The Ca2+-gated channel TMEM16A amplifies capillary pericyte contraction and reduces cerebral blood flow after ischemia
Nils Korte, … , David Attwell, Paolo Tammaro
Nils Korte, … , David Attwell, Paolo Tammaro
Published March 22, 2022
Citation Information: J Clin Invest. 2022;132(9):e154118. https://doi.org/10.1172/JCI154118.
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Research Article Cell biology Vascular biology

The Ca2+-gated channel TMEM16A amplifies capillary pericyte contraction and reduces cerebral blood flow after ischemia

Abstract

Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activated chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplified the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slowed the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction, and pericyte death; reduced neutrophil stalling; and improved cerebrovascular reperfusion. Genetic analysis implicated altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer’s disease and vascular dementia.

Authors

Nils Korte, Zeki Ilkan, Claire L. Pearson, Thomas Pfeiffer, Prabhav Singhal, Jason R. Rock, Huma Sethi, Dipender Gill, David Attwell, Paolo Tammaro

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Figure 6

Blocking TMEM16A slows the ischemia-evoked [Ca2+]i rise in pericytes, delays capillary constriction, and reduces pericyte death in acute cortical slices.

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Blocking TMEM16A slows the ischemia-evoked [Ca2+]i rise in pericytes, de...
(A) Mean normalized capillary diameter at pericyte somata during perfusion with aCSF (control, n = 6) or oxygen and glucose deprivation (OGD) solution in the presence (n = 6) or absence (n = 10) of Ani9 (2 μM) in acute rat cortical slices. (B) Ani9 reduces the ischemia-evoked pericyte-mediated capillary constriction at 30 minutes of OGD. Points indicate individual pericytes from 5 to 8 rats per condition (1-way ANOVA with Bonferroni’s post hoc multiple comparisons test). The OGD-evoked capillary constriction was not dependent on the sex of rats (Supplemental Figure 3B). (C) Time course of the mean change in normalized GCaMP5G fluorescence (F) in pericyte somata during OGD with or without Ani9 (2 μM) in NG2-CreERT2-GCaMP5G mice. (D) Ani9 reduces the [Ca2+]i rise (measured from the y axis value of 1) at 16 minutes of perfusion with OGD. Points indicate individual pericytes (OGD, n = 14; OGD+Ani9, n = 17) from 3 mice per condition (unpaired 2-tailed Student’s t test with Welch’s correction). (E) Confocal images of rat cortical capillaries labeled with isolectin B4 (IB4) to visualize pericytes labeled by the necrosis marker propidium iodide (PI) after a 1-hour exposure to aCSF or OGD in the presence or absence of Ani9 (2 μM). The inset illustrates examples of necrotic (PI +) and healthy (PI –) pericytes. Scale bar: 30 μm. (F) Ani9 reduces the OGD-evoked pericyte death. The percentage of dead pericytes was quantified by dividing the number of PI-labeled pericytes by the total number of pericytes in images as shown in (E) (aCSF: n = 32; OGD: n = 33; OGD+Ani9: n = 35) (Kruskal-Wallis test with Dunn’s post hoc test). Number of animals are detailed in Supplemental Table 2.