SLK, a germinal center kinase found in kidney epithelial cells, signals to promote apoptosis. Expression of SLK mRNA and protein, as well as kinase activity are increased during kidney development, and recovery from ischemic acute renal failure. The 3'-untranslated region (3'UTR) of SLK mRNA contains multiple adenine and uridine-rich elements, suggesting that the 3'UTR may regulate mRNA stability. This was confirmed in COS cell transient transfection studies, which showed that expression of the SLK open reading frame plus 3'UTR mRNA was reduced by 35% relative to the open reading frame alone. To further characterize the SLK-3'UTR, this nucleotide sequence was subcloned downstream of enhanced green fluorescent protein (EGFP) cDNA. In COS, 293T and glomerular epithelial cells (GECs), expression of EGFP mRNA and protein was markedly reduced in the presence of the SLK-3'UTR. After transfection and subsequent addition of actinomycin D, EGFP mRNA remained stable in cells for at least 6 hours, while EGFP-SLK-3'UTR mRNA decayed with a half-life of ~4 hours. A region containing five AUUUA motifs within the SLK-3'UTR destabilized EGFP mRNA. Deletion of this region from the SLK-3'UTR, in part, restored mRNA stability. By UV crosslinking and SDS-PAGE, the SLK-3'UTR bound to protein(s) of ~30 kDa in extracts of COS cells, GECs, and kidney. Co-transfection of HuR (a RNA binding protein of ~30 kDa) increased the steady state mRNA level of EGFP-SLK-3'UTR, but not EGFP. Thus, the SLK-3'UTR may interact with kidney RNA-binding proteins to regulate expression of SLK mRNA during kidney development and following ischemic injury.