Cloning and characterization of a testis and brain-specific isoform of mouse 3 ′-phosphoinositide-dependent protein kinase-1, mPDK-1β

• Published in: Biochemical and biophysical research communications 2002-05, Vol.294 (1), p.136-144
• Main Authors: Dong, Lily Q., Ramos, Fresnida J., Wick, Michael J., Ann Lim, Mei, Guo, Zhongmao, Strong, Randy, Richardson, Arlan, Liu, Feng
• Format: Article
• Language: English
• Subjects: 3-Phosphoinositide-Dependent Protein Kinases; Aging; Alternative Splicing; Amino Acid Sequence; Animals; Base Sequence; Brain - enzymology; CHO Cells; Cloning, Molecular; Cricetinae; Female; Humans; Insulin - pharmacology; Isoenzymes - genetics; Isoenzymes - metabolism; Male; Mice; Molecular Sequence Data; Phosphorylation; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-fyn; Sequence Alignment; Spermatogenesis; src-Family Kinases - metabolism; Testis - enzymology; Tyrosine - metabolism; Vanadates - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(02)00449-7

3 ′-Phosphoinositide-dependent protein kinase-1 (PDK-1) phosphorylates and activates members of the protein kinase AGC family and plays a key role in receptor tyrosine kinase signaling. Here we report the cloning and characterization of a splice variant of mouse PDK-1, mPDK-1β. The cDNA encoding mPDK-1β contains two alternative start codons and translation from these start codons generates proteins that are, respectively, 27 or 51 amino acid residues shorter at the amino-terminus than the previously identified PDK-1 isolated from mouse liver (now renamed mPDK-1α) [J. Biol. Chem. 274 (1999) 8117]. Analysis of mouse tissues shows that mPDK-1β is highly expressed in the testis and various functional regions of the brain. Expression of this isoform is increased in the brain of aged mice. Both mPDK-1α and mPDK-1β are autophosphorylated at both serine and threonine residues in vitro and showed similar levels of tyrosine phosphorylation when co-expressed with either constitutively active Src or Fyn tyrosine kinases in cells. However, the mPDK-1 isoforms showed significant differences in their response to pervanadate- or insulin plus vanadate-stimulated tyrosine phosphorylation. Taken together, our findings suggest that the two PDK-1 isoforms may be differentially regulated in cells. The specific expression of mPDK-1β in mouse testis and brains of aged mice also suggests potential involvement of this kinase in regulating animal spermatogenesis and aging.