2004 Fiscal Year Final Research Report Summary
Analysis of physiological function of calcium channel β subunit in heart muscle
| Project/Area Number |
14370015
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | Sapporo Medical University |
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Principal Investigator |
TOHSE Noritsugu Sapporo Medical University, School of Medicine, Professor, 医学部, 教授 (80192657)
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| Co-Investigator(Kenkyū-buntansha) |
HORIO Yoshiyuki Sapporo Medical University, School of Medicine, Professor, 医学部, 教授 (30181530)
YAMADA Yoichi Sapporo Medical University, School of Medicine, Assistant Professor, 医学部, 講師 (30284996)
KOBAYASHI Takeshi Sapporo Medical University, School of Medicine, Instructor, 医学部, 助手 (80363688)
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| Project Period (FY) |
2002 – 2004
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| Keywords | L-type Ca2+ channel / cardiomyocytes / patch clamp / β subunit / CSN-5 / Jab1 |
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| Research Abstract |
In order to clarify contribution of β subunit to function of cardiac L-type Ca^<2+> channel, genes of β subunit were cloned from rat cardiomyocytes. The obtained sequence of β subunit was different from those reported previously. The obtained β subunit was named as β _<2C> subunit. After introduction of β _<2C> subunit, Ca^<2+> current through the reconstituted L-type Ca^<2+> channels in cultured cell lines was observed in use of the patch clamp method. Characteristics of the reconstituted Ca^<2+> current were similar to those of the native Ca^<2+> current in cardiomyocytes. In single channel recordings, the single channel activity of the reconstituted Ca^<2+> channel exhibited similar behaviors to that of the native Ca^<2+> channel. These findings indicate that β _<2C> subunit is a functional splice variant of L-type Ca^<2+> channel in native cardiomyocytes. In addition, we have explored a possible protein molecule that can access and modulate L-type Ca^<2+> channel. In use of the yeast-two-hybrid method, CSN-5/Jab1, a transcription factor, directly bound to the II-III linker of α subunit of L-type Ca^<2+> channel. The finding was confirmed by the coimmunoprecipitation method. CSN-5/Jab1 colocalized with α subunit in sarcolemmal membrane of rat cardiomyocytes under the double immunofluorescence staining. The reconstituted Ca^<2+> current was increased in the cultured cell in which CSN-5/Jab1 was abolished by siRNA method. Therefore, CSN-5/Jab1 may produce an inhibitory regulation of L-type Ca^<2+> channel function.
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