| Research Abstract |
Transcriptional elongation is one of the major regulatory steps in gene expression by RNA polymerase II. Elongin is a general elongation factor which may be involved in oncogenesis associated with von Hippel Lindau (VHL) disease. To clarify the molecular basis of biological function of elongjn, we performed gene targeting of elongin A, and also cloned a novel elongin A gene family member, elongin A3.
(1) Both alleles of Elongin A gene were disrupted in mouse embryonic stem (ES) cells. The cells showed significant growth defect, and had a higher number of cells at G2/M phase of cell cycle. Furthermore, elongin A deficient cells showed DNA content over 8n. Both microarray cDNA analysis and RNA protection assay showed that only a subset of genes, at least 2〜3 %, including those of cell cycle-related genes, were affected in elongin A-deficient cells. The data suggested that elongin A is not essential for genreral gene transcription, but is required for proper progression of cell cycle.
(2) A novel elongin A gene family, elongin A3, was identified. Elongin A3 was composed of 553 amino acids with SII homology and elongin BC binding sequence. Recombinant A3 protein was active in transcriptional elongation, and bind elongin BC. A biochemical assay suggested that elongin A and A3 might function in not a complementary but competitive way. Thus, elongin A gene family interacts each other to modulate activity of the another member.
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