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Role of human transcription elongation factor DSIF in the suppression of senescence and apoptosis
Author(s) -
Komori Toshiharu,
Inukai Naoto,
Yamada Tomoko,
Yamaguchi Yuki,
Handa Hiroshi
Publication year - 2009
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2008.01273.x
Subject(s) - gene knockdown , biology , elongation factor , rna polymerase ii , transcription factor , senescence , apoptosis , transcription (linguistics) , microbiology and biotechnology , gene , promoter , gene expression , rna , genetics , ribosome , linguistics , philosophy
DSIF is an evolutionarily conserved, ubiquitously expressed, heterodimeric transcription elongation factor composed of two subunits, Spt4 and Spt5. Previous biochemical studies have shown that DSIF positively and negatively regulates RNA polymerase II elongation in collaboration with other protein factors. While several data suggest that DSIF is a ‘general’ elongation factor, there is also evidence that DSIF exerts a tissue‐ and gene‐specific function. Here we sought to address the question of whether physiological functions of DSIF are general or specific, by using a sophisticated knockdown approach and gene expression microarray analysis. We found that Spt5 is essential for cell growth of various human cell lines and that Spt5 knockdown causes senescence and apoptosis. However, Spt5 knockdown affects a surprisingly small number of genes. In Spt5 knockdown cells, the p53 signaling pathway is activated and mediates part of the knockdown‐induced transcriptional change, but apoptotic cell death occurs in the absence of p53. Structure‐function analysis of Spt5 shows that the C‐terminal approximately 300 amino acid residues are not required to support cell proliferation. These results suggest that one of the functions of Spt5 is to suppress senescence and apoptosis, and that this function is exerted through its association with Spt4 and Pol II.