Biochemistry (Moscow), Supplement Series B: Biomedical Chemistry

The Effect of The Neuroprotector Isatin on Complex Formation of Beta-Amyloid Peptide Fragments with Some Intracellular Proteins Abstract Amyloid-β peptide (1−42) (Aβ1-42) is a key player in the development and progression of Alzheimer's disease (AD) and related pathologies, determined by formation of protein aggregates in the central nervous system. Aβ1-42 binding to crucial intracellular targets (and their subsequent inactivation) obviously represents one of the earliest events preceding extracellular pathogenic oligomerization/aggregation of Aβ1-42. It is reasonable to expect that dissociation of the Aβ1-42 complexes with intracellular proteins by means of inhibitors followed by subsequent degradation of Aβ1-42 would not only protect critically important proteins but also prevent intracellular accumulation of Аβ1-42. The aim of this study was to investigate the effect of the neuroprotector isatin (100 µM) on interaction of known Aβ-binding proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and pyruvate kinase, with Aβ1-42 and its fragments (Aβ1-28, Aβ12-28, Aβ25-35). Aβ1-42 and its fragments (Aβ1-28, Aβ12-28, Aβ25-35) immobilized on the Biacore optical biosensor chip interacted with GAPDH and pyruvate kinase. The lowest and basically equal Kd values were determined for GAPDH and pyruvate kinase complexes with immobilized Aβ1-42 and Aβ25-35. The presence of 100 µM isatin caused a significant (more than fivefold) increase in the Kd values for GAPDH complexes with all Aβ peptides except Aβ1-28. In contrast to GAPDH isatin increased dissociation of pyruvate kinase complexes only with Aβ1-42 (causing a 30-fold increase in Kd) and to a lesser extent with Aβ12-28 and Aβ25-35 (a 10-fold increase in the Kd value). It should be noted that in the presence of isatin the Kd values for GAPDH and pyruvate kinase complexes with all Aβ studied were in a narrower concentration range (10–7 M–10−6 M) than in the absence of this neuroprotector (10–8 M–10–6 M). Data obtained suggest existence of principal possibility of (pharmacological) protection of crucial intracellular targets against both Aβ1-42, and its aggressive truncated peptides (Aβ25-35).

Chronic Alcoholism Influences the mRNA Level of the Orexin Receptor Type 1 (OX1R) in Emotiogenic Structures of the Rat Brain Abstract— Orexin and its receptors are involved in mechanisms of pathological craving to alcohol. This study has shown that the mRNA level of the orexin receptor type 1 (OX1R) significantly decreased in the prefrontal cortex in the group of chronically alcoholized (for 6 months) rats compared with intact control. The same changes in the OX1R gene expression were observed on day 1 and day 7 of alcohol withdrawal after chronic alcoholization. On the contrary, in the hippocampus, the OX1R mRNA level increased on day 1 and day 7 of alcohol withdrawal. In the ventral tegmental area, the OX1R mRNA level remained unchanged on both day 1 and day 7 of alcohol withdrawal compared with the groups of chronic alcoholization and intact control. This suggests involvement of the prefrontal cortex and hippocampus in mechanisms mediating chronic alcohol intoxication.

Comparative Analysis of Gene Expression in Vascular Cells of Patients with Advanced Atherosclerosis Abstract A comparative analysis of gene expression profiles of carotid atherosclerotic plaques and intact internal thoracic arteries of patients with advanced atherosclerosis was performed by using the Human-12 BeadChip Microarray (Illumina, USA). The most down-regulated genes in the carotid atherosclerotic plaques were APOD, FABP4, CIDEC, and FOSB, in contrast, up-regulated gene was SPP1 (|FC| > 64; pFDR < 0.05). The majority of differentially expressed genes were down-regulated in advanced atherosclerotic plaques. For example, genes involved in immune and inflammatory responses (arachidonic acid metabolism, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, Jak-STAT signaling pathway, TNF signaling pathway) were down-regulated in advanced atherosclerotic plaques as compared with the healthy arteries. The most significant biological process of genes down-regulated in carotid atherosclerotic plaques (compared to intact internal thoracic arteries) was "cellular response to metal ions" (metallothioneins), and for upregulated genes was the organization of the extracellular matrix.

CLEC-2-Induced Signaling in Blood Platelets Abstract— Platelet activating lectin-like receptor type C-2 (CLEC-2) has been identified on the platelet surface about a decade ago. The only known endogenous CLEC-2 agonist is podoplanin, a transmembrane protein expressed by lymphatic endothelial cells, lymph node fibroblastic reticular cells, kidney podocytes, and by cells of certain tumors. CLEC-2 and podoplanin are involved in metastases, sepsis, development of deep-vein thrombosis. The CLEC-2 signaling cascade includes tyrosine kinases (Syk, SFK, Btk) as well as LAT adapter, and phospholipase Cγ2, which induces calcium signalling. CLEC-2, podoplanin and proteins, participating in the CLEC-2 signalling cascade, are considered as perspective targets for antithrombotic therapy.

Aryl-Hydrocarbon Receptor as a Potential Target for Anticancer Therapy Abstract—Aryl-hydrocarbon receptor (Aryl Hydrocarbon Receptor, AHR) is a ligand-dependent transcription factor; its functions are related to xenobiotic detoxification, response to inflammation, and the maintenance of tissue homeostasis. Results of recent studies suggest that AHR also plays an important role in carcinogenesis. Increased expression of AHR is observed in several types of tumors and tumor derived cell lines. In addition, many AHR ligands are included in compositions of pharmaceutical drugs used in oncotherapy. These facts provide some ground to consider AHR as a potential target for anticancer therapy, especially for treatment of severe cancers which have very limited (if any) treatment options. In this review we have considered the examples of the effects of AHR ligands on tumor derived cell cultures and on model mice lines with analysis of the AHR-dependent response.

Genetic and Biochemical Features of the Monogenic Hereditary Kidney Stone Disease Abstract— Kidney stone disease (KSD) is a common urological problem. In most cases, this multifactorial pathology develops due to the combination of inherited low-penetrance gene variants and environment factors such as urinary tract infections, unbalanced diet, and gastrointestinal tract diseases with malabsorption. However, some cases of KSD represent monogenic diseases in which mutations are inherited from one or both parents. These hereditary forms of KSD, manifested in childhood, are characterized by multiple, bilateral or recurrent kidney stones and the earlier development of chronic kidney disease. Introduction of methods for exome and gene panels (NGS—Next Generation Sequencing) sequencing, significantly increased the proportion of detectable genetically identifiable hereditary forms of KSD in the group of patients under 18 year old, which exceeded 20%. In this review we have analyzed genetic and biochemical mechanisms of the main hereditary forms of KSD, associated with enzymopathies (primary hyperoxaluria, adenine phosphoribosyltransferase deficiency, phosphoribosylpyrophosphate synthetase superactivity, xanthinuria, Lesch-Nyhan syndrome) and impaired membrane transport (Dent's disease, familial hypomagnesemia with hypercalciuria and nephrocalcinosis, hypophosphatemic urolithiasis, distal tubular acidosis, cystinuria, Bartter's syndrome). We suggest a comprehensive gene panel for NGS diagnostics of the hereditary KSD. Accurate and timely diagnosis of hereditary forms of urolithiasis makes it possible to identify a pathological germinal mutation and make an accurate diagnosis, to analyze the heterozygous mutation carriage in affected families and evaluate the prognosis of KSD development in family members, as well as to perform personalized management of the patients with KSD.

Prospects for the Use of Gene Expression Analysis in Rheumatology Abstract— Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown etiology, characterized by disturbances in functioning of immune system signaling pathways. This is accompanied by injury of other tissues, pain and joint destruction. Modern treatment is aimed at correction of pathophysiological and biochemical mechanisms responsible for clinical manifestation of the disease. However, due to heterogeneity of RA patients there is a clear need in the personalized approach to the RA treatment; the choice of personalized treatment is complicated by the variability of RA patient responses to the therapy. Gene expression analysis may serve as a tool for the disease control and therapy personification, for inhibition of inflammation and pain as well as for prevention of joint destruction.

Factors Governing Development of Non-Alcoholic Fatty Liver Disease and Insulin Resistance in Obesity Abstract— The factors promoting development of non-alcoholic fatty liver disease in patients with obesity and different state of carbohydrate metabolism have been investigated in 43 patients. These included 26 patients with abdominal obesity (BMI = 52.9 ± 7.9 kg/m2) and 17 conditionally healthy donors (control group) without obesity (BMI = 18.9–24.9 kg/m2). Seven (of 17) conditionally healthy persons formed a comparison group that was included to compare the results of study on the levels of tissue-specific expression of HSP70 mRNA. The study of mRNA expression was performed by real-time PCR. Blood serum concentrations of IL-6 and TNF-α were evaluated by the ELISA method. In obese patients with diabetes mellitus type 2 (DM2), a significant increase in the serum level of pro-inflammatory cytokines was found in comparison with the group of patients without DM2 and control. The results of histological examination of liver biopsy specimens in obese patients revealed the most pronounced changes in the group of DM2 patients. Regardless of the stage of nonalcoholic fatty liver disease in obese DM2 patients, there was an increase in the area of fatty inclusions (relative to the group without DM2). The study of the HSP70 gene expression in peripheral blood mononuclear cells revealed a significant increase versus the comparison group. The relationship between the level of the HSP70 gene expression in metabolically active tissues (visceral, subcutaneous adipose tissue and liver) and the serum content of proinflammatory cytokines (IL-6 and TNF-α) found in all obese patients may indicate suppression of HSP70 expression in these tissues under conditions of systemic and local inflammation in obesity.

Neutrophils as a Source of Factors Increasing Duration of the Inflammatory Phase of Wound Healing in Patients with Type 2 Diabetes Mellitus Abstract— Oxidative stress and neutrophil activation leading to an increase in myeloperoxidase (MPO), elastase and neutrophil extracellular trap (NET) levels in blood are considered as the pathogenic mechanisms responsible for the development of extremity damage in people with type 2 diabetes mellitus (T2DM). The aim of this study was to analyze the relationship between factors, associated with neutrophil activation, and the duration of the initial phase of wound healing (the inflammatory phase) in T2DM patients. Patients were divided retrospectively into three groups depending on the severity of lower extent damage: group 1 (wound on toe) < group 2 (wound on foot) < group 3 (wound on lower leg). At admission to hospital, T2DM patients had significantly higher (р < 0.05) levels of blood glucose and glycated hemoglobin (groups 1−3), ESR (groups 1 and 3), blood neutrophil count (groups 2 and 3), plasma MPO concentration (groups 1−3) and blood NET concentration (group 3) and decreased levels of plasma thiols (groups 1−3) and erythrocyte glutathione peroxidase activity (groups 2 and 3) than in the control group (healthy volunteers). The length of hospital stay after surgery corresponded to the length of the inflammatory phase of the wound healing process and correlated with the number of blood neutrophils in patients before surgery (r = 0.72, p < 0.05). Leukocytic intoxication index depended on wound area (r = 0.59, р < 0.05), and it was significantly higher for groups 2 and 3 compared to the control group and group 1. The correlation found can be attributed to the increase in extracellular MPO and NETs due to the activation and degranulation of neutrophils and netosis. Thus, the duration of the inflammatory phase of wound healing depends on specific aspects of systemic inflammation increasing oxidative/halogenative stress and intoxication.

The Study of the Neuroprotective Effects of Carnosine in the Experimental Model of Focal Cerebral Ischemia/Reperfusion Abstract— Oxidative stress is one of the key factors responsible for brain tissue damage in ischemia; this points to the use of antioxidants under these conditions. One of the promising antioxidants for the therapy of ischemic stroke is a natural dipeptide carnosine. In this study the neuroprotective effect of dietary carnosine administration has been investigated in an experimental model of focal cerebral ischemia/reperfusion in Wistar rats. Animals received carnosine with a diet at a daily dose of 150 mg/kg for 7 days before transient occlusion of the middle cerebral artery (MCA), performed for 60 min. At 24 h after the onset of ischemia the effect of carnosine administration on the area of the infarct size was evaluated in animals. In brain tissue of animals the content of malondialdehyde (MDA), protein carbonyls (PC), total antioxidant capacity (TAC), total activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione transferase (GT), the content of isoprostanes and cytokines were measured. Treatment with carnosine significantly reduced the infarct size, increased TAC, and decreased the levels of MDA and isoprostanes in the brain tissue. Thus carnosine consumed prophylactically with the diet for 7 days before the ischemia induced by MCA occlusion in rats exhibited the direct neuroprotective effect, maintained high antioxidant activity of the brain tissue, reduced the level of oxidative damage markers (MDA and isoprostanes) but had no effect on the activity of antioxidant enzyme systems and production of cytokines in the brain tissue.

Alexandros Sfakianakis
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