Epigenetics in Alzheimer’s Disease: Perspective of DNA Methylation

Research over the years has shown that causes of Alzheimer’s disease are not well understood, but over the past years, the involvement of epigenetic mechanisms in the developing memory formation either under pathological or physiological conditions has become clear. The term epigenetics represents the heredity of changes in phenotype that are independent of altered DNA sequences. Different studies validated that cytosine methylation of genomic DNA decreases with age in different tissues of mammals, and therefore, the role of epigenetic factors in developing neurological disorders in aging has been under focus. In this review, we summarized and reviewed the involvement of different epigenetic mechanisms especially the DNA methylation in Alzheimer’s disease (AD), late-onset Alzheimer’s disease (LOAD), familial Alzheimer’s disease (FAD), and autosomal dominant Alzheimer’s disease (ADAD). Down to the minutest of details, we tried to discuss the methylation patterns like mitochondrial DNA methylation and ribosomal DNA (rDNA) methylation. Additionally, we mentioned some therapeutic approaches related to epigenetics, which could provide a potential cure for AD. Moreover, we reviewed some recent studies that validate DNA methylation as a potential biomarker and its role in AD. We hope that this review will provide new insights into the understanding of AD pathogenesis from the epigenetic perspective especially from the perspective of DNA methylation.     

Synthesis,structure-activity relationship and molecular docking studies of 3-O-flavonol glycosides as cholinesterase inhibitors

The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, ¹H, ¹³C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21–30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC₅₀ values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.     

Rational design of peptide affinity ligands for the purification of therapeutic enzymes

Non‐mAb biologics represent a growing class of therapeutics under clinical development. Although affinity chromatography is a potentially attractive approach for purification, the development of platform technologies, such as Protein A for mAbs, has been challenging due to the inherent chemical and structural diversity of these molecules. Here, we present our studies on the rapid development of peptide affinity ligands for the purification of biologics using a prototypical enzyme therapeutic in clinical use. Employing a suite of de novo rational and combinatorial design strategies we designed and screened a library of peptides on microarray platforms for their ability to bind to the target with high affinity and selectivity in cell culture fluid. Lead peptides were evaluated on resin in batch conditions and compared with a commercially available resin to evaluate their efficacy. Two lead candidates identified from microarray studies provided high binding capacity to the target while demonstrating high selectivity against culture contaminants and product variants compared to a commercial resin system. These findings provide a proof‐of‐concept for developing affinity peptide‐based bioseparations processes for a target biologic. Peptide affinity ligand design and screening approaches presented in this work can also be easily translated to other biologics of interest. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:987–998, 2018     

Short-Term Response of Switchgrass to Nitrogen,Phosphorus, and Potassium on Semiarid Sandy Wasteland Managed for Biofuel Feedstock

It is important to understand switchgrass (Panicum virgatum L.) productivity with relation to diverse nutrient deficiency conditions in order to optimize continuous biomass production in marginal lands. This study was conducted on a wasteland sandy soil (Aridosol) to assess biomass yield, nutrient uptake and nitrogen (N) recovery of switchgrass, and soil nitrate-N (NO₃^?-N) accumulation responses to N (120 kg N ha^?1), phosphorus (P, 100 kg P₂O₅ ha^?1), and potassium (K, 45 kg K₂O ha^?1) applications during 2015 and 2016 in Inner Mongolia, China. The experiment layout was a randomized complete block design with fertilizer mixture treatments of N, P, and K (NPK), P and K (PK), N and K (NK), N and P (NP), and a control with no fertilizer input (CK). Plant height and stem diameter remained unaffected by the different fertilizer treatments. Biomass yield with the NPK treatment in 2015 was 8.9 Mg ha^?1 and in 2016 it was 7.3 Mg ha^?1. In 2015, compared with the NPK treatment, a significant yield reduction of 33.7% was found with PK, 22.5% with NK, 28.1% with NP, and 40.5% with CK; however, in 2016, yield declined significantly only with CK compared to the rest of the fertilizer treatments, for which yields were statistically similar. Plant N content was reduced for the treatment PK (i.e. N omission); conversely, plant P and K content remained unaffected with P and K omission treatments. Plant nutrient uptake, particularly of N and K, was severely decreased by the nutrient omission treatments when averaged across 2 years. Apparent N recovery (ANR; quantity of N uptake per unit of N applied) was reduced for the NP and NK treatments, which led to an increase in soil NO₃^?-N accumulation in the top 0–20 cm layer, compared with the NPK treatment. However, ANR was the highest (37.2% in 2015) with the NPK treatment, which also reduced soil NO₃^?-N accumulation. A balanced N, P, and K fertilizer management approach is suggested to sustain switchgrass yield and stand persistence on semiarid, marginal, sandy wasteland.     

A novel mutation in <Emphasis Type="Italic">RDH5</Emphasis> gene causes retinitis pigmentosa in consanguineous Pakistani family

Retinitis pigmentosa (RP) is the most frequent genetically and clinically heterogeneous inherited retinal degeneration. To date, more than 80 genes have been identified that cause autosomal dominant, autosomal recessive and X linked RP. However, locus and allelic heterogeneity of RP has not been fully captured yet. This heterogeneity and lack of an accurate genotype phenotype correlation makes molecular dissection of the disease more difficult. The present study was designed to characterize the underlying pathogenic variants of RP in Pakistan. For this purpose, a large consanguineous family with RP phenotype showing autosomal recessive mode of inheritance was selected after a complete ophthalmological examination. Next generation sequencing was used for the identification of molecular determinant followed by Sanger-sequencing for confirmation. After sequence analysis a novel homozygous missense mutation, (c.602 C?>?T) in exon 4 of the RDH5 gene (MIM: 601617) was identified. This mutation resulted in substitution of phenyl alanine for serine at amino acid 201 (p.Ser201Phe) of the RDH5 gene. The same mutation was not detected in the 200 ethnically-matched control samples by Sanger sequencing. The identified mutant allele segregated in homozygous fashion in all the affected individuals of pedigree. Identification of this mutation reveals the allelic heterogeneity of RDH5 in patients with RP phenotype. The findings of this study demonstrate the clinical significance of next generation sequencing to understand the molecular basis of diseases and would help to reveal new proteins and their function in visual cycle will pave the way for early diagnosis, genetic counseling and better therapeutic inventions.     

The Carbohydrate-linked Phosphorylcholine of the Parasitic Nematode Product ES-62 Modulates Complement Activation

Parasitic nematodes manufacture various carbohydrate-linked phosphorylcholine (PCh)-containing molecules, including ES-62, a protein with an N-linked glycan terminally substituted with PCh. The PCh component is biologically important because it is required for immunomodulatory effects. We showed that most ES-62 was bound to a single protein, C-reactive protein (CRP), in normal human serum, displaying a calcium-dependent, high-avidity interaction and ability to form large complexes. Unexpectedly, CRP binding to ES-62 failed to efficiently activate complement as far as the C3 convertase stage in comparison with PCh-BSA and PCh-containing Streptococcus pneumoniae cell wall polysaccharide. C1q capture assays demonstrated an ES-62-CRP-C1q interaction in serum. The three ligands all activated C1 and generated C4b to similar extents. However, a C2a active site was not generated following ES-62 binding to CRP, demonstrating that C2 cleavage was far less efficient for ES-62-containing complexes. We proposed that failure of C2 cleavage was due to the flexible nature of carbohydrate-bound PCh and that reduced proximity of the C1 complex was the reason that C2 was poorly cleaved. This was confirmed using synthetic analogues that were similar to ES-62 only in respect of having a flexible PCh. Furthermore, ES-62 was shown to deplete early complement components, such as the rate-limiting C4, following CRP interaction and thereby inhibit classical pathway activation. Thus, flexible PCh-glycan represents a novel mechanism for subversion of complement activation. These data illustrate the importance of the rate-limiting C4/C2 stage of complement activation and reveal a new addition to the repertoire of ES-62 immunomodulatory mechanisms with possible therapeutic applications.     

Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) and Cyclic ADP-Ribose (cADPR) Mediate Ca2+ Signaling in Cardiac Hypertrophy Induced by β-Adrenergic Stimulation

Ca²⁺ signaling plays a fundamental role in cardiac hypertrophic remodeling, but the underlying mechanisms remain poorly understood. We investigated the role of Ca²⁺-mobilizing second messengers, NAADP and cADPR, in the cardiac hypertrophy induced by β-adrenergic stimulation by isoproterenol. Isoproterenol induced an initial Ca²⁺ transients followed by sustained Ca²⁺ rises. Inhibition of the cADPR pathway with 8-Br-cADPR abolished only the sustained Ca²⁺ increase, whereas inhibition of the NAADP pathway with bafilomycin-A1 abolished both rapid and sustained phases of the isoproterenol-mediated signal, indicating that the Ca²⁺ signal is mediated by a sequential action of NAADP and cADPR. The sequential production of NAADP and cADPR was confirmed biochemically. The isoproterenol-mediated Ca²⁺ increase and cADPR production, but not NAADP production, were markedly reduced in cardiomyocytes obtained from CD38 knockout mice. CD38 knockout mice were rescued from chronic isoproterenol infusion-induced myocardial hypertrophy, interstitial fibrosis, and decrease in fractional shortening and ejection fraction. Thus, our findings indicate that β-adrenergic stimulation contributes to the development of maladaptive cardiac hypertrophy via Ca²⁺ signaling mediated by NAADP-synthesizing enzyme and CD38 that produce NAADP and cADPR, respectively.     

Culex tritaeniorhynchus: Failure to detect heterosis in the life table characteristics of outcrossed laboratory colonies

Intra and interstrain crosses were made between unselected and inbred adults of the Balloki and Peshawar, Pakistan, laboratory colonies of C. tritaeniorhynchus and life tables were constructed for their progeny. No overall heterosis effects were detected. Inbreeding severely reduced fertility and fecundity and lowered the innate capacity for increase. Interstrain crosses among inbred adults restored some vigor, but all life table estimates relating to fecundity were significantly less than crosses among the unselected adults. Thus, outcrosses among laboratory-adapted colonies did not appear to impart marked heterosis and would probably not enhance the vigor of males used for genetic control.

---

Zusammenfassung Intra- und Interstammkreuzungen wurden zwischen unselektionierten und ingezüchteten Insekten der Balloki- und Peshawar-Laboratoriumskolonien von C. tritaeniorhynchus durchgeführt und es wurden Life Tables für ihre Nachkommenschaft erstellt. Dabei konnten keine allgemeinen Heterosis-effekte festgestellt werden. Inzucht verminderte die Fertilität und Fekundität stark und reduzierte die genetische Vermehrungsfähigkeit. Interstammkreuzungen zwischen Inzuchtinsekten brachte etwas Vigor zurück, aber alle Life Table-Schätzungen im Hinblick auf Fekundität waren gesichert tiefer als bei Kreuzungen zwischen nicht selektionierten Insekten. Demnach scheinen Kreuzungen zwischen verschiedenen dem Laboratorium angepassten Kolonien keine ausgeprägte Heterosis zu bringen. Sie würden wahrscheinlich die Qualität von Männchen und Weibchen, die für die genetische Bekämpfung verwendet werden, nicht verbessern.