Astrocytic neogenin/netrin-1 pathway promotes blood vessel homeostasis and function in mouse cortex
Ling-Ling Yao, … , Lin Mei, Wen-Cheng Xiong
Ling-Ling Yao, … , Lin Mei, Wen-Cheng Xiong
Published August 27, 2020
Citation Information: J Clin Invest. 2020;130(12):6490-6509. https://doi.org/10.1172/JCI132372.
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Astrocytic neogenin/netrin-1 pathway promotes blood vessel homeostasis and function in mouse cortex

Abstract

Astrocytes have multiple functions in the brain, including affecting blood vessel (BV) homeostasis and function. However, the underlying mechanisms remain elusive. Here, we provide evidence that astrocytic neogenin (NEO1), a member of deleted in colorectal cancer (DCC) family netrin receptors, is involved in blood vessel homeostasis and function. Mice with Neo1 depletion in astrocytes exhibited clustered astrocyte distribution and increased BVs in their cortices. These BVs were leaky, with reduced blood flow, disrupted vascular basement membranes (vBMs), decreased pericytes, impaired endothelial cell (EC) barrier, and elevated tip EC proliferation. Increased proliferation was also detected in cultured ECs exposed to the conditioned medium (CM) of NEO1-depleted astrocytes. Further screening for angiogenetic factors in the CM identified netrin-1 (NTN1), whose expression was decreased in NEO1-depleted cortical astrocytes. Adding NTN1 into the CM of NEO1-depleted astrocytes attenuated EC proliferation. Expressing NTN1 in NEO1 mutant cortical astrocytes ameliorated phenotypes in blood-brain barrier (BBB), EC, and astrocyte distribution. NTN1 depletion in astrocytes resulted in BV/BBB deficits in the cortex similar to those in Neo1 mutant mice. In aggregate, these results uncovered an unrecognized pathway, astrocytic NEO1 to NTN1, not only regulating astrocyte distribution, but also promoting cortical BV homeostasis and function.

Authors

Ling-Ling Yao, Jin-Xia Hu, Qiang Li, Daehoon Lee, Xiao Ren, Jun-Shi Zhang, Dong Sun, Hong-Sheng Zhang, Yong-Gang Wang, Lin Mei, Wen-Cheng Xiong

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Figure 1

Reduced DiI+ vessels, but increased PECAM-1+ vessels, in astrocytic, but not pyramidal neuronal, Neo1-KO cortex.

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Reduced DiI+ vessels, but increased PECAM-1+ vessels, in astrocytic, but...
(A) Schematic of the protocol for DiI perfusion. (B) Representative images of BVs in the cortex of control (Neofl/fl) and NeoGFAP-Cre mice (at P60). Brain sections were subjected to immunostaining analysis using antibodies against PECAM-1 (green). Images were captured from 6 slides per animal. Average number of DiI+ vessel length per cubic millimeters was calculated and is presented in C, and PECAM-1+ vessel length was quantified and is presented in D. BV tracing and quantification of BV branches are shown in E and F, respectively. (G) Representative images of BVs in cortices of littermate control Neofl/fl and NeoGFAP-CreER mice. Mice were injected with TAM at P30 and perfused with DiI at P60 before sacrifice. (H and I) Quantitative analyses of data in G. (J) Representative images of BVs in cortices of littermate control and NeoNex-cre mice at P60. (K and L) Quantitative analyses of data in J. Scale bars: 50 μm. Data are represented as mean ± SEM (n = 3 to 6 mice/group). *P < 0.05; **P < 0.01, Mann-Whitney U statistical test.