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Altered expression of thin filament‐associated proteins in hypertrophied urinary bladder smooth muscle
Author(s) -
Mannikarottu Anita S.,
DiSanto Michael E.,
Zderic Stephen A.,
Wein Alan J.,
Chacko Samuel
Publication year - 2006
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.20121
Subject(s) - actin , myosin , calponin , immunostaining , muscle hypertrophy , blot , immunofluorescence , tropomyosin , urinary bladder , western blot , medicine , reverse transcription polymerase chain reaction , cytoskeleton , gene isoform , immunohistochemistry , microbiology and biotechnology , pathology , messenger rna , biology , cell , immunology , antibody , biochemistry , gene
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 ( h 1) 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. Neurourol. Urodynam. © 2005 Wiley‐Liss, Inc.