Long Non-coding RNA XIST Attenuates Diabetic Peripheral Neuropathy by Inducing Autophagy Through MicroRNA-30d-5p/sirtuin1 Axis.

Diabetic peripheral neuropathy (DPN) is a prevalent diabetes mellitus (Feldman et al., 2017) complication and the primary reason for amputation. Meanwhile, long non-coding RNAs (lncRNAs) are a type of regulatory non-coding RNAs (ncRNAs) that broadly participate in DPN development. However, the correlation of lncRNA X-inactive specific transcript (XIST) with DPN remains unclear. In this study, we were interested in the role of XIST in the modulation of DPN progression. Significantly, our data showed that the expression of XIST and sirtuin1 (SIRT1) was inhibited, and the expression of microRNA-30d-5p (miR-30d-5p) was enhanced in the trigeminal sensory neurons of the diabetic mice compared with the normal mice. The levels of LC3II and Beclin-1 were inhibited in the diabetic mice. The treatment of high glucose (HG) reduced the XIST expression in Schwann cells. The apoptosis of Schwann cells was enhanced in the HG-treated cells, but the overexpression of XIST could block the effect in the cells. Moreover, the levels of LC3II and Beclin-1 were reduced in the HG-treated Schwann cells, while the overexpression of XIST was able to reverse this effect. The HG treatment promoted the production of oxidative stress, while the XIST overexpression could attenuate this result in the Schwann cells. Mechanically, XIST was able to sponge miR-30d-5p and miR-30d-5p-targeted SIRT1 in the Schwann cells. MiR-30d-5p inhibited autophagy and promoted oxidative stress in the HG-treated Schwann cells, and SIRT1 presented a reversed effect. MiR-30d-5p mimic or SIRT1 depletion could reverse XIST overexpression-mediated apoptosis and autophagy of the Schwann cells. Thus, we concluded that XIST attenuated DPN by inducing autophagy through miR-30d-5p/SIRT1 axis. XIST and miR-30d-5p may be applied as the potential targets for DPN therapy.

Regulatory mechanisms and therapeutic potential of microglial inhibitors in neuropathic pain and morphine tolerance.

Microglia are important cells involved in the regulation of neuropathic pain (NPP) and morphine tolerance. Information on their plasticity and polarity has been elucidated after determining their physiological structure, but there is still much to learn about the role of this type of cell in NPP and morphine tolerance. Microglia mediate multiple functions in health and disease by controlling damage in the central nervous system (CNS) and endogenous immune responses to disease. Microglial activation can result in altered opioid system activity, and NPP is characterized by resistance to morphine. Here we investigate the regulatory mechanisms of microglia and review the potential of microglial inhibitors for modulating NPP and morphine tolerance. Targeted inhibition of glial activation is a clinically promising approach to the treatment of NPP and the prevention of morphine tolerance. Finally, we suggest directions for future research on microglial inhibitors.

Long non­coding RNA BC168687 small interfering RNA reduces high glucose and high free fatty acid­induced expression of P2X7 receptors in satellite glial cells.

Purinergic signaling contributes to inflammatory and immune responses. The activation of the P2X purinoceptor 7 (P2X7) in satellite glial cells (SGCs) may be an essential component in the promotion of inflammation and neuropathic pain. Long non­coding RNAs (lncRNAs) are involved in multiple physiological and pathological processes. The aim of the present study was to investigate the effects of a small interfering RNA for the lncRNA BC168687 on SGC P2X7 expression in a high glucose and high free fatty acids (HGHF) environment. It was demonstrated that BC168687 small interfering (si)RNA downregulated the co­expression of the P2X7 and glial fibrillary acidic protein and P2X7 mRNA expression. Additionally, HGHF may activate the mitogen­activated protein kinase signaling pathway by increasing the release of nitric oxide and reactive oxygen species in SGCs. Taken together, these results indicate that silencing BC168687 expression may downregulate the increased expression of P2X7 receptors in SGCs induced by a HGHF environment.

Serum uric acid and lipid profiles in sporadic Creutzfeldt-Jakob disease.

OBJECTIVES: Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive, and fatal neurodegenerative disease affecting the central nervous system. Brain lipid homeostasis and oxidative stress seem to play an important role in the disease pathogenesis. But little was known whether serum lipids and uric acid (a natural antioxidant) levels changed in patients with prion disease. DESIGN AND METHODS: Here we retrospectively reviewed and compared the serum lipids and uric acid levels of 19 probable sporadic CJD patients and 26 healthy control subjects. RESULTS: We found that the serum uric acid levels in sporadic CJD patients were significantly lower than that in controls (P=0.01). Serum triglycerides, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and apolipoprotein A1 (ApoA1) were similar in sporadic CJD patients and controls. However, LDL/HDL ratio was lower in sporadic CJD patients (P=0.003). CONCLUSIONS: The low serum uric acid and LDL/HDL ratio levels in sporadic CJD indicate that dysfunction in the lipid homeostasis and oxidative stress is associated with sporadic prion disease.

Assessment of RIT2 rs12456492 association with Parkinson's disease in Mainland China.

A recent meta-analysis of genome-wide association studies in Parkinson's disease (PD) has identified the rs12456492 variant in RIT2 as a new susceptibility loci. Because the characteristics of this locus in a Han Chinese population from mainland China was still unknown, we performed a case-control replication study in this population and investigated RIT2 rs12456492 variant in a large cohort of Chinese Han individuals. In total, 933 subjects comprising 460 PD patients and 473 control subjects were genotyped. We found a significant difference in the distributions of genotype and allele between PD and control groups (genotype p = 0.008, allele p = 0.007, odds ratio = 1.296, 95% confidence interval = 1.075-1.563). This study replicates the association between rs12456492 variant and risk of developing PD in a Han Chinese population.

Analysis of several loci from genome-wide association studies in Parkinson's disease in mainland China.

Large-scale meta-analyses of genome-wide association studies in Parkinson's disease (PD) have identified a number of susceptibility loci in sporadic PD. Since the characteristics of those loci in a Han Chinese population from mainland China were unknown, we performed a case-control replication study in this population and evaluated several single nucleotide polymorphisms (SNPs) identified in a recent GWAS-meta-analysis. In total, 933 subjects comprised of 460 PD patients and 473 controls were genotyped. We found strong evidence of an association for rs708723 in RAB7L1 in the total sample (genotype p=0.01, allele p=0.01, OR=0.78, 95% CI=0.65-0.94). With rs156429 in GPNMB, there was a significant difference in genotype and allele distribution between male PD patients and the control subgroup (genotype p=0.01, allele p=0.01, OR=0.67, 95% CI=0.49-0.92). However, we did not observe any significant difference in genotype or allele distribution between PD and control for rs34016896 in NMD3 and rs6812193 in STBD1.

Phototropins function in high-intensity blue light-induced hypocotyl phototropism in Arabidopsis by altering cytosolic calcium.

Phototropins (phot1 and phot2), the blue light receptors in plants, regulate hypocotyl phototropism in a fluence-dependent manner. Especially under high fluence rates of blue light (HBL), the redundant function mediated by both phot1 and phot2 drastically restricts the understanding of the roles of phot2. Here, systematic analysis of phototropin-related mutants and overexpression transgenic lines revealed that HBL specifically induced a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]cyt) in Arabidopsis (Arabidopsis thaliana) hypocotyls and that the increase in [Ca(2+)]cyt was primarily attributed to phot2. Pharmacological and genetic experiments illustrated that HBL-induced Ca(2+) increases were modulated differently by phot1 and phot2. Phot2 mediated the HBL-induced increase in [Ca(2+)]cyt mainly by an inner store-dependent Ca(2+)-release pathway, not by activating plasma membrane Ca(2+) channels. Further analysis showed that the increase in [Ca(2+)]cyt was possibly responsible for HBL-induced hypocotyl phototropism. An inhibitor of auxin efflux carrier exhibited significant inhibitions of both phototropism and increases in [Ca(2+)]cyt, which indicates that polar auxin transport is possibly involved in HBL-induced responses. Moreover, PHYTOCHROME KINASE SUBSTRATE1 (PKS1), the phototropin-related signaling element identified, interacted physically with phototropins, auxin efflux carrier PIN-FORMED1 and calcium-binding protein CALMODULIN4, in vitro and in vivo, respectively, and HBL-induced phototropism was impaired in pks multiple mutants, indicating the role of the PKS family in HBL-induced phototropism. Together, these results provide new insights into the functions of phototropins and highlight a potential integration point through which Ca(2+) signaling-related HBL modulates hypocotyl phototropic responses.

Nitric oxide blocks blue light-induced K+ influx by elevating the cytosolic Ca2+ concentration in Vicia faba L. guard cells.

Ca(2+) plays a pivotal role in nitric oxide (NO)-promoted stomatal closure. However, the function of Ca(2+) in NO inhibition of blue light (BL)-induced stomatal opening remains largely unknown. Here, we analyzed the role of Ca(2+) in the crosstalk between BL and NO signaling in Vicia faba L. guard cells. Extracellular Ca(2+) modulated the BL-induced stomatal opening in a dose-dependent manner, and an application of 5 µM Ca(2+) in the pipette solution significantly inhibited BL-activated K(+) influx. Sodium nitroprusside (SNP), a NO donor, showed little effect on BL-induced K(+) influx and stomatal opening response in the absence of extracellular Ca(2+), but K(+) influx and stomatal opening were inhibited by SNP when Ca(2+) was added to the bath solution. Interestingly, although both SNP and BL could activate the plasma membrane Ca(2+) channels and induce the rise of cytosolic Ca(2+), the change in levels of Ca(2+) channel activity and cytosolic Ca(2+) concentration were different between SNP and BL treatments. SNP at 100 µM obviously activated the plasma membrane Ca(2+) channels and induced cytosolic Ca(2+) rise by 102.4%. In contrast, a BL pulse (100 µmol/m(2) per s for 30 s) slightly activated the Ca(2+) channels and resulted in a Ca(2+) rise of only 20.8%. Consistently, cytosolic Ca(2+) promoted K(+) influx at 0.5 µM or below, and significantly inhibited K(+) influx at 5 µM or above. Taken together, our findings indicate that Ca(2+) plays dual and distinctive roles in the crosstalk between BL and NO signaling in guard cells, mediating both the BL-induced K(+) influx as an activator at a lower concentration and the NO-blocked K(+) influx as an inhibitor at a higher concentration.

Exploration of P2X3 in the rat stellate ganglia after myocardial ischemia.

ATP is implicated in peripheral pain signaling by actions on P2X receptors, especially P2X(3) receptor. Cardiac primary afferents running in the sympathetic nerves are considered to be essential pathways for transmission of cardiac nociception to the central nervous system. Because little is known about P2X(3) involvement in cardiac nociception, this study observed the difference in P2X(3) localization and expression in stellate ganglia (SG) from naive rats and in a pathological model of myocardial ischemic injury induced by repeated subcutaneous isoprenaline injections. Distribution of P2X(3) and morphometry of neurons in SG were investigated by immunohistochemistry, Western blotting, in situ hybridization (ISH) and by sterological study. Diffuse cytoplasmic P2X(3) immunolabelling was observed by light microsocopy. No nuclear labeling was detected. The intensity of P2X(3) labeling in the experimental myocardial ischemic injury group was increased in relation to that of the control group. Numerical densities of stellate ganglion neurons in the experimental group were higher than those of the control group. By Western blotting and ISH, the signals of P2X(3) protein and its mRNA in the myocardial ischemic group were higher than those of the control group. The P2X(3) labeling intensity and the numerical density in SG of the experimental myocardial ischemic injury group were enhanced, suggesting the involvement of P2X(3) receptor for the transmission of pain after myocardial ischemic injury.

Effect of tetramethylpyrazine on acute nociception mediated by signaling of P2X receptor activation in rat.

Tetramethylpyrazine (TMP) has been used in traditional Chinese medicine as an analgesic for dysmenorrhea. In the present study, we try to investigate the effects of TMP on acute nociception mediated by P2X receptor activation of rat hindpaw and the membrane depolarization of rat dorsal root ganglion (DRG) neurons induced by P2X receptor agonists. The subcutaneous administration of TMP (0.1-10 mmol) into rat hindpaw in a dose-dependent manner decreased acute paw flinching responses mediated by adenosine 5'-triphosphate (ATP, 1000 nmol) or alpha,beta-methylene ATP (alpha,beta-meATP, 600 nmol). The subcutaneous administration of TMP (5 or 10 mmol) into rat hindpaw inhibited significantly the first phase of nociceptive behaviors induced by 5% formalin and attenuated slightly the second phase of nociceptive behaviors induced by 5% formalin. The subcutaneous administration of TMP (10 mmol) into rat hindpaw reduced the nociceptive responses induced by alpha,beta-meATP (200 nmol) co-injected with Prostaglandin E2 (PGE2), 5 micromol). The membrane depolarization induced by ATP (200 micromol) or alpha,beta-meATP (50 micromol) in DRG neurons was inhibited by TMP (300 micromol). The data suggest that the antinociceptive effect of TMP is involved in blocking the signaling of P2X3 receptor activation in rat.