TY - JOUR

T1 - Identification of tyrosine residues in the intracellular domain of the growth hormone receptor required for transcriptional signaling and Stat5 activation

AU - Hansen, L. H.

AU - Wang, X.

AU - Kopchick, J J

AU - Bouchelouche, P

AU - Galsgaard, E D

AU - Nielsen, Jens Høiriis

AU - Billestrup, N

PY - 1996/5/24

Y1 - 1996/5/24

N2 - The binding of growth hormone (GH) to its receptor results in its dimerization followed by activation of Jak2 kinase and tyrosine phosphorylation of the GH receptor itself, as well as Jak2 and the transcription factors Stat1, -3, and -5. In order to study the role of GH receptor tyrosine phosphorylation in intracellular signaling, we constructed GH receptors in which combinations of tyrosines were mutated to phenylalanines. We identified three tyrosine residues at positions 534, 566, and 627 that were required for activation of GH-stimulated transcription of the serine protease inhibitor (Spi) 2.1 promoter. Any of these three tyrosines is able to independently mediate GH-induced transcription, indicating redundancy in this part of the GH receptor. Tyrosine phosphorylation was not required for GH stimulation of mitogen-activated protein (MAP) kinase activity or for GH-stimulated Ca2+ channel activation since these pathways were normal in cells expressing a GH receptor in which all eight intracellular tyrosines were mutated to phenylalanines. Activation of Stat5 by GH was, however, abolished in cells expressing the GH receptor lacking intracellular tyrosines. This study demonstrates that specific tyrosines in the GH receptor are required for transcriptional signaling possibly by their role in the activation of transcription factor Stat5.

AB - The binding of growth hormone (GH) to its receptor results in its dimerization followed by activation of Jak2 kinase and tyrosine phosphorylation of the GH receptor itself, as well as Jak2 and the transcription factors Stat1, -3, and -5. In order to study the role of GH receptor tyrosine phosphorylation in intracellular signaling, we constructed GH receptors in which combinations of tyrosines were mutated to phenylalanines. We identified three tyrosine residues at positions 534, 566, and 627 that were required for activation of GH-stimulated transcription of the serine protease inhibitor (Spi) 2.1 promoter. Any of these three tyrosines is able to independently mediate GH-induced transcription, indicating redundancy in this part of the GH receptor. Tyrosine phosphorylation was not required for GH stimulation of mitogen-activated protein (MAP) kinase activity or for GH-stimulated Ca2+ channel activation since these pathways were normal in cells expressing a GH receptor in which all eight intracellular tyrosines were mutated to phenylalanines. Activation of Stat5 by GH was, however, abolished in cells expressing the GH receptor lacking intracellular tyrosines. This study demonstrates that specific tyrosines in the GH receptor are required for transcriptional signaling possibly by their role in the activation of transcription factor Stat5.

KW - Animals

KW - Base Sequence

KW - CHO Cells

KW - Calcium

KW - Cricetinae

KW - DNA-Binding Proteins

KW - Enzyme Activation

KW - Milk Proteins

KW - Molecular Sequence Data

KW - Phosphorylation

KW - Protein Kinases

KW - Receptors, Somatotropin

KW - STAT5 Transcription Factor

KW - Signal Transduction

KW - Trans-Activators

KW - Transcription, Genetic

KW - Tyrosine

M3 - Journal article

C2 - 8647880

VL - 271

SP - 12669

EP - 12673

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 21

ER -