Center Laboratory, Peking University School and Hospital of Stomatology, Beijing, 100081, People's Republic of China.
Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun South Street, Haidian District, Beijing, 100081, People's Republic of China.
J Mol Histol. 2018 Feb;49(1):99-110. doi: 10.1007/s10735-017-9750-3. Epub 2017 Dec 14.
Adiponectin functions as a promoter of saliva secretion in rat submandibular gland via activation of adenosine monophosphate-activated protein kinase (AMPK) and increased paracellular permeability. Ca mobilization is the primary signal for fluid secretion in salivary acinar cells. However, whether intracellular Ca mobilization is involved in adiponectin-induced salivary secretion is unknown. Here, we found that full-length adiponectin (fAd) increased intracellular Ca and saliva secretion in submandibular glands. Pre-perfusion with ethylene glycol-bis (2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) combined with thapsigargin (TG), an endoplasmic reticulum Ca-ATPase inhibitor, abolished fAd-induced salivary secretion, AMPK phosphorylation, and enlarged tight junction (TJ) width. Furthermore, in cultured SMG-C6 cells, co-pretreatment with EGTA and TG suppressed fAd-decreased transepithelial electrical resistance and increased 4-kDa FITC-dextran flux responses. Moreover, fAd increased phosphorylation of calcium/calmodulin-dependent protein kinase (CaMKKβ), a major kinase that is activated by elevated levels of intracellular Ca, but not liver kinase B1 phosphorylation. Pre-perfusion of the isolated gland with STO-609, an inhibitor of CaMKKβ, abolished fAd-induced salivary secretion, AMPK activation, and enlarged TJ width. CaMKKβ shRNA suppressed, whereas CaMKKβ re-expression rescued fAd-increased paracellular permeability. Taken together, these results indicate that adiponectin induced Ca modulation in rat submandibular gland acinar cells. Ca-CaMKKβ pathway is required for adiponectin-induced secretion through mediating AMPK activation and increase in paracellular permeability in rat submandibular glands.
脂联素通过激活腺苷单磷酸活化蛋白激酶 (AMPK) 和增加细胞旁通透性来促进大鼠颌下腺的唾液分泌。钙离子动员是唾液腺细胞分泌液的主要信号。然而，脂联素诱导的唾液分泌是否涉及细胞内钙离子动员尚不清楚。在这里，我们发现全长脂联素 (fAd) 增加了颌下腺的细胞内 Ca 和唾液分泌。预灌流 EGTA（一种内质网 Ca-ATP 酶抑制剂）与 thapsigargin (TG) 联合使用可消除 fAd 诱导的唾液分泌、AMPK 磷酸化和紧密连接 (TJ) 增宽。此外，在培养的 SMG-C6 细胞中，EGTA 和 TG 的共同预处理抑制了 fAd 降低跨上皮电阻和增加 4 kDa FITC-葡聚糖通量反应。此外，fAd 增加了钙/钙调蛋白依赖性蛋白激酶 (CaMKKβ) 的磷酸化，CaMKKβ 是一种由细胞内 Ca 水平升高激活的主要激酶，但不磷酸化肝激酶 B1。用 CaMKKβ 抑制剂 STO-609 预灌注分离的腺体可消除 fAd 诱导的唾液分泌、AMPK 激活和 TJ 增宽。CaMKKβ shRNA 抑制，而 CaMKKβ 再表达挽救了 fAd 增加的细胞旁通透性。综上所述，这些结果表明脂联素诱导了大鼠颌下腺腺泡细胞中的 Ca 调节。Ca-CaMKKβ 途径是脂联素诱导大鼠颌下腺分泌所必需的，通过介导 AMPK 激活和增加细胞旁通透性。
