Natural allelic variation of the IL-21 receptor modulates ischemic stroke infarct volume
Han Kyu Lee, … , Donald C. Lo, Douglas A. Marchuk
Han Kyu Lee, … , Donald C. Lo, Douglas A. Marchuk
Published July 11, 2016
Citation Information: J Clin Invest. 2016;126(8):2827-2838. https://doi.org/10.1172/JCI84491.
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Natural allelic variation of the IL-21 receptor modulates ischemic stroke infarct volume

Abstract

Risk for ischemic stroke has a strong genetic basis, but heritable factors also contribute to the extent of damage after a stroke has occurred. We previously identified a locus on distal mouse chromosome 7 that contributes over 50% of the variation in postischemic cerebral infarct volume observed between inbred strains. Here, we used ancestral haplotype analysis to fine-map this locus to 12 candidate genes. The gene encoding the IL-21 receptor (Il21r) showed a marked difference in strain-specific transcription levels and coding variants in neonatal and adult cortical tissue. Collateral vessel connections were moderately reduced in Il21r-deficient mice, and cerebral infarct volume increased 2.3-fold, suggesting that Il21r modulates both collateral vessel anatomy and innate neuroprotection. In brain slice explants, oxygen deprivation (OD) activated apoptotic pathways and increased neuronal cell death in IL-21 receptor–deficient (IL-21R–deficient) mice compared with control animals. We determined that the neuroprotective effects of IL-21R arose from signaling through JAK/STAT pathways and upregulation of caspase 3. Thus, natural genetic variation in murine Il21r influences neuronal cell viability after ischemia by modulating receptor function and downstream signal transduction. The identification of neuroprotective genes based on naturally occurring allelic variations has the potential to inform the development of drug targets for ischemic stroke treatment.

Authors

Han Kyu Lee, Sehoon Keum, Huaxin Sheng, David S. Warner, Donald C. Lo, Douglas A. Marchuk

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Figure 6

Neuronal cell death induced by ischemic stroke stimulation in explanted brain slices is rescued by the Il21r transcript containing the B6 allele.

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Neuronal cell death induced by ischemic stroke stimulation in explanted ...
(A) The Il21r transcript was isolated and cloned from B6 and BALB/c brain cortex, and each cDNA was introduced in gWIZ vector (Genlantis) containing YFP. Either empty, Il21r-B6, or Il21r-BALB/c containing YFP was introduced in explanted Il21r KO brain slices that are allowed to express YFP for 24 hours. Graph indicates average cell viability determined by following the same neurons before and 24 hours after OD. Il21r KO explanted brain slices were transfected with Il21r cDNA from either B6 or BALB/c, and neuronal cell viability was compared with transfection with empty (YFP alone) vector. Experiments were performed 3 times using 3 to 5 mice (Il21r KO) for each experiment. Total number of animals: Il21r KO, n = 13. The numbers of brain slices analyzed for empty vector, Il21r-B6, and Il21r-BALB/c were 96, 88, and 87, respectively. Values represent mean ± SEM. **P < 0.01; ***P < 0.001, 1-way ANOVA followed by Scheffe’s test. (B) Neuronal cell viability after OD for explanted brain slices was measured for 2 inbred mouse strains, B6 and BALB/c, as well as 2 Civq1 congenic lines, C.B6–Civq1–6 and C.B6–Civq1–7. Graph indicates average cell viability determined by observing the same neurons before and 24 hours after OD. Experiments were performed 3 times using 3 to 5 mice per strain for each experiment. Total number of animals: B6, n = 9; BALB/c, n = 9; C.B6–Civq1–6, n = 12; C.B6–Civq1–7, n = 13. Numbers of brain slices analyzed for B6, BALB/c, C.B6–Civq1–6, and C.B6–Civq1–7 were 45, 39, 42, and 45, respectively. Values represent mean ± SEM. **P < 0.01; ***P < 0.001, 1-way ANOVA followed by Scheffe’s test.