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No. 82 (PMB 8)
Analysis of Fas exon 6 splicing and gene expression of transcription factors in
various human organs and lymphocyte subsets
Ryo Uozumi 1 , Hitoshi Shibuya 1 , Akio Shigematsu 1 , Kazuhiko Matsuno 1 , Chikara Shimizu 1 ,
Seiichi Kobayashi 2 .
1 Department of Clinical Laboratory, Support of Clinical Practice, Hokkaido University Hospital,
2 Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Japan
Exclusion of Fas gene exon 6 by alternative splicing of the primary RNA transcript of the
apoptosis-inducing Fas gene produces a soluble isoform. The membrane Fas (mFas) isoform induces
apoptosis, while the soluble Fas (sFas) isoform prevents apoptosis. Serum levels of sFas in patients with
some autoimmune diseases and with cancer are higher than healthy individuals, and clinically correlate
with disease activity or tumor mass size. However, the regulatory mechanism for Fas gene splicing
remains unknown. Several pre-mRNA splicing regulators for Fas gene were reported, but these studies
only targeted extrinsic Fas minigene introduced into cell lines. Here, by quantitative real-time RT-PCR
analysis, we have investigated whether candidates of transcription factors including Hu antigen R
(HuR), T-cell intracellular antigen 1 (TIA-1) and TIA-1 related proteins (TIAR) actually regulate
intrinsic Fas gene splicing in various human organs and lymphocyte subsets. Each gene expression
was different in organs, but there was a poor correlation in gene expression between Fas and
transcription factors. We next analyzed
gene expression by CD45RA+ or CD45RO+ peripheral lymphocytes from healthy donors. Although
sFas and mFas gene expression by these subsets were significantly different, no correlation between
Fas, HuR, and (TIA-1+TIAR) gene expression was obtained. These results suggested that transcription
factors reported should not necessarily function as regulators for intrinsic Fas gene splicing.
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