CARD11对线粒体代谢的调节功能及其在弥漫性大B细胞淋巴瘤中的致病机制研究

Diffuse large B cell lymphoma (DLBCL) is one of the most common forms of Non-Hodgkin’s Lymphoma. Oncogenic mutations are frequently found in DLBCL patients, and 10% of these mutations are associated with Caspase recruitment domain-containing protein 11 (CARD11). Genetic and biochemical studies demonstrated that CARD11 is a scaffold protein mediating NF-κB activation upon antigen stimulation, and indicated that over-activated NF-κB, caused by oncogenic CARD11 mutations, results in B cell tumorigenesis. However, different CARD11 mutants cause variable NF-κB activation, and a transgenic mouse model with constitutively active NF-κB doesn’t spontaneously develop B cell lymphoma. These results suggest overlooked novel properties of CARD11 in DLBCL pathogenesis. We found that CARD11 associates with mitochondria and regulates the mitochondrial metabolism. Moreover, oncogenic CARD11 mutants cause aberrant mitochondrial metabolism. Thereby, I propose that CARD11 mutations may transform B cells through manipulating the intracellular metabolic pathway. Based on our previous progress in immuno-metabolism, we plan to utilize animal model as well as clinical patients sample to test this hypothesis. We expect that this study will discover the unexpected novel regulatory function of CARD11 in mitochondrial metabolism as well as the metabolic reprogramming during lymphoma pathogenesis. CARD11 together with the downstream regulators may be useful biomarkers for developing efficient treatments against B cell lymphoma.

弥漫性大B细胞淋巴瘤(DLBCL)是一种常见而危害性极大的恶性肿瘤，其中约10%的DLBCL与B细胞中CARD11基因突变有关。CARD11突变后可以自发激活细胞内NF-κB，这被认为是导致DLBCL发生的主要原因。动物模型研究体内实验表明，单纯的NF-κB的上调不足以诱发DLBCL的产生。因此我们认为CARD11还具有其他未知的功能与肿瘤发生有关。预实验中我们发现细胞内CARD11定位于线粒体上，并调节线粒体代谢功能。CARD11突变后导致细胞内线粒体相关免疫代谢发生紊乱并和DLBCL发病机制有关。本项目将借助实验室在免疫细胞代谢研究方向的积累（Cell. 159: 1578-90）；利用动物模型并结合相关临床样本深入研究CARD11突变影响线粒体代谢功能，以及DLBCL发生的分子机制。我们相信这一研究将为DLBCL的致病机制研究提供新的切入点；为开发精准医疗药物提供新的靶标。

致病性CARD11突变常造成NF-κB激活的异常，从而导致多种免疫应答异常。是否存在其他不依赖于NF-κB的机制从而致使CARD11突变产生致病性尚不得而知。在此我们通过三种不同的CARD11基因小鼠模型，其中包括CARD11敲除模型来模拟原发性免疫缺陷，CARD11的E134G突变模型来模拟 BENTA 疾病，以及CARD11上K215M的致病突变小鼠模型，发现CARD11还作为负调控因子参与AKT-FOXO1信号通路的调控，且不依赖于NF-κB的激活信号。在Card11 KO模型中，由于CARD11的缺失而导致 NF-kB信号通路的阻断，而在与BENTA疾病相关的E134G突变中其NF-κB表达上升，奇怪的是两种模型却表现出十分类似的B细胞表型。从机制上来说，E134G突变导致B细胞中AKT蛋白的过度活化并降低了FOXO1蛋白表达，而这与Card11 KO小鼠中一致。不同于E134G突变，CARD11的K215M突变则显示出对AKT活化更强的抑制作用，并且稳定FOXO1的表达。E134G与K215M突变导致了B细胞的发育与分化上表现出相反的表型。.我们的实验结果表明CARD11参与协调B细胞中的多重信号传导途径。由致病性CARD11突变引起的AKT-FOXO1信号失调的非经典调节功能具有不可或缺的作用。