Human RISC couples microRNA biogenesis and posttranscriptional gene silencing

RNA interference is implemented through the action of the RNA-induced silencing complex (RISC). Although Argonaute2 has been identified as the catalytic center of RISC, the RISC polypeptide composition and assembly using short interfering RNA (siRNA) duplexes has remained elusive. Here we show that RISC is composed of Dicer, the double-stranded RNA binding protein TRBP, and Argonaute2. We demonstrate that this complex can cleave target RNA using precursor microRNA (pre-miRNA) hairpin as the source of siRNA. Although RISC can also utilize duplex siRNA, it displays a nearly 10-fold greater activity using the pre-miRNA Dicer substrate. RISC distinguishes the guide strand of the siRNA from the passenger strand and specifically incorporates the guide strand. Importantly, ATP is not required for miRNA processing, RISC assembly, or multiple rounds of target-RNA cleavage. These results define the composition of RISC and demonstrate that miRNA processing and target-RNA cleavage are coupled.     

Tensegrin in context: Dual role of α8 integrin in the migration of different cell types

α8β1 integrin is highly expressed in cells with contractile function, such as mesangial cells of the kidneys and vascular smooth muscle cells (VSMCs). Although it promotes migration of neural crest cells and breast cancer cells, recent studies suggest that α8 integrin has a negative regulatory role in VSMC migration. In this Review, the question of why α8β1 integrin plays a dual role in cell migration is raised and discussed. It seems that cells require optimum contractility and balanced tensile forces for migration. α8β1 integrin promotes migration of cells that are initially in a less than optimal contractile state (e.g., neural cells) and reduces the migration of cells known as contractile cells. α8β1 integrin can be called “Tensegrin” as it fits perfectly into the tensegrity model (tensional integrity) and seems to play a prominent role in the integration of the tensile forces.Key words: integrin, migration, adhesion, mesenchymal cell, epithelial cell, vascular smooth muscle cell     

Cerebral Astrocytes Transport Ascorbic Acid and Dehydroascorbic Acid Through Distinct Mechanisms Regulated by Cyclic AMP

Abstract: Cerebral ischemia and trauma lead to rapid increases in cerebral concentrations of cyclic AMP and dehydroascorbic acid (DHAA; oxidized vitamin C), depletion of intracellular ascorbic acid (AA; reduced vitamin C), and formation of reactive astrocytes. We investigated astrocytic transport of AA and DHAA and the effects of cyclic AMP on these transport systems. Primary cultures of astrocytes accumulated millimolar concentrations of intracellular AA when incubated in medium containing either AA or DHAA. AA uptake was Na⁺-dependent and inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), whereas DHAA uptake was Na⁺-independent and DIDS-insensitive. DHAA uptake was inhibited by cytochalasin B, d -glucose, and glucose analogues specific for facilitative hexose transporters. Once inside the cells, DHAA was reduced to AA. DHAA reduction greatly decreased astrocytic glutathione concentration. However, experiments with astrocytes that had been previously depleted of glutathione showed that DHAA reduction does not require physiological concentrations of glutathione. Astrocyte cultures were treated with a permeant analogue of cyclic AMP or forskolin, an activator of adenylyl cyclase, to induce cellular differentiation and thus provide in vitro models of reactive astrocytes. Cyclic AMP stimulated uptake of AA, DHAA, and 2-deoxyglucose. The effects of cyclic AMP required at least 12 h and were inhibited by cycloheximide, consistent with a requirement for de novo protein synthesis. Uptake and reduction of DHAA by astrocytes may be a recycling pathway that contributes to brain AA homeostasis. These results also indicate a role for cyclic AMP in accelerating the clearance and detoxification of DHAA in the brain.     

Serum IL-10 involved in morphine tolerance development during adjuvant-induced arthritis

Opioid receptors play an important role in modulation of hyperalgesia in inflamed tissues, but chronic morphine application induces such side effects as tolerance. There is near communications between cytokines and mu opioid receptor expression. This study was aimed to assess the role of serum IL-10 in morphine tolerance development during adjuvant-induced arthritis. Adjuvant arthritis (AA) was induced on day 0 by single injection of Complete Freund’s Adjuvant (CFA) into the rats’ hindpaw. Hyperalgesia, edema, and spinal mu opioid receptor (mOR) variations were assessed on 0, 7, 14, and 21 days of the study. For assessment of the morphine tolerance development, morphine effective dose (4 mg/kg) was administered from the 14th day after CFA injection and continued until the morphine post-dose paw withdrawal latency (PWL); it did not significantly differ from the baseline. For assessment of the effects of IL-10 on tolerance induction, a neutralizing dose (ND50) of anti-IL-10 was administered daily during different stages of the study. AA induction in the right hindpaw of rats resulted in unilateral inflammation and hyperalgesia within 21 days of the study. Anti-IL-10 antibody administration in the AA rats induced marked elevation of hyperalgesia compared to the AA control group. Our data also indicated that morphine effective anti-hyperalgesic dose significantly decreased in the AA rats compared to the control group, which this symptom was aligned with spinal mu opioid receptor (mOR) expression increase during AA. Moreover, there was a significant difference in morphine tolerance induction between the AA and control rats, and our results also demonstrated that IL-10 played an important role in tolerance-induction process. It can be concluded that morphine tolerance slowly progressed when administered morphine effective dose was reduced during AA chronic inflammation. On the other hand, it seems that increased level of serum IL-10 may affect morphine tolerance development during inflammation.     

Retinoic Acid Correlates with Reduced Serum IL-10 And TGF-β in Allergic Rhinitis

Background:Retinoic acid (RA) plays a key role in naïve T cell differentiation into FOXP3+ Treg cell in the respiratory airways. The present study aims to investigate RA and Treg-related cytokine serum levels, salivary IgA levels, FOXP3 and IL-4 gene expression, and the relationships between RA serum levels and Treg-related cytokines in allergic rhinitis (AR) patients and healthy controls.Methods:Salivary IgA and serum IgE, RA, IL-10, and TGF-β concentrations were measured by ELISA in 37 AR patients and 30 age- and sex-matched healthy controls.Results:IL-10 and TGF-β concentrations were significantly less in AR patients than in healthy controls (p< 0.01 and P< 0.0001, respectively). Salivary IgA was significantly greater in patients than in controls (p< 0.05). RA was not significantly different between patients and controls (p> 0.05); however, a significant positive correlation was found between serum RA and both IL-10 and TGF-β in AR patients.Conclusion:Our data suggest that RA may influence AR risk via affecting the TGF-β and IL-10 production.Key Words: Allergic Rhinitis, Interleukin-10, Obesity, Retinoic Acid, Transforming Growth Factor-β     

Metoclopramide treatment blocks CD93-signaling-mediated self-renewal of chronic myeloid leukemia stem cells

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Finasteride induced depression: a prospective study

Background  

Finasteride is a competitive inhibitor of 5 alpha-reductase enzyme, and is used for treatment of benign prostatic hyperplasia and androgenetic alopecia. Animal studies have shown that finasteride might induce behavioral changes. Additionally, some cases of finasteride-induced depression have been reported in humans. The purpose of this study was to examine whether depressive symptoms or anxiety might be induced by finasteride administration.