Neuronatin (Nnat) is expressed in the pituitary, pancreas, and other tissues; however, the function of NNAT is still unclear. Recent studies have demonstrated that NNAT is localized in the sex-determining region Y-box 2-positive stem/progenitor cells in the developing rat pituitary primordium and is downregulated during differentiation into mature hormone-producing cells. Moreover, NNAT is widely localized in subcellular organelles, excluding the Golgi. Here, we further evaluated NNAT-positive cells and intracellular localization in embryonic and postnatal rat tissues such as the pancreas, tongue, whisker hair follicle, and testis. Immunohistochemistry revealed that NNAT was localized in undifferentiated cells (i.e., epithelial basal cells and basement cells in the papillae of the tongue and round and elongated spermatids of the testis) as well as in differentiated cells (insulin-positive cells and exocrine cells of the pancreas, taste receptor cells of the fungiform papilla, the inner root sheath of whisker hair follicles, and spermatozoa). In addition, NNAT exhibited novel intracellular localization in acrosomes in the spermatozoa. Because the endoplasmic reticulum (ER) is excluded from spermatozoa and sarco/ER Ca2+-ATPase isoform 2 (SERCA2) is absent from the inner root sheath, these findings suggested that NNAT localization in the ER and its interaction with SERCA2 are cell- or tissue-specific properties.

中文翻译：

---

神经素在大鼠睾丸，毛囊，舌和胰腺中的特征性定位。

Neuronatin（Nnat）在垂体，胰腺和其他组织中表达；但是，NNAT的功能仍不清楚。最近的研究表明，NNAT位于发育中的大鼠垂体原基的性别决定区Y-box 2阳性干/祖细胞中，在分化为成熟的激素产生细胞时被下调。此外，除高尔基体外，NNAT广泛分布于亚细胞器中。在这里，我们进一步评估了胚胎和出生后大鼠组织（例如胰腺，舌头，晶须毛囊和睾丸）中的NNAT阳性细胞和细胞内定位。免疫组化显示NNAT位于未分化的细胞中（即 舌头的乳头和睾丸的圆形和细长的精子中的上皮基底细胞和基底细胞，以及分化的细胞（胰腺的胰岛素阳性细胞和外分泌细胞，真菌状乳头的味觉受体细胞，内根晶须毛囊的鞘和精子）。另外，NNAT在精子的顶体中表现出新颖的细胞内定位。由于内质网（ER）被排除在精子之外，并且内根鞘中不存在sarco / ER Ca2 + -ATPase亚型2（SERCA2），因此这些发现表明ER中的NNAT定位及其与SERCA2的相互作用是细胞或组织特定的属性。晶须毛囊和精子的内部根鞘）。另外，NNAT在精子的顶体中表现出新颖的细胞内定位。由于内质网（ER）被排除在精子之外，并且内根鞘中不存在sarco / ER Ca2 + -ATPase亚型2（SERCA2），因此这些发现表明ER中的NNAT定位及其与SERCA2的相互作用是细胞或组织特定的属性。晶须毛囊和精子的内部根鞘）。另外，NNAT在精子的顶体中表现出新颖的细胞内定位。由于内质网（ER）被排除在精子之外，并且内根鞘中不存在sarco / ER Ca2 + -ATPase亚型2（SERCA2），因此这些发现表明ER中的NNAT定位及其与SERCA2的相互作用是细胞或组织特定的属性。