Mapping Angiopoietin1 Expression in the Developing and Adult Brain.

Angiopoietin1 (Angpt1) is a secreted protein that activates the endothelial Tie2 receptor. Angpt1 plays a critical role in cardiac development and vascular remodeling in response to disease or injury and shows cell type-restricted expression in the lung, eye, and hematopoietic system. However, the expression of Angpt1 in the developing and adult brain is not known. Here, we employ Angpt1-GFP knock-in reporter mice and a systematic analysis of multiple single-cell RNA sequencing datasets to map the expression of Angpt1 during brain development and adulthood. In the developing brain, Angpt1 displays specific spatiotemporal patterns, with strong expression in cerebellar GABA interneuron progenitors and, to a lower level, in glial progenitor and astrocyte lineages. In the adult brain, on the other hand, we show that neurons are the main source of Angpt1 in the cerebrum, while in the cerebellum, expression is mostly restricted to astrocytes. Together, our data provide clarity on the cell types that express Angpt1 in the developing and adult brain and can be utilized to guide future studies, examining Angpt1 function in brain development, homeostasis, and pathological conditions.