Hui-Juan Jin

MicroRNA-150 regulates blood-brain barrier permeability via Tie-2 after permanent middle cerebral artery occlusion in rats

The mechanism of blood‐brain barrier (BBB) disruption, involved in poststroke edema and hemorrhagic transformation, is important but elusive. We investigated microRNA‐150 (miR‐150)‐mediated mechanism in the disruption of BBB after stroke in rats. We found that up‐regulation of miR‐150 increased permeability of BBB as detected by MRI after permanent middle cerebral artery occlusion in vivo as well as increased permeability of brain microvascular endothelial cells after oxygen‐glucose deprivation in vitro. The expression of claudin‐5, a key tight junction protein, was decreased in the ischemic boundary zone after up‐regulation of miR‐150. We found in brain microvascular endothelial cells that overexpression of miR‐150 decreased not only cell survival rate but also the expression levels of claudin‐5 after oxygen‐glucose deprivation. With dual‐luciferase assay, we confirmed that miR‐150 could directly regulate the angiopoietin receptor Tie‐2. Moreover, silencing Tie‐2 with lentivirus‐delivered small interfering RNA reversed the effect of miR‐150 on endothelial permeability, cell survival, and claudin‐5 expression. Furthermore, poststroke treatment with antagomir‐150, a specific miR‐150 antagonist, contributed to BBB protection, infarct volume reduction, and amelioration of neurologic deficits. Collectively, our findings suggested that miR‐150 could regulate claudin‐5 expression and endothelial cell survival by targeting Tie‐2, thus affecting the permeability of BBB after permanent middle cerebral artery occlusion in rats, and that miR‐150 might be a potential alternative target for the treatment of stroke.—Fang, Z., He, Q.‐W., Li, Q., Chen, X.‐L., Baral, S., Jin, H.‐J., Zhu, Y.‐Y., Li, M., Xia, Y.‐P., Mao, L., Hu, B. MicroRNA‐150 regulates blood‐brain barrier permeability via Tie‐2 after permanent middle cerebral artery occlusion in rats. FASEB J. 30, 2097–2107 (2016). www.fasebj.org

MiR-150 Regulates Poststroke Cerebral Angiogenesis via Vascular Endothelial Growth Factor in Rats

Angiogenesis is a harmonized target for poststroke recovery. Therefore, exploring the mechanisms involved in angiogenesis after stroke is vitally significant. In this study, we are reporting a miR‐150‐based mechanism underlying cerebral poststroke angiogenesis.

MicroRNA-493 regulates angiogenesis in a rat model of ischemic stroke by targeting MIF

MicroRNA‐493 (miR‐493) is known to suppress tumour metastasis and angiogenesis and its expression is decreased in stroke patients. In the present study, we investigated a role for miR‐493 in regulating post‐stroke angiogenesis. We found decreased expression of miR‐493 in the ischemic boundary zone (IBZ) of rats subjected to middle cerebral artery occlusion (MCAO), and in rat brain microvascular endothelial cells (RBMECs) exposed to oxygen glucose deprivation. Down‐regulating miR‐493 with a lateral ventricular injection of antagomir‐493, a synthetic miR‐493 inhibitor, increased capillary density in the IBZ, decreased focal infarct volume and ameliorated neurologic deficits in rats subjected to MCAO. Intriguingly, MCAO also increased the expression of macrophage migration inhibitory factor (MIF) in the IBZ of rats; MIF expression was also increased in RBMECs exposed to oxygen glucose deprivation. We found that miR‐493 directly targeted MIF, and that the protective effect of miR‐493 inhibition in angiogenesis was attenuated by knocking down MIF. This effect could then be rescued by administration of recombinant MIF. Our findings highlight the importance of miR‐493 in regulating angiogenesis after MCAO, and indicate that miR‐493 is a potential therapeutic target in the treatment of stroke.

Diverse Functions and Mechanisms of Pericytes in Ischemic Stroke.

Background: Every year, strokes take millions of lives and leave millions of individuals living with permanent disabilities. Recently more researchers embrace the concept of the neurovascular unit (NVU), which encompasses neurons, endothelial cells (ECs), pericytes, astrocyte, microglia, and the extracellular matrix. It has been well-documented that NVU emerged as a new paradigm for the exploration of mechanisms and therapies in ischemic stroke. To better understand the complex NVU and broaden therapeutic targets, we must probe the roles of multiple cell types in ischemic stroke. The aims of this paper are to introduce the biological characteristics of brain pericytes and the available evidence on the diverse functions and mechanisms involving the pericytes in the context of ischemic stroke. Methods: Research and online content related to the biological characteristics and pathophysiological roles of pericytes is review. The new research direction on the Pericytes in ischemic stroke, and the potential therapeutic targets are provided. Results: During the different stages of ischemic stroke, pericytes play different roles: 1) On the hyperacute phase of stroke, pericytes constriction and death may be a cause of the no-reflow phenomenon in brain capillaries; 2) During the acute phase, pericytes detach from microvessels and participate in inflammatory-immunological response, resulting in the BBB damage and brain edema. Pericytes also provide benefit for neuroprotection by protecting endothelium, stabilizing BBB and releasing neurotrophins; 3) Similarly, during the later recovery phase of stroke, pericytes also contribute to angiogenesis, neurogenesis, and thereby promote neurological recovery. Conclusion: This emphasis on the NVU concept has shifted the focus of ischemic stroke research from neuro-centric views to the complex interactions within NVU. With this new perspective, pericytes that are centrally positioned in the NVU have been widely studied in ischemic stroke. More work is needed to elucidate the beneficial and detrimental roles of brain pericytes in ischemic stroke that may serve as a basis for potential therapeutic targets.

Alleviative effects of fluoxetine on depressive - like behaviors by epigenetic regulation of BDNF gene transcription in mouse model of post-stroke depression

Fluoxetine, one of the selective serotonin reuptake inhibitor (SSRI) antidepressants, has been thought to be effective for treating post-stroke depression (PSD). Recent work has shown that fluoxetine may exert an antidepressive effect through increasing the level of brain-derived neurotrophic factor (BDNF), but the underlying mechanism still remains unclear. In the present study, we successfully established the PSD model using male C57BL/6 J mice by photothrombosis of the left anterior cortex combined with isolatied-housing conditions. In the process, we confirmed that fluoxetine could improve the depression-like behaviors of PSD mice and upregulate the expression of BDNF in the hippocampus. However, depletion of BDNF by transfecting lentivirus-derived shBDNF in hippocampus suppressed the effect of fluoxetine. Furthermore, we demonstrated the epigenetic mechanisms involved in regulation of BDNF expression induced by fluoxetine. We found a statistically significant increase in DNA methylation at specific CpG sites (loci 2) of Bdnf promoter IV in the hippocampus of PSD mice. We also found that fluoxetine treatment could disassociate the MeCP2-CREB-Bdnf promoter IV complex via phosphorylation of MeCP2 at Ser421 by Protein Kinase A (PKA). Our research highlighted the importance of fluoxetine in regulating BDNF expression which could represent a potential strategy for preventing PSD.

P2Y12 Promotes Migration of Vascular Smooth Muscle Cells Through Cofilin Dephosphorylation During Atherogenesis

Objective— P2Y12 is a well-recognized receptor expressed on platelets and the target of thienopyridine-type antiplatelet drugs. However, recent evidence suggests that P2Y12 expressed in vessel wall plays a role in atherogenesis, but the mechanisms remain elusive. In this study, we examined the molecular mechanisms of how vessel wall P2Y12 mediates vascular smooth muscle cells (VSMCs) migration and promotes the progression of atherosclerosis. Approach and Results— Using a high-fat diet–fed apolipoprotein E–deficient mice model, we found that the expression of P2Y12 in VSMCs increased in a time-dependent manner and had a linear relationship with the plaque area. Moreover, administration of P2Y12 receptor antagonist for 12 weeks caused significant reduction in atheroma and decreased the abundance of VSMCs in plaque. In cultured VSMCs, we found that activation of P2Y12 receptor inhibited cAMP/protein kinase A signaling pathway, which induced cofilin dephosphorylation and filamentous actin disassembly, thereby enhancing VSMCs motility and migration. In addition, the number of P2Y12-positive VSMCs was decreased in the carotid artery plaque from patients receiving clopidogrel. Conclusions— Vessel wall P2Y12 receptor, which promotes VSMCs migration through cofilin dephosphorylation, plays a critical role in the development of atherosclerotic lesion and may be used as a therapeutic target for atherosclerosis.

Administration of sonic hedgehog protein induces angiogenesis and has therapeutic effects after stroke in rats

The Sonic hedgehog (Shh) signaling pathway is recapitulated in response to ischemic injury. Here, we investigated the clinical implications of Shh protein in the ischemic stroke and explored the underlying mechanism. Intracerebroventricular injection of Shh, Cyclopamine, or anti-vascular endothelial growth factor (VEGF) was performed immediately after permanent middle cerebral artery occlusion (pMCAO) surgery and lasted for 7days (d). Phosphate-buffered saline (PBS) was used as control. Neurological deficits and infarct volume were examined 7d after pMCAO. Microvascular density with fluorescein-iso-thiocyanate (FITC) assay and double staining with CD31 and Ki-67 was measured at 7d. To observe in vitro angiogenesis, rat brain microvascular endothelial cells (RBMECs) were incubated under oxygen glucose deprivation (OGD) for 6h (h) and treated with Shh/anti-VEGF. We found that (1) Shh improved neurological scores and reduced infarct volume, which was blocked by Cyclopamine, (2) Shh improved the microvascular density and promoted angiogenesis and neuron survival in the ischemic boundary zone, (3) Shh enhanced VEGF expression and VEGF antibody could reverse angiogenic and protective effect of Shh in vivo and in vitro. These data demonstrate that the administration of Shh protein could protect brain from ischemic injury, in part by promoting angiogenic repair.

Inhibiting the Migration of M1 Microglia at Hyperacute Period Could Improve Outcome of tMCAO Rats

To study whether inhibiting microglia migration to the ischemic boundary zone (IBZ) at the early phase could improve neurological outcomes after stroke.

Sema4D/PlexinB1 inhibition ameliorates blood–brain barrier damage and improves outcome after stroke in rats

The inflammatory process in stroke is the major contributor to blood‐brain barrier (BBB) breakdown. Previous studies indicated that semaphorin 4D (Sema4D), an axon guidance molecule, initiated inflammatory microglial activation and disrupted endothelial function in the CNS. However, whether Sema4D disrupts BBB integrity after stroke remains unclear. To study the effect of Sema4D on BBB disruption in stroke, rats were subjected to transient middle cerebral artery occlusion and targeted injection of lentivirus‐mediated clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene disruption of PlexinB1. We found that Sema4D synchronously increased with BBB permeability and accumulated in the perivascular area after stroke. Suppressing Sema4D/ PlexinB1 signaling in the periinfarct cortex significantly decreased BBB permeability as detected by MRI and fibrin deposition, and thereby improved stroke outcome. In vitro, we confirmed that Sema4D disrupted BBB integrity and endothelial tight junctions. Moreover, we found that Sema4D induced pericytes to acquire a CD11b‐positive phenotype and express proinflammatory cytokines. In addition, Sema4D inhibited AUF1‐induced proinflammatory mRNA decay effect. Taken together, our data provides evidence that Sema4D disrupts BBB integrity and promotes an inflammatory response by binding to PlexinB1 in pericytes after transient middle cerebral artery occlusion. Our study indicates that Sema4D may be a novel therapeutic target for treatment in the acute phase of stroke.— Zhou, Y.‐F., Li, Y.‐N., Jin, H.‐J., Wu, J.‐H., He, Q.‐W., Wang, X.‐X., Lei, H., Hu, B. Sema4D/PlexinB1 inhibition ameliorates blood‐brain barrier damage and improves outcome after stroke in rats. FASEB J. 32, 2181–2196 (2018). www.fasebj.org

MicroRNA-149-5p regulates blood–brain barrier permeability after transient middle cerebral artery occlusion in rats by targeting S1PR2 of pericytes

Blood‐brain barrier (BBB) disruption caused by reperfusion injury after ischemic stroke is an intractable event conducive to further injury. Brain pericytes play a vital role in maintaining BBB integrity by interacting with other components of the BBB. In this study, we found that sphingosine‐1‐phosphate receptor (S1PR)2 expressed in pericytes was significantly up‐regulated after ischemia in vivo and in vitro. By using a S1PR2 antagonist (JTE‐013), we showed that S1PR2 plays a critical role in the induction of BBB permeability of transient middle cerebral artery occlusion (tMCAO) rats and the in vitro BBB model. Furthermore, we discovered that S1PR2 may decrease N‐cadherin expression and increase pericyte migration via NF‐κB p65 signal and found that S1PR2 could be regulated by miR‐149–5p negatively, which was decreased in the ischemic boundary zone and cultured pericytes after ischemia. Overexpression of miR‐149–5p in cultured pericytes substantially increased N‐cadherin expression and decreased pericyte migration, which decreased BBB leakage in the in vitro model. Up‐regulating miR‐149–5p by intracerebroventricular injection of agomir‐149–5p attenuated BBB permeability and improved the outcomes of tMCAO rats significantly. Thus, our data suggest that miR‐149–5p may serve as a potential target for treatment of BBB disruption after ischemic stroke.—Wan, Y., Jin, H.‐J., Zhu, Y.‐Y., Fang Z., Mao, L., He, Q., Xia, Y.‐P., Li, M., Li, Y., Chen, X., Hu, B. MicroRNA‐149–5p regulates blood‐brain barrier permeability after transient middle cerebral artery occlusion in rats by targeting S1PR2 of pericytes. FASEB J. 32, 3133–3148 (2018). www.fasebj.org