Kejian Wang

Expression of aquaporin8 in human astrocytomas: Correlation with pathologic grade

Aquaporin8 (AQP8), a member of the aquaporin (AQP) protein family, is weakly distributed in mammalian brains. Previous studies on AQP8 have focused mainly on the digestive and the reproductive systems. AQP8 has a pivotal role in keeping the fluid and electrolyte balance. In this study, we investigated the expression changes of AQP8 in 75 cases of human brain astrocytic tumors using immunohistochemistry, Western blotting, and reverse transcription polymerase chain reaction. The results demonstrated that AQP8 was mainly distributed in the cytoplasm of astrocytoma cells. The expression levels and immunoreactive score of AQP8 protein and mRNA increased in low-grade astrocytomas, and further increased in high-grade astrocytomas, especially in glioblastoma. Therefore, AQP8 may contribute to the proliferation of astrocytomas, and may be a biomarker and candidate therapy target for patients with astrocytomas.

Chronic cerebral hypoperfusion induces memory deficits and facilitates Aβ generation in C57BL/6J mice

Alzheimers disease (AD) is the most common type of dementia frequently responsible for cognitive decline in the elderly. The etiology and molecular mechanism of AD pathogenesis remain inconclusive. Aging and vascular factors are important independent causes and contributors to sporadic AD. Clinical imaging studies showed that cerebral blood flow decreases before cognitive impairment in patients with AD. To investigate the effect of chronic cerebral hypoperfusion (CCH) on cognitive impairment and morphological features, we developed a new manner of CCH mouse model by narrowing bilateral common carotid arteries. Mice started to manifest spatial memory deficits 1month after the surgery and exhibited behavioral changes in a time-dependent manner. Mice also presented memory deficits accompanied with morphological changes at the neuronal and synaptic levels. CCH damaged the normal neuronal morphology and significantly reduced the expression level of PSD95. CCH activated astrocytes, increased the co-expression of GFAP and AQP4, and destroyed the blood-brain barrier (BBB). Furthermore, CCH facilitated intracellular and extracellular Aβ deposition by up-regulating γ-secretase and β-secretase levels. Our results showed good reproducibility of post-CCH pathological processes, which are characterized by neuronal apoptosis, axonal abnormalities, glial activation, BBB damage, amyloid deposition, and cognitive dysfunction; these processes may be used to decipher the complex interplay and pathological process between CCH and AD. This study provides laboratory evidence for the prevention and treatment of cognitive malfunction and AD.

Valproic acid modifies synaptic structure and accelerates neurite outgrowth via the glycogen synthase kinase 3β signaling pathway in an Alzheimer's disease model

Tau hyperphosphorylation and amyloid β‐peptide overproduction, caused by altered localization or abnormal activation of glycogen synthase kinase‐3β (GSK‐3β), is a pathogenic mechanism in Alzheimers disease (AD). Valproic acid (VPA) attenuates senile plaques and neuronal loss. Here, we confirmed that VPA treatment improved spatial memory in amyloid precursor protein (APP)/presenilin 1 (PS 1) double‐transgenic mice and investigated the effect of VPA on synaptic structure and neurite outgrowth.

Demyelination initiated by oligodendrocyte apoptosis through enhancing endoplasmic reticulum-mitochondria interactions and Id2 expression after compressed spinal cord injury in rats.

Demyelination is one of the most important pathological factors of spinal cord injury. Oligodendrocyte apoptosis is involved in triggering demyelination. However, fewer reports on pathological changes and mechanism of demyelination have been presented from compressed spinal cord injury (CSCI). The relative effect of oligodendrocyte apoptosis on CSCI‐induced demyelination and the mechanism of apoptosis remain unclear.

Both endoplasmic reticulum and mitochondrial pathways are involved in oligodendrocyte apoptosis induced by capsular hemorrhage.

OBJECTIVE The white matter injury caused by intracerebral hemorrhage (ICH) includes demyelination and axonal injury. Oligodendrocyte apoptosis is reported to be involved in triggering demyelination. Experimental observations indicate that both endoplasmic reticulum and mitochondrial pathways could mediate cell apoptosis. The purpose of this study was to investigate the demyelination and the possible mechanisms in an autologous blood-injected rat model of internal capsule hemorrhage. METHODS Transmission electron microscope was applied to examine the pathological changes of myelinated nerve fibers in internal capsule. Western blotting was used to detect the myelin basic protein (MBP) which was an important component of myelin sheath. Double immunofluorescence and Western blotting were used to determine the apoptosis and apoptotic pathways. The levels of caspase-12 (a representative protein of endoplasmic reticulum stress) and cytochrome c (an apoptosis factor released from mitochondria) were assessed in this study. RESULTS Demyelination occurred on day 1, 3, and 7 after ICH onset. Myelin sheaths of internal capsule nerve fibers were swollen and broken down in ICH groups. MBP expression showed a downregulation after ICH with its minimum value occurred on day 7 post-ICH. Besides, neuron and oligodendrocyte apoptosis were observed at different time intervals post-ICH accompanied with an upregulated caspase-12 expression and enhanced cytochrome c release. CONCLUSIONS These results suggested that oligodendrocyte and neuron apoptosis may contribute to the demyelination induced by internal capsule hemorrhage and oligodendrocyte apoptosis is positively mediated through both endoplasmic reticulum and mitochondrial pathways.

Lysosomal degradation of retinal glial AQP4 following its internalization induced by acute ocular hypertension

The membrane-bound water channel aquaporin-4 plays a significant role in the regulation of water movement within the retina. In retinal ischemia-reperfusion injury, changes in the expression and localization of aquaporin-4 have been reported. Previous studies also suggest that the internalization of several membrane-bound proteins, including aquaporin-4, may occur with or without lysosomal degradation. In this study, the internalization of aquaporin-4 was detected in the ischemic rat retina via double immunofluorescence labeling. Specifically, both aquaporin-4 and the mannose-6-phosphate receptor co-localized post-ischemic injury (10, 30 and 60 min). The same results were found during a 12-h reperfusion window (2, 4 and 8 h, respectively) following 60 min of ischemia. Moreover, the co-expression of aquaporin-4 and lysosomal-associated membrane protein-1 was observed at 1-12 h of reperfusion, with co-expression increasing followed by a gradual decrease. These combined findings suggest that AQP4 is internalized in the ischemic-reperfused retina, and the lysosome is involved in degrading the internalized aquaporin-4 during the reperfusion phase. Both the internalization of aquaporin-4 and its lysosomal degradation may serve as valuable therapeutic targets for managing ischemic-reperfused retinal injury.

Internalization of Aquaporin-4 After Collagenase-Induced Intracerebral Hemorrhage

Brain edema formation following intracerebral hemorrhage (ICH) appears to be related with aquaporin‐4 (AQP4), which is critically involved in brain volume homeostasis and water balance. Despite its importance, the regulation of AQP4 expression involved in transmembrane water movements still remains rudimentary. Many studies suggest that the internalization of several membrane‐bound proteins, including AQP4, may occur with or without lysosomal degradation. Previously, we investigated the internalization of AQP4 in retinal ischemic‐reperfusion model. Here, we test the hypothesis that AQP4 is internalized post‐ICH and then degraded in the lysosome. The results demonstrated that both AQP4 and the mannose‐6‐phosphate receptor (MPR) co‐localized in perihematomal region at 6 hr post‐ICH. In addition, AQP4 and lysosomal‐associated membrane protein 1 (LAMP1) also co‐localized in perihematomal region, with co‐expression increasing followed by a gradual decrease at different time windows post‐ICH (6, 12, 24, 48, and 72 hr). After ICH, the Evans blue leakage happened very early at 1 hr and the brain swelling occurred at 3 hr. Moreover, we also found the AQP4 mRNA and AQP4 protein were increased post‐ICH. These results suggest that AQP4 is internalized and the lysosome is involved in degrading the internalized AQP4 post‐ICH. Both the AQP4 internalization and lysosomal degradation may provide biophysical insights regarding the potential of new treatments for brain edema. Anat Rec, 298:554–561, 2015.

Long noncoding RNA GAS5 regulates the proliferation, migration, and invasion of glioma cells by negatively regulating miR-18a-5p: LIU et al.

Long noncoding RNAs, transcribed from a recently discovered class of noncoding genes, may play a critical role in regulating cellular processes, such as cell proliferation and apoptosis, as well as in cancer progression and metastasis. We previously detected the induction of growth arrest–specific 5 (GAS5) during glioma cell death. However, the function and underlying mechanism of GAS5 in human gliomas remain to be elucidated.

Dihydromyricetin inhibits microglial activation and neuroinflammation by suppressing NLRP3 inflammasome activation in APP/PS1 transgenic mice.

Activated microglia‐mediated inflammation plays a key role in the pathogenesis of Alzheimer’s disease (AD). In addition, chronic activation of NLRP3 inflammasomes triggered by amyloid β peptide (Aβ) in microglia contributes to persistent neuroinflammation. Here, the primary goal was to assess whether Dihydromyricetin (DHM), a plant flavonoid compound, is effective therapies for AD; it is crucial to know whether DHM will affect microglial activation and neuroinflammation in APP/PS1 transgenic mice.

A combined treatment with erythrocyte lysis solution and Sudan Black B reduces tissue autofluorescence in double-labeling immunofluorescence

The autofluorescence of animal tissues complicates the results obtained using fluorescence microscopy. Many techniques have been used to reduce autofluorescence; however, all these techniques have the disadvantage of reducing the intensity of immunofluorescence staining. We observed the features of autofluorescence in formalin-fixed paraffin-embedded (FFPE) vascularized liver and kidney sections and assessed the effects of an intravascular treatment with erythrocyte lysis solution (ELS) before a routine perfusion with normal saline (NS) and Sudan Black B (SBB) treatment after antigen retrieval on reducing autofluorescence reduction and the visualization of antigens to establish an optimal method for reducing autofluorescence. Erythrocytes exhibited bright autofluorescence in FFPE liver and kidney sections, which altered the results of actin and destrin immunofluorescence staining. The SBB treatment significantly reduced background autofluorescence and exerted a moderate effect on reducing the autofluorescence of erythrocytes, and the intravascular ELS treatment eliminated erythrocyte autofluorescence in FFPE liver and kidney sections. A combined treatment with ELS and SBB further reduced autofluorescence but did not decrease actin and destrin immunofluorescence staining in double-labeled FFPE liver and kidney sections. In conclusion, the application of an intravascular ELS treatment before the NS perfusion combined with an SBB treatment after antigen retrieval is a simple and efficient strategy for reducing autofluorescence in FFPE vascularized tissues and can be broadly used in fluorescence microscopy analyses.