Identification of the erythrocyte receptor for Plasmodium yoelii RhopH complex

寄生液泡的形成是疟原虫成功入侵宿主红细胞的关键步骤。尽管对液泡形成的生物学作用了解甚少，但液泡蛋白被认为在液泡形成中起着重要作用。为了了解寄生虫疟原虫蛋白在入侵过程中与红细胞之间的分子相互作用，我们利用啮齿动物疟原虫约利疟原虫表征了高分子质量疟原虫蛋白复合物（high molecular mass rhopry protein, RhopH）与红细胞的结合特异性，并提出RhopH复合物的主要红细胞受体是一种通过gpi锚点附着在红细胞表面的蛋白。为了进一步表征和鉴定未知受体蛋白，我们利用C57BL/6J （B6）和MSM/Ms菌株衍生的同种小鼠菌株，基于PyRhopH复合物与这些小鼠红细胞结合的差异（B6的红细胞比MSM/Ms的红细胞结合更高），进行了前瞻性遗传分析。这些经济菌株具有B6遗传背景，特定的染色体或染色体区域被来自MSM/Ms的染色体取代。对现有的一组经济型菌株进行了分析，发现经济型菌株之间的结合并没有明显区分为B6型或MSM/Ms型，表明这种结合涉及多种因素。然而，B6-11^<MSM/Ms>显示出明显的低结合，甚至低于MSM/Ms，因此我们认为受体蛋白可能位于11号染色体上。基于这一假设，我们正在通过进一步的B6与B6-11^<MSM/Ms>之间的连锁分析来缩小11号染色体上的候选区域。候选区域上的gpi锚定蛋白将被表征为PyRhopH复合物受体的主要候选蛋白。

Parasitophorous vacuole formation is a critical step for the successful invasion of host erythrocytes by malaria parasite. Rhoptry proteins are believed to have essential roles in vacuole formation, although their biological roles are poorly understood. To understand the molecular interactions between parasite rhoptry proteins and the erythrocyte during invasion, we have characterized the binding specificity of the high molecular mass rhoptry protein (RhopH) complex to erythrocytes using the rodent malaria parasite, Plasmodium yoelii and proposed that the major erythrocyte receptor for PyRhopH complex is a protein attached to the erythrocyte surface via GPI-anchor.To further characterize and identify the unknown receptor protein, we employed forward genetic analysis using consomic mouse strains derived from C57BL/6J (B6) and MSM/Ms strains based on the difference in the PyRhopH complex binding to the erythrocytes from these mice (erythrocytes from B6 exhibited higher binding than MSM/Ms). These consomic strains have B6 genetic background and a particular chromosome or chromosomal region is replaced with the one from MSM/Ms. A panel of consomic strains available were examined and the binding among consomic strains were found to be not clearly differentiate to B6 type or MSM/Ms type, indicating that multiple factors were involved in the observed binding. However B6-11^<MSM/Ms>, which harbored chromosome 11 derived from MSM/Ms, showed a prominent low binding, even lower than MSM/Ms, thus we considered that the receptor protein potentially located on chromosome 11. Based on this assumption, we are in a process to narrow the candidate region on the chromosome 11 by further linkage analysis between B6 and B6-11^<MSM/Ms>. The GPI-anchored protein on the candidate region would be characterized as a prime candidate for the PyRhopH complex receptor.