RET/PTC (rearranged in transformation/papillary thyroid carcinomas) tyrosine kinase phosphorylates and activates phosphoinositide-dependent kinase 1 (PDK1): an alternative phosphatidylinositol 3-kinase-independent pathway to activate PDK1.
Thyroid cancers are a leading cause of death due to endocrine malignancies. RET/PTC (rearranged in transformation/papillary thyroid carcinomas) gene rearrangements are the most frequent genetic alterations identified in papillary thyroid carcinoma. Although the oncogenic potential of RET/PTC is related to intrinsic tyrosine kinase activity, the substrates for this enzyme are yet to be identified. In this report, we show that phosphoinositide-dependent kinase 1 (PDK1), a pivotal serine/threonine kinase in growth factor-signaling pathways, is a target of RET/PTC. RET/PTC and PDK1 colocalize in the cytoplasm. RET/PTC phosphorylates a specific tyrosine (Y9) residue located in the N-terminal region of PDK1. Y9 phosphorylation of PDK1 by RET/PTC requires an intact catalytic kinase domain. The short (iso 9) and long forms (iso 51) of the RET/PTC kinases (RET/PTC1 and RET/PTC3) induce Y9 phosphorylation of PDK1. Moreover, Y9 phosphorylation of PDK1 by RET/PTC does not require phosphatidylinositol 3-kinase or Src activity. RET/PTC-induced phosphorylation of the Y9 residue results in increased PDK1 activity, decrease of cellular p53 levels, and repression of p53-dependent transactivation. In conclusion, RET/PTC-induced tyrosine phosphorylation of PDK1 may be one of the mechanisms by which it acts as an oncogenic tyrosine kinase in thyroid carcinogenesis.
Laboratory of Endocrine Cell Biology, National Research Laboratory Program, Department of Internal Medicine, Daejon, Korea.
Dong Wook
DW
Kim
Jung Hwan
JH
Hwang
Jae Mi
JM
Suh
Ho
H
Kim
Jung Hun
JH
Song
Eun Suk
ES
Hwang
Il Young
IY
Hwang
Ki Cheol
KC
Park
Hyo Kyun
HK
Chung
Jin Man
JM
Kim
Jongsun
J
Park
Brian A
BA
Hemmings
Minho
M
Shong
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002291:Carcinoma, Papillary / Q000201:enzymology / Q000378:metabolism; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D056918:Nuclear Receptor Coactivators; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013964:Thyroid Neoplasms / Q000201:enzymology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
D064413:3-Phosphoinositide-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D056918:Nuclear Receptor Coactivators; D015513:Oncogene Proteins; D015514:Oncogene Proteins, Fusion; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D014443:Tyrosine; D019061:src-Family Kinases; C111382:NCOA4 protein, human; C494999:Ret protein, mouse; C093573:ret-PTC fusion oncoproteins, human; C578562:PDPK1 protein, human; C578564:Pdpk1 protein, mouse