Growth hormone (GH)-independent dimerization of GH receptor by a leucine zipper results in constitutive activation
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Growth hormone (GH)-independent dimerization of GH receptor by a leucine zipper results in constitutive activation. / Behncken, S N; Billestrup, Nils; Brown, R; Amstrup, J; Conway-Campbell, B; Waters, M J.
I: The Journal of Biological Chemistry, Bind 275, Nr. 22, 02.06.2000, s. 17000-7.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Growth hormone (GH)-independent dimerization of GH receptor by a leucine zipper results in constitutive activation
AU - Behncken, S N
AU - Billestrup, Nils
AU - Brown, R
AU - Amstrup, J
AU - Conway-Campbell, B
AU - Waters, M J
PY - 2000/6/2
Y1 - 2000/6/2
N2 - Growth hormone initiates signaling by inducing homodimerization of two GH receptors. Here, we have sought to determine whether constitutively active receptor can be created in the absence of the extracellular domain by substituting it with high affinity leucine zippers to create dimers of the growth hormone receptor (GHR) signaling domain. The entire extracellular domain of the GHR was replaced by the hemagglutinin-tagged zipper sequence of either the c-Fos or c-Jun transcription factor (termed Fos-GHR and Jun-GHR, respectively). Transient transfection of Fos-GHR or Jun-GHR resulted in activation of the serine protease inhibitor 2.1 promoter in Chinese hamster ovary-K1 cells to a level equal to that achieved by fully activated wild type GHR. Furthermore, stable expression of Jun-GHR alone or Fos-GHR and Jun-GHR together in the interleukin 3-dependent BaF-B03 cell line resulted in cell proliferation after interleukin 3 withdrawal at a rate equal to maximally stimulated wild type GHR-expressing cells. Activation of STAT 5b was also observed in Fos-Jun-GHR-expressing cells at a level equal to that in chronically GH-treated GHR-expressing cells. Thus, forced dimerization of the transmembrane and cytoplasmic domains of the GHR in the absence of the extracellular domain can lead to the constitutive activation of known GH signaling end points, supporting the view that proximity of Janus kinase 2 (JAK2) kinases is the essential element in signaling. Such constitutively active GH receptors may have particular utility for transgenic livestock applications.
AB - Growth hormone initiates signaling by inducing homodimerization of two GH receptors. Here, we have sought to determine whether constitutively active receptor can be created in the absence of the extracellular domain by substituting it with high affinity leucine zippers to create dimers of the growth hormone receptor (GHR) signaling domain. The entire extracellular domain of the GHR was replaced by the hemagglutinin-tagged zipper sequence of either the c-Fos or c-Jun transcription factor (termed Fos-GHR and Jun-GHR, respectively). Transient transfection of Fos-GHR or Jun-GHR resulted in activation of the serine protease inhibitor 2.1 promoter in Chinese hamster ovary-K1 cells to a level equal to that achieved by fully activated wild type GHR. Furthermore, stable expression of Jun-GHR alone or Fos-GHR and Jun-GHR together in the interleukin 3-dependent BaF-B03 cell line resulted in cell proliferation after interleukin 3 withdrawal at a rate equal to maximally stimulated wild type GHR-expressing cells. Activation of STAT 5b was also observed in Fos-Jun-GHR-expressing cells at a level equal to that in chronically GH-treated GHR-expressing cells. Thus, forced dimerization of the transmembrane and cytoplasmic domains of the GHR in the absence of the extracellular domain can lead to the constitutive activation of known GH signaling end points, supporting the view that proximity of Janus kinase 2 (JAK2) kinases is the essential element in signaling. Such constitutively active GH receptors may have particular utility for transgenic livestock applications.
KW - Amino Acid Sequence
KW - Animals
KW - Base Sequence
KW - CHO Cells
KW - Cell Division
KW - Cricetinae
KW - DNA Primers
KW - DNA-Binding Proteins
KW - Dimerization
KW - Growth Hormone
KW - Humans
KW - Leucine Zippers
KW - Milk Proteins
KW - Proto-Oncogene Proteins c-fos
KW - Proto-Oncogene Proteins c-jun
KW - Receptors, Somatotropin
KW - Recombinant Fusion Proteins
KW - STAT5 Transcription Factor
KW - Trans-Activators
M3 - Journal article
C2 - 10828073
VL - 275
SP - 17000
EP - 17007
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 22
ER -
ID: 132900147