多肽∶N-寡糖酶在小鼠人工隐睾中表达下调

真核多肽∶N-寡糖酶（peptide∶N-glycanase或PNGase）可切除错误折叠糖蛋白上的N-寡糖链，并可与内质网关联降解（endoplasmic reticulum-associated degradation, ERAD）途径中的多种关键成分相结合.然而，对于PNGase的生理功能及其与疾病的关系尚无明确报道.本研究利用重组技术表达和纯化了包含人PNGase N末端片段的融合蛋白，并经融合蛋白免疫与亲和层析纯化家兔抗血清，制备了PNGase的特异性抗体.利用该抗体和Western 印迹技术研究了PNGase在小鼠组织中的表达.结果显示PNGase在7种小鼠组织（脑、心、肺、肝、脾、肾、睾丸）中均有不同程度的表达，其中表达量最高者为睾丸；PNGase表达水平在不同品系小鼠（C57BL/6N、BALB/cAnN和昆明小鼠）间有显著差异.在小鼠单侧隐睾模型中首次观察到，与对照侧阴囊内的正常睾丸相比，隐睾内PNGase含量明显下降，提示PNGase在睾丸生精过程中可能有重要作用.

Down Regulation of Peptide: N-glycanase in Mouse Artificial Cryptorchid Testes

Eukyrotic peptide∶N-glycanase or PNGase can remove N-glycans on misfolded glycoproteins. The enzyme binds to multiple key components involved in the endoplasmic reticulum-associated degradation (ERAD) pathway. However, the physiological and pathological significances of PNGase remain to be clarified. The fusion proteins containing N-terminal fragment of human PNGase were expressed and purified using recombinant techniques. Specific antibodies against PNGase were obtained by immunization with the fusion protein and affinity chromatography of the rabbit antiserum. The antibodies were used to study the expression of PNGase in mouse tissues by Western blot. The results showed expression of PNGase with varied levels in seven tissues (brains, heart, lung, liver, spleen, kidney and testis), while the highest expression level was found in testis. The expression profiles of PNGase in different mouse strains (C57BL/6N, BALB/cAnN and KM mice) were also significantly different. In the mouse model of unilateral experimental cryptorchidism, we observed that the PNGase levels in cryptorchid testes were significantly lowered than that in scrotal testes, which were used as normal controls. These results suggest that PNGase has important functions in spermatogenesis of testis.