Cloning and functional characterization of GMPR2, a novel human guanosine monophosphate reductase, which promotes the monocytic differentiation of HL-60 leukemia cells.

PURPOSE: To identify the biological function of a novel molecule which shows high homology with human guanosine monophosphate reductase (GMPR) and is named GMPR2. METHODS: GMPR2 cDNA was cloned from the cDNA library of human dendritic cells and was characterized by Bioinformatics. The expression pattern of GMPR2 was analyzed by Northern blotting. The enzymatic activity of the purified recombinant GMPR2 protein was determined using a spectrophotometric assay. HL-60 leukemia cells were transfected with GMPR2 and the expression of CD14 and myeloperoxidase (MPO) in HL-60 cells with and without 12- o-tetra-decanoyl-phorbol-13-acetate (TPA) induction was monitored by FACS analysis. RESULTS: The novel gene contained ten exons and nine introns and was mapped to 14q11-21. Northern blotting indicated a ubiquitous expression of GMPR2 mRNA in most of the human tissues and cancer cell lines investigated. The recombinant GMPR2 protein was able to reduce GMP. The expression of CD14 and MPO in HL-60 leukemia cells overexpressing GMPR2 clearly increased after induction by TPA. CONCLUSIONS: GMPR2 is a novel human GMP reductase, and overexpression of GMPR2 can promote the monocytic differentiation of HL-60 leukemia cells.