Laboratório de Biologia Estrutural, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, (Av, Brasil 4365), Rio de Janeiro (21040-361), Brazil.
BMC Microbiol. 2011 May 18;11:110. doi: 10.1186/1471-2180-11-110.
Toxoplasma gondii belongs to a large and diverse group of obligate intracellular parasitic protozoa. Primary culture of mice skeletal muscle cells (SkMC) was employed as a model for experimental toxoplasmosis studies. The myogenesis of SkMC was reproduced in vitro and the ability of T. gondii tachyzoite forms to infect myoblasts and myotubes and its influence on SkMC myogenesis were analyzed.
In this study we show that, after 24 h of interaction, myoblasts (61%) were more infected with T. gondii than myotubes (38%) and inhibition of myogenesis was about 75%. The role of adhesion molecules such as cadherin in this event was investigated. First, we demonstrate that cadherin localization was restricted to the contact areas between myocytes/myocytes and myocytes/myotubes during the myogenesis process. Immunofluorescence and immunoblotting analysis of parasite-host cell interaction showed a 54% reduction in cadherin expression at 24 h of infection. Concomitantly, a reduction in M-cadherin mRNA levels was observed after 3 and 24 h of T. gondii-host cell interaction.
These data suggest that T. gondii is able to down regulate M-cadherin expression, leading to molecular modifications in the host cell surface that interfere with membrane fusion and consequently affect the myogenesis process.
刚地弓形虫属于一大组专性细胞内寄生的原始生物。原代培养的小鼠骨骼肌细胞（SkMC）被用作实验性弓形体病研究的模型。体外重现了 SkMC 的成肌分化，并分析了速殖子形式的刚地弓形虫感染成肌细胞和肌管的能力及其对 SkMC 成肌分化的影响。
在这项研究中，我们表明，在相互作用 24 小时后，成肌细胞（61%）比肌管（38%）更容易被刚地弓形虫感染，并且成肌分化的抑制率约为 75%。我们研究了细胞间黏附分子（如钙黏蛋白）在这一事件中的作用。首先，我们证明钙黏蛋白定位在成肌细胞/成肌细胞和成肌细胞/肌管之间的接触区域，在成肌分化过程中。寄生虫-宿主细胞相互作用的免疫荧光和免疫印迹分析显示，感染 24 小时后钙黏蛋白表达减少 54%。同时，在刚地弓形虫-宿主细胞相互作用 3 小时和 24 小时后，M-cadherin 的 mRNA 水平也降低了。
这些数据表明，刚地弓形虫能够下调 M-cadherin 的表达，导致宿主细胞表面的分子修饰，干扰膜融合，从而影响成肌分化过程。
