Endothelial Piezo1 sustains muscle capillary density and contributes to physical activity
Fiona Bartoli, … , Lee D. Roberts, David J. Beech
Fiona Bartoli, … , Lee D. Roberts, David J. Beech
Published January 13, 2022
Citation Information: J Clin Invest. 2022;132(5):e141775. https://doi.org/10.1172/JCI141775.
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Research Article Muscle biology Vascular biology

Endothelial Piezo1 sustains muscle capillary density and contributes to physical activity

Abstract

Piezo1 forms mechanically activated nonselective cation channels that contribute to endothelial response to fluid flow. Here we reveal an important role in the control of capillary density. Conditional endothelial cell–specific deletion of Piezo1 in adult mice depressed physical performance. Muscle microvascular endothelial cell apoptosis and capillary rarefaction were evident and sufficient to account for the effect on performance. There was selective upregulation of thrombospondin-2 (TSP2), an inducer of endothelial cell apoptosis, with no effect on TSP1, a related important player in muscle physiology. TSP2 was poorly expressed in muscle endothelial cells but robustly expressed in muscle pericytes, in which nitric oxide (NO) repressed the Tsp2 gene without an effect on Tsp1. In endothelial cells, Piezo1 was required for normal expression of endothelial NO synthase. The data suggest an endothelial cell–pericyte partnership of muscle in which endothelial Piezo1 senses blood flow to sustain capillary density and thereby maintain physical capability.

Authors

Fiona Bartoli, Marjolaine Debant, Eulashini Chuntharpursat-Bon, Elizabeth L. Evans, Katie E. Musialowski, Gregory Parsonage, Lara C. Morley, T. Simon Futers, Piruthivi Sukumar, T. Scott Bowen, Mark T. Kearney, Laeticia Lichtenstein, Lee D. Roberts, David J. Beech

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Figure 5

Downstream signaling mediated by eNOS and TSP2.

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Downstream signaling mediated by eNOS and TSP2. (A) Relative mRNA levels...
(A) Relative mRNA levels for candidate downstream genes in whole gastrocnemius muscle from control (gray) and Piezo1ΔEC (green) mice. (B) Representative Western blot for TSP2 protein in gastrocnemius muscle. (C) For data of the type shown in B, quantification of TSP2 protein normalized to GAPDH and expressed as fold-change in Piezo1ΔEC compared to Ctrl. (D and E) Relative mRNA levels for (D) the Tsp2 gene in isolated endothelial cells from skeletal muscle (SkECs) of Ctrl (gray) and Piezo1ΔEC (blue) mice and (E) eNOS (Nos3 gene) mRNA in whole gastrocnemius muscle from Ctrl (gray) and Piezo1ΔEC (green) mice and isolated SkECs of Ctrl (gray) and Piezo1ΔEC (blue) mice. mRNA abundance was determined by qRT-PCR, normalized to housekeeping gene expression, and is presented as the fold-change relative to Ctrl mice. (F) Representative Western blot for eNOS phosphorylation at serine 1177 (p-eNOS) and total eNOS (t-eNOS) in isolated SkECs. (G) For data of the type shown in F, quantification of p-eNOS relative to t-eNOS in Piezo1ΔEC compared to Ctrl mice. (H) For data of the type shown in F, quantification of t-eNOS relative to the housekeeper protein GAPDH in Piezo1ΔEC compared to Ctrl. (I) Immunohistochemistry for CD31 (green) and eNOS (yellow) in gastrocnemius muscle longitudinal sections. Merged images are shown on the right. eNOS fluorescence intensity was measured in CD31+ regions (red). Scale bars: 15 μm. (J) Quantification of eNOS fluorescence intensity in CD31+ regions corresponding to endothelial cells. Data are for n = 8 to 9 mice per group (A and F–H), n = 10 to 13 (B and C), n = 5 to 6 (D and E), and n = 7 to 8 (I and J) (mean ± SD). Superimposed dots are the underlying data values for each mouse. #P < 0.05, ##P < 0.01 vs. Ctrl mice. Statistical significance was evaluated using Student’s t test.