Conjugates of adenosine mimetics and arginine-rich peptides serve as inhibitors and fluorescent probes but not as long-lifetime photoluminescent probes for protein arginine methyltransferases

The conjugates of an adenosine mimetic and oligo-l -arginine or oligo-d -arginine (ARCs) were initially designed in our research group as inhibitors and photoluminescent probes targeting basophilic protein kinases. Here, we explored a panel of ARCs and their fluorescent derivatives in biochemical assays with members of the protein arginine methyltransferase (PRMT) family, focusing specifically on PRMT1. In the binding/displacement assay with detection of fluorescence anisotropy, we found that ARCs and arginine-rich peptides could serve as high-affinity ligands for PRMT1, whereas the equilibrium dissociation constant values depended dramatically on the number of arginine residues within the compounds. The fluorescently labeled probe ARC-1081 was displaced from its complex with PRMT1 by both S-adenosyl-l -methionine (SAM) and S-adenosyl-l -homocysteine (SAH), indicating binding of the adenosine mimetic of ARCs to the SAM/SAH-binding site within PRMT1. The ARCs that had previously shown microsecond-lifetime photoluminescence in complex with protein kinases did not feature such property in complex with PRMT1, demonstrating the selectivity of the time-resolved readout format. When tested against a panel of PRMT family members in single-dose inhibition experiments, a micromolar concentration of ARC-902 was required for the inhibition of PRMT1 and PRMT7. Overall, our results suggest that the compounds containing multiple arginine residues (including the well-known cell-penetrating peptides) are likely to inhibit PRMT and thus interfere with the epigenetic modification status in complex biological systems, which should be taken into consideration during interpretation of the experimental data.     

In-Silico Analyses of Nonsynonymous Variants in the BRCA1 Gene

BReast CAncer gene 1 (BRCA1)—a tumor suppressor gene plays an important role in the DNA repair mechanism. Several BRCA1 variants perturb its structure and function, including synonymous and nonsynonymous single nucleotide polymorphisms (SNPs). In the present study, we performed in-silico analyses of nonsynonymous SNPs (nsSNPs) of the BRCA1 gene. In total, 122 nsSNPs were retrieved from the NCBI SNP database and in-silico analyses were performed using computational prediction tools: SIFT, PROVEAN, Mutation Taster, PolyPhen-2, MutPred, and ConSurf. Of these tools, SIFT, PROVEAN, and Mutation Taster predicted 61 out of 122 nsSNPs as “damaging”, based on structural homology analysis. PolyPhen-2 classified 22 nsSNPs as “probably damaging”. These nsSNPs were further analyzed by MutPred to predict basic molecular mechanisms of amino acid alteration. ConSurf analysis predicted eleven conserved amino acid residues with structural and functional consequences. We identified five amino acid residues in the RING finger domain (L22, C39, H41, C44, and C47) and two in the BRCT domain (P1771 and I1707) with the potential to deter the BRCA1 protein function. This study provides insights into the effect of nsSNPs and amino acid substitutions in BRCA1.

     

Rat model of fractionated (2 Gy/day) 60 Gy irradiation of the liver: long-term effects

The liver is considered a radiosensitive organ. However, in rats, high single-dose irradiation (HDI) showed only mild effects. Consequences of fractionated irradiation (FI) in such an animal model have not been studied so far. Rats were exposed to selective liver FI (total dose 60 Gy, 2 Gy/day) or HDI (25 Gy) and were killed three months after the end of irradiation. To study acute effects, HDI-treated rats were additionally killed at several time points between 1 and 48 h. Three months after irradiation, no differences between FI and HDI treatment were found for macroscopically detectable small “scars” on the liver surface and for an increased number of neutrophil granulocytes distributed in the portal fields and through the liver parenchyma. As well, no changes in HE-stained tissues or clear signs of fibrosis were found around the portal vessels. Differences were seen for the number of bile ducts being increased in FI- but not in HDI-treated livers. Serum levels indicative of liver damage were determined for alkaline phosphatase (AP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (γGT) and lactate dehydrogenase (LDH). A significant increase of AP was detected only after FI while HDI led to the significant increases of AST and LDH serum levels. By performing RT-PCR, we detected up-regulation of matrix metalloproteinases, MMP-2, MMP-9, MMP-14, and of their inhibitors, TIMP-1, TIMP-2 and TIMP-3, shortly after HDI, but not at 3 month after FI or HDI. Overall, we saw punctual differences after FI and HDI, and a diffuse formation of small scars at the liver surface. Lack of “provisional clot”-formation and absence of recruitment of mononuclear phagocytes could be one explanation for scar formation as incomplete repair response to irradiation.     

Plant‐based oral vaccines against zoonotic and non‐zoonotic diseases

The shared diseases between animals and humans are known as zoonotic diseases and spread infectious diseases among humans. Zoonotic diseases are not only a major burden to livestock industry but also threaten humans accounting for >60% cases of human illness. About 75% of emerging infectious diseases in humans have been reported to originate from zoonotic pathogens. Because antibiotics are frequently used to protect livestock from bacterial diseases, the development of antibiotic‐resistant strains of epidemic and zoonotic pathogens is now a major concern. Live attenuated and killed vaccines are the only option to control these infectious diseases and this approach has been used since 1890. However, major problems with this approach include high cost and injectable vaccines is impractical for >20 billion poultry animals or fish in aquaculture. Plants offer an attractive and affordable platform for vaccines against animal diseases because of their low cost, and they are free of attenuated pathogens and cold chain requirement. Therefore, several plant‐based vaccines against human and animals diseases have been developed recently that undergo clinical and regulatory approval. Plant‐based vaccines serve as ideal booster vaccines that could eliminate multiple boosters of attenuated bacteria or viruses, but requirement of injectable priming with adjuvant is a current limitation. So, new approaches like oral vaccines are needed to overcome this challenge. In this review, we discuss the progress made in plant‐based vaccines against zoonotic or other animal diseases and future challenges in advancing this field.     

Histone h1(0) and its carboxyl-terminal domain bind in the major groove of DNA

The binding of histone H1(0) to T4 bacteriophage DNA was investigated using thermal denaturation of the DNA titrated with varying concentrations of protein. The H1(0) used was expressed in and purified from a strain of E. coli and is therefore homogeneous with respect to H1 subtype and posttranslational modifications. Two types of T4 DNA were used: wild-type, which contains a modification of the cytosine residues that projects into the major groove: and a mutant type, which lacks the modification of the cytosines. Data were compared to simulated thermal denaturation curves to determine estimates for binding affinity and binding site size in base pairs of the protein. Analysis of the data yielded values of 10(8) M(-1) for K, the binding affinity, and 10 base pairs for n, the number of base pairs covered by one protein, for the mutant T4 DNA. Analysis of the wild-type DNA data suggested that the glucose projecting into the major groove of this DNA decreases the number of sites to which the H1(0) protein can bind, indicating that there are interactions between the protein and the major groove of DNA. The binding site size on this DNA is 10 base pairs, the same as on the unmodified DNA. The affinity for wild-type DNA is slightly higher, 10(9) M(-1). Data were collected and analyzed for binding of two domains of the protein as well, the carboxyl-terminal domain and the central globular domain. Binding of the carboxyl-terminal domain was quantitatively and qualitatively similar to that of the full-length protein. In contrast, binding of the globular domain was quite different: it binds much more weakly, with a K of 6 x 10(4) M(-1), and covers fewer base pairs, with an n of 3. Also, there was no evidence that the globular domain interacts with the major groove of DNA.     

Multiple cysteine residues are implicated in Janus kinase 2-mediated catalysis

The redox regulation of Janus kinase 2 (JAK2) is poorly understood, and there are contradictory reports as to whether the enzyme's activity is inhibited or stimulated by oxidizing conditions in the cell. Here we demonstrate that multiple cysteine residues within the JAK2 catalytic domain may be crucial for enzymatic activity. The enzyme is catalytically inactive when oxidized; activity can be restored via reduction to the thiol state. A series of recombinant variants of JAK2 were overproduced using the baculoviral expression vector system. A truncated variant of JAK2, GST/(NDelta661)rJAK2, provided evidence that the amino-terminal autoinhibitory domain was not essential for direct redox regulation and that only nine cysteine residues were potentially involved. The effect of individually and combinatorially altering these nine cysteines was examined via cysteine-to-serine mutagenesis. This identified four cysteine residues in the catalytic domain (Cys866, Cys917, Cys1094, and Cys1105) that cooperatively maintain JAK2's catalytic competency. Our data are consistent with a direct mechanism for redox regulation of JAK2 via oxidation and reduction of critical cysteine residues.     

Glyoxalase in ageing

The glyoxalase system has been studied since 1913. The biochemical function of this enzymatic system is the metabolism of reactive dicarbonyl metabolites, glyoxal and methylglyoxal, to less reactive products. In the last decade research has shown that methylglyoxal is the precursor of quantitatively important damage to the proteome and genome, forming mainly hydroimidazolone and imidazopurinone adducts in protein and DNA respectively. The aim of this article is to review the evidence of the involvement of the glyoxalase system in ageing and role of glyoxalase in future research into healthy ageing-mainly in mammalian systems for insights into consequences and interventions in human health. Protein and DNA damage by glyoxalase system substrates is linked to dysfunction of proteins susceptible to dicarbonyl modification-the dicarbonyl proteome, and DNA instability and mutation. A component of the glyoxalase system, glyoxalase 1, is a gene with expression influential on lifespan-increasing longevity being associated with increased expression of glyoxalase 1. The glyoxalase 1 gene is also a site of copy number variation in both transcribed and non-transcribed regions giving rise to population variation of expression. The glyoxalase system and Glo1 expression particularly is therefore likely linked to healthy ageing.     

Protein damage in diabetes and uremia--identifying hotspots of proteome damage where minimal modification is amplified to marked pathophysiological effect

Increased protein glycation, oxidation and nitration are found in diabetes and renal failure. Steady state levels of glycated, oxidized and nitrated proteins are generally low, yet often have significant physiological effects--particularly linked to development and progression of vascular complications, including often fatal cardiovascular disease. Identification of sites activated toward damaging modifications or 'hotspots' in functional domains within proteins appears key to assessing targets of functional impairment. Disease progression is likely linked to instances where change in low level of hotspot damage influences metabolic control or physiological function. Examples discussed are: type IV collagen modification leading to endothelial cell detachment and anoikis, mitochondrial protein modification leading to oxidative stress and apolipoprotein B100 modification in low density lipoprotein leading to vascular retention and atherosclerosis. The role of mathematical systems biology, bioinformatics and proteome dynamics in future investigations is discussed.