Identification of intracellular domains in the growth hormone receptor involved in signal transduction

TY - JOUR

T1 - Identification of intracellular domains in the growth hormone receptor involved in signal transduction

AU - Billestrup, N

AU - Allevato, G

AU - Norstedt, G

AU - Møldrup, Annette

AU - Nielsen, Jens Høiriis

PY - 1994/7

Y1 - 1994/7

N2 - The growth hormone (GH) receptor belongs to the GH/prolactin/cytokine super-family of receptors. The signal transduction mechanism utilized by this class of receptors remains largely unknown. In order to identify functional domains in the intracellular region of the GH receptor we generated a number of GH receptor mutants and analyzed their function after transfection into various cell lines. A truncated GH receptor missing 184 amino acids at the C-terminus was unable to mediate GH effects on transcription of the Spi 2.1 and insulin genes. However, this mutant was fully active in mediating GH-stimulated metabolic effects such as protein synthesis and lipolysis. Furthermore, this mutant GH receptor internalized rapidly following GH binding. Another truncated GH receptor lacking all but five amino acids of the cytoplasmic domain could not mediate any effects of GH nor did it internalize. Deletion of the proline-rich region or changing the four prolines to alanines also resulted in a GH receptor deficient in signaling. Mutation of phenylalanine 346 to alanine resulted in a GH receptor which did not internalize rapidly; however, this mutant GH receptor was capable of mediating GH-stimulated transcription as well as metabolic effects. These results indicate that the intracellular part of the GH receptor can be divided into at least three functional domains: (i) for transcriptional activity, two domains are involved, one located in the C-terminal 184 amino acids and the other in the proline-rich domain; (ii) for metabolic effects, a domain located in or near the proline-rich region is of importance; and (iii) for internalization, phenylalanine 346 is necessary.

AB - The growth hormone (GH) receptor belongs to the GH/prolactin/cytokine super-family of receptors. The signal transduction mechanism utilized by this class of receptors remains largely unknown. In order to identify functional domains in the intracellular region of the GH receptor we generated a number of GH receptor mutants and analyzed their function after transfection into various cell lines. A truncated GH receptor missing 184 amino acids at the C-terminus was unable to mediate GH effects on transcription of the Spi 2.1 and insulin genes. However, this mutant was fully active in mediating GH-stimulated metabolic effects such as protein synthesis and lipolysis. Furthermore, this mutant GH receptor internalized rapidly following GH binding. Another truncated GH receptor lacking all but five amino acids of the cytoplasmic domain could not mediate any effects of GH nor did it internalize. Deletion of the proline-rich region or changing the four prolines to alanines also resulted in a GH receptor deficient in signaling. Mutation of phenylalanine 346 to alanine resulted in a GH receptor which did not internalize rapidly; however, this mutant GH receptor was capable of mediating GH-stimulated transcription as well as metabolic effects. These results indicate that the intracellular part of the GH receptor can be divided into at least three functional domains: (i) for transcriptional activity, two domains are involved, one located in the C-terminal 184 amino acids and the other in the proline-rich domain; (ii) for metabolic effects, a domain located in or near the proline-rich region is of importance; and (iii) for internalization, phenylalanine 346 is necessary.

KW - Amino Acid Sequence

KW - Animals

KW - Gene Expression Regulation

KW - Molecular Sequence Data

KW - Mutagenesis, Site-Directed

KW - Receptors, Somatotropin

KW - Signal Transduction

KW - Structure-Activity Relationship

KW - Transfection

M3 - Journal article

C2 - 8016155

SN - 0037-9727

VL - 206

SP - 205

EP - 209

JO - Proceedings of the Society for Experimental Biology and Medicine

JF - Proceedings of the Society for Experimental Biology and Medicine

IS - 3

ER -