Modulation of beta1A integrin functions by tyrosine residues in the beta1 cytoplasmic domain.
Modulation of beta1A integrin functions by tyrosine residues in the beta1 cytoplasmic domain.
复制标题
通过 beta1 胞质结构域中的酪氨酸残基调节 beta1A 整合素功能。
DOI：
10.1083/jcb.141.2.527
复制
发表时间：
1998-04-20
影响因子：
7.8
通讯作者：
Mosher, D F
中科院分区：
文献类型：
--
作者：
Sakai, T;Zhang, Q;Fassler, R;Mosher, D F
β1A整合素亚基胞质结构域点突变在来源于β1-null干细胞的成纤维细胞中表达。β1A（其中两个NPXY基序（Y 783、Y 795）的一个或两个酪氨酸改变为苯丙氨酸）形成活性α5β1和α6β1整合素，其介导细胞粘附并支持纤连蛋白的组装。基序（P781，P793）中的脯氨酸突变为丙氨酸或基序间序列（T788）中的苏氨酸突变为脯氨酸导致表达差的无活性β1A。Y 783，795 F细胞形成许多精细的局灶性接触，并在表面上表现出运动性。当与表达野生型β1A或具有保守的近膜天冬氨酸的D 759 A激活突变的β1A的细胞相比时，Y 783，795 F细胞在趋化性测定中具有受损的穿过滤器的能力。对表达具有单个Tyr至Phe取代的β1A的细胞的分析表明，Y 783和Y 795对于定向迁移都是重要的。与表达野生型β1A的细胞相比，Y 783，795 F细胞中含有肌动蛋白的微丝更短且更外周。这些结果表明，在NPXY基序的苯酚侧链的苯基基团（不能磷酸化）的变化有重大影响的组织焦点接触和细胞骨架和定向细胞运动。
β1A integrin subunits with point mutations of the cytoplasmic domain were expressed in fibroblasts derived from β1-null stem cells. β1A in which one or both of the tyrosines of the two NPXY motifs (Y783, Y795) were changed to phenylalanines formed active α5β1 and α6β1 integrins that mediated cell adhesion and supported assembly of fibronectin. Mutation of the proline in either motif (P781, P793) to an alanine or of a threonine in the inter-motif sequence (T788) to a proline resulted in poorly expressed, inactive β1A. Y783,795F cells developed numerous fine focal contacts and exhibited motility on a surface. When compared with cells expressing wild-type β1A or β1A with the D759A activating mutation of a conserved membrane–proximal aspartate, Y783,795F cells had impaired ability to transverse filters in chemotaxis assays. Analysis of cells expressing β1A with single Tyr to Phe substitutions indicated that both Y783 and Y795 are important for directed migration. Actin-containing microfilaments of Y783,795F cells were shorter and more peripheral than microfilaments of cells expressing wild-type β1A. These results indicate that change of the phenol side chains in the NPXY motifs to phenyl groups (which cannot be phosphorylated) has major effects on the organization of focal contacts and cytoskeleton and on directed cell motility.