HUMAN RIBONUCLEASE-4 (RNASE-4) - CODING SEQUENCE, CHROMOSOMAL LOCALIZATION AND IDENTIFICATION OF 2 DISTINCT TRANSCRIPTS IN HUMAN SOMATIC TISSUES

We have isolated a unique genomic fragment encoding human ribonuclease 4 (RNase 4) of the mammalian ribonuclease gene family, whose members include pancreatic ribonuclease, eosinophil-derived neurotoxin, eosino phil cationic protein and angiogenin. We have determined that the codi ng sequence of RNase 4 resides on a single exon found on human chromos ome 14, The mRNA encoding RNase 4 was detected by Northern analysis in a number of human somatic tissues, including pancreas, lung, skeletal muscle, heart, kidney and placenta, but not brain; liver represents t he most abundant source, Interestingly, the mRNA encoding RNase 4 is s imilar to 2 kb in length, which is approximately twice as large as the mRNAs encoding other members of this gene family, A larger (similar t o 2,4 kb), second transcript was detected in hepatic, pancreatic and r enal tissues, The similar to 2 kb RNase 4 mRNA was detected in cells o f the human promyelocytic leukemia line, HL-60, that had been treated with dibutyryl-cAMP to promote neutrophilic differentiation, In contra st, no mRNA encoding RNase 4 could be detected in cells treated with p horbol myristic acid (PMA), an agent promoting differentiation toward monocyte/macrophages, suggesting the existence of elements regulating tissue specific expression of this gene.