The signaling of protease-activated receptor-2 activating peptide-induced contraction in cat esophageal smooth muscle cells

Abstract

Protease-activated receptors (PARs) are a family of G protein-coupled receptors with a unique activation mechanism involving proteolytic cleavage of the extracellular N-terminal domain of the receptor. PAR2 has a contractile effect on esophageal smooth muscle. We investigate the signaling pathways of the PAR2-activating peptide (PAR2-AP) induced contraction in cat esophageal smooth muscle cells. The length of freshly isolated smooth muscle cells and permeabilized cells from feline esophagus were measured by scanning micrometry, and by confirming molecular basis via western blot analysis. The responses to PAR2-AP were initial and sustained contractions, depending on time. The maximum contraction of the initial phase occurred at 60 s. The PAR2-AP-induced contraction was mediated by Gαi1, Gαi3, and Gαq protein activation, leading to phospholipase-c (PLC) and myosin light chain kinase (MLCK) activation. 20 kDa myosin light chain (MLC20) was phosphorylated by PAR2-AP. Rho kinase-2 (ROCK-2), an activator of 17 kDa C-kinase potentiated Protein phosphatase-1 Inhibitor (CPI-17), was increased by PAR2 receptor activation. In conclusion, PAR2-AP produced an initial contraction mediated by Gαi1, Gαi3, and Gαq protein activation, resulting in PLC and MLCK activation. The sustained contraction by PAR2-AP was mediated by the Rho/Rho kinase-dependent pathway.

Protease‐activated receptor 2 activates CRAC‐mediated Ca 2+ influx to cause prostate smooth muscle contraction

“…PAR2 has been shown to cause contraction of bronchial, vascular, and esophageal smooth muscles . However, it is not known if PAR2 stimulation can cause contraction of smooth muscles in the prostate.…”

“…In an attempt to determine the function of PAR2, we sought to investigate the effect of PAR2 stimulation in prostatic smooth muscles. Sriwai et al and Ha et al showed that PAR2 activation caused biphasic contraction of gastric and esophageal smooth muscles. However, our study has further characterized the different sources of the intracellular Ca 2+ that cause the distinctive biphasic Ca 2+ flux and demonstrated the involvement of CRAC channels, and not L‐type VDCC, in PAR2‐mediated contraction of prostate smooth muscles.…”

“…PAR2 has been shown to cause contraction of bronchial, 10 vascular, 1 and esophageal smooth muscles. 9 However, it is not known if PAR2 stimulation can cause contraction of smooth muscles in the prostate. To address the involvement of PAR2 in prostatic smooth muscle contraction, we performed an in vitro collagen hydrogel contraction assay.…”

“…In patients with CP/CPPS, ultrasound evaluation of the bladder neck and posterior urethra show lesions in the fibromuscular stroma that could lead to painful contracture and alter urinary flow . Incidentally, PAR2 has been shown to play a role in the physiology of smooth muscles in different tissues . Although, these studies suggest a potential role for PAR2 in the involvement of prostatic smooth muscles in the pathology of urinary dysfunction, to date there is no report investigating this phenomenon.…”

“…8 Incidentally, PAR2 has been shown to play a role in the physiology of smooth muscles in different tissues. 1,9,10 Although, these studies suggest a potential role for PAR2 in the involvement of prostatic smooth muscles in the pathology of urinary dysfunction, to date there is no report investigating this phenomenon.…”