Extracellular Vesicular Transmission of miR-423-5p from HepG2 Cells Inhibits the Differentiation of Hepatic Stellate Cells.

Liver fibrosis (LF) is a major cause of morbidity and mortality worldwide. Hepatic stellate cells (HSCs) are the primary source of extracellular matrix in the liver and their activation is a central event in LF development. Extracellular vesicles (EVs) are intercellular communication agents, which play important roles in physiological processes in chronic liver diseases. The aim of this study was to examine the crosstalk between hepatocytes and HSCs mediated by hepatocyte-secreted EVs. EVs were purified from primary mouse hepatocytes, HepG2 cell lines, under normal or stressed conditions. The effect of EVs on primary HSCs (pHSCs) differentiation was evaluated by measuring of differentiation markers. In addition, their impact on the carbon tetrachloride (CCl4)-induced fibrosis mouse model was evaluated. The results demonstrated that HepG2-EVs regulate HSC differentiation and that under stress conditions, promoted pHSCs differentiation into the myofibroblast phenotype. The evaluation of miRNA sequences in the HepG2 secreted EVs demonstrated high levels of miR-423-5p. The examination of EV cargo following stress conditions identified a significant reduction of miR-423-5p in HepG2-EVs relative to HepG2-EVs under normal conditions. In addition, pHSCs transfected with miR-423-5p mimic and exhibit lower mRNA levels of alpha smooth muscle actin and Collagen type 1 alpha, and the mRNA expression level of genes targeted the family with sequence-similarity-3 (FAM3) and Monoacylglycerol lipase (Mgll). This study strengthened the hypothesis that EVs are involved in LF and that their cargo changes in stress conditions. In addition, miR-423-5p was shown to be involved in HSCs differentiation and hence, fibrosis development.

Dynamic mapping using an electrified ultrasonic aspirator in lipomyelomeningocele and spinal cord detethering surgery-a feasibility study.

BACKGROUND: Intraoperative neurophysiologic monitoring (IONM) is an established technique and adjunct of brain and spinal lesion resection surgery. In spina bifida syndrome surgery, mapping of the surgical wound is a common and accepted method in determining the position and functionality of nerve roots of the cauda equina (CE), especially when the anatomy is not straightforward and roots are splayed across or entangled within the lesion. Here, we describe a novel technique of continuous CE mapping using an electrified cavitron ultrasonic aspirator (eCUSA) in children with lipomyelomeningocele (LMMC) lesions. METHODS: We assessed a method of dynamic CE mapping using an eCUSA as a stimulation probe. Twenty children (0.5-18 years) were included in this study, diagnosed with occult spina bifida LMMC in which the eCUSA stimulator was applied. IONM data and 2-weeks post-operative data were collected. RESULTS: LMMC lesions were located in the lumbar, sacral, and lumbosacral spine. eCUSA stimulation at 0.3-3.0 mA intensities elicited positive lower extremity muscle responses in 12 of the 20 patients included in the study. These responses allowed the surgeon real-time identification of the nerve roots tangent at the LMMC-cauda equina structure and intensive removal of the fat tissue in the area non-responding to the eCUSA stimulation. CONCLUSION: Continuous eCUSA-based stimulation of the cauda equina during LMMC resection is a feasible mapping technique with potential added value improving safety of untethering. Future studies evaluating extension of untethering, as well as the rates of retethering and long-term neurological and urological outcomes, are warranted.

Augmentation of Ouabain-Induced Increase in Heart Muscle Contractility by Akt Inhibitor MK-2206.

Cardiac steroids (CSs), such as ouabain and digoxin, increase the force of contraction of heart muscle and are used for the treatment of congestive heart failure (CHF). However, their small therapeutic window limits their use. It is well established that Na+, K+-ATPase inhibition mediates CS-induced increase in heart contractility. Recently, the involvement of intracellular signal transduction was implicated in this effect. The aim of the present study was to test the hypothesis that combined treatment with ouabain and Akt inhibitor (MK-2206) augments ouabain-induced inotropy in mammalian models. We demonstrate that the combined treatment led to an ouabain-induced increase in contractility at concentrations at which ouabain alone was ineffective. This was shown in 3 experimental systems: neonatal primary rat cardiomyocytes, a Langendorff preparation, and an in vivo myocardial infarction induced by left anterior descending coronary artery (LAD) ligation. Furthermore, cell viability experiments revealed that this treatment protected primary cardiomyocytes from MK-2206 toxicity and in vivo reduced the size of scar tissue 10 days post-LAD ligation. We propose that Akt activity imposes a constant inhibitory force on muscle contraction, which is attenuated by low concentrations of MK-2206, resulting in potentiation of the ouabain effect. This demonstration of the increase in the CS effect advocates the development of the combined treatment in CHF.

Na⁺, K⁺-ATPase Signaling and Bipolar Disorder.

Bipolar disorder (BD) is a severe and common chronic mental illness characterized by recurrent mood swings between depression and mania. The biological basis of the disease is poorly understood and its treatment is unsatisfactory. Although in past decades the "monoamine hypothesis" has dominated our understanding of both the pathophysiology of depressive disorders and the action of pharmacological treatments, recent studies focus on the involvement of additional neurotransmitters/neuromodulators systems and cellular processes in BD. Here, evidence for the participation of Na⁺, K⁺-ATPase and its endogenous regulators, the endogenous cardiac steroids (ECS), in the etiology of BD is reviewed. Proof for the involvement of brain Na⁺, K⁺-ATPase and ECS in behavior is summarized and it is hypothesized that ECS-Na⁺, K⁺-ATPase-induced activation of intracellular signaling participates in the mechanisms underlying BD. We propose that the activation of ERK, AKT, and NFκB, resulting from ECS-Na⁺, K⁺-ATPase interaction, modifies neuronal activity and neurotransmission which, in turn, participate in the regulation of behavior and BD. These observations suggest Na⁺, K⁺-ATPase-mediated signaling is a potential target for drug development for the treatment of BD.

Essential Opposite Roles of ERK and Akt Signaling in Cardiac Steroid-Induced Increase in Heart Contractility.

Interaction of cardiac steroids (CS) with the Na(+), K(+)-ATPase elicits, in addition to inhibition of the enzyme's activity, the activation of intracellular signaling such as extracellular signal-regulated (ERK) and protein kinase B (Akt). We hypothesized that the activities of these pathways are involved in CS-induced increase in heart contractility. This hypothesis was tested using in vivo and ex vivo wild type (WT) and sarcoplasmic reticulum Ca(2+) atpase1a-deficient zebrafish (accordion, acc mutant) experimental model. Heart contractility was measured in vivo and in primary cardiomyocytes in WT zebrafish larvae and acc mutant. Ca(2+) transients were determined ex vivo in adult zebrafish hearts. CS dose dependently augmented the force of contraction of larvae heart muscle and cardiomyocytes and increased Ca(2+) transients in WT but not in acc mutant. CS in vivo increased the phosphorylation rate of ERK and Akt in the adult zebrafish heart of the two strains. Pretreatment of WT zebrafish larvae or cardiomyocytes with specific MAPK inhibitors completely abolished the CS-induced increase in contractility. On the contrary, pretreatment with Akt inhibitor significantly enhanced the CS-induced increase in heart contractility both in vivo and ex vivo without affecting CS-induced Ca(2+) transients. Furthermore, pretreatment of the acc mutant larvae or cardiomyocytes with Akt inhibitor restored the CS-induced increase in heart contractility also without affecting Ca(2+) transients. These results support the notion that the activity of MAPK pathway is obligatory for CS-induced increases in heart muscle contractility. Akt activity, on the other hand, plays a negative role, via Ca(2+) independent mechanisms, in CS action. These findings point to novel potential pharmacological intervention to increase CS efficacy.