Hypoxic preconditioning promotes the translocation of protein kinase C ε binding with caveolin-3 at cell membrane not mitochondrial in rat heart

Deletion of the Neuronal Transcription Factor Satb1 Induced Disturbance of the Kinome and Mechanisms of Hypoxic Preconditioning

Genetic disorders affecting the functioning of the brain lead not only to the development of numerous hereditary diseases but also to the development of neurodegenerative and cognitive disorders. The result of this may be the disability of part of the able-bodied population. Almost all pathological states of the brain are characterized by serious defects in the intracellular and intercellular signaling of neurons and glial cells. At the same time, the mechanisms of disruption of these signaling cascades are not well understood due to the large number of molecules, including transcription factors that, when mutated, cause brain malformations. The transcription factor Satb1 is one of the least studied factors in the cerebral cortex, and the effects of its deletion in the postnatal brain are practically not studied. Hyperexcitability of neurons is observed in many genetic diseases of the nervous system (Hirschsprung's disease, Martin-Bell syndrome, Huntington's disease, Alzheimer's, etc.), as well as in ischemic brain phenomena and convulsive and epileptic conditions of the brain. In turn, all these disorders of brain physiology are associated with defects in intracellular and intercellular signaling and are often the result of genetic disorders. Using Satb1 mutant mice and calcium neuroimaging, we show that Satb1 deletion in projection neurons of the neocortex causes downregulation of protein kinases PKC, CaMKII, and AKT/PKB, while a partial deletion does not cause a dramatic disruption of kinome and Ca2+ signaling. As a result, Satb1-null neurons are characterized by increased spontaneous Ca2+ activity and hyperexcitability when modeling epileptiform activity. As a result of the deletion of Satb1, preconditioning mechanisms are disrupted in neurons during episodes of hypoxia. This occurs against the background of increased sensitivity of neurons to a decrease in the partial pressure of oxygen, which may indicate the vulnerability of neuronal networks and be accompanied by impaired expression of the Satb1 transcription factor. Here, we show that Satb1 deletion impaired the expression of a number of key kinases and neuronal hyperexcitation in models of epileptiform activity and hypoxia.

IKACh is constitutively active via PKC epsilon in aging mediated atrial fibrillation

Atrial fibrillation (AF), the most common abnormal heart rhythm, is a major cause for stroke. Aging is a significant risk factor for AF; however, specific ionic pathways that can elucidate how aging leads to AF remain elusive. We used young and old wild-type and PKC epsilon- (PKCϵ) knockout mice, whole animal, and cellular electrophysiology, as well as whole heart, and cellular imaging to investigate how aging leads to the aberrant functioning of a potassium current, and consequently to AF facilitation. Our experiments showed that knocking out PKCϵ abrogates the effects of aging on AF by preventing the development of a constitutively active acetylcholine sensitive inward rectifier potassium current (IKACh). Moreover, blocking this abnormal current in the old heart reduces AF inducibility. Our studies demonstrate that in the aging heart, IKACh is constitutively active in a PKCϵ-dependent manner, contributing to the perpetuation of AF.

The roles of PKC-δ and PKC-ε in myocardial ischemia/reperfusion injury

Ischemia and reperfusion (I/R) cause a reduction in arterial blood supply to tissues, followed by the restoration of perfusion and consequent reoxygenation. The reestablishment of blood flow triggers further damage to ischemic tissue through reactive oxygen species (ROS) accumulation, interference with cellular ion homeostasis, opening of mitochondrial permeability transition pores (mPTPs) and promotion of cell death (apoptosis or necrosis). PKC-δ and PKC-ε, belonging to a family of serine/threonine kinases, have been demonstrated to play important roles during I/R injury in cardiovascular diseases. However, the cardioprotective mechanisms of PKC-δ and PKC-ε in I/R injury have not been elaborated until now. This article discusses the roles of PKC-δ and PKC-ε during myocardial I/R in redox regulation (redox signaling and oxidative stress), cell death (apoptosis and necrosis), Ca²⁺ overload, and mitochondrial dysfunction.

A Novel Role of A2AR in the Maintenance of Intestinal Barrier Function of Enteric Glia from Hypoxia-Induced Injury by Combining with mGluR5

During acute intestinal ischemia reperfusion (IR) injury, the intestinal epithelial barrier (IEB) function is often disrupted. Enteric glial cells (EGCs) play an important role in maintaining the integrity of IEB functions. However, how EGCs regulate IEB function under IR stimulation is unknown. The present study reveals that the adenosine A_2A receptor (A_2AR) is important for mediating the barrier-modulating roles of EGCs. A_2AR knockout (KO) experiments revealed more serious intestinal injury in A_2AR KO mice than in WT mice after IR stimulation. Moreover, A_2AR expression was significantly increased in WT mice when challenged by IR. To further investigate the role of A_2AR in IEB, we established an in vitro EGC-Caco-2 co-culture system. Hypoxia stimulation was used to mimic the process of in vivo IR. Treating EGCs with the CGS21680 A_2AR agonist attenuated hypoxia-induced intestinal epithelium damage through up-regulating ZO-1 and occludin expression in cocultured Caco-2 monolayers. Furthermore, we showed that A_2AR and metabotropic glutamate receptor 5 (mGluR5) combine to activate the PKCα-dependent pathway in conditions of hypoxia. This study shows, for the first time, that hypoxia induces A_2AR-mGluR5 interaction in EGCs to protect IEB function via the PKCα pathway.

Prenatal hypoxia attenuated contraction of offspring coronary artery associated with decreased PKCβ Ser660 phosphorylation and intracellular calcium

AIMS

Prenatal hypoxia (PH) could affect peripheral vascular tone of the offspring, thus increasing the risk of cardiovascular diseases in adult. However, it's still unknown whether functions of coronary arteries (COA) in adult offspring would be influenced by PH. The present study aimed at effects of PH on vascular tone of COA and its related mechanisms.

METHODS

Coronary arteries of adult offspring exposed to hypoxic or normoxic circumstances during gestational day 5 to 21 were collected. Wire myograph system, whole-cell patch clamp technique, IonOptix MyoCam system, PCR, and western blot were used to detect vascular function of adult offspring COA.

KEY FINDINGS

PH significantly attenuated serotonin- and phorbol 12, 13-dibutyrate (PDBu)-induced constriction. Iberiotoxin potentiated PDBu-induced constriction and the effect was augmented by PH, however, no significant differences were found in whole-cell BK_Ca channel currents and its protein expression. Nifedipine inhibited PDBu-mediated constriction and the inhibitory effect was reduced in PH group, and whole-cell calcium channel current was decreased in offspring COA. Besides, PH reduced the capability of calcium release from the endoplasmic reticulum in COA. The phosphorylated PKCβ protein expression at Ser⁶⁶⁰ site, not Thr⁶⁴¹ site, was significantly decreased in PH offspring. Chronic hypoxia during pregnancy attenuated PDBu-mediated constriction in offspring COA, presumably through decreased phosphorylated PKCβ at serine⁶⁶⁰ sites and decreased intracellular calcium-related weaker PKC activation.

SIGNIFICANCE

The findings provided new information on the influence of prenatal hypoxia on COA, and suggested potential use of PKCβ-serine⁶⁶⁰ for early prevention of coronary heart diseases in developmental origins.

Nanoscale Technologies in Highly Sensitive Diagnosis of Cardiovascular Diseases

Cardiovascular diseases (CVD) are the leading cause of death and morbidity in the world and are a major contributor to healthcare costs. Although enormous progress has been made in diagnosing CVD, there is an urgent need for more efficient early detection and the development of novel diagnostic tools. Currently, CVD diagnosis relies primarily on clinical symptoms based on molecular imaging (MOI) or biomarkers associated with CVDs. However, sensitivity, specificity, and accuracy of the assay are still challenging for early-stage CVDs. Nanomaterial platform has been identified as a promising candidate for improving the practical usage of diagnostic tools because of their unique physicochemical properties. In this review article, we introduced cardiac biomarkers and imaging techniques that are currently used for CVD diagnosis. We presented the applications of various nanotechnologies on diagnosis within cardiac immunoassays (CIAs) and molecular imaging. We also summarized and compared different cardiac immunoassays based on their sensitivities and working ranges of biomarkers.

Membrane TLR9 Positive Neutrophil Mediated MPLA Protects Against Fatal Bacterial Sepsis

Sepsis is a major cause of patient mortality and morbidity from bacterial infections. Although neutrophils are known to be important in the development of sepsis, how distinctive neutrophil subtypes regulate inflammatory processes involved in septicemia remains unclear. Preconditioning protects organisms against subsequent higher-dose exposures to the same, or even different, stimuli. Several studies have reported various effects of preconditioning on immune cells. However, the detailed mechanisms underlying neutrophil-mediated protection through preconditioning in sepsis remain unknown.

Methods: Flow cytometry was conducted to sort the mice peritoneal lavage cells and the blood samples from patients with sepsis. Western blotting and ELISA were carried out to elucidate the expression of TLR9 signal transduction pathway proteins. Histological analysis was used to assess the effect of InP on intestine and liver structure in tlr9^-/- and cav-1^-/- mice. Fluorescence microscopy, Co-IP, and FRET were carried out to determine the association of TLR9 with Cav-1.

Results: We show that membrane toll-like receptor-9 positive (mTLR9⁺) neutrophils exert a protective effect against fatal bacterial infections through the process of inflammatory preconditioning (InP). InP, which occurs in the setting of a low-dose bacterial challenge, active ingredient is Monophosphoryl lipid A (MPLA), triggers the membrane translocation of TLR9 from the neutrophil cytosol, where it binds to Cav-1. Our findings showed that InP enables TLR9 to facilitate MyD88-mediated TRAF3 and IRF3 signal transduction. Depletion of either TLR9 or Cav-1 largely eliminates the neutrophil-mediated InP effect in sepsis models in vitro and in vivo. Further, examination of clinical samples from patients with sepsis showed that clinical outcomes and likelihood of recovery are closely correlated with mTLR9 and Cav-1 expression in circulating neutrophils.

Conclusion: These results demonstrate that the TLR9-Cav-1 axis is a critical signaling pathway involved in the regulation of neutrophil-dependent MPLA mediated InP, and the presence of mTLR9⁺ neutrophils could be an attractive indicator of clinical outcomes in bacterial sepsis that could be further explored as a potential therapeutic target.

Role of IRF4 in the Protection of Metformin-Mediated Sepsis Myocarditis

AIMS

Metformin has been shown to play a protective role in diabetes. However, we found that metformin could mediate myocardial protection. Given that protein kinase C eplison (PKCε) and interferon regulatory factor 4 (IRF4) are critical for cardioprotection signaling. And measurement of fluorescence resonance energy transfer (FRET) efficiency can be used to determine whether 2 fluorophores are within a certain distance of each other. So we sought to determine whether metformin promotes PKCε/IRF4 activation by FRET.

METHODS AND RESULTS

The study built a mouse septic myocarditis model by intraperitoneal injection of Escherichia coli; thus, it provides valuable experimental data for the diagnosis and treatment of septic myocarditis. And cellular model of cardiomyocyte damage from adult rat cardiacmyocytes or H9c2 cells was induced by lipopolysaccharide employed to examine PKCε by molecular, biochemical, and cellular imaging analysis. Life span of septic myocarditis mouse was significantly prolonged by metformin. Metformin also decreased transforming growth factor β level and increased interleukin-10 productions. The FRET analysis in H9c2 cells suggested that there is prominent FRET signal for PKCε along in mitochondrial by metformin.

CONCLUSION

We demonstrate that metformin promotes rapid association of PKCε with IRF4 at mitochondrial microdomain of cardiac myocytes and PKCε via direct molecular interaction with IRF4. This regulatory mechanism may play an important role in cardioprotection.

The Effect of Photothermal Therapy on Osteosarcoma With Polyacrylic Acid-Coated Gold Nanorods

Background:

Polyacrylic acid (PAA)–coated gold nanorods (GNRs) were prepared in this research, and then the structure, stability, temperature increment efficiency, and biocompatibility of GNRs@PAA were detected.

Methods:

It was demonstrated that GNRs@PAA coupled with an 808 nm laser had superior efficiency of hyperthermia therapy for MG63 human osteosarcoma cell.

Results:

The mechanism of photothermal therapy of GNRs@PAA was explored, and it was proved that damaged cell membrane and DNA integration caused cell apoptosis and death, and the cell apoptosis rate had been obviously promoted by in vitro photothermal therapy which exhibited time–dose dependence.

Conclusion:

The results demonstrated that the GNRs@PAA could be a promising candidate for phototherapeutic applications in human osteosarcoma.

MicroRNA-143 promotes cardiac ischemia-mediated mitochondrial impairment by the inhibition of protein kinase Cepsilon

The cardioprotection of protein kinase Cepsilon (PKCε) against myocardial infarction (MI) mediated by its anti-apoptotic property and underlying mechanism of targeted regulation by microRNA (miRNA) are not established. MI-induced injury, PKCε expression, and targeted regulation of miRNA-143 (miR-143) to PKCε have been evaluated using animal MI and cellular hypoxic models conjugated with series of state-of-art molecular techniques. The results demonstrated that PKCε significantly downregulated along with increased infarcted area and apoptotic and necrotic damage in MI model, and the targeted relationship and potential binding profile were established between miR-143 and PKCε. Both in vivo and in vitro ischemic tests showed that miR-143 induced apoptosis and necrosis, which was reversed by antagomiR-143 or AMO-143. The upregulation of miR-143 by transfection of miR-143 in vitro also induced cell loss, and this effect of miR-143 was completely reversed by co-transfection of miR-143 with AMO-143. The identically deleterious action of miR-143 on mitochondrial membrane potential and ATP synthesis was also observed in both animal MI and cellular hypoxic models, as well as miR-143 overexpressed models and converted by either antagomiR or AMO. Importantly, overexpression of miR-143 downregulated PKCε in all tested models and this downregulation was reversed in the presence of antagomiR or AMO. The direct targeted regulation of miR-143 on PKCε was confirmed by luciferase reporter and miRNA-masking tests. In conclusion, MI-mediated upregulation of miR-143 inhibits PKCε expression and consequently interference with the cardioprotection of PKCε to mitochondrial, and leads to mitochondrial membrane potential dissipation and myocardial death eventually.

Cardioprotective kinase signaling to subsarcolemmal and interfibrillar mitochondria is mediated by caveolar structures

The demonstration that caveolin-3 overexpression reduces myocardial ischemia/reperfusion injury and our own finding that multiprotein signaling complexes increase in mitochondria in association with caveolin-3 levels, led us to investigate the contribution of caveolae-driven extracellular signal-regulated kinases 1/2 (ERK1/2) on maintaining the function of cardiac mitochondrial subpopulations from reperfused hearts subjected to postconditioning (PostC). Rat hearts were isolated and subjected to ischemia/reperfusion and to PostC. Enhanced cardiac function, reduced infarct size and preserved ultrastructure of cardiomyocytes were associated with increased formation of caveolar structures, augmented levels of caveolin-3 and mitochondrial ERK1/2 activation in PostC hearts in both subsarcolemmal (SSM) and interfibrillar (IFM) subpopulations. Disruption of caveolae with methyl-β-cyclodextrin abolished cardioprotection in PostC hearts and diminished pho-ERK1/2 gold-labeling in both mitochondrial subpopulations in correlation with suppression of resistance to permeability transition pore opening. Also, differences between the mitochondrial subpopulations in the setting of PostC were evaluated. Caveolae disruption with methyl-β-cyclodextrin abolished the cardioprotective effect of postconditioning by inhibiting the interaction of ERK1/2 with mitochondria and promoted decline in mitochondrial function. SSM, which are particularly sensitive to reperfusion damage, take advantage of their location in cardiomyocyte boundary and benefit from the cardioprotective signaling driven by caveolae, avoiding injury propagation.

Functional exosome-mimic for delivery of siRNA to cancer: in vitro and in vivo evaluation

Exosomes, the smallest subgroup of extracellular vesicles, have been recognized as extracellular organelles that contain genetic and proteomic information for long distance intercellular communication. Exosome-based drug delivery is currently a subject of intensive research. Here, we report a novel strategy to produce nanoscale exosome-mimics (EMs) in sufficient quantity for gene delivery in cancer both in vitro and in vivo. Size-controllable EMs were generated at a high yield by serial extrusion of non-tumorigenic epithelial MCF-10A cells through filters with different pore sizes. siRNA was then encapsulated into the EMs by electroporation. Biosafety and uptake efficiency of the EMs were evaluated both in vitro and in vivo. The mechanism underlying their cellular endocytosis was also studied.

The mitochondrial permeability transition pore in AD 2016: An update

Over the past 30years the mitochondrial permeability transition - the permeabilization of the inner mitochondrial membrane due to the opening of a wide pore - has progressed from being considered a curious artifact induced in isolated mitochondria by Ca(2+) and phosphate to a key cell-death-inducing process in several major pathologies. Its relevance is by now universally acknowledged and a pharmacology targeting the phenomenon is being developed. The molecular nature of the pore remains to this day uncertain, but progress has recently been made with the identification of the FOF1 ATP synthase as the probable proteic substrate. Researchers sharing this conviction are however divided into two camps: these believing that only the ATP synthase dimers or oligomers can form the pore, presumably in the contact region between monomers, and those who consider that the ring-forming c subunits in the FO sector actually constitute the walls of the pore. The latest development is the emergence of a new candidate: Spastic Paraplegia 7 (SPG7), a mitochondrial AAA-type membrane protease which forms a 6-stave barrel. This review summarizes recent developments of research on the pathophysiological relevance and on the molecular nature of the mitochondrial permeability transition pore. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

Caveolin-1/-3: therapeutic targets for myocardial ischemia/reperfusion injury

Myocardial ischemia/reperfusion (I/R) injury is a major cause of morbidity and mortality worldwide. Caveolae, caveolin-1 (Cav-1), and caveolin-3 (Cav-3) are essential for the protective effects of conditioning against myocardial I/R injury. Caveolins are membrane-bound scaffolding proteins that compartmentalize and modulate signal transduction. In this review, we introduce caveolae and caveolins and briefly describe the interactions of caveolins in the cardiovascular diseases. We also review the roles of Cav-1/-3 in protection against myocardial ischemia and I/R injury, and in conditioning. Finally, we suggest several potential research avenues that may be of interest to clinicians and basic scientists. The information included, herein, is potentially useful for the design of future studies and should advance the investigation of caveolins as therapeutic targets.