Dorsal-Ventral Pattern Formation in the Zebrafish Embryo

描述（申请人提供）：信号在胚胎发生过程中指导多个器官和组织的发育，是多种先天性和成人疾病的致病因素。大量研究表明，BMP信号调节在肾脏疾病、肺动脉高压等疾病的治疗以及骨科、牙髓学和组织工程等医学应用中具有潜力。由于BMP异二聚体对BMP同型二聚体具有较高的信号活性及其在治疗方面的潜力，近年来受到越来越多的关注。为了了解BMP信号如何在无数的生物学环境中产生不同的细胞反应并影响疾病，以及BMP异二聚体如何最有效地用于治疗，了解BMP信号的机制是必要的。BMP信号在脊椎动物发育过程中的一个关键功能是在囊胚晚期和原胚阶段沿背腹侧（DV）胚胎轴形成细胞。BMP信号活动被认为是一种形态形成因子，在不同的活动水平上指定不同的细胞类型。背侧分泌的BMP拮抗剂在产生BMP活性梯度中具有重要作用，其水平在背侧低，在腹侧高。在之前的资助期内，BMP异二聚体被发现只在斑马鱼DV模式中发出信号，这为脊椎动物体内BMP异二聚体信号传递提供了一种生理分析。本研究将使用这种独特的体内动物模型设置来阐明斑马鱼DV模式中BMP异源二聚体的排他性信号传导机制。该结果有望在其他生物学背景下广泛应用于BMP异二聚体信号机制。一个知之甚少的机制限制了BMP拮抗剂在囊胚后期的背侧区域。在过去的研究期间，在斑马鱼中发现了这一过程的一个新的遗传调节因子，当缺乏该基因时，BMP拮抗剂和背中线中表皮的腹侧扩张导致多个背轴的急剧形成。突变基因编码整合子复合体亚基6 (ints6)，代表了该基因在任何生物体中被研究的第一个功能丧失突变。这些研究将在这里扩展，以确定Ints6如何与DV模式的其他母体调节因子一起发挥作用，以阐明其作用机制。最后，我们将研究一个新的具有类似于ints6缺陷的母系效应突变基因的分子性质及其作用。假设在DV模式中编码一个新的基因或已知的具有新功能的基因，这将允许详细阐述介导脊椎动物DV模式的分子机制。！

DESCRIPTION (provided by applicant): signaling directs the development of multiple organs and tissues in embryogenesis, and is the causative factor in multiple congenital and adult diseases. Numerous studies suggest the potential for modulating BMP signaling in the treatment of disorders as diverse as kidney disease, pulmonary hypertension, and in medical applications such as orthopedics, endodontics, and tissue engineering. BMP heterodimers are receiving increasing attention recently due to their higher signaling activity to BMP homodimers and their potential in therapeutics. To understand how BMP signaling can generate diverse cellular responses in a myriad of biological contexts and affect disease, as well as how BMP heterodimers can be most effectively used in therapeutics, it is imperative to understand the mechanism by which BMPs signal. A key function of BMP signaling in vertebrate development is to pattern the cells along the dorsoventral (DV) embryonic axis during late blastula and gastrula stages. BMP signaling activity is thought to act as a morphogen, specifying distinct cell types at different activity levels. Dorsally-emanating BMP antagonists are important in generating the gradient of BMP activity with low levels dorsally and highest levels ventrally. In the previous grant period, BMP heterodimers were found to exclusively signal in zebrafish DV patterning, providing an in vivo, physiological assay in vertebrates for BMP heterodimer signaling. The studies here will use this unique in vivo animal model setting to elucidate the mechanism that leads to the exclusive signaling by BMP heterodimers in zebrafish DV patterning. The results are expected to be broadly relevant to BMP heterodimer signaling mechanisms in other biological contexts. A poorly understood mechanism restricts BMP antagonists to dorsal regions during late blastula stages. A new genetic regulator of this process in zebrafish was identified in the past grant period, which when deficient leads to the ventral expansion of BMP antagonists and dorsal midline mesoderm causing the dramatic formation of multiple dorsal axes. The mutant gene encodes the integrator complex subunit 6 (ints6), representing the first loss-of-function mutation of this gene to be studied in any organism. These studies will be extended here to determine how Ints6 functions with the other maternal regulators of DV patterning to elucidate its mechanism of action. Lastly, the molecular nature and role played by a new maternal-effect mutant gene with a defect similar to ints6 will be studied. It is postulated to encode a novel gene or an already known gene with a new function in DV patterning, which will allow the elaboration of the molecular mechanisms mediating vertebrate DV patterning. !