1997 Fiscal Year Final Research Report Summary
Molecular Mechanism of the Production of Autoantibodies to RNA Polymerase II.
| Project/Area Number |
08670534
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
内科学一般
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| Research Institution | Kieo University |
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Principal Investigator |
HIRAKATA Michito Keio University, Dept.of Internal Medicine, Instructor, 医学部, 助手 (30199046)
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| Project Period (FY) |
1996 – 1997
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| Keywords | autoantibodies / autoantigens / autoimmune diseases / epitope / transcription / transcription factor / HLA class II gene / systemic sclerosis |
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| Research Abstract |
Previous studies have demonstrated antibodies to the large (220 kDa) polypeptide subunit of RNA polymerase II (RNAP II) in sera from certain patients with scleroderma. In the present study, we have sought to identify the autoantigenic region on this polypeptide. Fefteen Patient sera containing antibodies to RNAP II were studies. All bound RNAP II in immunoprecipitation assays and 11 recognized a fusion protein bearing the carboxyl terminal domain (CTD) of the 220 kDa polypeptide in immunoblots. This region consists of a heptapeptide motif that is repeated 52 times in mammalian cells. A synthetic 18 amino acid peptide representing two and one half cassettes of the CTD completely inhibited RNAP II immunoprecipitation with 5 sera and partially inhibited four additional sera. Thus the CTD is a focal point for autoimmune responses in scleroderma. The repetitive sequence of highly charged, and heavily phosphorylated amino acids of the CTD are likely to contribute to its role as an autoantigen.
On the other hand, we have found that 14 of 15 of our anti-RNAP II sera immunoprecipitate the 23 kDa subunit of RNAP II translated in vitro ; this subunit is also associated with RNAP I and RNAP III.In total, these results suggest that sera directed against RNA polymerases may contain antibodies that bind subunits specific for each polymerase, as well as antibodies that target shared subunits.
Immunogenetic studies indicate that anti-RNAP autoantibodies in Japanese patients are likely to be associated with the amino acid sequence ^<67>FLEDR^<71> of HLA DR beta1.
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