Department of Clinical Chemistry, University of Helsinki and Helsinki University Hospital Laboratory, Helsinki, Finland;
Finnish Centre for Laboratory Animal Pathology, Faculty of Veterinary Science, University of Helsinki, Helsinki, Finland; and.
Am J Physiol Cell Physiol. 2014 Jun 1;306(11):C1017-27. doi: 10.1152/ajpcell.00062.2014. Epub 2014 Apr 9.
We have previously shown that in addition to the well-known secreted isoform of prostatic acid phosphatase (sPAP), a transmembrane isoform exists (TMPAP) that interacts with snapin (a SNARE-associated protein) and regulates the endo-/exocytic pathways. We have also shown that PAP has 5'-ectonucleotidase and thiamine monophosphatase activity and elicits antinociceptive effects in mouse models of chronic inflammatory and neuropathic pain. Therefore, to determine the physiological role of PAP in a typical exocrine organ, we studied the submandibular salivary gland (SMG) of PAP(-/-) and wild-type C57BL/6J mice by microarray analyses, microRNA sequencing, activity tests, immunohistochemistry, and biochemical and physiological analyses of saliva. We show that PAP is the main acid phosphatase in the wild-type male mouse saliva, accounting for 50% of the total acid phosphatase activity, and that it is expressed only in the granular convoluted tubules of the SMGs, where it is the only 5'-ectonucleotidase. The lack of PAP in male PAP(-/-) mice was associated with a significant increase in the salivation volume under secretagogue stimulation, overexpression of genes related to cell proliferation (Mki67, Aurkb, Birc5) and immune response (Irf7, Cxcl9, Ccl3, Fpr2), and upregulation of miR-146a in SMGs. An increased and sustained acinar cell proliferation was detected without signs of glandular hyperplasia. Our results indicate that in PAP(-/-) mice, SMG homeostasis is maintained by an innate immune response. Additionally, we suggest that in male mice, PAP via its 5'-ectonucleotidase activity and production of adenosine can elicit analgesic effects when animals lick their wounds.
我们之前已经表明，除了众所周知的前列腺酸性磷酸酶的分泌型同工酶（sPAP）之外，还存在一种跨膜同工酶（TMPAP），它与衔接蛋白（一种 SNARE 相关蛋白）相互作用，调节内/外分泌途径。我们还表明，PAP 具有 5'-核苷酸酶和硫胺素单磷酸酶活性，并在慢性炎症和神经病理性疼痛的小鼠模型中产生镇痛作用。因此，为了确定 PAP 在典型外分泌器官中的生理作用，我们通过微阵列分析、miRNA 测序、活性测试、免疫组织化学以及唾液的生化和生理学分析，研究了 PAP(-/-)和野生型 C57BL/6J 小鼠的颌下腺（SMG）。我们表明，PAP 是野生型雄性小鼠唾液中的主要酸性磷酸酶，占总酸性磷酸酶活性的 50%，仅在 SMG 的颗粒卷曲小管中表达，是唯一的 5'-核苷酸酶。雄性 PAP(-/-)小鼠缺乏 PAP 与促分泌刺激下唾液分泌量的显著增加有关，与细胞增殖（Mki67、Aurkb、Birc5）和免疫反应（Irf7、Cxcl9、Ccl3、Fpr2）相关基因的过度表达以及 SMG 中 miR-146a 的上调有关。在没有腺体增生迹象的情况下，检测到腺泡细胞的增殖增加且持续。我们的结果表明，在 PAP(-/-) 小鼠中，SMG 稳态通过先天免疫反应得以维持。此外，我们建议在雄性小鼠中，PAP 通过其 5'-核苷酸酶活性和腺苷的产生，在动物舔舐伤口时可以产生镇痛作用。
