Regulation of rat HspB5/alphaB-Crystallin by microRNAs miR-101a-3p, miR-140-5p, miR-330-5p, and miR-376b-3p.

HspB5/alphaB-crystallin is an ubiquitously expressed member of the small heat shock protein family which help cells to survive cellular stress conditions and are also implicated in neurodegenerative diseases. MicroRNAs are small non-coding RNAs fine-tuning protein expression mainly by inhibiting the translation of target genes. Our earlier finding of an increase in HspB5/alphaB-crystallin protein amount after heat shock in rat hippocampal neurons without a concomitant increase of mRNA prompted us to look for microRNAs as a posttranscriptional regulatory mechanism.

HspB5/αB-crystallin phosphorylation at S45 and S59 is essential for protection of the dendritic tree of rat hippocampal neurons.

Rarefaction of the dendritic tree leading to neuronal dysfunction is a hallmark of many neurodegenerative diseases and we have shown previously that heat shock protein B5 (HspB5)/αB-crystallin is able to increase dendritic complexity in vitro. The aim of this study was to investigate if this effect is also present in vivo, if HspB5 can counteract dendritic rarefaction under pathophysiological conditions and the impact of phosphorylation of HspB5 in this process. HspB5 and eight mutants inhibiting or mimicking phosphorylation at the three phosphorylation sites serine (S)19, S45, and S59 were over-expressed in cultured rat hippocampal neurons with subsequent investigation of the complexity of the dendritic tree.

Integration of Scientific Competence into Gross Anatomy Teaching Using Poster Presentations: Feasibility and Perception among Medical Students.

Scientific competences as defined in the German competency framework describes the ability to think independently and act scientifically, and forms a central component of medical education. This report describes its integration into anatomical teaching. On the basis of the findings in dissection courses from two consecutive years, students worked on either a case report (n = 70) or an original work (n=6) in the format of a scientific poster while learning to use primary literature.

The Use of a Mobile Learning Tool by Medical Students in Undergraduate Anatomy and its Effects on Assessment Outcomes.

Hand-held devices have revolutionized communication and education in the last decade. Consequently, mobile learning (m-learning) has become popular among medical students. Nevertheless, there are relatively few studies assessing students' learning outcomes using m-learning devices.

-nitrosylation of VASP at cysteine 64 mediates the inflammation-stimulated increase in microvascular permeability.

We tested the hypothesis that platelet-activating factor (PAF) induces -nitrosylation of vasodilator-stimulated phosphoprotein (VASP) as a mechanism to reduce microvascular endothelial barrier integrity and stimulate hyperpermeability. PAF elevated -nitrosylation of VASP above baseline levels in different endothelial cells and caused hyperpermeability. To ascertain the importance of endothelial nitric oxide synthase (eNOS) subcellular location in this process, we used ECV-304 cells transfected with cytosolic eNOS (GFPeNOSG2A) and plasma membrane eNOS (GFPeNOSCAAX).

Water transport through the intestinal epithelial barrier under different osmotic conditions is dependent on LI-cadherin trans-interaction.

In the intestine water has to be reabsorbed from the chymus across the intestinal epithelium. The osmolarity within the lumen is subjected to high variations meaning that water transport often has to take place against osmotic gradients. It has been hypothesized that LI-cadherin is important in this process by keeping the intercellular cleft narrow facilitating the buildup of an osmotic gradient allowing water reabsorption.

Upregulation and phosphorylation of HspB1/Hsp25 and HspB5/αB-crystallin after transient middle cerebral artery occlusion in rats.

Ischemic stroke leads to cellular dysfunction, cell death, and devastating clinical outcomes. The cells of the brain react to such a cellular stress by a stress response with an upregulation of heat shock proteins resulting in activation of endogenous neuroprotective capacities. Several members of the family of small heat shock proteins (HspBs) have been shown to be neuroprotective.

The growing world of small heat shock proteins: from structure to functions.

Small heat shock proteins (sHSPs) are present in all kingdoms of life and play fundamental roles in cell biology. sHSPs are key components of the cellular protein quality control system, acting as the first line of defense against conditions that affect protein homeostasis and proteome stability, from bacteria to plants to humans. sHSPs have the ability to bind to a large subset of substrates and to maintain them in a state competent for refolding or clearance with the assistance of the HSP70 machinery.

The Impact of Small Heat Shock Proteins (HspBs) in Alzheimer's and Other Neurological Diseases.

Background: Heat shock proteins are powerful endogenous cytoprotective proteins which help cells to survive recurrent cellular stress events. Identifying the underlying molecular mechanisms and molecular targets is especially interesting since it may help to develop new therapeutic strategies for the treatment of diseases.

Objective: This review will focus on the group of small heat shock proteins, also named HspBs.

HspB5/αB-crystallin increases dendritic complexity and protects the dendritic arbor during heat shock in cultured rat hippocampal neurons.

The small heat shock protein ΗspΒ5 (αB-crystallin) exhibits generally cytoprotective functions and possesses powerful neuroprotective capacity in the brain. However, little is known about the mode of action of ΗspΒ5 or other members of the HspB family particularly in neurons. To get clues of the neuronal function of HspBs, we overexpressed several HspBs in cultured rat hippocampal neurons and investigated their effect on neuronal morphology and stress resistance.

Induction and phosphorylation of the small heat shock proteins HspB1/Hsp25 and HspB5/αB-crystallin in the rat retina upon optic nerve injury.

Several eye diseases are associated with axonal injury in the optic nerve, which normally leads to degeneration of retinal ganglion cells (RGCs) and subsequently to loss of vision. There is experimental evidence that some members of the small heat shock protein family (HspBs) are upregulated upon optic nerve injury (ONI) in the retina and sufficient to promote RGC survival. These data raise the question as to whether other family members may play a similar role in this context.

Reaction of small heat-shock proteins to different kinds of cellular stress in cultured rat hippocampal neurons.

Upregulation of small heat-shock proteins (sHsps) in response to cellular stress is one mechanism to increase cell viability.We previously described that cultured rat hippocampal neurons express five of the 11 family members but only upregulate two of them (HspB1 and HspB5) at the protein level after heat stress. Since neurons have to cope with many other pathological conditions, we investigated in this study the expression of all five expressed sHsps on mRNA and protein level after sublethal sodium arsenite and oxidative and hyperosmotic stress.

αB-crystallin/HspB5 regulates endothelial-leukocyte interactions by enhancing NF-κB-induced up-regulation of adhesion molecules ICAM-1, VCAM-1 and E-selectin.

αB-crystallin is a small heat shock protein, which has pro-angiogenic properties by increasing survival of endothelial cells and secretion of vascular endothelial growth factor A. Here we demonstrate an additional role of αB-crystallin in regulating vascular function, through enhancing tumor necrosis factor α (TNF-α) induced expression of endothelial adhesion molecules involved in leukocyte recruitment. Ectopic expression of αB-crystallin in endothelial cells increases the level of E-selectin expression in response to TNF-α, and enhances leukocyte-endothelial interaction in vitro.

Different pH-dependencies of the two synaptic adhesion molecules N-cadherin and cadherin-11 and the possible functional implication for long-term potentiation.

Ca(2+) -dependent adhesion molecules, cadherins, localised at synaptic sites are critically involved in long-term potentiation (LTP). N-cadherin is thought to promote LTP whereas cadherin-11 seems to counteract LTP. Since high synaptic activity is accompanied by local transient changes of the pH in the synaptic cleft, we studied whether the binding activity of cadherins is dependent on the pH and whether this might play a role during LTP.

Phosphorylation-dependent subcellular localization of the small heat shock proteins HspB1/Hsp25 and HspB5/αB-crystallin in cultured hippocampal neurons.

The so-called stress response involving upregulation of heat shock proteins (Hsps) is a powerful mechanism of cells to deal with harmful conditions to which they are exposed throughout life, such as hyperthermia, hypoxia or oxidative stress. To gain more information about the molecular targets by which HspB1 (Hsp25) and HspB5 (αB-crystallin) might exert their neuroprotective effect we investigated the subcellular localization of unphosphorylated and phosphorylated HspB1 and B5 in neurons by immunocytochemistry and subcellular fractionation. In cultured hippocampal neurons, the unphosphorylated forms of both Hsps were localized in the perikaryon and nucleus, whereas the phosphorylated forms were recruited into neuronal processes.

Different regulation of N-cadherin and cadherin-11 in rat hippocampus.

Cadherin-mediated specific cell adhesion is an important process in brain development as well as in synaptic plasticity in the adult brain. In this study the authors quantified mRNA levels of N-cadherin and cadherin-11 in different brain regions for the first time. In hippocampus N-cadherin mRNA levels were very high at embryonic stages and decreased during further development, whereas cadherin-11 mRNA levels were highest at postnatal stages.

Differential expression and induction of small heat shock proteins in rat brain and cultured hippocampal neurons.

The so-called stress response involving up-regulation of heat shock proteins (Hsps) is a powerful mechanism of cells to deal with harmful conditions to which they are exposed throughout life, such as hyperthermia, hypoxia, or oxidative stress. Some members of the group of small Hsps (sHsps) seem to play a neuroprotective role in the brain. Here we analyzed the expression of all 11 sHsps in the rat brain by using RNA in situ hybridization and quantitative real-time RT-PCR.

Protein kinase C-mediated endothelial barrier regulation is caveolin-1-dependent.

Protein kinase C (PKC) is activated in response to various inflammatory mediators and contributes significantly to the endothelial barrier breakdown. However, the mechanisms underlying PKC-mediated permeability regulation are not well understood. We prepared microvascular myocardial endothelial cells from both wild-type (WT) and caveolin-1-deficient mice.

Occludin as direct target for glucocorticoid-induced improvement of blood-brain barrier properties in a murine in vitro system.

Homeostasis of the central nervous system (CNS) microenvironment is essential for its normal function. It is maintained by the blood-brain barrier (BBB) which regulates the transport of molecules from blood into brain and backwards. The integrity of the BBB is compromised in many disorders of the human CNS; therapeutical strategies for several of these diseases include treatment with glucocorticoids, but the molecular basis of how glucocorticoids regulate BBB permeability is not understood.

Comparison of the small heat shock proteins alphaB-crystallin, MKBP, HSP25, HSP20, and cvHSP in heart and skeletal muscle.

Seven members of the small heat shock protein (sHSP) family are exceptional with respect to their constitutive high abundance in muscle tissue. It has been suggested that sHSPs displaying chaperone-like properties may stabilize myofibrillar proteins during stress conditions and prevent them from loss of function. In the present study five sHSPs (alphaB-crystallin, MKBP, HSP25, HSP20, and cvHSP) were investigated with respect to similarities and differences of their expression in heart and skeletal muscle under normal and ischemic conditions.

Role of transglutaminase 1 in stabilisation of intercellular junctions of the vascular endothelium.

Microvascular endothelial monolayers from mouse myocardium (MyEnd) cultured for up to 5 days postconfluency became increasingly resistant to various barrier-compromising stimuli such as low extracellular Ca(2+) and treatment with the Ca(2+) ionophore A23187 and with the actin depolymerising compound cytochalasin D. In contrast, microvascular endothelial monolayers from mouse lung microvessels (PulmEnd) remained sensitive to these conditions during the entire culture period which corresponds to the well-known in vivo sensitivity of the lung microvasculature to Ca(2+) depletion and cytochalasin D treatment. One molecular difference between pulmonary and myocardial endothelial cells was found to be transglutaminase 1 (TGase1) which is strongly expressed in myocardial endothelial cells but is absent from pulmonary endothelial cells.

Ca2+ dependency of N-cadherin function probed by laser tweezer and atomic force microscopy.

This study was undertaken to provide a biophysical basis for the hypothesis that activity-dependent modulation of cadherin-mediated adhesion by transient changes of extracellular calcium ([Ca2+]e) is causally involved in coordination of synaptic plasticity. Characterization of homophilic N-cadherin binding by atomic force microscopy and laser tweezer trapping of N-cadherin-coated microbeads attached to the cell surface of cultured neuronal cells showed that adhesive activity of N-cadherin is effectively regulated between 0.3 and 0.

Cadherin function probed by laser tweezer and single molecule fluorescence in vascular endothelial cells.

In endothelial monolayers agonist-induced influx of Ca(2+) and activities of the actin cytoskeleton have been shown to be crucially involved in regulation of barrier properties. By laser tweezer application we demonstrated that the strength of adhesion of VE-cadherin-coated microspheres to the surface of cultured endothelial monolayers is significantly reduced by treatment with two well-established permeability-increasing compounds, cytochalasin D and the Ca(2+)-ionophore A23187, which shows that both compounds directly affect cadherin-mediated adhesion. Cytochalasin D and A23187 caused considerable decay of F-actin (30-60%).