Disease-associated mutations in TUBA1A result in a spectrum of defects in the tubulin folding and heterodimer assembly pathway
Disease-associated mutations in TUBA1A result in a spectrum of defects in the tubulin folding and heterodimer assembly pathway
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DOI：
10.1093/hmg/ddq276
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发表时间：
2010-09-15
影响因子：
3.5
通讯作者：
Cowan, Nicholas J.
中科院分区：
文献类型：
--
作者：
Tian, Guoling;Jaglin, Xavier H.;Cowan, Nicholas J.
皮质发育畸形是一系列疾病的特征，包括多小脑回、脑室周围和皮质下异位和无脑畸形。TUBA1A和TUBB2B都是编码α-微管蛋白和β-微管蛋白的多基因家族的成员，最近发现它们的突变与这些疾病有关。在这里，我们检查了TUBA1A中九个致病突变(I188L、I238V、P263T、L286F、V303G、L397P、R402C、402H、S419L)造成的缺陷。我们发现，所有突变蛋白在体外的表达导致不同产率的微管蛋白异源二聚体的产生，并且这些异源二聚体可以在体外与微管共聚合。我们发现了由这些突变引起的几种缺陷。其中包括导致新生微管蛋白异源二聚体形成的伴侣依赖途径中的各种缺陷。这些问题包括与伴侣蛋白前折叠蛋白的相互作用有缺陷，与胞质伴侣蛋白CCT的相互作用效率低下，以及在某些情况下，未能稳定地与TBCB相互作用，TBCB是微管蛋白异源二聚体组装途径中CCT下游的五个微管蛋白特异性伴侣蛋白之一。其他缺陷包括体外结构不稳定，体内稳定性降低，体内与微管共同组装的能力受损，以及培养神经元突起(但不是胞体)中微管生长速度受到抑制。我们的数据与以下观点一致，即TUBA1A的一些突变会导致微管蛋白缺陷，而其他突变则反映了与一个或多个MAP的相互作用受损，这对正确的神经元迁移是必不可少的。
Malformations of cortical development are characteristic of a plethora of diseases that includes polymicrogyria, periventricular and subcortical heterotopia and lissencephaly. Mutations in TUBA1A and TUBB2B, each a member of the multigene families that encode alpha- and beta-tubulins, have recently been implicated in these diseases. Here we examine the defects that result from nine disease-causing mutations (I188L, I238V, P263T, L286F, V303G, L397P, R402C, 402H, S419L) in TUBA1A. We show that the expression of all the mutant proteins in vitro results in the generation of tubulin heterodimers in varying yield and that these can co-polymerize with microtubules in vitro. We identify several kinds of defects that result from these mutations. Among these are various defects in the chaperone-dependent pathway leading to de novo tubulin heterodimer formation. These include a defective interaction with the chaperone prefoldin, a reduced efficiency in the generation of productive folding intermediates as a result of inefficient interaction with the cytosolic chaperonin, CCT, and, in several cases, a failure to stably interact with TBCB, one of five tubulin-specific chaperones that act downstream of CCT in the tubulin heterodimer assembly pathway. Other defects include structural instability in vitro, diminished stability in vivo, a compromised ability to co-assemble with microtubules in vivo and a suppression of microtubule growth rate in the neurites (but not the soma) of cultured neurons. Our data are consistent with the notion that some mutations in TUBA1A result in tubulin deficit, whereas others reflect compromised interactions with one or more MAPs that are essential to proper neuronal migration.