Altered expression of thin filament-associated proteins in hypertrophied urinary bladder smooth muscle

Anita S. Mannikarottu, Michael E. DiSanto, Stephen A. Zderic, Alan J. Wein, Samuel Chacko

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Aims: Obstruction of the urinary bladder outlet induces detrusor smooth muscle (DSM) hypertrophy. The goal of this study was to determine whether the composition of thin filament-associated proteins, known to play important roles in cytoskeletal structure and/or the regulation of contraction, is altered in DSM during hypertrophy. Methods: DSM hypertrophy was induced in male rabbits by partial ligation of the urethra. Sham-operated rabbits served as a control. Reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR revealed a significant increase in the expression of mRNAs for basic (h1) calponin (CaP), and α-isoform of tropomyosin (Tm) in hypertrophied DSM compared to controls. Western blotting and two-dimensional (2-D) gel electrophoresis showed enhanced expression of these proteins and also a significant increase in the expression of β-non muscle and γ-smooth muscle actin in the DSM from obstructed bladders, while α-actin remained constant. Results: Enhanced expression of these proteins in the DSM from obstructed bladders was confirmed by immunofluorescence microscopy. Double immunostaining with Cap/ Tm and α/β-actin-specific antibodies showed co-localization of these proteins in myocytes. Colocalization of smooth muscle specific myosin and CaP to cytoplasmic filaments in cells dissociated from the hypertrophied DSM indicated that these cells are differentiated smooth muscle cells. Conclusions: The change in the isoforms of actin, Cap, and Tm may be part of the molecular mechanism for bladder compensation in increased urethral resistance.

Original languageEnglish (US)
Pages (from-to)78-88
Number of pages11
JournalNeurourology and Urodynamics
Volume25
Issue number1
DOIs
StatePublished - 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Clinical Neurology
  • Urology

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