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.

Abstract

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.

• Authors: Dong Wook Kim, Jung Hwan Hwang, Jae Mi Suh, Ho Kim, Jung Hun Song, Eun Suk Hwang, Il Young Hwang, Ki Cheol Park, Hyo Kyun Chung, Jin Man Kim, Jongsun Park, Brian A Hemmings, Minho Shong
• Journal: Molecular endocrinology (Baltimore, Md.) (Mol Endocrinol) Vol. 17 Issue 7 Pg. 1382-94 (Jul 2003) ISSN: 0888-8809 [Print] United States
• PMID: 12738763 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enzyme Inhibitors
• NCOA4 protein, human
• Nuclear Receptor Coactivators
• Oncogene Proteins
• Oncogene Proteins, Fusion
• Phosphoinositide-3 Kinase Inhibitors
• Proto-Oncogene Proteins
• Transcription Factors
• Tumor Suppressor Protein p53
• Tyrosine
• Protein-Tyrosine Kinases
• Proto-Oncogene Proteins c-ret
• Receptor Protein-Tyrosine Kinases
• Ret protein, mouse
• ret-PTC fusion oncoproteins, human
• src-Family Kinases
• 3-Phosphoinositide-Dependent Protein Kinases
• PDPK1 protein, human
• Pdpk1 protein, mouse
• Protein Serine-Threonine Kinases
• Proto-Oncogene Proteins c-akt

Topics

• 3-Phosphoinositide-Dependent Protein Kinases
• Amino Acid Sequence
• Animals
• CHO Cells
• Carcinoma, Papillary (enzymology, metabolism)
• Cricetinae
• Enzyme Inhibitors (pharmacology)
• Fibroblasts (metabolism)
• Humans
• Mice
• Molecular Sequence Data
• Nuclear Receptor Coactivators
• Oncogene Proteins (genetics, metabolism)
• Oncogene Proteins, Fusion (genetics, metabolism)
• Phosphatidylinositol 3-Kinases (metabolism)
• Phosphoinositide-3 Kinase Inhibitors
• Phosphorylation
• Protein Serine-Threonine Kinases (metabolism)
• Protein-Tyrosine Kinases
• Proto-Oncogene Proteins (genetics, metabolism)
• Proto-Oncogene Proteins c-akt
• Proto-Oncogene Proteins c-ret
• Receptor Protein-Tyrosine Kinases (genetics, metabolism)
• Signal Transduction
• Thyroid Neoplasms (enzymology, metabolism)
• Transcription Factors (genetics, metabolism)
• Transcriptional Activation
• Tumor Suppressor Protein p53 (genetics, metabolism)
• Tyrosine (metabolism)
• src-Family Kinases (genetics, metabolism)