Gunel Murat, Laurans Maxwell S H, Shin Dana, DiLuna Michael L, Voorhees Jennifer, Choate Keith, Nelson-Williams Carol, Lifton Richard P
Department of Neurosurgery, Yale Neurovascular Surgery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
Proc Natl Acad Sci U S A. 2002 Aug 6;99(16):10677-82. doi: 10.1073/pnas.122354499. Epub 2002 Jul 24.
Mutations in Krev1 interaction trapped gene 1 (KRIT1) cause cerebral cavernous malformation, an autosomal dominant disease featuring malformation of cerebral capillaries resulting in cerebral hemorrhage, strokes, and seizures. The biological functions of KRIT1 are unknown. We have investigated KRIT1 expression in endothelial cells by using specific anti-KRIT1 antibodies. By both microscopy and coimmunoprecipitation, we show that KRIT1 colocalizes with microtubules. In interphase cells, KRIT1 is found along the length of microtubules. During metaphase, KRIT1 is located on spindle pole bodies and the mitotic spindle. During late phases of mitosis, KRIT1 localizes in a pattern indicative of association with microtubule plus ends. In anaphase, the plus ends of the interpolar microtubules show strong KRIT1 staining and, in late telophase, KRIT1 stains the midbody remnant most strongly; this is the site of cytokinesis where plus ends of microtubules from dividing cells overlap. These results establish that KRIT1 is a microtubule-associated protein; its location at plus ends in mitosis suggests a possible role in microtubule targeting. These findings, coupled with evidence of interaction of KRIT1 with Krev1 and integrin cytoplasmic domain-associated protein-1 alpha (ICAP1 alpha), suggest that KRIT1 may help determine endothelial cell shape and function in response to cell-cell and cell-matrix interactions by guiding cytoskeletal structure. We propose that the loss of this targeting function leads to abnormal endothelial tube formation, thereby explaining the mechanism of formation of cerebral cavernous malformation (CCM) lesions.
Krev1相互作用捕获基因1（KRIT1）的突变会导致脑海绵状血管畸形，这是一种常染色体显性疾病，其特征是脑毛细血管畸形，可导致脑出血、中风和癫痫发作。KRIT1的生物学功能尚不清楚。我们使用特异性抗KRIT1抗体研究了内皮细胞中KRIT1的表达。通过显微镜检查和免疫共沉淀，我们发现KRIT1与微管共定位。在间期细胞中，KRIT1沿微管全长分布。在中期，KRIT1位于纺锤极体和有丝分裂纺锤体上。在有丝分裂后期，KRIT1以一种表明与微管正端相关的模式定位。在后期，极间微管的正端显示出强烈的KRIT1染色，在末期后期，KRIT1对中体残余物的染色最强；这是胞质分裂的部位，来自分裂细胞的微管正端在此重叠。这些结果表明KRIT1是一种微管相关蛋白；其在有丝分裂中位于正端表明它可能在微管靶向中发挥作用。这些发现，再加上KRIT1与Krev1以及整合素胞质结构域相关蛋白-1α（ICAP1α）相互作用的证据，表明KRIT1可能通过引导细胞骨架结构，在响应细胞间和细胞与基质的相互作用时，有助于确定内皮细胞的形状和功能。我们认为这种靶向功能的丧失会导致内皮管形成异常，从而解释脑海绵状血管畸形（CCM）病变的形成机制。
