Abstract:
Thin filament-associated proteins such as calponin, caldesmon, tropomyosin, and smoothelin
are thought to regulate acto-myosin interaction and thus, muscle contraction. However, the effect of
inflammation on the expression of thin filament-associated proteins is not known. The aim of the present
study is to determine the changes in the expression of calponin, caldesmon, tropomyosin, and smoothelin
in colonic smooth muscle from trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulphate
(DSS)-induced colitis in mice. Expression of h-caldesmon, h2-calponin, ?-tropomyosin, and
smoothelin-Awas measured by qRT-PCR andWestern blot. Contraction in response to acetylcholine in
dispersedmuscle cells wasmeasured by scanningmicrometry. mRNA and protein expression of ?-actin,
h2-calponin, h-caldesmon, smoothelin, and ?-tropomyosin in colonic muscle strips from mice with
TNBS- or DSS-induced colitis was significantly increased compared to control animals. Contraction in
response to acetylcholine was significantly decreased in muscle cells isolated from inflamed regions of
TNBS- or DSS-treated mice compared to control mice. Our results show that increase in the expression
of thin filament-associated contractile proteins, which inhibit acto-myosin interaction, could contribute
to decrease in smooth muscle contraction in inflammation.