Caveolin-1 and -2 and their relationship to cerebral amyloid angiopathy in Alzheimer's disease

Cognitive Dysfunction and Exercise: From Epigenetic to Genetic Molecular Mechanisms

Maintaining good health is crucial, and exercise plays a vital role in achieving this goal. It offers a range of positive benefits for cognitive function, regardless of age. However, as our population ages and life expectancy increases, cognitive impairment has become a prevalent issue, often coexisting with age-related neurodegenerative conditions. This can result in devastating consequences such as memory loss, difficulty speaking, and confusion, greatly hindering one's ability to lead an ordinary life. In addition, the decrease in mental capacity has a significant effect on an individual's physical and emotional well-being, greatly reducing their overall level of contentment and causing a significant financial burden for communities. While most current approaches aim to slow the decline of cognition, exercise offers a non-pharmacological, safe, and accessible solution. Its effects on cognition are intricate and involve changes in the brain's neural plasticity, mitochondrial stability, and energy metabolism. Moreover, exercise triggers the release of cytokines, playing a significant role in the body-brain connection and its impact on cognition. Additionally, exercise can influence gene expression through epigenetic mechanisms, leading to lasting improvements in brain function and behavior. Herein, we summarized various genetic and epigenetic mechanisms that can be modulated by exercise in cognitive dysfunction.

Endocytosis and Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and is the most common cause of dementia. The pathogenesis of AD still remains unclear, including two main hypotheses: amyloid cascade and tau hyperphosphorylation. The hallmark neuropathological changes of AD are extracellular deposits of amyloid-β (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). Endocytosis plays an important role in a number of cellular processes including communication with the extracellular environment, nutrient uptake, and signaling by the cell surface receptors. Based on the results of genetic and biochemical studies, there is a link between neuronal endosomal function and AD pathology. Taking this into account, we can state that in the results of previous research, endolysosomal abnormality is an important cause of neuronal lesions in the brain. Endocytosis is a central pathway involved in the regulation of the degradation of amyloidogenic components. The results of the studies suggest that a correlation between alteration in the endocytosis process and associated protein expression progresses AD. In this article, we discuss the current knowledge about endosomal abnormalities in AD.

Single-Cell Transcriptional Response of the Placenta to the Ablation of Caveolin-1: Insights into the Adaptive Regulation of Brain-Placental Axis in Mice

Caveolin-1 (Cav1) is a major plasma membrane protein that plays important functions in cellular metabolism, proliferation, and senescence. Mice lacking Cav1 show abnormal gene expression in the fetal brain. Though evidence for placental influence on brain development is emerging, whether the ablation of Cav1 affects the regulation of the brain-placental axis remains unexamined. The current study tests the hypothesis that gene expression changes in specific cells of the placenta and the fetal brain are linked to the deregulation of the brain-placental axis in Cav1-null mice. By performing single-nuclei RNA sequencing (snRNA-seq) analyses, we show that the abundance of the extravillious trophoblast (EVT) and stromal cells, but not the cytotrophoblast (CTB) or syncytiotrophoblast (STB), are significantly impacted due to Cav1 ablation in mice. Interestingly, specific genes related to brain development and neurogenesis were significantly differentially expressed in trophoblast cells due to Cav1 deletion. Comparison of single-cell gene expression between the placenta and the fetal brain further showed that specific genes such as plexin A1 (Plxna1), phosphatase and actin regulator 1 (Phactr1) and amyloid precursor-like protein 2 (Aplp2) were differentially expressed between the EVT and STB cells of the placenta, and also, between the radial glia and ependymal cells of the fetal brain. Bulk RNA-seq analysis of the whole placenta and the fetal brain further identified genes differentially expressed in a similar manner between the placenta and the fetal brain due to the absence of Cav1. The deconvolution of reference cell types from the bulk RNA-seq data further showed that the loss of Cav1 impacted the abundance of EVT cells relative to the stromal cells in the placenta, and that of the glia cells relative to the neuronal cells in the fetal brain. Together, the results of this study suggest that the ablation of Cav1 causes deregulated gene expression in specific cell types of the placenta and the fetal brain in mice.

Role of caveolin-1 in metabolic programming of fetal brain

Mice lacking caveolin-1 (Cav1), a key protein of plasma membrane, exhibit brain aging at an early adult stage. Here, integrative analyses of metabolomics, transcriptomics, epigenetics, and single-cell data were performed to test the hypothesis that metabolic deregulation of fetal brain due to the ablation of Cav1 is linked to brain aging in these mice. The results of this study show that lack of Cav1 caused deregulation in the lipid and amino acid metabolism in the fetal brain, and genes associated with these deregulated metabolites were significantly altered in the brain upon aging. Moreover, ablation of Cav1 deregulated several metabolic genes in specific cell types of the fetal brain and impacted DNA methylation of those genes in coordination with mouse epigenetic clock. The findings of this study suggest that the aging program of brain is confounded by metabolic abnormalities in the fetal stage due to the absence of Cav1.

Cognitive-exercise dual-task intervention ameliorates cognitive decline in natural aging rats via inhibiting the promotion of LncRNA NEAT1/miR-124-3p on caveolin-1-PI3K/Akt/GSK3β Pathway

Aging-related cognitive impairment (ARCI) is rapidly becoming a healthcare priority. However, there is currently no excellent cure for it. Cognitive-exercise dual-task intervention (CEDI) is a promising method to improve ARCI, while the underlying mechanisms remain unclear. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are involved in the onset, development, and rehabilitation of ARCI. This study aimed to investigate the effects of CEDI and the role of regulation of the lncRNA NEAT1/miR-124-3p on the caveolin-1-PI3K/Akt/GSK3β pathway in CEDI improving cognitive function. Forty 18-month-old natural aging rats were randomly assigned to four groups: exercise training group, cognitive training group, CEDI group, and aging control group, and underwent 12 weeks of intervention. A novel object recognition test was performed to determine the cognitive function, and the hippocampus was separated three days after the behavioral tests for further molecular detection. In an in vitro study, the mouse hippocampal neuronal cell line HT22 was cultured. MiR-124-3p and lncRNA NEAT1 were over-expressed or down-expressed, respectively. The expressions of related proteins, lncRNA, and miRNA were examined by WB and/or qRT-PCR. The results showed that compared with the aging control group, the CEDI group had a higher discrimination index, and significantly decreased the expressions of lncRNA NEAT1, and the protein expressions of caveolin-1 and p-GSK3β, while significantly increased the expressions of miR-124-3p, and the protein expressions of p-PI3K and p-Akt. Inhibition of the lncRNA NEAT1 could significantly increase the protein expressions of p-PI3K and p-Akt in HT22 cells. Upregulation of miR-124-3p decreased the protein expressions of caveolin-1 and p-GSK3β, and increased the protein expressions of p-PI3K and p-Akt significantly. Inhibition of miR-124-3p had the opposite effects. Our study demonstrated that CEDI improved cognitive function in aging rats better than a single intervention. The mechanisms of cognitive improvement could be related to the regulation of the lncRNA NEAT1/miR-124-3p on the caveolin-1-PI3K/Akt/GSK3β pathway.

Upregulation of endocytic protein expression in the Alzheimer's disease male human brain

Amyloid-beta (Aβ) is produced from amyloid precursor protein (APP) primarily after APP is internalised by endocytosis and clathrin-mediated endocytic processes are altered in Alzheimer's disease (AD). There is also evidence that cholesterol and flotillin affect APP endocytosis. We hypothesised that endocytic protein expression would be altered in the brains of people with AD compared to non-diseased subjects which could be linked to increased Aβ generation. We compared protein expression in frontal cortex samples from men with AD compared to age-matched, non-diseased controls. Soluble and insoluble Aβ40 and Aβ42, the soluble Aβ42/Aβ40 ratio, βCTF, BACE1, presenilin-1 and the ratio of phosphorylated:total GSK3β were significantly increased while the insoluble Aβ42:Aβ40 ratio was significantly decreased in AD brains. Total and phosphorylated tau were markedly increased in AD brains. Significant increases in clathrin, AP2, PICALM isoform 4, Rab-5 and caveolin-1 and 2 were seen in AD brains but BIN1 was decreased. However, using immunohistochemistry, caveolin-1 and 2 were decreased. The results obtained here suggest an overall increase in endocytosis in the AD brain, explaining, at least in part, the increased production of Aβ during AD.

Deciphering the roles of caveolin in neurodegenerative diseases: The good, the bad and the importance of context

Neurodegenerative diseases (NDDs), which contribute to progressive and irreversible impairments of both the structure and function of the nervous system, pose a substantial socioeconomic burden on society. Mitochondrial dysfunction, oxidative stress, membrane damage, DNA damage, and abnormal protein degradation pathways play pivotal roles in the etiology of NDDs. Recently, growing evidence has demonstrated that caveolins are important in the pathology of NDDs due to their cellular functions in signal transduction, endocytosis, transcytosis, cholesterol transport, and lipid homeostasis. Given the significance of caveolins, here we review the literature to clarify their molecular mechanisms and roles in NDDs. We first briefly introduce the general background on caveolins. Next, we focus on the various important functions of caveolins in the brain. Finally, we emphasize recent progress regarding caveolins, especially Cav-1, which exert both benefit and unfavorable effects in NDDs such as AD and PD. Collectively, the data presented here should advance the investigation of caveolins for the future development of innovative strategies for the treatment of NDDs.

Neurodegeneration and Neuro-Regeneration-Alzheimer's Disease and Stem Cell Therapy

Aging causes many changes in the human body, and is a high risk for various diseases. Dementia, a common age-related disease, is a clinical disorder triggered by neurodegeneration. Brain damage caused by neuronal death leads to cognitive decline, memory loss, learning inabilities and mood changes. Numerous disease conditions may cause dementia; however, the most common one is Alzheimer’s disease (AD), a futile and yet untreatable illness. Adult neurogenesis carries the potential of brain self-repair by an endogenous formation of newly-born neurons in the adult brain; however it also declines with age. Strategies to improve the symptoms of aging and age-related diseases have included different means to stimulate neurogenesis, both pharmacologically and naturally. Finally, the regulatory mechanisms of stem cells neurogenesis or a functional integration of newborn neurons have been explored to provide the basis for grafted stem cell therapy. This review aims to provide an overview of AD pathology of different neural and glial cell types and summarizes current strategies of experimental stem cell treatments and their putative future use in clinical settings.

MiR-124-3p attenuates hyperphosphorylation of Tau protein-induced apoptosis via caveolin-1-PI3K/Akt/GSK3β pathway in N2a/APP695swe cells

Hyperphosphorylation of Tau forming neurofibrillary tangles has been considered as a crucial event in the pathogenesis of Alzheimer's disease (AD). MiR-124-3p belongs to microRNA (miRNA) family and was markedly decreased in AD, however, the functions of miR-124-3p in the pathogenesis of AD remain unknown. We observed that the expression of miR-124-3p was significantly decreased in N2a/APP695swe cells; and transfection of miR-124-3p mimics not only attenuated cell apoptosis and abnormal hyperphosphorylation of Tau protein without any changes of total Tau protein, but also increased expression levels of Caveolin-1, phosphoinositide 3-kinase (PI3K), phospho-Akt (Akt-Ser473)/Akt, phospho-glycogen synthase kinase-3 beta (GSK-3β-Ser9)/GSK-3β in N2a/APP695swe cells. We further found that miR-12-3p directly targeted Caveolin-1; miR-124-3p inhibited abnormal hyperphosphorylation of Tau by regulating Caveolin-1-PI3K/Akt/GSK3β pathway in AD. This study reveals that miR-124-3p may play a neuroprotective role in AD, which may provide new ideas and therapeutic targets for AD.

Versatile Functions of Caveolin-1 in Aging-related Diseases

Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases.

Lower Serum Caveolin-1 Is Associated with Cerebral Microbleeds in Patients with Acute Ischemic Stroke

Caveolin-1 (Cav-1) plays pivotal roles in the endothelial damage following stroke. The present study aimed to investigate whether serum Cav-1 level is associated with the presence of cerebral small vessel disease (cSVD) in patients with acute ischemic stroke. To this end, 156 patients were consecutively enrolled. Cranial magnetic resonance imaging was analyzed to determine the surrogates of cSVD, including cerebral microbleeds (CMBs), silent lacunar infarcts (SLIs), and white matter hyperintensities (WMHs). After adjusting for potential confounders, patients with low Cav-1 level had a higher risk of CMBs than patients with high Cav-1 level (OR: 4.05, 95% CI: 1.77-9.30). However, there was no relationship between Cav-1 and the presence of SLIs or WMHs. When CMBs were stratified by location and number, a similar association was found in patients with deep or infratentorial CMBs (OR: 4.04, 95% CI: 1.59-10.25) and with multiple CMBs (OR: 3.18, 95% CI: 1.16-8.72). These results suggest lower serum Cav-1 levels may be associated with CMBs, especially those that are multiple and located in deep brain or infratentorial structures, in patients with acute ischemic stroke. Cav-1 may be involved in the pathophysiology of CMBs, and may act as a potential target for treating cSVD.

Overnutrition Determines LPS Regulation of Mycotoxin Induced Neurotoxicity in Neurodegenerative Diseases

Chronic neurodegenerative diseases are now associated with obesity and diabetes and linked to the developing and developed world. Interests in healthy diets have escalated that may prevent neurodegenerative diseases such as Parkinson's and Alzheimer's disease. The global metabolic syndrome involves lipoprotein abnormalities and insulin resistance and is the major disorder for induction of neurological disease. The effects of bacterial lipopolysaccharides (LPS) on dyslipidemia and NAFLD indicate that the clearance and metabolism of fungal mycotoxins are linked to hypercholesterolemia and amyloid beta oligomers. LPS and mycotoxins are associated with membrane lipid disturbances with effects on cholesterol interacting proteins, lipoprotein metabolism, and membrane apo E/amyloid beta interactions relevant to hypercholesterolemia with close connections to neurological diseases. The influence of diet on mycotoxin metabolism has accelerated with the close association between mycotoxin contamination from agricultural products such as apple juice, grains, alcohol, and coffee. Cholesterol efflux in lipoproteins and membrane cholesterol are determined by LPS with involvement of mycotoxin on amyloid beta metabolism. Nutritional interventions such as diets low in fat/carbohydrate/cholesterol have become of interest with relevance to low absorption of lipophilic LPS and mycotoxin into lipoproteins with rapid metabolism of mycotoxin to the liver with the prevention of neurodegeneration.

Reduced vascular endothelial growth factor and capillary density in the occipital cortex in dementia with Lewy bodies

In dementia with Lewy bodies (DLB), blood flow tends to be reduced in the occipital cortex. We previously showed elevated activity of the endothelin and angiotensin pathways in Alzheimer's disease (AD). We have measured endothelin-1 (ET-1) level and angiotensin-converting enzyme (ACE) activity in the occipital cortex in DLB and control brains. We also measured vascular endothelial growth factor (VEGF); factor VIII-related antigen (FVIIIRA) to indicate microvessel density; myelin-associated glycoprotein (MAG), a marker of ante-mortem hypoperfusion; total α-synuclein (α-syn) and α-synuclein phosphorylated at Ser129 (α-syn-p129). In contrast to findings in AD, ACE activity and ET-1 level were unchanged in DLB compared with controls. VEGF and FVIIIRA levels were, however, significantly lower in DLB. VEGF correlated positively with MAG concentration (in keeping with a relationship between reduction in VEGF and hypoperfusion), and negatively with α-syn and α-syn-p129 levels. Both α-syn and α-syn-p129 levels increased in human SH-SY5Y neuroblastoma cells after oxygen-glucose deprivation (OGD), and VEGF level was reduced in SH-SY5Y cells overexpressing α-syn. Taken together, our findings suggest that reduced microvessel density rather than vasoconstriction is responsible for lower occipital blood flow in DLB, and that the loss of microvessels may result from VEGF deficiency, possible secondary to the accumulation of α-syn.

Permeability of the blood-tumor barrier is enhanced by combining vascular endothelial growth factor with papaverine

This study aims to determine the effects of vascular endothelial growth factor (VEGF), papaverine (PA), and the combination of VEGF and PA on the permeability of the blood-tumor barrier (BTB) and to determine possible molecular mechanisms contributing to the effects. In the rat C6 glioma model, the extravasation of Evans blue (EB) through the BTB was increased significantly by VEGF and PA. VEGF-induced and PA-induced increase of EB extravasation was further increased after combining VEGF with PA infusion. Transmission electron microscopy (TEM) showed that the combination of VEGF and PA not only opened tight junctions (TJ) dramatically but increased the presence of pinocytotic vesicles of brain microvascular endothelial cells (BMECs) significantly. Meanwhile, the downregulation of the TJ-associated proteins occludin and claudin-5 and the upregulation of the caveolae structure proteins caveolin-1 and caveolin-2 caused by the combination of VEGF and PA were observed by Western blot and immunohistochemistry, which were more remarkable than those by the two strategies separately. In addition, after VEGF and PA infusion, the results of radioimmunoassay, Western blot, and enzyme-linked immunosorbent assay (ELISA) revealed a significant increase in expression levels of cGMP and protein kinase G-1 (PKG-1) and the activation of nuclear factor-κB (NF-κB) p65. This study demonstrates that combination of VEGF and PA can increase the permeability of the BTB by a paracellular pathway (downregulation of occludin and claudin-5) and a transcellular pathway (upregulation of caveolin-1 and caveolin-2) and that the cGMP/PKG/NF-κB signal pathway might be involved in the modulation process.

Low-dose endothelial monocyte-activating polypeptide-ii increases permeability of blood-tumor barrier by caveolae-mediated transcellular pathway

Low-dose endothelial monocyte-activating polypeptide-II (EMAP-II) can selectively increase blood-tumor barrier (BTB) permeability via the paracellular pathway. The role of the transcellular pathway in this process is unclear. This study was conducted to evaluate the potential involvement of the transcellular pathway in EMAP-II-induced opening of the BTB and to identify the associated mechanisms. Evans blue extravasation test was used to measure changes in BTB permeability after EMAP-II (80 ng/kg) administration in a rat model of C6 glioma. Changes in the quantity of pinocytotic vesicles in rat brain microvascular endothelial cells (BMECs) were observed using transmission electron microscopy. Reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry assays were performed to detect the expression of the caveolar structural proteins, caveolin-1 and caveolin-2, in BMECs. Alterations in the expression of phospho (p)-Src, p-caveolin-1, and p-caveolin-2 and the activity of RhoA also were measured. Effects of tyrosine kinase inhibition on EMAP-II-induced RhoA/Rho kinase activations and tyrosine kinase, RhoA, or Rho kinase inhibition on EMAP-II-induced caveolin-1 and caveolin-2 phosphorylation were determined by inhibition studies. One hour after EMAP-II administration, the quantity of pinocytotic vesicles in BMECs increased markedly, consistent with changes in BTB permeability. The expression levels of caveolin-1, caveolin-2, p-caveolin-1, and p-caveolin-2 in BMECs also were significantly increased at 1 h. The peak expression level of p-Src and the peak activity of RhoA occurred at 0.25 and 0.5 h, respectively. Inhibition of tyrosine kinase significantly diminished the activities of RhoA and Rho kinase induced by EMAP-II. In addition, EMAP-II-induced phosphorylation of caveolin-1 and caveolin-2 was completely blocked by inhibition of tyrosine kinase, RhoA, or Rho kinase. We suggest that low-dose EMAP-II can induce BTB hyperpermeability via the transcellular pathway, which is associated with phosphorylation and upregulation of caveolin-1 and caveolin-2 and involves the tyrosine kinase/RhoA/Rho kinase signaling pathway.

Prediction and validation of gene-disease associations using methods inspired by social network analyses

Correctly identifying associations of genes with diseases has long been a goal in biology. With the emergence of large-scale gene-phenotype association datasets in biology, we can leverage statistical and machine learning methods to help us achieve this goal. In this paper, we present two methods for predicting gene-disease associations based on functional gene associations and gene-phenotype associations in model organisms. The first method, the Katz measure, is motivated from its success in social network link prediction, and is very closely related to some of the recent methods proposed for gene-disease association inference. The second method, called Catapult (Combining dATa Across species using Positive-Unlabeled Learning Techniques), is a supervised machine learning method that uses a biased support vector machine where the features are derived from walks in a heterogeneous gene-trait network. We study the performance of the proposed methods and related state-of-the-art methods using two different evaluation strategies, on two distinct data sets, namely OMIM phenotypes and drug-target interactions. Finally, by measuring the performance of the methods using two different evaluation strategies, we show that even though both methods perform very well, the Katz measure is better at identifying associations between traits and poorly studied genes, whereas Catapult is better suited to correctly identifying gene-trait associations overall.

The authors want to thank Jon Laurent and Kris McGary for some of the data used, and Li and Patra for making their code available. Most of Ambuj Tewari's contribution to this work happened while he was a postdoctoral fellow at the University of Texas at Austin.

Forced exercise enhances functional recovery after focal cerebral ischemia in spontaneously hypertensive rats

Caveolin is the principal protein of caveolae and has been implicated in the pathogenesis of cerebral ischemia. To investigate whether changed expression of caveolins has a pivotal role in focal cerebral ischemia, we induced middle cerebral artery occlusion (MCAo)-reperfusion and examined expression of caveolins, inflammatory activation markers, and mediators of autophagic cell death. We also treated MCAo rats with forced exercise to determine its effects on neurological outcome. Particularly, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were used to compare the effects of hypertension on focal cerebral ischemia. All MCAo groups showed neurological deficiencies, motor dysfunction, and disruption of balancing ability; however, these pathological changes were more severe in SHR than WKY rats. Expression of caveolins was decreased in MCAo brain tissue, whereas the levels of iNOS and glial fibrillary acidic protein (GFAP) increased. Additionally, LC3-II and beclin-1 levels were elevated in the MCAo groups. Forced exercise attenuated both molecular and behavioral changes in MCAo animals, but SHR rats showed delayed functional recovery and residual molecular changes when compared to WKY rats. These results suggest that forced exercise may be beneficial for promoting functional recovery following cerebral ischemia through caveolin-dependent mechanisms or interactions between caveolins and these signaling molecules in ischemic brain regions.

Vascular endothelial growth factor increases permeability of the blood-tumor barrier via caveolae-mediated transcellular pathway

The first goal of this study was to determine the effect of vascular endothelial growth factor (VEGF) on permeability of the blood-tumor barrier (BTB). The second goal was to determine possible cellular mechanisms by which VEGF increases permeability of the BTB. In the rat C6 glioma model, the permeability of the BTB was significantly increased after VEGF injection at dose of 0.05 ng/g and reached its peak at 45 min. Meanwhile, we observed that the density of pinocytotic vesicles of brain microvascular endothelial cells (BMECs) in the BTB increased dramatically by transmission electron microscopy. The immunohistochemistry and western blot analysis revealed that the expression level of caveolae structure proteins caveolin-1 and caveolin-2 in BMECs was increased after VEGF injection, peaked at 45 min, and then decreased to the untreated level. The time peak of expression level of caveolin-1 and caveolin-2 was identical with the peak time of permeability of the BTB and the density of pinocytotic vesicles. All of these results strongly indicated that VEGF increased permeability of the BTB caused by enhancement of the density of pinocytotic vesicles, and the molecular mechanism might be associated with upregulated expression of caveolin-1 and caveolin-2.

Kallikrein-related peptidase 6 in Alzheimer's disease and vascular dementia

Human kallikrein-related peptidase 6 (KLK6) is highly expressed in the central nervous system. Although the physiological roles of this serine protease are unknown, in vitro substrates include amyloid precursor protein and components of the extracellular matrix, which are altered in neurological disease, particularly Alzheimer's disease (AD). We have compared KLK6 expression in post-mortem brain tissue in AD, vascular dementia (VaD) and controls. We studied the distribution of KLK6 in the temporal cortex and white matter by immunohistochemistry, and measured KLK6 mRNA and protein levels in the frontal and temporal cortex from 15 AD, 15 VaD and 15 control brains. Immunohistochemistry showed KLK6 to be restricted to endothelial cells. After adjustment for variations in vessel density by measurement of factor VIII-related antigen, we found KLK6 protein and mRNA levels to be significantly decreased in the frontal but not the temporal cortex in AD. In VaD, KLK6 protein level was significantly increased in the frontal cortex. Our findings suggest that an altered KLK6 expression may contribute to vascular abnormalities in AD and VaD.

Bradykinin increases the permeability of the blood-tumor barrier by the caveolae-mediated transcellular pathway

Bradykinin (BK) increases the permeability of the blood-tumor barrier (BTB) selectively through the transcellular pathway; however, the role of the caveolae structural proteins caveolin-1 and caveolin-2 in this process has not been precisely elucidated. Thus, this study was performed to examine whether caveolin-1 and caveolin-2 are involved in the regulation of this biological process. In the rat brain glioma (C6) model, western blot, immunohistochemistry, and immunofluorescence assays were used to detect the expression levels and locations of caveolin-1 and caveolin-2. The results showed that caveolin-1 and caveolin-2 levels increased 5 min after BK infusion, peaked at 15 min, and then decreased. Meanwhile, Evans blue (EB) assay showed that the permeability of the BTB increased significantly after BK infusion. In our previous study we demonstrated that the quantity of pinocytotic vesicles in the endothelial cells was dramatically augmented 15 min after BK infusion. The time point at which changes of caveolin-1 and caveolin-2 reached their peak was the same as that at which EB and the quantity of pinocytotic vesicles reached their peaks. This led to the conclusion that the BK-mediated BTB permeability increase resulting from augmentation of the quantity of pinocytotic vesicles (transcellular pathway) is associated with the significantly up-regulated expression of caveolin-1 and caveolin-2. This study thus contributes further to elucidating the molecular mechanism of opening of the BTB by BK and provides a theoretical basis for clinical application of BK.

Caveolae contribute to the apoptosis resistance induced by the alpha(1A)-adrenoceptor in androgen-independent prostate cancer cells

BACKGROUND

During androgen ablation prostate cancer cells' growth and survival become independent of normal regulatory mechanisms. These androgen-independent cells acquire the remarkable ability to adapt to the surrounding microenvironment whose factors, such as neurotransmitters, influence their survival. Although findings are becoming evident about the expression of alpha(1A)-adrenoceptors in prostate cancer epithelial cells, their exact functional role in androgen-independent cells has yet to be established. Previous work has demonstrated that membrane lipid rafts associated with key signalling proteins mediate growth and survival signalling pathways in prostate cancer cells.

METHODOLOGY/PRINCIPAL FINDINGS

In order to analyze the membrane topology of the alpha(1A)-adrenoceptor we explored its presence by a biochemical approach in purified detergent resistant membrane fractions of the androgen-independent prostate cancer cell line DU145. Electron microscopy observations demonstrated the colocalization of the alpha(1A)-adrenoceptor with caveolin-1, the major protein component of caveolae. In addition, we showed that agonist stimulation of the alpha(1A)-adrenoceptor induced resistance to thapsigargin-induced apoptosis and that caveolin-1 was necessary for this process. Further, immunohistofluorescence revealed the relation between high levels of alpha(1A)-adrenoceptor and caveolin-1 expression with advanced stage prostate cancer. We also show by immunoblotting that the TG-induced apoptosis resistance described in DU145 cells is mediated by extracellular signal-regulated kinases (ERK).

CONCLUSIONS/SIGNIFICANCE

In conclusion, we propose that alpha(1A)-adrenoceptor stimulation in androgen-independent prostate cancer cells via caveolae constitutes one of the mechanisms contributing to their protection from TG-induced apoptosis.

Mechanisms of the increase in the permeability of the blood-tumor barrier obtained by combining low-frequency ultrasound irradiation with small-dose bradykinin

The research was conducted to study the characteristics of the noninvasive, reversible, targeted opening of the blood-brain barrier (BBB) by use of low-frequency ultrasound (LFU) irradiation and the selective opening of the blood-tumor barrier (BTB) by intracarotid infusion of bradykinin (BK) in small-dose, with the objective of exploring maximum opening of the BTB by combining LFU irradiation with BK infusion. Thus, it provides new therapeutic strategies for targeted transport of macromolecular or granular drugs to the brain. By using the rat C6 glioma model it was shown that extravasation of Evans blue (EB) through the BTB was significantly increased by combining LFU irradiation (frequency = 1.0 MHz, power = 12 mW, duration = 20 s) with intracarotid small-dose BK infusion, compared with utilizing the two methods separately. By transmission electron microscopy (TEM) we observed that this combination significantly increased the number of pinocytotic vesicles of brain microvascular endothelial cells (BMECs) in the BTB. An even more significant increase was observed by using RT-PCR, western blot, immunohistochemistry, and immunofluorescence to detect mRNA and changes of expression of the caveolae structure proteins caveolin-1 and caveolin-2 of BMECs. In summary, this research concludes that LFU irradiation and small-dose BK together selectively enhance the permeability of the BTB and increase the number of pinocytic vesicles of BMECs to a maximum. Significant up-regulation of the level of expression of caveolae structure proteins caveolin-1 and caveolin-2 might be the molecular mechanism of the co-enhanced endocytotic transport by BMECs. Thus, this research provides new therapeutic strategies for targeted transport of macromolecular drugs and the design of drugs.

Genetic dissection of the mouse brain using high-field magnetic resonance microscopy

Magnetic resonance (MR) imaging has demonstrated that variation in brain structure is associated with differences in behavior and disease state. However, it has rarely been practical to prospectively test causal models that link anatomical and functional differences in humans. In the present study we have combined classical mouse genetics with high-field MR to systematically explore and test such structure-functional relations across multiple brain regions. We segmented 33 regions in two parental strains-C57BL/6J (B) and DBA/2J (D)-and in nine BXD recombinant inbred strains. All strains have been studied extensively for more than 20 years using a battery of genetic, functional, anatomical, and behavioral assays. We compared levels of variation within and between strains and sexes, by region, and by system. Average within-strain variation had a coefficient of variation (CV) of 1.6% for the whole brain; while the CV ranged from 2.3 to 3.6% for olfactory bulbs, cortex and cerebellum, and up to approximately 18% for septum and laterodorsal thalamic nucleus. Variation among strain averages ranged from 6.7% for cerebellum, 7.6% for whole brain, 9.0% for cortex, up to approximately 26% for the ventricles, laterodorsal thalamic nucleus, and the interpeduncular nucleus. Heritabilities averaged 0.60+/-0.18. Sex differences were not significant with the possible (and unexpected) exception of the pons ( approximately 20% larger in males). A correlation matrix of regional volumes revealed high correlations among functionally related parts of the CNS (e.g., components of the limbic system), and several high correlations between regions that are not anatomically connected, but that may nonetheless be functionally or genetically coupled.