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）再生仍然是科学研究的前沿。虽然已经取得了一些进展，但是许多控制CNS再生的细胞机制仍然是难以捉摸的。数以百万计的人患有使人衰弱的神经缺陷，如阿尔茨海默氏症？s和帕金森？脊柱裂、癫痫和脊髓损伤，仅举几例。此外，衰老和与年龄有关的疾病最终会影响每个人。再生可以减缓衰老过程，干细胞有潜力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在海洋橡子蠕虫再生过程中制造缺失的组织。一些种类的橡子蠕虫，如黄褶角虫，在截肢后完全再生了整个中枢神经系统。了解橡子蠕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（包括人类）的再生提供线索。我将与台湾中央研究院细胞与器官生物学研究所的Yi-Hsien Su博士合作进行这个项目。她经常收集和使用这种动物进行生物学研究。她的实验室专门研究基因网络调节动物身体计划进化，发展和模式化，使用分子技术，针对特定的基因和细胞类型。该项目可能是一个跳板，可以为新的干细胞疗法和人类神经再生提供见解。 橡子蠕虫，也被称为半索动物，是海洋无脊椎动物的后口动物，也是棘皮动物的姐妹群。橡子蠕虫有一个三部分的身体计划与前吻，中间领区，和一个长的后躯干。作为后口动物，半索动物与脊索动物有一些共同的形态和发育特征。单生的半索动物，黄褶角动物，有一个中空的背神经管，其发育方式与脊索动物的神经管非常相似。在截肢后，黄腹蛛在大约两周内可靠地再生了它们的整个神经管和前部的头状结构。没有脊索动物被证明有这种能力。我们的实验室已经表明，广泛的细胞死亡和细胞增殖过程中激活的前部再生中的P.黄。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，然后变得多能产生新的结构。为了帮助确认黄球藻中增殖细胞的来源和身份，我将用针对半索膜血管蛋白的抗体对非再生动物进行染色。Vasa是许多动物门中生殖系干细胞的标志物。Vasa也在一些非生殖系多能干细胞中表达。我还将使用干细胞标记物c-Myc、pax 6和碱性磷酸酶的原位杂交。如果这些标记物的表达与非生殖细胞中vasa蛋白的染色共定位，这将支持黄青霉中真正的干细胞的假设。如果这一点得到证实，P. flava提出了一个令人兴奋的模型，用于研究后口动物中枢神经系统再生过程中干细胞募集和特化的分子机制。这是一项由美国国家科学基金会和台湾科技部联合资助的东亚及太平洋暑期研究所项目，旨在资助美国研究生的暑期研究。

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.