突触囊泡循环
中文名称
通路描述
神经元的通信是通过从突触囊泡（SVs）释放神经递质介导的。在神经末梢，SVs 经历重复的胞吐和胞吞循环。负载的 SVs 通过主动运输填充神经递质。随后，它们被定位到突触前质膜上的特殊区域，称为活性区，在此处发生激活反应。当动作电位到达时，电压门控通道允许 Ca2+ 进入，并通过胞吐作用释放神经递质，通常小于毫秒。融合后，囊泡通过胞吞作用被回收并重新装载，以进行下一次胞吐循环。
英文描述
Formation of axial mesoderm Axial mesoderm, also called chordamesoderm, is formed by cells ingressing at the anterior end of the primitive streak. The axial mesoderm produces three types of cells, namely (from anterior to posterior) prechordal plate, anterior head process, and node-derived notochord precursors (reviewed in Balmer et al. 2016). In mouse and rat, the prechordal plate gives rise to cells in the foregut endoderm, oral endoderm, and ventral cranial mesoderm (Aoto et al. 2009); the anterior head process gives rise to the anterior portion of the notochord; notochord precursors give rise to the remaining posterior region of the notochord. Contribution of axial mesoderm in humans is less well characterized (Muller and O'Rahilly 2003). (
All these cells initially form a single columnar epithelium, the notochordal plate, that is contiguous with the endoderm. The notochordal plate then submerges into the embryo to form the tubular notochord structure. During embryogenesis the notochord not only provides physical stiffness but also produces signaling molecules such as Sonic Hedgehog (SHH) that pattern surrounding tissues. After the notochord forms, it regresses in regions where vertebrae form and expands in the perichordal disc to form the nuclei pulposi, cartilage-like discs that are interspersed with the vertebrae (reviewed in Williams et al. 2019).
Formation of the axial mesoderm is initiated by NODAL signaling via SMAD2,3 proteins that interact with the FOXH1 pioneer transcription factor (inferred from the activities of mouse homologs, as described by Hoodless et al. 2001, Yamamoto et al. 2001). TEAD proteins (inferred from mouse homologs as described by Sawada et al. 2005), which are negatively regulated by the HIPPO signaling pathway, and TBXT (T, BRACHURY) (inferred from mouse homologs, as described by Lolas et al. 2014), whose expression is initiated prior to primitive streak formation, act with the SMADs and FOXH1 to activate FOXA2, which then participates in activating downstream targets such as NOTO and SHH.
All these cells initially form a single columnar epithelium, the notochordal plate, that is contiguous with the endoderm. The notochordal plate then submerges into the embryo to form the tubular notochord structure. During embryogenesis the notochord not only provides physical stiffness but also produces signaling molecules such as Sonic Hedgehog (SHH) that pattern surrounding tissues. After the notochord forms, it regresses in regions where vertebrae form and expands in the perichordal disc to form the nuclei pulposi, cartilage-like discs that are interspersed with the vertebrae (reviewed in Williams et al. 2019).
Formation of the axial mesoderm is initiated by NODAL signaling via SMAD2,3 proteins that interact with the FOXH1 pioneer transcription factor (inferred from the activities of mouse homologs, as described by Hoodless et al. 2001, Yamamoto et al. 2001). TEAD proteins (inferred from mouse homologs as described by Sawada et al. 2005), which are negatively regulated by the HIPPO signaling pathway, and TBXT (T, BRACHURY) (inferred from mouse homologs, as described by Lolas et al. 2014), whose expression is initiated prior to primitive streak formation, act with the SMADs and FOXH1 to activate FOXA2, which then participates in activating downstream targets such as NOTO and SHH.
所含基因
14 个基因