Caveolin-1 Derived from Brain Microvascular Endothelial Cells Inhibits Neuronal Differentiation of Neural Stem/Progenitor Cells In Vivo and In Vitro

Increased caveolin 1 by human antigen R exacerbates Porphyromonas gingivali-induced atherosclerosis by modulating oxidative stress and inflammatory responses

Objective

Many different types of infectious oral diseases have been identified clinically, including chronic periodontitis. Porphyromonas gingivalis is the main pathogen causing chronic periodontitis, which is closely related to atherosclerosis (AS) and can promote the expression levels of caveolin 1 (Cav-1) and induced ribonucleic acid (RNA)-binding protein human antigen R (HuR). However, the roles of Cav-1 and its relationship with HuR in P. gingivalis-mediated AS progression remain largely unknown. Here, we aimed to detect the role and molecular mechanisms of Cav-1 in P. gingivalis-mediated AS.

Material and Methods

To investigate the role of Cav-1 in P. gingivalis-mediated AS, we infected human umbilical vein endothelial cells (HUVECs) with P. gingivalis at a multiplicity of infection of 100:1 for 6, 12, and 24 h to simulate P. gingivalis-induced AS models in vitro and then transfected them with Cav-1 small interfering RNA to silence Cav-1. Combining molecular biology experimental techniques such as cell counting kit-8 assay, enzyme-linked immunosorbent assay, immunofluorescence staining, flow cytometry, Western blotting, and Oil Red O staining, and apolipoprotein E-deficient AS model mice, the impacts of Cav-1 on cell viability, inflammation, oxidative stress, apoptosis, Cav-1 and intercellular cell adhesion molecule-1 (ICAM-1) levels, and atherosclerotic plaque formation were investigated. Then, the relationship between Cav-1 and HuR was investigated through biotin pull-down and RNA immunoprecipitation assays, reverse transcription quantitative polymerase chain reaction, and Western blot.

Results

P. gingivalis can induce Cav-1 expression in a time- and dose-dependent manner (P < 0.05). This effect can inhibit the proliferation of HUVECs (P < 0.05). Cav-1 interference repressed inflammatory response, reactive oxygen species (ROS) and ICAM-1 levels, and apoptosis in the HUVECs (P < 0.05). Cav-1 messenger RNA was stabilized by HuR, which can bind to the 3' untranslated region of Cav-1. Increase in HuR level reversed the effects of Cav-1 silencing on ROS and ICAM-1 levels and apoptosis in the HUVECs (P < 0.05). In addition, the levels of inflammatory response, oxidative stress, and atherosclerotic plaque formation induced by P. gingivalis in the mouse model were significantly reduced after Cav-1 expression was inhibited (P < 0.05).

Conclusion

HuR-activated Cav-1 may promote atherosclerotic plaque formation by modulating inflammatory response and oxidative stress, leading to AS.

MiR-199a-5p enhances neuronal differentiation of neural stem cells and promotes neurogenesis by targeting Cav-1 after cerebral ischemia

AIMS

MicroRNAs (miRs) are involved in endogenous neurogenesis, enhancing of which has been regarded as a potential therapeutic strategy for ischemic stroke treatment; however, whether miR-199a-5p mediates postischemic neurogenesis remains unclear. This study aims to investigate the proneurogenesis effects of miR-199a-5p and its possible mechanism after ischemic stroke.

METHODS

Neural stem cells (NSCs) were transfected using Lipofectamine 3000 reagent, and the differentiation of NSCs was evaluated by immunofluorescence and Western blotting. Dual-luciferase reporter assay was performed to verify the target gene of miR-199a-5p. MiR-199a-5p agomir/antagomir were injected intracerebroventricularly. The sensorimotor functions were evaluated by neurobehavioral tests, infarct volume was measured by toluidine blue staining, neurogenesis was detected by immunofluorescence assay, and the protein levels of neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), caveolin-1 (Cav-1), vascular endothelial growth factor (VEGF), and brain-derived neurotrophic factor (BDNF) were measured by Western blotting.

RESULTS

MiR-199a-5p mimic enhanced neuronal differentiation and inhibited astrocyte differentiation of NSCs, while a miR-199a-5p inhibitor induced the opposite effects, which can be reversed by Cav-1 siRNA. Cav-1 was through the dual-luciferase reporter assay confirmed as a target gene of miR-199a-5p. miR-199a-5p agomir in rat stroke models manifested multiple benefits, such as improving neurological deficits, reducing infarct volume, promoting neurogenesis, inhibiting Cav-1, and increasing VEGF and BDNF, which was reversed by the miR-199a-5p antagomir.

CONCLUSION

MiR-199a-5p may target and inhibit Cav-1 to enhance neurogenesis and thus promote functional recovery after cerebral ischemia. These findings indicate that miR-199a-5p is a promising target for the treatment of ischemic stroke.

Reduced endothelial caveolin-1 underlies deficits in brain insulin signalling in type 2 diabetes

Patients with type 2 diabetes exhibit severe impairments in insulin signalling in the brain and are five times more likely to develop Alzheimer's disease. However, what leads to these impairments is not fully understood. Here, we show reduced expression of endothelial cell caveolin-1 (Cav-1) in the db/db (Leprdb) mouse model of type 2 diabetes. This reduction correlated with alterations in insulin receptor expression and signalling in brain microvessels as well as brain parenchyma. These findings were recapitulated in the brains of endothelial cell-specific Cav-1 knock-out (Tie2Cre; Cav-1fl/fl) mice. Lack of Cav-1 in endothelial cells led to reduced response to insulin as well as reduced insulin uptake. Furthermore, we observed that Cav-1 was necessary for the stabilization of insulin receptors in lipid rafts. Interactome analysis revealed that insulin receptor interacts with Cav-1 and caveolae-associated proteins, insulin-degrading enzyme and the tight junction protein Zonula Occludence-1 in brain endothelial cells. Restoration of Cav-1 in Cav-1 knock-out brain endothelial cells rescued insulin receptor expression and localization. Overall, these results suggest that Cav-1 regulates insulin signalling and uptake by brain endothelial cells by modulating IR-α and IR-β localization and function in lipid rafts. Furthermore, depletion of endothelial cell-specific Cav-1 and the resulting impairment in insulin transport leads to alteration in insulin signalling in the brain parenchyma of type 2 diabetics.

Prognostic Values Serum Cav-1 and NGB Levels in Early Neurological Deterioration After Intravenous Thrombolysis in Patients with Acute Ischemic Stroke

Early neurological deterioration after intravenous thrombolysis (IAT) leads to increased mortality and morbidity in patients with acute ischemic stroke (AIS). This study investigated the correlation between serum Cav-1 and NGB levels and END after IAT and explored their predictive values for poor prognosis of AIS. Totally 210 patients with AIS who underwent IAT within 4.5 h of onset were included and assigned into END group (n = 90) and Non-END group (n = 120). ELISA was used to detect serum Cav-1 and NGB levels before IAT in AIS patients. The prognosis of END patients after 3 months of treatment was evaluated using the modified Rankin Scale. Logistic multifactorial regression was used to analyze independent risk factors for END and poor prognosis after IAT. ROC curve was used to analyze the predictive effect of Cav-1 and NGB on END and poor prognosis after IAT. The area under the ROC curve was analyzed by MedCalc comparison. Compared with the Non-END group, serum Cav-1 was lower and NGB was higher in the END group. Cav-1 and NGB were independent risk factors for END after IAT. Cav-1 + NGB better predicted END after IAT than Cav-1 or NGB alone. Cav-1 and NGB were independent risk factors for END poor prognosis after IAT. Cav-1 combined with NGB better predicted poor prognosis of END after IAT than Cav-1 or NGB alone. Serum Cav-1 combined with NGB may assist in predicting the risk of END occurrence and poor prognosis after IAT in patients with AIS.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.

Voltage-dependent potassium channel Kv4.2 alleviates the ischemic stroke impairments through activating neurogenesis

As well as their ion transportation function, the voltage-dependent potassium channels could act as the cell signal inducer in a variety of pathogenic processes. However, their roles in neurogenesis after stroke insults have not been clearly illustrated. In our preliminary study, the expressions of voltage-dependent potassium channels Kv4.2 was significantly decreased after stroke in cortex, striatum and hippocampus by real-time quantitative PCR assay. To underlie the neuroprotection of Kv4.2 in stroke rehabilitation, recombinant plasmids encoding the cDNAs of mouse Kv4.2 was constructed. Behavioral tests showed that the increased Kv4.2 could be beneficial to the recovery of the sensory, the motor functions and the cognitive deficits after stroke. Temozolomide (TMZ), an inhibitor of neurogenesis, could partially abolish the mentioned protections of Kv4.2. The immunocytochemical staining showed that Kv4.2 could promote the proliferations of neural stem cells and induce the neural stem cells to differentiate into neurons in vitro and in vivo. And Kv4.2 could up-regulate the expressions of ERK1/2, p-ERK1/2, p-STAT3, NGF, p-TrkA, and BDNF, CAMKII and the concentration of intracellular Ca²⁺. Namely, we concluded that Kv4.2 promoted neurogenesis through ERK1/2/STAT3, NGF/TrkA, Ca²⁺/CAMKII signal pathways and rescued the ischemic impairments. Kv4.2 might be a potential drug target for ischemic stroke intervention.