"New"-clear functions of PDK1: beyond a master kinase in the cytosol?
Activation of cytosolic phosphoinositide-3 kinase (PI-3K) signaling pathway has been well established to regulate gene expression, cell cycle, and survival by feeding signals to the nucleus. In addition, strong evidences accumulated over the past few years indicate the presence of an autonomous inositol lipid metabolism and PI-3K signaling within the nucleus. Much less, however, is known about the role and regulation of this nuclear PI-3K pathway. Components of the PI-3K signaling pathway, including PI 3-kinase and its downstream kinase Akt, have been identified at the nuclear level. Consistent with the presence of a complete PI-3K signaling pathway in the nucleus, we have recently found that phosphoinositide-dependent kinase 1 (PDK1), a kinase functioning downstream of PI-3K and upstream of Akt, is a nucleo-cytoplasmic shuttling protein. In the present review, we update our current knowledge on the regulatory mechanisms and the functional roles of PDK1 nuclear translocation. We also summarize some of the kinase-independent activities of PDK1 in cell signaling.
Kikani
Chintan K
CK
Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA.
Dong
Lily Q
LQ
Liu
Feng
F
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
D064413:3-Phosphoinositide-Dependent Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; C578562:PDPK1 protein, human