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Regulation of cleavage by protein kinase C in Chaetopterus
Author(s) -
Yang Dazhi,
Hinton Shantá D.,
Eckberg William R.
Publication year - 2004
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20135
Subject(s) - biology , protein kinase c , cleavage (geology) , microbiology and biotechnology , gene isoform , cytokinesis , kinase , cell division , biochemistry , gene , cell , paleontology , fracture (geology)
We report that protein kinase C (PKC) plays a regulatory role in early cleavage in Chaetopterus eggs. Using Western blotting, we assayed the expression patterns of conventional PKCs (cPKC), novel PKCs (nPKC), and atypical PKCs (aPKC). During early development after fertilization, PKC protein levels varied independently by isoform. PKC protein expression during differentiation, without cleavage and after parthenogenetic activation, was very similar to that during normal development indicating that PKC gene expression does not require cellularization. Since PKC has been shown to regulate meiosis in this organism, we also assayed the membrane association of these isoforms as an indicator of their activation during meiosis and early cleavage. PKC‐γ transiently associated with membranes and therefore became activated before meiotic division and cleavage, whereas PKC‐α and ‐β transiently dissociated from membranes and therefore became inactivated at these times. Inhibition of these PKC isoforms by bisindolylmaleimide I had no effect on cleavage or early development to the trochophore larva, indicating that PKC‐γ activation is not essential for cleavage or early development. However, their persistent activation by thymeleatoxin blocked cleavage. The results indicate that the dissociation of PKC‐α and/or ‐β from the membrane fraction, and therefore their inactivation, is essential for normal cleavage. Elevated PKC activity is essential for nuclear envelope breakdown and spindle formation at meiosis I. By contrast, down‐regulation of this activity is essential for cleavage after fertilization. Mol. Reprod. Dev. 69: 308–315, 2004. © 2004 Wiley‐Liss, Inc.