Houliang Deng

Roles of long noncoding RNAs in brain development, functional diversification and neurodegenerative diseases.

Long noncoding RNAs (lncRNAs) have been attracting immense research interest, while only a handful of lncRNAs have been characterized thoroughly. Their involvement in the fundamental cellular processes including regulate gene expression at epigenetics, transcription, and post-transcription highlighted a central role in cell homeostasis. However, lncRNAs studies are still at a relatively early stage, their definition, conservation, functions, and action mechanisms remain fairly complicated. Here, we give a systematic and comprehensive summary of the existing knowledge of lncRNAs in order to provide a better understanding of this new studying field. lncRNAs play important roles in brain development, neuron function and maintenance, and neurodegenerative diseases are becoming increasingly evident. In this review, we also highlighted recent studies related lncRNAs in central nervous system (CNS) development and neurodegenerative diseases, including Alzheimers disease (AD), Parkinsons disease (PD), Huntingtons disease (HD) and amyotrophic lateral sclerosis (ALS), and elucidated some specific lncRNAs which may be important for understanding the pathophysiology of neurodegenerative diseases, also have the potential as therapeutic targets.

Regulation of lncRNA expression

Long non-coding RNAs (lncRNAs) are series of transcripts with important biological functions. Various diseases have been associated with aberrant expression of lncRNAs and the related dysregulation of mRNAs. In this review, we highlight the mechanisms of dynamic lncRNA expression. The chromatin state contributes to the low and specific expression of lncRNAs. The transcription of non-coding RNA genes is regulated by many core transcription factors applied to protein-coding genes. However, specific DNA sequences may allow their unsynchronized transcription with their location-associated mRNAs. Additionally, there are multiple mechanisms involved in the post-transcriptional regulation of lncRNAs. Among these, microRNAs might have indispensible regulatory effects on lncRNAs, based on recent discoveries.

Tumor-targeted in vivo gene silencing via systemic delivery of cRGD-conjugated siRNA.

RNAi technology is taking strong position among the key therapeutic modalities, with dozens of siRNA-based programs entering and successfully progressing through clinical stages of drug development. To further explore potentials of RNAi technology as therapeutics, we engineered and tested VEGFR2 siRNA molecules specifically targeted to tumors through covalently conjugated cyclo(Arg-Gly-Asp-d-Phe-Lys[PEG-MAL]) (cRGD) peptide, known to bind αvβ3 integrin receptors. cRGD-siRNAs were demonstrated to specifically enter and silence targeted genes in cultured αvβ3 positive human cells (HUVEC). Microinjection of zebrafish blastocysts with VEGFR2 cRGD-siRNA resulted in specific inhibition of blood vessel growth. In tumor-bearing mice, intravenously injected cRGD-siRNA molecules generated no innate immune response and bio-distributed to tumor tissues. Continuous systemic delivery of two different VEGFR2 cRGD-siRNAs resulted in down-regulation of corresponding mRNA (55 and 45%) and protein (65 and 45%) in tumors, as well as in overall reduction of tumor volume (90 and 70%). These findings demonstrate strong potential of cRGD-siRNA molecules as anti-tumor therapy.

Meta-analysis of methylcobalamin alone and in combination with lipoic acid in patients with diabetic peripheral neuropathy

AIMS To compare the efficacy and safety of daily lipoic acid (300-600 mg i.v.) plus methylcobalamin (500-1000 mg i.v. or im.) (LA-MC) with that of methylcobalamin alone (MC) on diabetic peripheral neuropathy (DPN). METHODS Electronic database were searched for studies published up to November 1, 2012 and study quality was assessed in duplicate. A random or a fixed effect model was used to analyse outcomes which were expressed as risk ratios (RRs) or mean difference (MD). I(2) statistic was used to assess heterogeneity. RESULTS Seventeen studies were included. Combined data from all studies showed that the LA-MC combination therapy was significantly superior to MC monotherapy (RR=1.47; 95% CI: 1.37-1.58). Superiority of the LA-MC combination was shown in nerve conduction velocity (NCV) with WMDs of 6.89 (95% CI: 4.24-9.73) for median motor nerve conduction velocity (MNCV), 5.24 (4.14-6.34) for median sensory nerve conduction velocity (SNCV), 4.34 (3.03-5.64) for peroneal MNCV, and 4.53 (3.2-5.85) for peroneal SNCV. There were no serious adverse events associated with treatment. CONCLUSIONS The results of the meta-analysis show that treatment with LA-MC for 2-4 weeks is associated with better outcomes in NCV and neuropathic symptoms relative to MC treatment. However larger well-designed studies are required to confirm this conclusion.

Self-assembled nanoparticles based on the c(RGDfk) peptide for the delivery of siRNA targeting the VEGFR2 gene for tumor therapy.

The clinical application of small interfering RNA (siRNA) has been restricted by their poor intracellular uptake, low serum stability, and inability to target specific cells. During the last several decades, a great deal of effort has been devoted to exploring materials for siRNA delivery. In this study, biodegradable, tumor-targeted, self-assembled peptide nanoparticles consisting of cyclo(Arg–Gly–Asp–d–Phe–Lys)-8–amino–3,6–dioxaoctanoic acid–β–maleimidopropionic acid (hereafter referred to as RPM) were found to be an effective siRNA carrier both in vitro and in vivo. The nanoparticles were characterized based on transmission electron microscopy, circular dichroism spectra, and dynamic light scattering. In vitro analyses showed that the RPM/VEGFR2-siRNA exhibited negligible cytotoxicity and induced effective gene silencing. Delivery of the RPM/VEGFR2 (zebrafish)-siRNA into zebrafish embryos resulted in inhibition of neovascularization. Administration of RPM/VEGFR2 (mouse)-siRNA to tumor-bearing nude mice led to a significant inhibition of tumor growth, a marked reduction of vessels, and a down-regulation of VEGFR2 (messenger RNA and protein) in tumor tissue. Furthermore, the levels of IFN-α, IFN-γ, IL-12, and IL-6 in mouse serum, assayed via enzyme-linked immunosorbent assay, did not indicate any immunogenicity of the RPM/VEGFR2 (mouse)-siRNA in vivo. In conclusion, RPM may provide a safe and effective delivery vector for the clinical application of siRNAs in tumor therapy.

α‑lipoic acid protects against cerebral ischemia/reperfusion‑induced injury in rats

It is well established that the brain is sensitive to ischemia/reperfusion (I/R)‑induced injury. α‑lipoic acid (LA), a free radical scavenger and antioxidant, has a neuroprotective effect against cerebral I/R‑induced injury, however, the underlying mechanisms remain to be elucidated. Therefore, the present study was undertaken to evaluate whether LA was able to protect against cerebral I/R‑induced injury and to examine the potential mechanisms. The neuroprotective effects of LA were investigated in a rat model of transient focal ischemia induced by middle cerebral artery occlusion (MCAO) followed by reperfusion. Adult male Sprague‑Dawley rats were randomly assigned into the sham, cerebral I/R injury model and model plus LA groups. Cerebral I/R injury was induced by 90 min MCAO followed by reperfusion for 24 h. Cerebral infarct size was detected by 2,3,5‑triphenyltetrazolium chloride staining. Neurological deficit score (NDS), brain water content and oxidative parameters, including malondialdehyde (MDA), nitric oxide (NO), total antioxidant capacity (T‑AOC) and superoxide dismutase (SOD) were measured. The expression of cleaved caspase‑3, brain‑derived neurotrophic factor (BDNF), phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K), p‑Akt and phosphorylated extracellular signal‑regulated kinase 1/2 (p‑ERK1/2) were also analyzed using western blotting. The present study demonstrated that pretreatment with LA significantly decreased the infarction size, brain water content and improved NDS. LA reversed the levels of oxidative parameters, including MDA, NO, T‑AOC and SOD to their normal state in rat brains following cerebral I/R. Furthermore, the expression of cleaved caspase‑3 markedly decreased and the expression of BDNF, PI3K, p‑Akt and p‑ERK1/2 significantly increased following administration of LA. On the basis of these findings, it was concluded that LA protected the brain from cerebral I/R damage by attenuation of oxidative stress and caspase‑dependent apoptosis. Furthermore, LA exerts its neuroprotective effects potentially through activation of the BDNF‑PI3K/Akt‑ERK1/2 pathway.

Something between the amazing functions and various morphologies of self-assembling peptides materials in the medical field

In recent years, there are a growing number of researches in the field of self-assembling peptides. Due to their diversity structures and the promising applications, self-assembling peptides have already become the focus of studies in the fields of materials and biological science. Some amazing functions of these peptides in the medical field caught our attention, such as tissue repair and regeneration, therapeutic delivery, haemostasis, antimicrobial and so on. There are different morphologies of self-assembling peptides in different functions. This review provides an overview of the relationship between some amazing functions and various morphologies of self-assembling peptides principally. Furthermore, the mechanisms of peptide self-assembly are also discussed.

α-lipoic acid protects against hypoxia/reoxygenation-induced injury in human umbilical vein endothelial cells through suppression of apoptosis and autophagy

α-lipoic acid (ALA) is known as a powerful antioxidant, which has been reported to have protective effects against various cardiovascular diseases. The present study aimed to determine whether ALA pre- or post-treatment induced protective effects against hypoxia/reoxygenation-induced injury via inhibition of apoptosis and autophagy in human umbilical vein endothelial cells (HUVECs). In order to simulate the conditions of hypoxia/reoxygenation, HUVECs were subjected to 4 h of oxygen-glucose deprivation (OGD) followed by 12 h of reoxygenation. For the pre-treatment, ALA was added to the buffer 12 h prior to OGD, whereas for the post-treatment, ALA was added at the initiation of reoxygenation. The results demonstrated that ALA pre- or post-treatment significantly reduced lactate dehydrogenase (LDH) release induced through hypoxia/reoxygenation in HUVECs in a dose-dependent manner; of note, 1 mM ALA pre- or post-treatment exhibited the most potent protective effects. In addition, ALA significantly reduced hypoxia/reoxygenation-induced loss of mitochondrial membrane potential, apoptosis and the expression of cleaved caspase-3 in HUVECs. In the presence of the specific autophagy inhibitor 3-methyladenine, hypoxia/reoxygenation-induced apoptosis was significantly reduced. Furthermore, the formation of autophagosomes, cytosolic microtubule-associated protein 1A/1B-light chain 3 ratio and beclin1 levels significantly increased following hypoxia/reoxygenation injury; however, all of these effects were ameliorated following pre- or post-treatment with ALA. The results of the present study suggested that ALA may provide beneficial protection against hypoxia/reoxygenation-induced injury via attenuation of apoptosis and autophagy in HUVECs.

Comparison of repaglinide and metformin versus metformin alone for type 2 diabetes: a meta-analysis of randomized controlled trials.

We conducted a meta-analysis to compare the efficacy and safety of repaglinide plus metformin with metformin alone on type 2 diabetes. Twenty-two studies were included in this meta-analysis. Results showed combination therapy was safe and could gain better outcomes in glycemic control. Well-designed studies are required to confirm this conclusion.

Do different reperfusion methods affect the outcomes of stroke induced by MCAO in adult rats

There are two patterns of ischemia/reperfusion (I/R) models used in rat middle cerebral artery occlusion (MCAO) I/R models, which differ in the use of unilateral or bilateral carotid artery reperfusion. The primary difference between the two patterns of I/R models is the complexity of the surgery procedure. However, researchers in this field have no idea whether there are any differences in outcomes of these two methods. In this study, we investigated the effects of the two methods on neurological deficits, infarct volume, blood–brain barrier (BBB) integrity and brain derived neurotrophic factor (BDNF) expression. Through evaluating the current way of bilateral common carotid artery reperfusion, we tried to find whether it could be replaced by an easier way. We found that there were no statistical significant differences between the different methods in infarct volume, neurological deficits, BBB integrity, and the level of BDNF (P > 0.05). These data demonstrated that different methods did not affect the neurological deficits, infarct volume, BBB integrity, and the BDNF protein level, which provides reference when we use an experimental stroke. These results suggest that the two methods have similar capability for inducing cerebral I/R injury and can be interchanged.