Mechanobiology of Erythrocytes from Adult Mice Homozygous for a Targeted Disruption of the E-Tmod Gene at Exon 1
Mechanobiology of Erythrocytes from Adult Mice Homozygous for a Targeted Disruption of the E-Tmod Gene at Exon 1
复制标题
DOI：
10.1007/s12195-011-0203-x
复制
发表时间：
2011-10
影响因子：
2.8
通讯作者：
T. Green;C. Vera;Mark A Sussman;M. Martone;L. Sung
中科院分区：
文献类型：
--
作者：
T. Green;C. Vera;Mark A Sussman;M. Martone;L. Sung
红细胞膜骨架是一种为红细胞提供变形能力和稳定性的蛋白质网络。网络的缺陷会导致功能障碍和疾病。41 kDa的红细胞原调节蛋白(E-Tmod)是一种生长缓慢端的肌动蛋白封帽蛋白，与原肌球蛋白5或5b一起被认为是决定肌动蛋白原丝长度的分子标尺。我们之前已经通过靶向破坏包含AUG起始密码子的外显子1建立了A-T基因敲除小鼠模型。在这项研究中，我们证明了通过培育心脏高表达E-Tmod的转基因小鼠来挽救E-Tmod−/−小鼠的胚胎致死性，并研究了红细胞的生物力学及其网络拓扑。Western印迹分析表明，E-Tmod−/−红细胞中没有N-末端F-肌动蛋白结合区的胞质E-Tmod29亚型保持不变，但被氧化后高度二聚化。微管抽吸显示较高的弹性剪切模数，红细胞计数显示较低的平均综合伸长指数。E-Tmod−/−小鼠在透射电子显微镜下可见较多的小红细胞，且网状结构致密。这些结果证明了E-Tmod41这一膜结合型长异构体在红细胞网络组织和机械生物学中的重要性。
The erythrocyte membrane skeleton is a protein network that provides deformability and stability to erythrocytes. Defects in the network lead to dysfunction and diseases. Erythrocyte tropomodulin (E-Tmod) of 41 kDa is an actin-capping protein at the slow-growing end, and together with tropomyosin 5 or 5b, has been proposed to form a “molecular ruler” dictating the length of actin protofilament of 37 nm in the network. We have previously created anE-Tmodknockout mouse model by targeted disruption of exon 1, which contains the AUG initiation codon. In this study, we showed that the embryonic lethality of theE-Tmod−/−mice was rescued by breeding with transgenic mice overexpressingE-Tmodin the heart and investigated the biomechanics of erythrocytes and its network topology. Western blot analysis revealed that a cytosolic E-Tmod29 isoform, which lacks the N-terminal F-actin binding domain, remains intact in theE-Tmod−/−erythrocytes, but is highly dimerized by oxidation. Micropipette aspiration indicated a higher elastic shear modulus and ektacytometry showed a lower average integrated elongation index.E-Tmod−/−mice had more microcytic erythrocytes with more compacted network on transmission electron microscopy. These results demonstrated the importance of E-Tmod41, the membrane-bound long isoform, in the network organization and mechanobiology of erythrocytes.