Structure, Expression, and Properties of an Atypical Protein Kinase C (PKC3) from Caenorhabditis elegans
PKC3 IS REQUIRED FOR THE NORMAL PROGRESSION OF EMBRYOGENESIS AND VIABILITY OF THE ORGANISM*
- From the ‡Department of Molecular Pharmacology, Atran Laboratories, Albert Einstein College of Medicine, Bronx, New York 10461, the §Molecular Endocrinology Department, Glaxo Wellcome, Research Triangle Park, North Carolina, and the¶Department of Molecular Biology and Oncology, The University of Texas Southwestern Medical Center, Dallas, Texas 75235
Abstract
Little is known about differential expression, functions, regulation, and targeting of “atypical” protein kinase C (aPKC) isoenzymes in vivo. We have cloned and characterized a novel cDNA that encodes a Caenorhabditis elegans aPKC (PKC3) composed of 597 amino acids. In post-embryonic animals, a 647-base pair segment of promoter/enhancer DNA directs transcription of the 3.6-kilobase pair pkc-3 gene and coordinates accumulation of PKC3 protein in ∼85 muscle, epithelial, and hypodermal cells. These cells are incorporated into tissues involved in feeding, digestion, excretion, and reproduction. Mammalian aPKCs promote mitogenesis and survival of cultured cells. In contrast,C. elegans PKC3 accumulates in non-dividing, terminally differentiated cells that will not undergo apoptosis. Thus, aPKCs may control cell functions that are independent of cell cycle progression and programmed cell death. PKC3 is also expressed during embryogenesis. Ablation of PKC3 function by microinjection of antisense RNA into oocytes yields disorganized, developmentally arrested embryos. Thus, PKC3 is essential for viability. PKC3 is enriched in particulate fractions of disrupted embryos and larvae. Immunofluorescence microscopy revealed that PKC3 accumulates near cortical actin cytoskeleton/plasma membrane at the apical surface of intestinal cells and in embryonic cells. A candidate anchoring/targeting protein, which binds PKC3 in vitro, has been identified.
Footnotes
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↵* This work was supported in part by National Institutes of Health Grant DK44597 (to C. S. R.) and the Lucille P. Markey Charitable Trust (to C. S. R.).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) AF025666.
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↵‖ To whom correspondence should be addressed: Dept. of Molecular Pharmacology, F-229, Albert Einstein College of Medicine, Bronx, NY 10461. Tel.: 718-430-2505; Fax: 718-430-8922; E-mail:rubin{at}aecom.yu.edu.
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↵1 The abbreviations used are: PKC, protein kinase C; PS, phosphatidylserine; DAG, diacylglycerol; bp, base pair(s); kbp, kilobase pairs; GST, glutathione S-transferase; cPKC, classical Ca2+, DAG-activated PKC; nPKC, novel Ca2+-independent, DAG-activated PKC, aPKC, atypical Ca2+, DAG-independent PKC; PBS, phosphate-buffered saline; DTT, dithiothreitol.
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↵2 J. Staudinger, J. Lu, and E. N. Olson, manuscript submitted for publication.
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↵3 In accord with standard C. elegansnomenclature, genes are named with three lowercase italic letters and a number (pkc-3); the same uppercase roman letters (PKC3) are used to designate protein encoded by the corresponding gene.
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↵4 D. Hall, S.-L. Wu, and C. S. Rubin, unpublished results.
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↵5 S.-L. Wu and C. S. Rubin, unpublished results.
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- Received September 23, 1997.
- Revision received November 4, 1997.
- The American Society for Biochemistry and Molecular Biology, Inc.
