 (Cx43)–positive gap junctions to
syncytia. Gap junctional communication likely is necessary for
detrusor contractions and is supposed to be altered in voiding
disturbances. Other authors have shown that the pleiotropic cytokine
TGF-b1 upregulates Cx43 expression in human aortic smooth muscle
Objective: In this study, we examined the TGF-b1 effects on Cx43 expression in cultured hBSMCs.
Design, Setting, and Participants: hBSMC cultures, established from patients undergoing cystectomy, were treated with recombinant human TGF-b1.
Measurements: Cx43 expression was then examined by Western blotting, real-time PCR, and immunocytochemistry. Dye-injection experiments were used to study the size of functional syncytia.
Results and Limitations: Dye-coupling experiments revealed stable formation of functional syncytia in passaged cell cultures (P1–P4). Stimulation with TGF-b1 led to significant reduction of Cx43 immunoreactivity and coupling. Cx43 protein expression was significantly downregulated and Cx43 mRNA was only 30% of the control level. Interestingly, low phosphorylation species of Cx43 were particularly affected.
Conclusions: Our experiments demonstrated a significant down regulation of connexin 43 by TGF-b1 in cultured hBSMCs. These findings support the view that TGF-b1 is involved in the pathophysiology of urinary bladder dysfunction.