Worm Breeder's Gazette 14(2): 74 (February 1, 1996)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
NEC Fundamental Research Laboratories, Tsukuba, Ibaraki 305, Japan
Protein kinase C is thought to play pivotal roles in various cellular signaling pathways. More than ten isoforms have been identified from mammalian species to form a PKC family having similar structures and functions. From C. elegans, three PKC isoforms were so far reported, one of them being the gene tpa-1, which is, amongst others, most similar to PKCdelta/theta of a novel PKC type(1). The tpa-1 gene mediates the action of tumor-promoting phorbol esters to cause behavioral abnormality and developmental arrest. Although loss-of-function mutaions in tpa-1 confer resistance to phobol esters on C. elegans(2), mutants do not show phenotypes detectably different from the wild type in the absence of phorbol esters. This observation has led us to suppose that some other isoform(s) with lower sensitivity to phorbol compounds operates in the tpa-1 signaling pathway. To understand more about the tpa-1 pathway, as well as those other pathways mediated by other PKC isoforms, it is necessary to identify and analyze other PKCs. Several cDNA clones presumptive for encoding PKCs have been identified by Y. Kohara et al. in their cDNA sequencing project: they are yk4h6, yk17b2, yk45d8, yk17b9, and yk5d4. As we reported at the last C. elegans meeting, we started to analyze these clones. Sequencing the clone yk4h6 and its extended 5' region, which was obtained by 5' RACE, we found that it is a derivative from a message homologous to PKCzeta as implied by its overall similarity to human PKCzeta of 55%. It was mapped onto chromosome II, and the genomic region that covers the clone was sequenced by the C. elegans Genome Consortium. Comparison of our cDNA sequence with the sequence data from the Consortium showed that the gene consists of nine exons and contains those exon/intron boundaries as exactly predicted by Genefinder. A trans-spliced leader sequence different from either SL1 and SL2 was found on the the 5' end of the message. The cDNA clones of both yk17b2 and yk45d8 were originally indicated by Y. Kohara et al. to encode PKCmu homolog. Since yk17b2 contains a short insert, we screened and sequenced a longer clone from Barstead's cDNA library. Although a partial sequence of the clone proved to be similar to that of PKCmu, it turned out to be different from that of yk45d8. So, C. elegans seems to possess at least two PKCmu isoforms. Partial sequences of the clones yk17b9 and yk5d4 revealed that they are similar to the amino-terminal half and the carboxy-terminal half of the tpa-1 product, respectively. These clones, however, each detected mRNA of different sizes, thus indicating different genic origins of these clones. We plan to analyze the expression patterns of genes for these clones with lacZ or GFP gene fusion and to find out their functions with antisense RNA expression. (1) T. Sano et al. J. Mol. Biol. (1995) 251, 477-485. (2) Y. Tabuse et al. Biochem. J. (1995) 312, 69-74.