Human semen-specific γ-glutamyl transpeptidase active protein (SEGAP) is a unique enzyme complex of ubiquitinated CD10 and CD13. In our previous study, we examined the potential of SEGAP to induce phosphorylation of tyrosine in HeLa (human cervical carcinoma) and HL60 (human promyelocytic leukemia) cells, and we observed phosphorylation of 110-kDa, 70-kDa and 60-kDa proteins that are thought to be PI3 kinase, Syk/ZAP-70 and Scr family proteins, respectively. These results suggested that SEGAP affects mRNA expressions of cytokines and other signals in HeLa and HL60 cells.
In this study, we investigated the changes in mRNA levels in SEGAP-treated HeLa and HL60 cells. IL-1β, IL-8, IL-12, TNF-a, Lyn, Fas and c-fos mRNAs were all expressed in HeLa cells, and their expression levels were not affected by SEGAP. Mannose-binding lectin (MBL) mRNAs were not expressed in control HeLa cells. On the other hand, SEGAP induced MBL mRNA expression in HeLa cells after 15 to 30 min of incubation. Since MBL initiates the lectin complement pathway that mediates the innate immune system, SEGAP may activate the defense system against invading microorganisms. SEGAP did not affect mRNA levels of IL-1β, IL-8, IL-12, TNF-a, Lyn or c-fos in HL60 cells. CT-1 and iNOS mRNAs were not expressed in control HL60 cells. In a manner similar to that in HeLa cells, SEGAP induced CT-1 and iNOS mRNA expressions in HL60 cells after 15 to 30 min of incubation. NO is one of the messenger molecules involved in the bacteria killing process. These results suggest that SEGAP induces lectin, CT-1 and iNOS mRNA expressions in order to protect sperm from invading microorganisms.