Structure and expression of the human small cytokine B subfamily member 11(SCYB11/formerly SCYB9B, alias I-TAC) gene cloned from IFN-gamma-treated human monocytes (THP-1)

Among CXC chemokines, monokine induced by interferon-gamma (IFN-gamma) (MIG ) and IGN-gamma-inducible protein, 10 kDa (INP10), constitute a distinct gr oup because of their sequence and function. We studied genomic structure an d expression of a third, recently identified member of this group named sma ll inducible cytokine B subfamily member 11 (SCYB11, formerly SCYB9B) or IF N-inducible T cell alpha chemoattractant (I-TAC), The cDNA (1445 bp) for th is 94 amino acid protein (M-r 10,364) was cloned from IFN-gamma-treated hum an myelomonocytic cells (THP-1). The reading frame of SCYB11 is distributed to 4 exons spanning 1197 bp of the genomic sequence. In vitro transcriptio n/translation yielded a single protein of about 10 kDa, indicating that the deduced reading frame is translated by eukaryotic ribosomes, The recombina nt 73 amino acid mature protein overexpressed in Escherichia coil was chemo tactic for interleukin-2 (IL-2)-selected T memory cells. Studying various c ytokines and lipopolysaccharide in THP-1 cells identified IFN-gamma as the major stimulus for SCYB11 mRNA expression, followed by IFN-alpha and IFN-be ta, which were about 25 times less effective. Of a panel of different human cells tested, SCYB11 mRNA was also induced in umbilical vein endothelial c ells, dermal fibroblasts, and tumor cell lines from various organs, whereas it was not found in T lymphocytes activated via anti-CD3 antibodies or via IL-2.