Structure and Expression of the Caenorhabditis elegans Protein Kinase C2 Gene

doi:10.1074/jbc.272.10.6629

Structure and Expression of the Caenorhabditis elegans Protein Kinase C2 Gene

ORIGINS AND REGULATED EXPRESSION OF A FAMILY OF Ca²⁺-ACTIVATED PROTEIN KINASE C ISOFORMS*

From the Department of Molecular Pharmacology, Atran Laboratories, Albert Einstein College of Medicine, Bronx, New York 10461

^§ To whom correspondence should be addressed. Tel.: 718-430-2505; Fax: 718-430-8922; E-mail: rubin{at}aecom.yu.edu

↵^‡ Present address: School of the Environment, Box 90328, Duke University, Durham, NC 27708.

Abstract

The molecular and cellular basis for concerted Ca²⁺/lipid signaling in Caenorhabditis elegans was investigated. A unique gene (pkc-2) and cognate cDNAs that encode six Ca²⁺/diacylglycerol-stimulated PKC2 isoenzymes were characterized. PKC2 polypeptides (680-717 amino acid residues) share identical catalytic, Ca²⁺-binding, diacylglycerol-activation and pseudosubstrate domains. However, sequences of the N- and C-terminal regions of the kinases diverge. PKC2 diversity is partly due to differential activation of transcription by distinct promoters. Each promoter precedes an adjacent exon that encodes 5′-untranslated RNA, an initiator AUG codon and a unique open reading frame. PKC2 mRNAs also incorporate one of two 3′-terminal exons via alternative splicing. Cells that are capable of receiving and propagating signals carried by Ca²⁺/diacylglycerol were identified by assessing activities of pkc-2 gene promoters in transgenic C. elegans and visualizing the distribution of PKC2 polypeptides via immunofluorescence. Highly-selective expression of certain PKC2 isoforms was observed in distinct subsets of neurons, intestinal and muscle cells. A low level of PKC2 isoforms is observed in embryos. When L1 larvae hatch and interact with the external environment PKC2 content increases 10-fold. Although 77- and 78-kDa PKC2 isoforms are evident throughout post-embryonic development, an 81-kDa isoform appears to be adapted for function in L1 and L2 larvae.

Footnotes

↵* This work was supported in part by National Institute of Health Grant DK44957 (to C. S. R.), a grant from the Lucille P. Markey Charitable Trust (to C. S. R.), and National Institutes of Health Training Grant DK07513 (to M. L.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U82935[GenBank] and U82936[GenBank].
↵¹ The abbreviations used are:

PKC

protein kinase C

cPKCs

classical PKC isoforms (α, βI, βII, γ)

nPKCs

novel PKC isoforms (δ, ϵ, η, Θ)

MES

4-morpholineethanesulfonic acid

kbp

kilobase pair(s)

bp

base pair(s)

RACE

rapid amplification of cDNA ends

RACK

receptors for activated protein kinase Cs.
↵²In accordance with standard C. elegans nomenclature, genes are named with three lower case letters and a number (pkc-2); the same upper case letters (PKC2) are used to designate mRNAs and proteins encoded by the corresponding gene. The gene encoding PKC2 isoforms is designated “kin-11” on the C. elegans genetic map. In this paper the alternative gene name pkc-2, is used to (a) clearly delineate relationships among the gene and its cognate mRNA and protein products and (b) emphasize the ultimate functional significance of this genetic locus.
- Received October 30, 1996.
- Revision received December 12, 1996.