Isolation and characterization of a novel PDGF-induced human gene

Using a differential display RT-PCR strategy to identify novel growth-facto r-induced transcripts, we cloned and characterized the human homolog of yea st NOP5/NOP58, whose gene product has been implicated in the execution of e arly pre-rRNA processing steps. Human NOP5 cDNA was isolated from an M426 f ibroblast cDNA library. Determination of the cDNA nucleotide sequence revea led an open reading frame of 1587 nucleotides encoding a predicted gene pro duct of 529 amino acids and mass of 59 554 Da. The yeast and human NOP5 gen e products were found to share 63% homology and 46% identity. NOP5 mRNA was induced within 2 h of platelet-derived growth factor (PDGF) treatment of h uman M426 fibroblasts. Pretreatment with cycloheximide enhanced, while acti nomycin blocked induction of the NOP5 transcript. In vitro translational an alysis of the cDNA revealed a 60 kDa species? consistent with the predicted molecular weight of the gene product. Ubiquitous, but differential NOP5 mR NA expression was revealed after Northern blot analysis of total RNA from s everal human tissues. Moreover, NOP5 mRNA expression was also demonstrated in cell lines of fibroblast, epithelial, and myeloid origin. A highly charg ed carboxy terminal domain and consensus phosphorylation sites were identif ied. The presence of potential regulatory elements, together with growth fa ctor induction and widespread expression is consistent with the hypothesis that the NOP5 gene product may play a role in fundamental cellular growth p rocesses. (C) 2000 Elsevier Science B.V. All rights reserved.