Regulation of ribonuclease expression by estradiol in Rana catesbeiana (Bullfrog)

Abstract

Multiple ribonucleases are widely found in living organisms, but the function and regulation of individual ribonucleases are still not clear. In the present study, we found that one oocytic ribonuclease, RC-RNase, is developmentally expressed in the liver and stored in the oocyte of the bullfrog, while another ribonuclease, RC-RNase L1, is constitutively expressed and retained in the liver at all stages. In females, the expression of RC-RNase increased with the degree of maturity and the concentration of plasma estradiol during oogenesis. In males, the RC-RNase gene was activated in the liver and the newly synthesized protein was secreted into plasma if estradiol was administered. To investigate the mechanism of estrogen-mediated activation of ribonuclease expression, we cloned the RC-RNase promoter and analyzed the putative transcription factor binding sites, e.g. TATA box, ERE, AP1 and CAAT box. Using luciferase as a reporter gene, we found that an estrogen response element in the promoter of RC-RNase was essential for both basic transcription and estradiol-mediated gene activation in estrogen receptor-positive MCF7 cells. These results support the hypothesis that RC-RNase is synthesized in the liver upon stimulation by estradiol during oogenesis, then secreted into the bloodstream and stored in oocytes for embryonic development.

The RNase a superfamily: Generation of diversity and innate host defense

“…However, what has not been explored at all is the role of these lectin-ribonucleases in vivo and their potential for host defense in their natural setting. Liao and colleagues [143] have shown that estrogen can control expression of these genes. Furthermore, multiple Rana sequences have evolved under positive selection pressure into multigene clusters [144,145], in a manner similar to that observed for the rodent eosinophil-associated ribonuclease genes [70].…”

Sialic Acid-Binding Lectin from Bullfrog Eggs Exhibits an Anti-Tumor Effect Against Breast Cancer Cells Including Triple-Negative Phenotype Cells

“…It has been reported that cSBL acts as an anti-cancer agent against various human cancer cells including carcinoma (cervical, oral, hepatocellular, and breast), leukemia, lymphoma, mesothelioma, and glioblastoma [ 24 , 41 , 42 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. Interestingly, although cSBL induces apoptosis in those cancer cells, normal tissue-derived cells, such as fibroblasts, melanocytes, keratinocytes, and mesothelial cells, are relatively insensitive to this agent [ 53 , 56 , 58 , 59 , 60 ].…”