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J Clin Endocrinol Metab. 1996 Jun;81(6):2257-63.

Decreased insulin-like growth factor I receptor expression and function in immortalized African Pygmy T cells.

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Program in Molecular Pharmacology and Therapeutics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.


Efe Pygmies of northeast Zaire have the shortest mean adult stature of any population on earth. Although various alterations in the GH/insulin-like growth factor I (IGF-I) axis have been suggested, the basis for short stature in the Pygmy is unknown. We previously described IGF-I unresponsiveness in a T lymphoblast cell line derived from an Efe Pygmy, and studies in five additional lines have confirmed severe IGF-I resistance in these cells. We have now performed experiments to determine the molecular basis for the IGF-I resistance in these cells. We found markedly decreased cell surface expression of IGF-I receptors with normal ligand binding affinity. The Pygmy IGF-I receptors were not autophosphorylated and did not transmit a signal in response to physiological concentrations of IGF-I. There was a substantially decreased level of IGF-I receptor messenger ribonucleic acid in the Pygmy cells with a normal messenger ribonucleic acid half-life. The nucleotide sequence of the full-length IGF receptor complementary DNA in Pygmy 1 showed no significant variation. These results indicate decreased IGF-I receptor gene transcription and IGF-I receptor signaling as the primary variation in the Pygmy cell lines. The findings point to the IGF-I receptor as the locus governing short stature in the African Pygmy and suggest that human stature may be genetically controlled by expression of the IGF-I receptor.

[Indexed for MEDLINE]

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