Expression of CPI-17 in smooth muscle during embryonic development and in neointimal lesion formation.
Ca(2+) sensitivity of smooth muscle (SM) contraction is determined by CPI-17, an inhibitor protein for myosin light chain phosphatase (MLCP). CPI-17 is highly expressed in mature SM cells, but the expression level varies under pathological conditions. Here, we determined the expression of CPI-17 in embryonic SM tissues and arterial neointimal lesions using immunohistochemistry. As seen in adult animals, the predominant expression of CPI-17 was detected at SM tissues on mouse embryonic sections, whereas MLCP was ubiquitously expressed. Compared with SM alpha-actin, CPI-17 expression doubled in arterial SM from embryonic day E10 to E14. Like SM alpha-actin and other SM marker proteins, CPI-17 was expressed in embryonic heart, and the expression was down-regulated at E17. In adult rat, CPI-17 expression level was reduced to 30% in the neointima of injured rat aorta, compared with the SM layers, whereas the expression of MLCP was unchanged in both regions. Unlike other SM proteins, CPI-17 was detected at non-SM organs in the mouse embryo, such as embryonic neurons and epithelium. Thus, CPI-17 expression is reversibly controlled in response to the phenotype transition of SM cells that restricts the signal to differentiated SM cells and particular cell types.
Department of Molecular Physiology and Biophysics, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
Jee In
JI
Kim
Garbo D
GD
Young
Li
L
Jin
Avril V
AV
Somlyo
Masumi
M
Eto
D000818:Animals; D001011:Aorta / Q000201:enzymology* / Q000293:injuries; D047108:Embryonic Development; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009124:Muscle Proteins / Q000032:analysis / Q000096:biosynthesis*; D009130:Muscle, Smooth / Q000196:embryology / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D010750:Phosphoproteins / Q000032:analysis / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017539:Tunica Intima / Q000201:enzymology* / Q000293:injuries
D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; C491520:Ppp1r14a protein, mouse; C491519:Ppp1r14a protein, rat