Bacteriophytochrome-based optogenetic tools for mammalian gene regulation

描述（由申请人提供）：一旦基因工程细胞，如用于修复受损组织的干细胞，用于识别和破坏肿瘤的免疫细胞，或用于内分泌失调的激素产生细胞，被运送到哺乳动物宿主体内，它们就变得难以控制。这种情况带来了前所未有的风险，与工程细胞易发生转化和/或功能障碍有关。药物无法区分体内功能正常和故障的细胞，而基因内置的安全机制可能被证明是不够的。控制生物过程的光遗传学方法提供了化学物质无法比拟的时空分辨率，但紫外线-可见光无法到达哺乳动物组织的深处。相比之下，近红外窗口的光是安全的，可以穿透哺乳动物组织达几厘米深，至少比紫外线可见光深几倍。因此，从外部放置的激光器或插入体腔的光导发出的光可以到达内部器官并控制生物活动。细菌色素是唯一一类能感知近红外光的感光蛋白。细菌色素可以自动催化地结合它们的发色团（胆绿素）

DESCRIPTION (provided by applicant): Once genetically engineered cells, such as stem cells designed to repair damaged tissues, immune cells programmed to recognize and destroy tumors, or hormone-producing cells for endocrine disorders, are delivered into a mammalian host, they become poorly controllable. This situation poses unprecedented risks associated with the predisposition of the engineered cells to transformation and/or malfunction. Drugs cannot distinguish between properly functioning and malfunctioning cells inside the body, while genetically build-in safety mechanisms may prove insufficient. Optogenetic approaches to control biological processes offer spatiotemporal resolution unmatched by chemicals, yet UV-visible light cannot reach deep mammalian tissues. In contrast, light in the near-infrared window is known to be safe and penetrate mammalian tissues to the depth of several centimeters, at least several-fold deeper than UV-visible light. Therefore, light from externally placed lasers or light guides inserted into body cavities can reach internal organs and control biological activitie. Bacteriophytochromes are the only class of photoreceptor proteins that sense near-infrared light. Bacteriophytochromes autocatalytically bind their chromophore (biliverdin) that is naturally made in mammalian cells. This fortunate circumstance obviates the need for exogenous chromophore supply. In this project we intend to engineer bacteriophytochrome-based genetic modules for orthogonal gene regulation in mammals, including humans. We plan to optimize these light-activated modules for several mouse tissues. The optogenetic tools developed here will allow researchers to execute conditional and reversible gene knockouts (or gene activation) in specific tissues of live animals, which will deepened our understanding of progression of various diseases, improve our knowledge of mammalian development, and offer real-time insights into host- pathogen interactions. These tools will also make gene and engineered cell therapies safer and smarter.