24p3蛋白與小白鼠子宮及副睾發育的關係

Abstract

24p3的基因產物（mRNA)，最早是在SV40感染培養基中培養的小白鼠腎臟細胞中發現，它曾一度被視為一種致癌基因（oncogene）。因為SV40的感染導致24p3 mRNA大量表現，可能可以當作一種細胞被轉型的指標分子，但這方面的說法一直沒有具說服力的證據出現。本實驗室在先前的研究當中，順利地從受動情素（estrogen）刺激的未成熟小白鼠子宮液中得到24p3基因轉譯的蛋白。24p3蛋白在雌鼠可以用動情素加以誘導產生，即使是未成熟的雌性小白鼠。24p3蛋白及mRNA的表現和雌性小白鼠的年齡關係由西方墨點法或北方墨點法研究，都可以發現，24p3蛋白的產生應該是在性成熟以後，而且24p3蛋白在子宮中出現的時間，可能僅局限於動情前期（proestrus）。這個現象可由24p3蛋白的不規律變化提示，似乎只有在動情素濃度升高的時期，24p3蛋白才被誘導產生。另外，在雄性小白鼠的副睾中亦發現了一種能和24p3蛋白的抗體產生反應的蛋白，經過cDNA的比對結果發現，從基因的層次來看，在小白鼠子宮及副睾中均存在著24p3的基因產物，但是在雄性小白鼠24p3蛋白及其mRNA的表現似乎相當恆定，從幼鼠（兩週）到成鼠（十二週）都發現它的表現並沒有太大的變化，而且它無法用動情素（DES,17β-estradiol）或是睾固酮(testosterone）加以誘導產生，從免疫化學染色法的觀測，證實在副睾中，24p3蛋白僅在副睾的頭部（caput）出現，不論是在幼鼠或成鼠均可在副睾頭部的柱狀細胞（columnar cells）中及腔道的分泌液中發現。

The cellular level of mRNA derived from 24p3 gene was promoted in SV40 infected mouse kidney cells by Suzanne et al.,(Oncogene 4, 601-608, 1989) and they tented to regard it an oncogene, suggesting that 24p3 protein was a maker molecule when the normal cells had been transformed. However, no evidence has supported this assumption. In fact, we identified a 26 kDa glycoprotein derived from 24p3 gene in the uterine luminal fluid of immature mice being stimulated by estrogen. According to our results of Western blotting and Northern blotting, both 24p3 protein and 24p3 mRNA could be detected only in mature female mice. Perhaps the secretion of 24p3 protein took place at proestrous phase. The phenomenon of variation of 24p3 protein during the development of uterus suggested that the gene expression for the production of 24p3 protein might be coorelated with the estrous cycle. A protein in the epididymis of male mice could be immunodetected with 24p3 protein antiserum. We could amplify the open reading frame of 24p3 cDNA in the cDNA library constructed for mice epididymis. We found that the expression of 24p3 protein and mRNA transcript in mice epididymis took place in immature baby mice, indicating the constitutive expression of 24p3 gene in the sexual organ. The gene expression in epididymis could not be induced by sexual steroid hormones such as DES, 17β-estradiol and testosterone. The 24p3 protein was detected only at the caput of epididymis according to the results of immunocytochemistry. The 24p3 protein was found in the columnar cells of epididymal tubules and in the epididymal secretory fluid.