Identification of three related human GRO genes encoding cytokine functions.

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Abstract
The product of the human GRO gene is a cytokine with inflammatory and growth-regulatory properties; GRO is also called MGSA for melanoma growth-stimulatory activity. We have identified two additional genes, GRO.beta. and GRO.gamma., that share 90% and 86% identity at the deducted amino acid level with the original GRO.alpha. isolate. One amino acid substitution of proline in GRO.alpha. by leucine in GRO.beta. and GRO.gamma. leads to a large predicted change in protein conformation. Significant differences also exist in the 3'' untranslated region, including different numbers of ATTTA repeats associated with mRNA instability. A 122-base-pair region in the 3'' region is conserved among the three GRO genes, and a part of it is also conserved in the Chinese hamster genome, suggesting a role in regulation. DNA hybridization with oligonucleotide probes and partial sequence analysis of the genomic clones confirm that the three forms are derived from related but different genes. Only one chromosomal locus has been identified, at 4q21, by using a GRO.alpha. cDNA that hybridized to all three genes. Expression studies reveal tissue-specific regulation as well as regulation by specific inducing agents, including interleukin 1, tumor necrosis factor, phorbol 12-myristate 13-acetate, and lipopolysaccharide.