Myosin 5b is required for proper localization of the intermicrovillar adhesion complex in the intestinal brush border.
Myosin 5b is required for proper localization of the intermicrovillar adhesion complex in the intestinal brush border.
复制标题
肌球蛋白 5b 是微绒毛间粘附复合物在肠刷状缘正确定位所必需的。
DOI：
10.1152/ajpgi.00212.2022
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Engevik,AmyC
中科院分区：
文献类型：
--
作者：
Dooley,SarahA;Engevik,KristenA;Digrazia,Jessica;Stubler,Rachel;Kaji,Izumi;Krystofiak,Evan;Engevik,AmyC
肠上皮细胞有一个精致的顶端膜，富含肌动蛋白的突起称为微绒毛。微绒毛的组织是由微绒毛间粘附复合体（IMAC）协调的，它连接相邻微绒毛的远端。IMAC由CDHR 2和CDHR 5以及支架蛋白USH 1C、ANKS 4 B和肌球蛋白7 b（MYO 7 B）组成。为了产生IMAC，细胞必须将蛋白质转运到顶膜。肌球蛋白5 b（MYO 5 B）是一种分子马达，将离子转运体运输到肠上皮细胞的顶膜，我们假设MYO 5 B也可能负责IMAC蛋白的定位。为了解决这个问题，我们使用了两种不同的小鼠模型：1）新生儿生殖系MYO 5 B基因敲除（MYO 5 B KO）小鼠和2）成年大鼠特异性他莫昔芬诱导的VillinCreERT 2; MYO 5 Bflox/MYO 5 B小鼠。在对照小鼠中，免疫染色显示CDHR 2、CDHR 5、USH 1C和MYO 7 B在微绒毛的尖端高度富集。相比之下，新生儿生殖系和成年MYO 5 B缺陷型小鼠表现出顶端CDHR 2，CDHR 5和MYO 7 B在刷状缘的损失和在根尖下室的积累。共定位分析显示，与对照小鼠相比，成年诱导型MYO 5 B缺陷小鼠的CDHR 2、CDHR 5、USH 1C和MYO 7 B的Mander系数降低。扫描电子显微镜图像进一步证实了成年诱导MYO 5 B缺陷小鼠小肠中异常的微绒毛包装。这些数据表明MYO 5 B负责将IMAC组分递送到顶膜。新&值得注意的是肠上皮通过高度组织化的微绒毛的精细顶膜吸收营养物质和水。微绒毛组织由微绒毛间粘附复合体调节，该复合体在相邻微绒毛之间建立联系并控制微绒毛的堆积和密度。在这项研究中，我们报告了一个新的运输伙伴的IMAC，肌球蛋白5 b。肌球蛋白5 b的缺失导致刷状缘紊乱和IMAC蛋白无法到达微绒毛的远端。
Intestinal enterocytes have an elaborate apical membrane of actin-rich protrusions known as microvilli. The organization of microvilli is orchestrated by the intermicrovillar adhesion complex (IMAC), which connects the distal tips of adjacent microvilli. The IMAC is composed of CDHR2 and CDHR5 as well as the scaffolding proteins USH1C, ANKS4B, and Myosin 7b (MYO7B). To create an IMAC, cells must transport the proteins to the apical membrane. Myosin 5b (MYO5B) is a molecular motor that traffics ion transporters to the apical membrane of enterocytes, and we hypothesized that MYO5B may also be responsible for the localization of IMAC proteins. To address this question, we used two different mouse models:1) neonatal germline MYO5B knockout (MYO5B KO) mice and2) adult intestinal-specific tamoxifen-inducible VillinCreERT2;MYO5Bflox/floxmice. In control mice, immunostaining revealed that CDHR2, CDHR5, USH1C, and MYO7B were highly enriched at the tips of the microvilli. In contrast, neonatal germline and adult MYO5B-deficient mice showed loss of apical CDHR2, CDHR5, and MYO7B in the brush border and accumulation in a subapical compartment. Colocalization analysis revealed decreased Mander’s coefficients in adult inducible MYO5B-deficient mice compared with control mice for CDHR2, CDHR5, USH1C, and MYO7B. Scanning electron microscopy images further demonstrated aberrant microvilli packing in adult inducible MYO5B-deficient mouse small intestine. These data indicate that MYO5B is responsible for the delivery of IMAC components to the apical membrane.NEW & NOTEWORTHYThe intestinal epithelium absorbs nutrients and water through an elaborate apical membrane of highly organized microvilli. Microvilli organization is regulated by the intermicrovillar adhesion complexes, which create links between neighboring microvilli and control microvilli packing and density. In this study, we report a new trafficking partner of the IMAC, Myosin 5b. Loss of Myosin 5b results in a disorganized brush border and failure of IMAC proteins to reach the distal tips of microvilli.