Tyrosine 343 in the erythropoietin receptor positively regulates erythropoietin-induced cell proliferation and Stat5 activation.
While previous studies with truncated erythropoietin receptors (EpRs) have suggested that the tyrosine phosphorylation of the EpR does not play a role in Ep-induced proliferation, we have found, using a more subtle, full length EpR mutant, designated Null, in which all eight of the intracellular tyrosines have been substituted with phenylalanine residues, that Null cells require substantially more Ep than wild-type cells in order to proliferate as efficiently. A comparison of Ep-induced proliferation with Ep-induced tyrosine phosphorylation patterns, using wild-type and Null EpR-expressing cells, revealed that Stat5 tyrosine phosphorylation and activation correlated directly with proliferation. Moreover, studies with a Y343F EpR point mutant and various EpR deletion mutants revealed that both Ep-induced proliferation and Stat5 activation were mediated primarily through Y343, but that other tyrosines within the EpR could activate Stat5 in its absence.
Terry Fox Laboratory, BC Cancer Agency, Vancouver, Canada.
J E
JE
Damen
H
H
Wakao
A
A
Miyajima
J
J
Krosl
R K
RK
Humphries
R L
RL
Cutler
G
G
Krystal
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division / Q000502:physiology*; D002460:Cell Line; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004921:Erythropoietin / Q000494:pharmacology*; D053614:Janus Kinase 2; D008894:Milk Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D050799:STAT5 Transcription Factor; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000502:physiology*; D018631:ras Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D003115:Colony-Stimulating Factors; D004268:DNA-Binding Proteins; D008894:Milk Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin; D050799:STAT5 Transcription Factor; D055765:Shc Signaling Adaptor Proteins; D015534:Trans-Activators; D004921:Erythropoietin; D014443:Tyrosine; D010649:Phenylalanine; D011505:Protein-Tyrosine Kinases; D053614:Janus Kinase 2; D018631:ras Proteins