在2009年9月21日的Journal of Cell Biology的一篇報(bào)道中,，Nowak等人介紹了上皮細(xì)胞脂膜中維持細(xì)胞形狀的蛋白質(zhì)網(wǎng)絡(luò)，以及在老鼠晶狀體中該網(wǎng)絡(luò)維持細(xì)胞形狀和有序排列的機(jī)制,。
蛋白網(wǎng)絡(luò)中的血影蛋白（Spectrin）,，F(xiàn)肌動(dòng)蛋白（F-actin）以及其他的相關(guān)蛋白能夠支撐和定形紅細(xì)胞的脂膜。在其他類型的細(xì)胞中同樣存在著相似的網(wǎng)絡(luò),，包括晶體上皮細(xì)胞,。脂膜骨架中的肌絲（Actin filament），是通過網(wǎng)絡(luò)中的相關(guān)蛋白固定的,，如肌動(dòng)蛋白結(jié)合蛋白（actin-binding protein）的原肌球蛋白家族和原肌球調(diào)節(jié)蛋白家族的成員,。
在缺少肌球調(diào)節(jié)蛋白1的老鼠中，其晶體上皮細(xì)胞質(zhì)膜骨架中的gamma原肌球蛋白同樣也會(huì)缺失,。F肌動(dòng)蛋白和血影蛋白雖然仍在細(xì)胞的脂膜中,，以往連續(xù)的網(wǎng)絡(luò)中卻出現(xiàn)了裂口，表明這兩個(gè)肌動(dòng)蛋白結(jié)合蛋白穩(wěn)固了肌絲,，而肌絲對(duì)網(wǎng)絡(luò)來數(shù)是必需的,。電子顯微掃描顯示，缺少肌球調(diào)節(jié)蛋白1的細(xì)胞出現(xiàn)形狀扭曲以及不規(guī)則的排列,。
Velia Fowler解釋說,，血影肌動(dòng)蛋白網(wǎng)絡(luò)的破壞改變了相鄰細(xì)胞間的相互粘合，導(dǎo)致細(xì)胞形狀改變和晶狀體相關(guān)的機(jī)械應(yīng)力混亂,。（生物谷Bioon.com）
生物谷推薦原始出處：
The Journal of Cell Biology, Vol. 186, No. 6, 915-928 doi:10.1083/jcb.200905065
Tropomodulin1 is required for membrane skeleton organization and hexagonal geometry of fiber cells in the mouse lens
Roberta B. Nowak1, Robert S. Fischer1, Rebecca K. Zoltoski2, Jerome R. Kuszak3, and Velia M. Fowler1
1 Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037
2 Department of Biological Health Sciences, Illinois College of Optometry, Chicago, IL 60616
3 Departments of Pathology and Ophthalmology, Rush University Medical Center, Chicago, IL 60612
Hexagonal packing geometry is a hallmark of close-packed epithelial cells in metazoans. Here, we used fiber cells of the vertebrate eye lens as a model system to determine how the membrane skeleton controls hexagonal packing of post-mitotic cells. The membrane skeleton consists of spectrin tetramers linked to actin filaments (F-actin), which are capped by tropomodulin1 (Tmod1) and stabilized by tropomyosin (TM). In mouse lenses lacking Tmod1, initial fiber cell morphogenesis is normal, but fiber cell hexagonal shapes and packing geometry are not maintained as fiber cells mature. Absence of Tmod1 leads to decreased TM levels, loss of F-actin from membranes, and disrupted distribution of β2-spectrin along fiber cell membranes. Regular interlocking membrane protrusions on fiber cells are replaced by irregularly spaced and misshapen protrusions. We conclude that Tmod1 and TM regulation of F-actin stability on fiber cell membranes is critical for the long-range connectivity of the spectrin–actin network, which functions to maintain regular fiber cell hexagonal morphology and packing geometry.
