Cloning and characterization of an androgen-dependent acidic epididymal glycoprotein/CRISP1-like protein from the monkey

A cDNA encoding an acidic epididymal glycoprotein (AEG)-like, CRISP1 (cyste ine-rich secretory protein) protein from the monkey (Macaca mullata) epidid ymis has been cloned and sequenced. The monkey AEG (mAEG) has an open readi ng frame that encodes a protein containing 249 amino acids with a deduced m olecular mass of 28 kDa. The mAEG protein sequence is 85% identical to huma n and 44% identical to mouse CRISP1, including all 16 conserved cysteine re sidues. mAEG also shows a significant amino acid homology with other CRISP proteins, rat AEG/DE, human TPX1/CRISP2, and guinea pig acrosomal autoantig en 1 (AA1). In addition, mAEG shows somewhat less homology to a toxin from the Mexican beaded lizard and to a human glioma pathogenesis-related protei n. Northern blot analysis shows that the mRNA for mAEG is expressed in all the regions of the epididymis except the caput and was not detected in the testis, prostate, seminal vesicle, and brain. In castrated animals, mAEG ge ne expression in the epididymis is significantly diminished; however, testo sterone enanthate replacement restored the normal level of expression, demo nstrating that expression of mAEG is androgen dependent. Western blot analy sis of monkey epididymal regions using mouse antirecombinant human AEG iden tified a 28-kDa protein only in the caudal region. Immunohistochemical anal ysis identified mAEG only in the principal cells of the cauda epididymal ep ithelium. Immunofluorescence analysis identified mAEG on the principal piec e of the sperm tail and as small patches over the middle piece and head reg ions. The results described in the present study suggest that mAEG (CRISP1) is secreted in the monkey epididymis, regulated by androgens and present o n epididymal spermatozoa.