[Effect of papillary thyroid carcinoma related gene PTC1 on subcellular localization and function of ATM cell].
OBJECTIVE
Papillary thyroid carcinoma is characterized by RET (rearranged during transfection)/PTC (papillary thyroid carcinoma) rearrangements. However, the function of RET/PTC in carcino- genesis is not well understood. This study was designed to investigate the interaction between DNA double-strand break sensor ATM (mutated in ataxia telangiectasia) kinase and PTC1, a rearranged form of proto-oncogene ret, to explore the role of ret rearrangements in carcinogenesis.


METHODS
RET TK phosphorylation was determined by in vitro kinase assay using the immunoprecipitation with anti-ATM antibody as kinase and the immunoprecipitation of HA-tagged TK as substrate. The location of ATM-LZPR in COS7 cells coexpressed with PTC1 was investigated by protein extracts of cytoplasm and nucleus. The phosphorylation level of p53, was determined by Western blot analysis with the antibody against phosphorylated p53, and the cell cycle was determined by flow cytometry when PTC1 overexpressed.


RESULTS
ATM directly phosphorylated TK domain of PTC1 in vitro kinase assay. ATM-LZPR was located in both cell cytoplasm and nucleus when PTC1 was not expressed, however, co-overexpression of PTC1 and ATM-LZPR made the latter locate only in the cytoplasm. In addition, overexpression of PTC1 inhibited the phosphorylation level of p53 by ATM and caused G(1)/S phase arrest of cell cycle.


CONCLUSIONS
PTC1 may remain ATM kinase in cytoplasm and inhibit the phosphorylation of p53 by ATM. PTC1, a rearrangement form of ret, may result in the disorder of cell damage repair and cell cycle checkpoint and destroy cell homeostasis.
Tie
Yi
Y
Beijing Institute of Radiation Medicine, Beijing, 100850, PR China.
Mao
Jian-Ping
JP
Liu
Bin
B
Song
Yi
Y
Dong
Yan
Y
Sun
Zhi-Xian
ZX
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D016193:G1 Phase; D006367:HeLa Cells; D006801:Humans; D016350:Leucine Zippers / Q000235:genetics; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases; D000090063:Proto-Oncogene Mas; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D016196:S Phase; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D015513:Oncogene Proteins; D015514:Oncogene Proteins, Fusion; D000090063:Proto-Oncogene Mas; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D011505:Protein-Tyrosine Kinases; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D020794:Receptor Protein-Tyrosine Kinases; C093573:ret-PTC fusion oncoproteins, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases