Expression of cAMP response element binding protein (CREB)-binding protein (CBP) and the implication in retinoic acid-inducible transcription activation in human salivary gland adenocarcinoma cell line HSG.
In the process of retinoic acid (RA) signaling, retinoic acid receptor interacts with a coactivator complex composed of various transcription cofactors such as CREB-binding protein (CBP)/p300 and p160 family member proteins represented by steroid receptor coactivator-1 (SRC-1)/NCoA1 and p300/CBP cointegrator protein (p/CIP)/ACTR. In order to investigate the relationship of CBP to the RA signaling in a human salivary gland (HSG) adenocarcinoma cell line, we examined the expression of CBP in the cells. Immunoprecipitation and immunoblotting of the nuclear extract of HSG cells with anti-human CBP antibody showed a specific 270-kDa band, indicating the expression of CBP in HSG cells. The immunocytochemical analysis confirmed the nuclear localization of CBP. The transfection of HSG cells with a luciferase reporter plasmid harboring an RA-response element at the 5'-upstream region of the reporter gene increased RA-dependent luciferase activity approximately 3-fold. Co-transfection with a CBP-expression plasmid and the luciferase reporter gene enhanced the RA-dependent transcription activation approximately 10-fold. The immunoprecipitates obtained with anti-CBP antibody exhibited a histone acetyl-transferase (HAT) activity 2-fold higher than that obtained with the control antibody, whereas the HAT activity of the immunoprecipitates with anti-SRC-1 and anti-p/CIP, which were used as comparisons, were only a little increased. The RA treatment had no effect on the level of HAT activity except in the case of using the immunoprecipitate obtained with anti-RARalpha, in which case it increased the activity. These findings indicate that CBP expressed in HSG cells mediates the RA-inducible growth and differentiation-regulating transcription activation in concert with the retinoic acid receptors.
Kyakumoto
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Department of Biochemistry, Iwate Medical University School of Dentistry, Chuodori, Morioka, Iwate, Japan. kyakumot@iwate-med.ac.jp
Kito
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Sato
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D000123:Acetyltransferases / Q000378:metabolism; D000230:Adenocarcinoma / Q000378:metabolism*; D050882:CREB-Binding Protein; D045744:Cell Line, Tumor; D017930:Genes, Reporter / Q000235:genetics; D051548:Histone Acetyltransferases; D006801:Humans; D007150:Immunohistochemistry; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D011233:Precipitin Tests; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D020218:Response Elements; D012468:Salivary Gland Neoplasms / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects* / Q000502:physiology; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*
D009687:Nuclear Proteins; D018168:Receptors, Retinoic Acid; D015534:Trans-Activators; D014212:Tretinoin; D000123:Acetyltransferases; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; D051548:Histone Acetyltransferases