Roles of melanocytes in choroid homeostasis

脉络膜是高度血管化的，为视网膜提供氧气和营养。这种有色结缔组织主要由黑素细胞(有色细胞)、间质成纤维细胞、大小不一的血管以及支持胶原和弹性纤维组成。人们对脉络膜黑素细胞的生物学和功能知之甚少。我的研究项目将使用包含黑素细胞、成纤维细胞和内皮细胞的人脉络膜三维组织模型来研究它们在稳态下的细胞间合作，以及微环境因素对脉络膜黑素细胞衰老过程中旁分泌信号和表观基因组的影响。远处的细胞可以通过装满被称为细胞外小泡的生物活性分子的口袋发出信号来交换信息。我们最近确定脉络膜黑素细胞释放细胞外小泡。此外，表观遗传机制，如DNA羟甲基化，在细胞分化中发挥着积极的作用。我们最近证实，脉络膜黑素细胞的基因组中显示出高DNA羟甲基化含量。我的假设是，黑素细胞通过囊外信号在脉络膜血管生成中发挥作用，DNA羟甲基化参与黑素细胞的分化。因此，我们将确定黑素细胞胞外小泡中包含的血管生成因子，以及它们对血管内皮细胞的作用。我们还将研究调控脉络膜黑素生成的基因中DNA羟甲基化的分布。我的研究计划还将确定与年龄相关的微环境因素，如氧化应激和基质硬化对脉络膜黑素细胞生理的影响。这项研究计划将提高我们对脉络膜中黑素细胞功能的理解。这对于提高我们对微环境因素对胞外囊泡生物发生和表观遗传修饰的影响的一般知识也是非常有用的。

The choroid is highly vascularized and supplies oxygen and nutrients to the retina. This pigmented connective tissue is mainly composed of melanocytes (pigmented cells), stromal fibroblasts, blood vessels of various sizes, and supporting collagenous and elastic fibers. Little is known about the biology and functions of choroidal melanocytes. My research program will use 3-dimensional tissue models of human choroid containing melanocytes, fibroblasts and endothelial cells to study their intercellular cooperation at homeostasis, as well as the impact of microenvironmental factors on the paracrine signaling and epigenome of choroidal melanocytes during aging. Distant cells can exchange information by sending out signals via pockets filled with bioactive molecules called extracellular vesicles. We recently determined that choroidal melanocytes release extracellular vesicles. In addition, epigenetic mechanisms, such as DNA hydroxymethylation, play an active role in cell differentiation. We recently confirmed that choroidal melanocytes exhibit high DNA hydroxymethylation content in their genome. My hypothesis is that melanocytes play a role in choroidal angiogenesis through extravesicular signaling, and that DNA hydroxymethylation is involved in melanocytic differentiation. We will thus determine the angiogenic factors contained in melanocytic extracellular vesicles, and their action on endothelial cells. We will also study the DNA hydroxymethylation distribution in genes that regulate choroidal melanogenesis. My research program will as well determine the impact of age-related microenvironmental factors such as oxidative stress and matrix stiffening on the physiology of choroidal melanocytes. This research program will improve our understanding of the function of melanocytes in the choroid. It will also be very useful for advancing our general knowledge about the impact of microenvironmental factors on extracellular vesicle biogenesis and epigenetic modifications.