Department of Experimental Zoology and Neurobiology, University of Pécs.
Department of Experimental Zoology and Neurobiology, University of Pécs; Department of Translational Medicine, Semmelweis University, Budapest.
Eur J Histochem. 2022 Apr 27;66(2):3373. doi: 10.4081/ejh.2022.3373.
Identified as a member of the secretin/glucagon/VIP superfamily, pituitary adenylate cyclase-activating polypeptide (PACAP1-38) has been recognized as a hormone, neurohormone, transmitter, trophic factor, and known to be involved in diverse and multiple developmental processes. PACAP1-38 was reported to regulate the production of important morphogens (Fgf1, Bmp4, Gdf3) through PAC1-receptor in the newborn rat retina. To follow up, we aimed to reveal the identity of retinal cells responsible for the production and secretion of Fgf1, Bmp4, and Gdf3 in response to PACAP1-38 treatment. Newborn (P1) rats were treated with 100 pmol PACAP1-38 intravitreally. After 24 h, retinas were dissected and processed for immunohistochemistry performed either on flat-mounted retinas or cryosections. Brn3a and PAC1-R double labeling revealed that 90% of retinal ganglion cells (RGCs) expressed PAC1-receptor. We showed that RGCs were Fgf1, Bmp4, and Gdf3-immunopositive and PAC1-R was co-expressed with each protein. To elucidate if RGCs release these secreted regulators, the key components for vesicle release were examined. No labeling was detected for synaptophysin, Exo70, or NESP55 in RGCs but an intense Rab3a-immunoreactivity was detected in their cell bodies. We found that the vast majority of RGCs are responsive to PACAP, which in turn could have a significant impact on their development or/and physiology. Although Fgf1, Bmp4, and Gdf3 were abundantly expressed in PAC1-positive RGCs, the cells lack synaptophysin and Exo70 in the newborn retina, thus unable to release these proteins. These proteins could regulate postnatal RGC development acting through intracrine pathways.
作为分泌素/胰高血糖素/血管活性肠肽超级家族的一员，垂体腺苷酸环化酶激活肽（PACAP1-38）已被确认为一种激素、神经激素、递质、营养因子，并且已知参与多种发育过程。PACAP1-38 通过新生大鼠视网膜中的 PAC1 受体被报道调节重要形态发生素（Fgf1、Bmp4、Gdf3）的产生。为了跟进研究，我们旨在揭示对 PACAP1-38 处理有反应的视网膜细胞负责产生和分泌 Fgf1、Bmp4 和 Gdf3 的身份。将新生（P1）大鼠用 100 pmol PACAP1-38 玻璃体内注射处理。24 小时后，将视网膜分离并进行免疫组织化学处理，在平面视网膜或冷冻切片上进行。Brn3a 和 PAC1-R 双重标记显示 90%的视网膜神经节细胞（RGCs）表达 PAC1 受体。我们表明 RGCs 是 Fgf1、Bmp4 和 Gdf3 免疫阳性的，并且 PAC1-R 与每种蛋白质共表达。为了阐明 RGCs 是否释放这些分泌调节剂，检查了囊泡释放的关键成分。在 RGCs 中未检测到突触小泡蛋白、Exo70 或 NESP55 的标记，但在其细胞体中检测到强烈的 Rab3a 免疫反应性。我们发现，绝大多数 RGCs 对 PACAP 有反应，这反过来又可能对其发育或/和生理学产生重大影响。尽管 Fgf1、Bmp4 和 Gdf3 在 PAC1 阳性 RGCs 中大量表达，但在新生视网膜中，这些细胞缺乏突触小泡蛋白和 Exo70，因此无法释放这些蛋白质。这些蛋白质可以通过细胞内途径调节出生后 RGC 的发育。
