Overexpression of the short form of the growth hormone receptor in 3T3-L1 mouse preadipocytes
- Univ. of Massachusetts Medical School, Worchester, MA (United States); and others
In rodents, the gene for the growth hormone receptor (GHR) gives rise to two mRNA transcripts encoding two proteins: a larger membrane spanning receptor (GHR{sub L}) and a smaller isoform, GHR{sub S} that consists of the extracellular domain and a unique hydrophillic carboxyl terminus. We examined the hypothesis that GHR{sub S} may contribute to cellular binding of GH and play a role in growth hormone (GH) signaling. Rat cDNA encoding GHR{sub S} was ligated into the mammalian expression vector pcDNA-I/neo and stably transfected into mouse 3T3-L1 preadipocytes which have endogenous GH receptors and, when differentiated into adipocytes, have the biochemical machinery to express the various GH effects. Sixteen of 24 neomycin resistant clones secreted at least twice as much GHR{sub s} in the growth medium as cells transfected with the vector alone, and in nine of these, GH binding was increased 2- to 4-fold. The amount of GHR{sub L} in extracts of these cells was unchanged, indicating that increased binding could not be accounted for by effects on formation or degradation of GHR{sub L}. The transfected cDNA for GHR{sub S} directs the synthesis of a 50 kDa protein. We conclude that GHR{sub S} contributes to GH binding and may therefore be a functional receptor. In addition, overexpression of GHR{sub S} in 3T3-L1 cells altered cell function in the absence of GH. 20 refs., 4 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 466613
- Journal Information:
- Proceedings of the Society for Experimental Biology and Medicine, Vol. 206; Other Information: PBD: 1994
- Country of Publication:
- United States
- Language:
- English
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BASIC STUDIES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
STH
RECEPTORS
GENE REGULATION
STRUCTURE-ACTIVITY RELATIONSHIPS
TRANSCRIPTION
SPLICING
CROSS-LINKING
ANIMAL CELLS
CELL DIFFERENTIATION
CLONING
PROTEINS
BIOSYNTHESIS
PHOSPHORYLATION
IODINE 125
RADIONUCLIDE KINETICS
MESSENGER-RNA
MICE
RATS
AMINO ACIDS