West Coast Worm Meeting Abstracts - Caenorhabditis elegans ...

West Coast Worm Meeting 2000
THE L TYPE CYCLIN SAG-4 IS REQUIRED FOR HEAT-SHOCK
INDUCED PROTEIN EXPRESSION
Wen J. Chen, Yvonne M. Hajdu-Cronin, Paul W. Sternberg
HHMI and Dept. of Biology, Caltech, Pasadena, CA91125, USA
In a screen for suppressors of activated GOA-1 under the control of a heat shock promoter, we identified
four genetic loci that affect heat-shock induction of GOA-1. sag-4 and sag-8 are wild type in appearance,
while sag-3 and sag-5 are egg-laying defective. Western analysis indicated that sag-4 or sag-8 mutations
suppress activated Goa by decreasing heat-shock induced protein expression. Although endogenous
GOA-1 expression is not affected, heat-shock induction of GOA-1 decreased in the suppressor strains.
We cloned sag-4 locus, which encodes a cyclin most similar to cyclin L. The latter is a novel type of cyclin
with unknown function, but also similar to cyclin T, K or C, which was identified as a subunit of TFIIH, part
of RNA polymerase II complex and functions in basal transcription. Only transgenes with hsp16-2
promoter can be affected by sag-4. These results suggest that sag-4 must suppress heat-shock GOA-1
phenotypes by preventing heat- shock mediated transcription in C. elegans. We propose that cyclin L is
the type of cyclin acting in TFIIH during heat-shock induced mRNA transcription, which carries function
similar to cyclin T, K or C during basal transcription. sag-3, sag-5 and sag-8 might also be involved in
similar processes.
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