Browsing by Author "de Aquino dos Santos Martins, Tomás"

Angiopoietin 1 (ANGPT1) is an endothelial growth factor and the ligand of the tyrosine endothelial kinase (TEK). The ANGPT-TEK system is known to mediate endothelial cell (EC) interactions and contributes to angiogenesis and vascular remodeling through angiocrine signaling. Although TEK is expressed in neural stem and progenitor cells, a vascular-independent role for ANGPT1 in neurogenesis is still unclear. This study focused on the embryonic expression of angiopoietins and their receptors in wild-type (WT) zebrafish (Danio rerio) and on further characterization of two zebrafish lines: the Angpt1sa14264 line, with a nonsense mutation in the angpt1 gene, and a transgenic line of angpt1 overexpression. Whole-mount in situ hybridization (WISH) and real-time quantitative polymerase chain reaction (RT-qPCR) showed a relatively high expression of angpt1 and tek throughout the first three days of WT development. Imaging of live Angpt1sa14264 and transgenic overexpression embryos revealed the bidirectional effect of angpt1 on the cardiovascular system, suggesting an essential role for normal embryonic development. In the absence of angpt1, gene expression analysis showed a dramatic disturbance in genes involved in neural patterning and neuronal development. The spatiotemporal expression of wingless-type MMTV integration site 1 (wnt1) implicated the midbrain-hindbrain boundary as a major site of Angpt1-mediated regulation of neuronal organization. The downregulated spatiotemporal expression of nestin (nes) indicated a decrease in neural progenitor-like cells throughout the central nervous system (CNS). In the context of angpt1 overexpression, the neurogenic locus notch homolog 1a (notch1a) was slightly increased despite the unchanged expression of all other neuronal markers and neural patterning genes analyzed. The spatiotemporal expression of notch1a was exacerbated in a large cranial vein, albeit detected in typical notch1a domains in the brain. These findings suggest that Angpt1 plays an important role in zebrafish embryogenesis and possibly regulates the organization of the zebrafish midbrain and hindbrain regions.