Mechanistic analysis and significance of sphingomyelinase-mediated decreases in transepithelial CFTR currents in nHBEs.
Mechanistic analysis and significance of sphingomyelinase-mediated decreases in transepithelial CFTR currents in nHBEs.
复制标题
NHBE中跨跨性别的CFTR电流中鞘磷脂酶介导的降低的机械分析和重要性。
DOI：
10.14814/phy2.15023
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发表时间：
2021-09
影响因子：
2.5
通讯作者：
McCarty NA
中科院分区：
文献类型：
--
作者：
Cottrill KA;Giacalone VD;Margaroli C;Bridges RJ;Koval M;Tirouvanziam R;McCarty NA
囊性纤维化跨膜传导调节因子（CFTR）的功能丧失导致囊性纤维化（CF）。在肺部，这表现为免疫细胞浸润和细菌感染，导致组织破坏。先前的工作已经确定，急性细菌鞘磷脂酶（SMase）降低了来自无CF（nHBE）和CF（cfHBE，纯合ΔF508-CFTR突变）个体的支气管上皮细胞中的CFTR功能。本研究的重点是探索这种效应的机制。SMase增加了二氢神经酰胺的丰度，这一结果通过使用ceranib-1阻断神经酰胺酶来模拟，这也降低了CFTR功能。SMase介导的抑制机制不涉及细胞CFTR丰度的减少或从顶面去除CFTR，也不涉及5′腺苷一磷酸活化蛋白激酶的激活。为了确定这些鞘脂失衡的病理学相关性，我们评价了cfHBE和cfHNE（鼻）与非CF对照相比的鞘脂谱。CF细胞中鞘磷脂、神经酰胺和二氢神经酰胺大量增加。用VX 445 + VX 661校正ΔF508-CFTR运输减少了一些鞘磷脂和所有神经酰胺，但加剧了二氢神经酰胺的增加。用CFTR增效剂VX 770的额外处理不影响这些变化，表明错误折叠的CFTR的拯救是足够的。我们进一步确定cfHBE比nHBE表达更多的酸性SM酶蛋白。最后，我们确定了CF肺中增加的气道样中性粒细胞分泌酸性SM酶。鉴于CF细胞中鞘脂的不平衡以及CF相关细胞类型分泌酸性SMase，确定SMase介导的CFTR抑制机制将非常重要。
Loss of function of the cystic fibrosis transmembrane conductance regulator (CFTR) causes cystic fibrosis (CF). In the lungs, this manifests as immune cell infiltration and bacterial infections, leading to tissue destruction. Previous work has determined that acute bacterial sphingomyelinase (SMase) decreases CFTR function in bronchial epithelial cells from individuals without CF (nHBEs) and with CF (cfHBEs, homozygous ΔF508‐CFTR mutation). This study focuses on exploring the mechanisms underlying this effect. SMase increased the abundance of dihydroceramides, a result mimicked by blockade of ceramidase enzyme using ceranib‐1, which also decreased CFTR function. The SMase‐mediated inhibitory mechanism did not involve the reduction of cellular CFTR abundance or removal of CFTR from the apical surface, nor did it involve the activation of 5′ adenosine monophosphate‐activated protein kinase. In order to determine the pathological relevance of these sphingolipid imbalances, we evaluated the sphingolipid profiles of cfHBEs and cfHNEs (nasal) as compared to non‐CF controls. Sphingomyelins, ceramides, and dihydroceramides were largely increased in CF cells. Correction of ΔF508‐CFTR trafficking with VX445 + VX661 decreased some sphingomyelins and all ceramides, but exacerbated increases in dihydroceramides. Additional treatment with the CFTR potentiator VX770 did not affect these changes, suggesting rescue of misfolded CFTR was sufficient. We furthermore determined that cfHBEs express more acid‐SMase protein than nHBEs. Lastly, we determined that airway‐like neutrophils, which are increased in the CF lung, secrete acid‐SMase. Identifying the mechanism of SMase‐mediated inhibition of CFTR will be important, given the imbalance of sphingolipids in CF cells and the secretion of acid‐SMase from cell types relevant to CF.