Ca2+ dynamics in salivary acinar cells:: distinct morphology of the acinar lumen underlies near-synchronous global Ca2+ responses
Ca2+ dynamics in salivary acinar cells:: distinct morphology of the acinar lumen underlies near-synchronous global Ca2+ responses
复制标题
DOI：
10.1242/jcs.02533
复制
发表时间：
2005-09-15
影响因子：
4
通讯作者：
Thorn, P
中科院分区：
文献类型：
--
作者：
Larina, O;Thorn, P
在唾液腺泡细胞中，调节液体和酶分泌的Ca2+信号的模式尚未得到解决，因为文献中有相互矛盾的报道。我们使用双光子技术直接观察外分泌组织活片段中的腺泡细胞腔，同时记录激动剂诱导的细胞内Ca2+的变化。我们在下颌腺泡细胞中显示了近乎同步的全球Ca2+反应，不同于通常在啮齿动物胰腺腺泡细胞中看到的典型的顶端到基部的Ca2+波。为了解释这些几乎同步的全球Ca2+反应的基础，我们使用免疫细胞化学实验来定位组织片段中的管腔蛋白和肌醇三磷酸受体（InsP(3)Rs）。封闭带1 （ZO-1）是一种紧密连接蛋白，显示单个颌下腺泡细胞通常几乎完全被狭窄的管腔结构包围。相比之下，在胰腺碎片中，ZO-1染色显示单个腺泡细胞的短管腔分支突然终止于顶极。InsP(3)Rs 2型和3型的共免疫染色显示它们在两种外分泌组织中与ZO-1位于同一区域。功能实验表明，在没有细胞外Ca2+和有ryanodine存在的情况下，仍然观察到近同步的全局Ca2+反应。我们得出结论，下颌下细胞精细的腔区导致了迄今为止未被识别的InsP(3)Rs在细胞周围的广泛分布，这是对激动剂几乎同步的全球Ca2+反应的基础。我们认为这可能是下颌下细胞的结构适应，以支持大量的分泌液。
In salivary acinar cells, the pattern of the Ca2+ signals that regulates fluid and enzyme secretion has yet to be resolved, as there are conflicting reports in the literature. We have used a two-photon technique to directly visualize the acinar cell lumen in living fragments of exocrine tissue and simultaneously recorded agonist-induced changes in intracellular Ca2+. We show near-synchronous global Ca2+ responses in submandibular acinar cells, distinct from the typical apical to basal Ca2+ wave usually seen in rodent pancreatic acinar cells. In an effort to explain the basis of these near-synchronous global Ca2+ responses we used immunocytochemical experiments to localize luminal proteins and inositol trisphosphate receptors (InsP(3)Rs) in tissue fragments. Zona occludens 1 (ZO-1), a tight junction protein, shows that individual submandibular acinar cells are often nearly completely encircled by a narrow luminal structure. By contrast, in pancreatic fragments, ZO-1 staining shows short luminal branches terminating abruptly at the apical pole of single acinar cells. Coimmunostaining of InsP(3)Rs type 2 and type 3 showed them in the same region as ZO-1 in both exocrine tissues. Functional experiments showed that the near-synchronous global Ca2+ responses were still observed in the absence of extracellular Ca2+ and also in the presence of ryanodine. We conclude that the elaborate luminal region of submandibular cells leads to a hitherto unrecognized extensive distribution of InsP(3)Rs in a band around the cell and that this underlies the near-synchronous global Ca2+ response to agonists. We suggest that this may be a structural adaptation in submandibular cells to support the copious amounts of fluid secreted.