TAILIEUCHUNG - Báo cáo khoa học: Protein kinase C e phosphorylates keratin 8 at Ser8 and Ser23 in GH4C1 cells stimulated by thyrotropin-releasing hormone

Protein kinase Ce (PKCe) is activated by thyrotropin-releasing hormone (TRH), a regulator of pituitary function in rat pituitary GH4C1 cells. We analyzed the downstream mechanism after PKCe activation. Exposure of GH4C1 cells to TRH or a phorbol ester increased the phosphorylation of three p52 proteins (p52a, p52b and p52c) and decreased the phosphoryla-tion of destrin and cofilin. | ễFEBS Journal Protein kinase C e phosphorylates keratin 8 at Ser8 and Ser23 in GH4C1 cells stimulated by thyrotropin-releasing hormone Yoshiko Akita1 Hiroshi Kawasaki2 Shinobu Imajoh-Ohmi3 Hiroyuki Fukuda3 Shigeo Ohno4 Hisashi Hirano2 Yoshitaka Ono5 and Hiromich Yonekawa1 1 Department of Laboratory AnimalScience The Tokyo Metropolitan Institute of MedicalScience Japan 2 Supramolecular Biology InternationalGraduate Schoolof Arts and Sciences Yokohama City University Japan 3 Department of Basic MedicalSciences Institute of MedicalScience University of Tokyo Japan 4 Department of Molecular Biology Yokohama City University Schoolof Medicine Japan 5 BiosignalResearch Center Kobe University Japan Keywords GH4C1 cells keratin 8 phosphorylation protein kinase C e thyrotropin-releasing hormone Correspondence Y. Akita Department of Laboratory Animal Science The Tokyo Metropolitan Institute of MedicalScience 3-18-22 Honkomagome Bunkyo-ku Tokyo 113-8613 Japan Fax 81 3 3823 2130 Tel 81 3 3823 2105 ext. 5430 E-mail akita@ Received 7 March 2007 revised 26 April 2007 accepted 30 April 2007 doi Protein kinase C e PKCe is activated by thyrotropin-releasing hormone TRH a regulator of pituitary function in rat pituitary GH4C1 cells. We analyzed the downstream mechanism after PKCe activation. Exposure of GH4C1 cells to TRH or a phorbol ester increased the phosphorylation of three p52 proteins p52a p52b and p52c and decreased the phosphorylation of destrin and cofilin. GF109203X an inhibitor of protein kinases including PKC inhibited phosphorylation of the p52 proteins by TRH stimulation. Peptide mapping amino-acid sequencing and immunochemical studies indicated that p52a p52b and p52c are the differentially phosphorylated isoforms of keratin 8 K8 an intermediate filament protein. The unphosphorylated K8 p52n localized exclusively to the cytoskeleton whereas the phosphorylated forms especially p52c which are increased in TRH-stimulated .

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