Structural and functional properties of glycerol-3-phosphate dehydrogenase from a mammalian hibernator

[Lymphocytes enzymatic status and peripheral blood neutrophils oxygen-dependent metabolism in patients with renal cancer]

The immune system, one of the most important homeostatic organism systems, is actively involved in the protection against malignant tumors. The earliest sighs of immune homeostasis disorders should be invetigated at the cellular level, because of cell functional manifestations depend on the state of intracellular metabolic reactions. The study of lymphocyte NAD(P)-dependent dehydrogenases activity and peripheral blood neutrophils oxygen-dependent metabolism in patients with renal cellular carcinoma (RCC) showed a decrease in the intensity of ribose-5-phosphate and NADH-dependent synthetic processes, inhibition of terminal reactions of glycolysis. Altered activities of the studied enzymes favor an increase in outflow of intermediates of the Krebs cycle on the reaction of amino acid metabolism in peripheral blood lymphocytes. Radical nephrectomy was accompanied by increased activity of glycolysis. The basal level chemiluminescent of peripheral neutrophils of RCC patients response was higher both before and after operations. Stimulation of neutrophils by opsonized zymosan in vitro leads to increase in oxidative metabolism activity, most in 14 days after surgery period. Before and 30 days after surgery, adaptive metabolic capabilities of neutrophilic granulocytes decreased.

Exploring Thermal Sensitivities and Adaptations of Oxidative Phosphorylation Pathways

Temperature shifts are a major challenge to animals; they drive adaptations in organisms and species, and affect all physiological functions in ectothermic organisms. Understanding the origin and mechanisms of these adaptations is critical for determining whether ectothermic organisms will be able to survive when faced with global climate change. Mitochondrial oxidative phosphorylation is thought to be an important metabolic player in this regard, since the capacity of the mitochondria to produce energy greatly varies according to temperature. However, organism survival and fitness depend not only on how much energy is produced, but, more precisely, on how oxidative phosphorylation is affected and which step of the process dictates thermal sensitivity. These questions need to be addressed from a new perspective involving a complex view of mitochondrial oxidative phosphorylation and its related pathways. In this review, we examine the effect of temperature on the commonly measured pathways, but mainly focus on the potential impact of lesser-studied pathways and related steps, including the electron-transferring flavoprotein pathway, glycerophosphate dehydrogenase, dihydroorotate dehydrogenase, choline dehydrogenase, proline dehydrogenase, and sulfide:quinone oxidoreductase. Our objective is to reveal new avenues of research that can address the impact of temperature on oxidative phosphorylation in all its complexity to better portray the limitations and the potential adaptations of aerobic metabolism.

Temperature and serine phosphorylation regulate glycerol-3-phosphate dehydrogenase in skeletal muscle of hibernating Richardson's ground squirrels

Glycerol-3-phosphate dehydrogenase (G3PDH) bridges carbohydrate and lipid metabolism by interconverting glycerol-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). This reversible reaction converts G3P derived from triglyceride hydrolysis to DHAP that can then enter glycolysis or gluconeogenesis and, in the reverse reaction, makes G3P for use in triglyceride biosynthesis. Small hibernating mammals rely almost exclusively on triglyceride reserves as their fuel for energy production during torpor and the recovery of glycerol after lipolysis is an important source of carbohydrate over the nonfeeding winter months. G3PDH (∼37 kDa) was purified from skeletal muscle of euthermic and hibernating Richardson's ground squirrels (Urocitellus richardsonii) using three column chromatography steps. Analysis of enzyme kinetic properties revealed that G3PDH from hibernator muscle had higher affinities for G3P and NAD at low (5 °C) assay temperature compared with high (21 or 37 °C) and a greater stability in the presence of denaturing agents (urea, guanidine hydrochloride) or high temperature (50 °C). Immunoblotting showed that hibernator muscle G3PDH had a higher phosphoserine content than the enzyme from euthermic controls and incubation studies showed that enzyme affinity for G3P changed significantly by stimulating endogenous protein kinases or phosphatases. Overall, this study suggests that the properties of ground squirrel muscle G3PDH are modulated by temperature and post-translational phosphorylation to alter enzyme function under euthermic versus hibernating states.

[The immunological characteristics and enzymatic activity of lymphocytes from the peripheral blood of the children presenting with pharyngeal tonsillar hypertrophy]

The objective of the present work was to study the immunological characteristics and activity of NAD(P)-dependent dehydrogenases in peripheral blood lymphocytes in the young children presenting with pharyngeal tonsil hypertrophy (PTH). A total of 57 children at the age from 1 to 3 years with PTH were available for the examination. The control group was comprised of 35 age-matched practically healthy children. The amount of CD3+, CD4+, CD8+, CD16+/56-, and CD19+ cells in the peripheral blood was determined with the use of the cytoflowmetric technique. The activity of NAD(P)-dependent dehydrogenases in the peripheral blood lymphocytes was quantified by the method of A.A. Savchenko and co-workers ([14]. Serum IgA, IgM, and IgG levels were measured as described by G. Mancini and co-workers [12], and the levels of the circulating immune complexes (CIC) by the method of Haskova and co-workers [13]. The children presenting with pharyngeal tonsil hypertrophy were found to undergo changes in the immune-phenotypic spectrum of peripheral bloods lymphocytes, the decrease of serum IgA concentration, and the increase in the serum CIC level. The activity of riboso-5-phpsphate- and NADH-dependent reactions of the macromolecular synthesis was increased whereas the role of the malate-aspartate shunt in the cellular energy metabolism and activity of glycolysis decreased. On the contrary, the substrate flow in the tricarbonic acid cycle was rather high while glutathione reductase activity was low. The present study has shown that the children presenting with pharyngeal tonsil hypertrophy underwent changes in the immune and phenotypic spectrum of peripheral bloods lymphocytes, the decrease of serum IgA concentration, and the increase in the serum CIC level.

Transcriptional Activation of p53 during Cold Induced Torpor in the 13-Lined Ground Squirrel Ictidomys tridecemlineatus

The transcription factor p53 is located at the centre of multiple pathways relating the cellular response to stress. Commonly known as a tumor suppressor, it is responsible for initiating diverse actions to protect the integrity of the genome, ranging from cell cycle arrest to apoptosis. This study investigated the regulation of p53 protein in hibernating 13-lined ground squirrel Ictidomys tridecemlineatus during multiple stages of the torpor-arousal cycle. Transcript and protein levels of p53 were both elevated in the skeletal muscle during early and late torpor stages of the hibernation cycle. Nuclear localization of p53 was also increased during late torpor, and this is associated with an increase in its DNA binding activity and expression of p53 transcriptional targets p21CIP, gadd45α, and 14-3-3σ. The increase in p53 transcriptional activity appears to be independent of its phosphorylation at Ser-15, Ser-46, and Ser-392, consistent with an absence of checkpoint kinase activation during torpor. Sequence analysis revealed unique amino acid substitutions in the ground squirrel p53 protein, which may contribute to an increase in protein stability compared to nonhibernators. Overall, the study results provided evidences for a potential role of p53 in the protection of the skeletal muscle during torpor.