EAPSI: Characterizing Regenerative Cells during Central Nervous System Regeneration in Marine Acorn Worms

经过几十年的研究，中枢神经系统(CNS)的再生一直处于科学研究的前沿。尽管已经取得了进展，但控制中枢神经系统再生的许多细胞机制仍然难以捉摸。数以百万计的人患有使人衰弱的神经缺陷，如阿尔茨海默病、S和帕金森？S病、脊柱裂、癫痫和脊髓损伤，仅举几例。此外，衰老和与年龄相关的疾病最终会影响到每个人。再生可能会减缓衰老过程，干细胞有可能成为体内任何类型的细胞，包括神经细胞，这是对抗神经疾病和损伤的一种可行方法。该项目的目标是确定真正的干细胞是否正在修复海洋橡子蠕虫再生过程中丢失的组织。一些种类的橡子蠕虫，如黄原甲虫，在截肢后完全再生它们的整个中枢神经系统。了解橡子虫的再生机制可能会为解锁其他中枢神经系统再生有限的动物的再生提供线索，包括人类。我将与台湾中研院细胞与组织生物学研究所的苏毅贤博士就这一项目进行合作。她经常收集这种动物，并将其用于生物学研究。她的实验室专门研究基因网络，使用针对特定基因和细胞类型的分子技术来调节动物身体计划的进化、发育和模式。这个项目可能是一个跳板，可以为人类的新干细胞疗法和神经再生提供见解。橡子虫，也被称为半角类动物，是海洋无脊椎动物后口动物，与棘皮动物是姊妹类。橡子虫有一个三部分的身体平面，有一个前鼻孔，一个中颈区和一个长的后部躯干。作为后口动物，半角类动物与脊索动物有一些共同的形态和发育特征。孤立的半脊索动物，黄原甲藻，有一个中空的背部神经管，其发育方式与脊索神经管非常相似。截肢后，黄杆菌在大约两周内可靠地再生其整个神经管和前头状结构。没有脊索被证明具有这种能力。我们的实验室已经证明，在黄腐菌的前再生过程中，大量的细胞死亡和细胞增殖被激活。目前尚不清楚真正的干细胞是否在这种动物中增殖，或者体细胞是否正在去分化，然后成为多能细胞来产生新的结构。为了帮助确认黄色葡萄球菌中增殖细胞的来源和身份，我将用针对一种半碳酸盐血管蛋白的抗体对不能再生的动物进行染色。VASA是许多动物门中生殖系干细胞的标志。VASA在一些非生殖系、多能干细胞中也有表达。我还将使用干细胞标记物c-Myc、Pax6和碱性磷酸酶的原位杂交。如果这些标记的表达与血管蛋白在非生殖细胞中的染色共同定位，这将支持黄腐菌中真正的干细胞的假说。如果这一点得到证实，黄曲霉提出了一个令人兴奋的模型来研究后口动物中枢神经系统再生过程中干细胞招募和规范的分子机制。还需要进一步的实验来证明干细胞可以自我更新，并在再生过程中分化为其他类型的细胞。东亚和太平洋夏季学院项目下的这个奖项支持一名美国研究生的夏季研究，由NSF和台湾科技部联合资助。

Central nervous system (CNS) regeneration remains on the forefront of scientific research after decades of study. Progress and advances have been made, however, many of the cellular mechanisms controlling CNS regeneration continue to be elusive. Millions of people suffer from debilitating neurological defects, like Alzheimer?s and Parkinson?s disease, spina bifida, epilepsy, and spinal cord injuries, to name a few. Furthermore, aging and age related diseases eventually affect everyone. Regeneration may slow the aging process and stem cells, which have the potential to become any type of cell in the body, including nerve cells, present one feasible way to combat neural diseases and injuries. The goal of this project is to determine whether bona fide stem cells are elaborating missing tissue during regeneration in marine acorn worms. Some species of acorn worms, like Ptychodera flava, completely regenerate their entire CNS after amputation. Understanding the mechanisms for regeneration in acorn worms may yield clues to unlocking regeneration in other animals with limited CNS regeneration, including humans. I will be working with Dr. Yi-Hsien Su at the Institute of Cellular and Organismic Biology at Academia Sinica in Taiwan on this project. She routinely collects and uses this animal for biological studies. Her lab specializes in gene networks regulating animal body plan evolution, development, and patterning using molecular techniques that target specific genes and cell types. This project may be a springboard that could give insights for new stem cell therapies and nerve regeneration in humans. Acorn worms, also known as hemichordates, are marine, invertebrate deuterostomes and sister group to the echinoderms. Acorn worms have a tripartite body plan with an anterior proboscis, a middle collar region, and a long posterior trunk. As deuterostomes, hemichordates share several morphological and developmental features with the chordates. The solitary hemichordate, Ptychodera flava, has a hollow, dorsal neural tube that develops in a very similar fashion to the chordate neural tube. Upon amputation, P. flava reliably regrows their entire neural tube and anterior head-like structure in about two weeks. No chordate has been shown to have this ability. Our lab has shown that extensive cell death and cell proliferation are activated during anterior regeneration in P. flava. It is not known whether bona fide stem cells are proliferating in this animal or whether somatic cells are de-differentiating and then becoming multi-potent to generate new structures. To help confirm the origin and identity of proliferating cells in P. flava, I will stain non-regenerating animals with antibodies raised against a hemichordate vasa protein. Vasa is a marker for germline stem cells across numerous animal phyla. Vasa is also expressed in some non-germline, multi-potent stem cells. I will also use in situ hybridization with the stem cell markers, c-Myc, pax6, and alkaline phosphatase. If expression of these markers co-localize with staining of vasa protein in non-germ cells, this will support a hypothesis of bona fide stem cells in P. flava. If this is confirmed, P. flava presents an exciting model to study the molecular mechanisms of stem cell recruitment and specification during central nervous system regeneration in the deuterostomes. Further experiments will be required to prove that the stem cells can self renew and also differentiate into other cell types during regeneration.This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Ministry of Science and Technology of Taiwan.