title: Reciprocal regulation controlling the expression of CPI-17, a specific inhibitor protein for the myosin light chain phosphatase in vascular smooth muscle cells.
abstract: Cellular activity of the myosin light chain phosphatase (MLCP) determines agonist-induced force development of smooth muscle (SM). CPI-17 is an endogenous inhibitor protein for MLCP, responsible for mediating G-protein signaling into SM contraction. Fluctuations in CPI-17 expression occur in response to pathological stresses, altering excitation-contraction coupling in SM. Here, we determined the signaling pathways regulating CPI-17 expression in rat aorta tissues and the cell culture using a pharmacological approach. CPI-17 transcription was suppressed in response to the proliferative stimulus with platelet-derived growth factor (PDGF) through the ERK1/2 pathway, whereas it was elevated in response to inflammatory, stress-induced and excitatory stimuli with transforming growth factor-β, IL-1β, TNFα, sorbitol, and serotonin. CPI-17 transcription was repressed by inhibition of JNK, p38, PKC, and Rho-kinase (ROCK). The mouse and human CPI-17 gene promoters were governed by the proximal GC-boxes at the 5'-flanking region, where Sp1/Sp3 transcription factors bound. Sp1 binding to the region was more prominent in intact aorta tissues, compared with the SM cell culture, where the CPI-17 gene is repressed. The 173-bp proximal promoter activity was negatively and positively regulated through PDGF-induced ERK1/2 and sorbitol-induced p38/JNK pathways, respectively. By contrast, PKC and ROCK inhibitors failed to repress the 173-bp promoter activity, suggesting distal enhancer elements. CPI-17 transcription was insensitive to knockdown of myocardin/Kruppel-like factor 4 small interfering RNA or histone deacetylase inhibition. The reciprocal regulation of Sp1/Sp3-driven CPI-17 expression through multiple kinases may be responsible for the adaptation of MLCP signal and SM tone to environmental changes.
authors.affiliation: Department of Molecular Physiology and Biophysics, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Jee In
authors.initials: JI
authors.lastname: Kim
authors.forename: Mark
authors.initials: M
authors.lastname: Urban
authors.forename: Garbo D
authors.initials: GD
authors.lastname: Young
authors.forename: Masumi
authors.initials: M
authors.lastname: Eto
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics; D020935:MAP Kinase Signaling System; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D034622:RNA Interference; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D015398:Signal Transduction; D013012:Sorbitol / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors; D000099251:Myocardin
chemical_list: D053583:Interleukin-1beta; D048031:JNK Mitogen-Activated Protein Kinases; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D009124:Muscle Proteins; D043263:Myosin-Light-Chain Phosphatase; D009687:Nuclear Proteins; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D011493:Protein Kinase C; D034741:RNA, Small Interfering; D012701:Serotonin; D013012:Sorbitol; D016329:Sp1 Transcription Factor; D051705:Sp3 Transcription Factor; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D054460:rho-Associated Kinases; D000099251:Myocardin; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; C000715469:Klf4 protein, rat; C491519:Ppp1r14a protein, rat