ROLE OF NUCLEAR PROTEIN KINASE C IN CELL GROWTH

Project: Research project

Project Details

Description

The calcium/phospholipid-dependent protein kinase (PKC) is an integral
part of a major signal transduction pathway for many growth stimuli.
Cellular mitogens, including polypeptide growth factors and the tumor
promoting phorbol esters, activate PKC and initiate a coordinated cascade
of events leading to the entrance of cells into cell cycle. The
mechanisms by which such proliferative signals, generated at the cell
surface, reach the nucleus are virtually unknown. Recently, a novel
protein kinase C-like activity (PKCn) has been identified in our
laboratory. PKCn appears to be translocated and activated at the nuclear
membrane in a variety of cell types in response to both pharmacological
PKC activators and the polypeptide growth factors interleukin-3, platelet-
derived growth factor and fibroblast growth factor. Several specific
nuclear substrates were also identified for PKCn; these include the
nuclear envelope polypeptide lamins and RNA polymerase II. An in-vitro
reconstitution system has been devised in which PKCn is selectively
translocated to purified nuclear membranes from purified rat brain PKC
preparations. Using this as an assay system, the first aim of this
proposal is to purify PKCn and characterize its specificity for
identified nuclear membrane substrates, requirements for cofactors and
sensitivity to pharmacologic activators and inhibitors of PKC. The role
for nuclear membrane phospholipid and protein in the specific
translocation of PKCn to nuclear membranes will be assessed in related
studies. Specific immunological probes will be generated against purified
PKCn and used in immunolocalization studies to determine the intracellular
distribution of PKCn in several cell types. The effect of various growth
t\stimuli, including polypeptide growth factors, on the intracellular
distribution and expression of PKCn will be investigated. The role of
PKCn in the mitogenic responses of both PKC activators and polypeptide
growth factors will be assessed by determining the effects of specific
activators and inhibitors of PKCn on these responses. Finally, the
involvement of PKCn-mediated phosphorylation of the nuclear envelope lamin
proteins and RNA polymerase II in mediating growth responses will be
investigated. These aims will be accomplished using a combination of
biochemical, immunohistochemical, immunological and pharmacological
approaches.
StatusFinished
Effective start/end date12/1/8911/30/95

ASJC

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)