Role of the TFG N-terminus and coiled-coil domain in the transforming activity of the thyroid TRK-T3 oncogene.
The thyroid TRK-T3 oncogene results from the fusion of the tyrosine kinase (TK) domain of NTRK1 (one of the receptors for the Nerve Growth Factor) on chromosome 1 to sequences of a novel gene, TFG, on chromosome 3. The 68 kDa TRK-T3 fusion oncoprotein displays a constitutive tyrosine kinase activity resulting in its capability to transform mouse NIH3T3 cells. The TFG portion of TRK-T3 contains a coiled-coil domain most likely responsible for the constitutive, ligand-independent activation of the receptor tyrosine kinase activity. We have previously shown that TRK-T3 oncoprotein forms, in vivo, complexes of three or four molecules. By mean of different experimental approaches, we show here that TRK-T3 activity depends on oligomers formation. In addition, the analysis of different TRK-T3 mutants indicates that the TFG coiled-coil domain and its N-terminal region are both required for the activation and the fully transforming activity of the TRK-T3 oncoprotein, although, most likely, they play a role in different steps of the transforming process. The deletion of the coiled-coil domain abrogates the oligomers formation leading to a constitutive activation; the deletion of the N-terminal region, although not affecting phosphorylation and complexes formation, abrogates transformation, thus suggesting a role in cellular localization and/or interaction with substrata.
Greco
A
A
Division of Experimental Oncology A, Istituto Nazionale Tumori, Milan, Italy.
Fusetti
L
L
Miranda
C
C
Villa
R
R
Zanotti
S
S
Pagliardini
S
S
Pierotti
M A
MA
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002471:Cell Transformation, Neoplastic; D003001:Cloning, Molecular; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000235:genetics*; D013961:Thyroid Gland / Q000378:metabolism; D033921:Vesicular Transport Proteins
D011506:Proteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor; C484335:Tfg protein, mouse; D033921:Vesicular Transport Proteins