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PKCα and CPI‐17 expression and spatial‐temporal distribution with activation in pig stomach antrum and fundus
Author(s) -
Eddinger Thomas J,
Zhang Yu
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.819.15
Regulation of myosin light chain phosphatase (MLCP) via protein kinase C (PKC) and PKC‐potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa (CPI‐17) has been reported as a signaling pathway resulting in Ca 2+ sensitization in smooth muscle (SM) cells. This study examined the protein expression and spatial‐temporal distribution of PKCα and CPI‐17 in intact SM tissues. Stimulation of tonic stomach fundus SM generates greater relative force than phasic stomach antrum with 1μM phorbol 12, 13‐dibutyrate (PDBu) stimulation. Western blot analyses demonstrated that this difference was not caused by a difference in the protein expression of PKCα or CPI‐17 between these two tissues. Immunohistochemical results show that under relaxed conditions the distribution of PKCα in the longitudinal and circular layers of the fundus and antrum is predominantly localized near the SM cell plasma membrane. Stimulation of the tissues with 1μM PDBu or 1μM carbachol (CCh) does not alter the distribution pattern of PKCα. Distinct from PKCα, CPI‐17 appeared to be diffusely distributed throughout the cytoplasm under relaxed conditions. Stimulation of the tissues with 1μM PDBu or 1μM CCh caused a significant shift of CPI‐17 from a diffuse cytosolic distribution to a primarily peripheral distribution at the plasma membrane. Results from double labeling of PKCα and vinculin/talin under relaxed conditions or CPI‐17 and vinculin/talin under stimulated condition show that PKCα and CPI‐17 are not associated with these proteins at the adherens junction. Possible implications of these results are discussed in the paper.