Identification of JAK protein tyrosine kinases as signaling molecules for prolactin. Functional analysis of prolactin receptor and prolactin-erythropoietin receptor chimera expressed in lymphoid cells.
The mechanism of action of prolactin (PRL) was studied in murine lymphoid BAF-3 cells transfected with either the long form of the PRL receptor (PRL-R), or a chimeric receptor consisting of the extracellular domain of the PRL-R and the transmembrane and intracellular domain of the erythropoietin receptor (PRL/EPO-R). PRL sustained normal and long-term proliferation of BAF-3 cells expressing either the PRL-R or the hybrid PRL/EPO-R. Upon [125I]PRL cross-linking, both types of BAF-3 transfectants were shown to express two [125I]PRL cross-linked species differing in size by 20 kDa. These cross-linked complexes, after denaturation, were recognized by antibody against the PRL-R, indicating that they contain the transfected receptor. PRL induced rapid and transient tyrosine phosphorylation of both the PRL-R and the PRL/EPO-R in BAF-3 transfectants. Furthermore, PRL induced rapid tyrosine phosphorylation of the Janus kinase 2 (JAK2) which was already physically associated with the PRL-R or the PRL/EPO-R in the absence of ligand. JAK1 was also associated with PRL-R and PRL/EPO-R in the absence of ligand. However, only in BAF-3 cells expressing the PRL-R does PRL induce rapid and transient tyrosine phosphorylation of JAK1. These results demonstrate that JAK protein tyrosine kinases couple PRL binding to tyrosine phosphorylation and proliferation.
Dusanter-Fourt
I
I
INSERM U. 363, ICGM Hopital Cochin, Paris, France.
Muller
O
O
Ziemiecki
A
A
Mayeux
P
P
Drucker
B
B
Djiane
J
J
Wilks
A
A
Harpur
A G
AG
Fischer
S
S
Gisselbrecht
S
S
D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003432:Cross-Linking Reagents; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011388:Prolactin / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism*; D011981:Receptors, Prolactin / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection
D003432:Cross-Linking Reagents; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin; D011981:Receptors, Prolactin; D011993:Recombinant Fusion Proteins; D011388:Prolactin; D011505:Protein-Tyrosine Kinases; C507905:Jak1 protein, mouse; C507926:Jak2 protein, mouse; D053613:Janus Kinase 1; D053614:Janus Kinase 2