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Functional activity of permeability transition pore in energized and deenergized rat liver mitochondria
O. V. Akopova*, L. I. Kolchinskaya, V. I. Nosar
Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv;
*e-mail: ov_akopova@ukr.net
Received: 15 June 2020; Accepted: 13 November 2020
Permeability transition pore (mPTP) opening was studied under energized and deenergized conditions in rat liver mitochondria, and the effect of membrane depolarization on mPTP activity was evaluated. To assess mPTP activity, cyclosporine-sensitive swelling and cyclosporine sensitive Ca2+ efflux from mitochondria was studied using light absorbance techniques. In energized mitochondria, mPTP opening in sub-conductance states, at [Ca2+] ≤ Ka, contributed positively to the rate of respiration, without affecting ΔΨm. Threshold Ca2+ concentrations were found, which excess resulted in fast mitochondrial depolarization upon mPTP opening. An estimate of mPTP activity by cyclosporine-sensitive Ca2+ transport under energized and deenergized conditions have shown that membrane depolarization by protonophore CCCP essentially increased initial rate (V0), at simultaneous decrease of the half-time (t1/2) of Ca2+ efflux, which indicated mPTP activation, as compared to energized mitochondria. However, only partial release of Ca2+ via mPTP upon membrane depolarization was observed. With the use of selective blockers of Ca2+ uniporter and mPTP, ruthenium red (RR) and cyclosporine A (CsA), partial contribution of Ca2+ uniporter and mPTP in Ca2+ transport was found. “Titration” of Ca2+ transport by adding RR at different times from the onset of depolarization showed that depolarization dramatically reduced “life span” of mPTP as compared to energized mitochondria, which agreed with the kinetic characteristics of CsA-sensitive Ca2+ transport after the abolition of ΔΨm. Ca2+ added from the outer side of mitochondrial membrane produced dual effect on mPTP activity: activation at the onset of depolarization, but consequent promotion of mPTP closure. Based on the experiments, it was concluded that mitochondrial energization was required for prolonged mPTP functioning in sub-conductance states, whereas membrane depolarization promoted the transition of mPTP to inactive state during calcium release from mitochondria.
The replicative CMG helicase: the ideal target for cancer therapy
W. Henderson, K. Nyman, M. Stoney, S. I. Borysov*
College of Arts and Sciences, Saint Leo University, St. Leo, Florida, USA;
*e-mail: Sergiy.Borysov@saintleo.edu
Received: 31 May 2020; Accepted:13 November 2020
This review focuses on Cdc45-Mcm2-7-GINS (CMG) helicase which is a key component of the cellular replication machinery and a new promising target for cancer therapy. In normal cells, only a small proportion of helicases becomes activated through the step-wise acquisition of all necessary subunits during genome replication and a large quantity of reserve dormant helicases exist to replace inhibited helicases, making the normal cells insensitive to helicase inhibition. The collective evidence in the field shows that in contrast to normal cells, cancer cells have a significantly reduced pool of dormant helicases and might be vulnerable to CMG helicase inhibitors. Functional studies confirm that targeted inhibition of CMG helicase could be a strong and specific anticancer approach that ensures efficiency against a broad spectrum of cancers and limited adverse effects on normal cells. We anticipate that therapeutics that inhibit CMG helicase can be used not only as a stand-alone therapy but also as effective chemosensitizers in combination with other drugs, thus increasing their clinical application.
A glance on the role of Hsien Wu in immunology development
Mohammad Ebrahimi
Department of History of Science and Scientific Archaeology,
University of Science and Technology of China, People’s Republic of China;
e-mail: ebrahimi@mail.ustc.edu.cn
Received: 13 April 2020; Accepted: 25 June 2020
Early in the 20th century, a number of researchers in the field of immunology investigated this science chemically. Immunochemistry is the study of antigens and antibodies and their chemical basis and resistance to disease, developed from immunology. The immunochemistry period began in 1918 and continued through the early 1960s. Since the beginning of the immunochemical period, many researchers have been working in the field of immunochemistry by introducing important immunohistochemical and immunocytochemical methods. Hsien Wu was inspired by the science of immunochemistry and was able to determine a method for the determination of hemoglobin. In this article, I attempt to illustrate Hsien’s achievements in this period by presenting Hsien Wu’s scientific biography and immunochemical history. Furthermore, providing documentary and scientific information on the course of immunochemistry and the role of Hsien in this course may be a spark for some researchers to explore the reasons for some of the chemical approaches and theories of this period.
A new view of RNA: the 1989 discovery by Sidney Altman and Thomas Cech
M. V. Grigorieva*, V. M. Danilova, S. V. Komisarenko
Palladin Biochemistry Institute, National Academy of Sciences of Ukraine, Kyiv;
*e-mail: mvgrigorieva@biochem.kiev.ua
Received: 23 June 2020; Accepted: 25 June 2020
The 1989 Nobel Prize Laureates in Chemistry Sidney Altman and Thomas Robert Cech made one of the most important discoveries in molecular genetics. Independently of each other, they demonstrated new experimental evidence that RNA molecules can not only transmit information from DNA but, in certain conditions, have the enzymatic (catalytic) properties too. As it turned out, the functions previously attributed exclusively to protein enzymes can be also performed by RNA called ribozymes. Later, ribozymes became a new tool in genetic engineering, biochemistry, biotechnology and medicine.
Research on structure, mechanism and regulation of enzyme activity. Works of Nobel laureates C. Anfinsen, S. Moore, W. Stein, S. Prusiner, J. Skou, P. Boyer, J. Walker
R. P. Vynogradova, V. M. Danilova*, S. V. Komisarenko
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
*e-mail: valdan@biochem.kiev.ua
Received: 17 May 2020; Accepted: 25 June 2020
Although the protein nature of enzymes was identified in the 40s of the 20th century, (we wrote about this in our previous article), their molecular structure and the specific mechanism of action remained unknown. Researchers of the next generations faced the challenges and a major breakthrough was achieved. In 1960, American biochemists S. Moore and W. Stein determined the complete amino acid sequence of enzyme ribonuclease. It was one of the first proteins and the first enzyme whose primary structure was established. In 1972, for this discovery, they received the Nobel Prize in Chemistry jointly to Christian Anfinsen who worked on the same problem. Works of Nobel Laureates in Chemistry in 1997 – Jens Christian Skou (for the discovery of the Na+,K+-activated ATPase), Paul Boyer and John Walker (for the discovery of the mechanism of action of H+-ATP synthase – the most important enzyme for bioenergy) were a huge step forward in the deciphering the mechanisms of enzyme action. The second half of the 20th century was marked by another outstanding discovery in the field of biology and medicine – the identification and characterization of prions – the proteins that cause neurodegenerative spongiform encephalopathies in humans and animals. For this work, American biochemist Stanley B. Prusiner received the Nobel Prize in Physiology or Medicine in 1997. This discovery is of great theoretical significance for biochemical science. The development of new research methods and technological advances formed the basis for significant scientific achievements in this field of biochemistry and molecular biology. This was the golden era of protein chemistry.
Oxidative stress regulation in the yeast Ogataea polymorpha producer of human α-synuclein
N. V. Hrushanyk1, O. V. Stasyk2, O. G. Stasyk1*
1Ivan Franko National University of Lviv, Ukraine;
2Institute of Cell Biology, National Academy of Sciences of Ukraine, Lviv;
*e-mail: olenastasyk@gmail.com
Received: 02 March 2020; Accepted: 25 June 2020
In this study we analyzed how exogenous glucose levels affect enzymatic and non-enzymatic antioxidant defense systems and markers of oxidative stress in cells of the methylotrophic yeast Ogataea polymorpha producing recombinant human α-synuclein, implicated in pathogenesis of neurodegenerative Parkinson’s disease (PD). We found that glucose depletion up-induced activity of antioxidant enzymes superoxide dismutase, and catalase, and increased content of reduced and oxidized glutathione in the cells cultivated in the medium with 0.1% glucose, as compared to physiological growth condition (1% glucose-containing medium). In addition, low glucose concentration in the medium upregulated content of proteins carbonyl groups and of products of lipid peroxidation. Notably, the shift in the equilibrium toward pro-oxidant changes was similar for recombinant α-synuclein producer and parental wild-type strain. Thus, glucose limitation leads to the overproduction of reactive oxygen species in the methylotrophic yeast cells independently of the recombinant human α-synuclein production.
Changes in gene expression of lactate carriers (MCT1 and CD147) in cardiac muscle of diabetic male rats: the effect of dichloroacetate and endurance training
H. Rezaeinasab1*, A. Habibi1, M. Nikbakht1, M. Rashno2,3, S. Shakerian1
1Department of Exercise Physiology, Faculty of Sport Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran;
2Department of Immunology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran;
3Department of Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
e-mail: hamed.rezaei2020@gmail.com
Received: 23 March 2020; Accepted: 25 June 2020
Lactate accumulation can activate the pathways of mitochondrial biogenesis in the heart muscle. The purpose of this study was to investigate the effects of Pyruvate Dehydrogenase Kinase 4 (PDK4) inhibition and endurance training on the gene expression of lactate carriers (MCT1 and CD147) in the cardiac muscle of STZ-diabetic rats. In this experimental study, 64 male Wistar rats were selected and randomly divided into eight groups after induction of diabetes with streptozotocin (STZ). The endurance training protocol was performed on a treadmill for 6 weeks. Intraperitoneal injection of DCA of 50 mg/ kg body weight was used for the inhibition of PDK4 in the myocardium. Gene expression were measured using real-time PCR. The two-way ANOVA test was used to analyze the data. The results of the study showed that after endurance training, the expression of MCT1, PDK4, and CD147 genes increased significantly in line with each other (P < 0.05), and by inhibition of PDK4 in the heart muscle, the expression of MCT1 and CD147 genes in the endurance training group + diabetes + DCA and in the diabetes group + DCA decreased significantly (P < 0.05). According to the results of this study, it can be concluded that the repeated accumulation of lactate caused by exercise training in diabetic patients decrease through mitochondrial adaptation by DCA injection and subsequently oxidative stress can be reduced in cardiac tissue of diabetic patients and heart efficacy can be increased.
Effect of sucralose on the blood content of thyroid hormones
O. Oliynyk1,2*, A. Slifirczyk1, Y. Oliynyk3, B. Pereviznyk3
1Pope John Paul II State School of Higher Education, Biała Podlaska, Poland ;
2Bogomolets National Medical University, Kyiv, Ukraine;
3I. Horbachevsky Ternopil National Medical University, Ukraine;
*e-mail: Alexanderoliynyk8@gmail.com
Received: 22 February 2020; Accepted: 25 June 2020
Sugar substitutes are among the most widely used food additives. Increasing number of scientific research on their adverse effect on various body functions has been appearing lately. The objective of this research is to study the effect of sucralose, a sugar substitute, on the thyroid functional state. Involved in the research were 30 women, aged 19-28, estimating themselves healthy. The blood content of free and general triiodothyronine, free and general thyroxine, as well as of thyrotropic hormone was determined. Thereafter, the women were taking sucralose for a month daily in a dose of 15 mg/kg, the blood content of the hormones mentioned above having been tested again. Reliable 2.0, 1.58, and 1.46 times decrease in the blood content of free and general triiodothyronine, and general thyroxine, respectively, as well as reliable 4.41 times increase in the blood content of thyrotropic hormone (Р < 0.001) has been found. Our findings on the sucralose-induced decrease in the level of thyroid hormones confirm the results of other researchers regarding sucralose as biologically inert compound that should be kept in mind when evaluating its effect on the patients with endocrine pathology.