Previous research has studied the alterations in the regulation of oxidative phosphorylation by extramitochondrial calcium in brain cells and changes in the crosstalk between oxidative phosphorylation and glycolysis in the pathogenesis of cardiac and skeletal muscle disorders (cardiac failure and sarcopenia). In addition, the role of some signalling pathways (HIF-1alpha, PKB/Akt) and metabolic substrates (creatine) in cellular damage during heart failure and sarcopenia has been studied. We have found that aged skeletal muscles have reduced regenerative potential combined with disturbed energy metabolism, which increases vulnerability of myoblasts to hypoxia and calcium overload. In our research program we combine systems genetics with more focused studies on cellular bioenergetics and ER stress. Ongoing projects include the following:
Department of Pathophysiology has expertise in cellular energy metabolism, disease models, genomics (genome and exome sequencing, RNAseq, genotyping), human studies, biobanking and complex data analysis.
Figure 1. Translational studies on bone and muscle pathologies include different disorders, different target tissues and combine four different approaches.
Translational studies on bone and muscle pathologies
Principal investigator: Sulev Kõks
Diseases of muscles and bones are one of the largest groups of clinical disorders and have significant impact on disease burden for society. These disorders are highly prevalent in elderly people and have significant impact for societies with aging population. Despite their high prevalence, the pathophysiology behind these disorders is not well understood and for many conditions neither existing therapies nor prophylaxis are completely efficacious. Better understanding about the pathophysiology and a translational approach are needed. The general goal of our research is to describe novel pathogenetic pathways (energy metabolism, endoplasmic reticulum (ER) stress) and to discover gene networks for these disorders. Currently ongoing activities include cellular bioenergetics on aging muscle and heart. We also analyze diseased bones and joints (osteoporosis, osteoarthritis). For these research activities, we combine systems genetics analysis with more focused studies on cellular bioenergetics and ER stress.
European Commission 7-th Framework Programme Project MARTO13136R 01.08.2013–31.07.2018 www.hyporth.eu
HypOrth - New approaches in the development of Hypoallergenic implant material in Orthopedics: steps to personalised medicine
Principal investigator: Aare Märtson, Sulev Kõks
Due to increasing life span of human beings in industrialized countries the diagnosis of osteoarthritis is the most common indication for implantation of artificial joints. The implantation of total hip (THA) and total knee arthroplasties (TKA) is based on 50 years of experience and is one of the most successful and most common treatments for osteoarthritis of the joint. Although the clinical outcome of total joint arthroplasty is usually excellent, some implants become loose and require re-implantation. Re-implantation surgery is more complex than primary joint replacement, takes longer to perform, implants are more expensive and the patient`s hospital stay is prolonged, incurring higher costs. To date, there are no predictive measures or indicative markers for an adverse immune reaction (AIR) to implant material exist, since results of patch tests of skin for allergy do not correlate with the risk for implant hypersensitivity. In addition, no clear strategic diagnostic methods have been found to differentiate prosthetic loosening caused by AIR from a low-grade infection. The materials used for artificial prosthesis by default are Titanium (TiAl6V4, TiAl6Nb7 – forged alloy), CoCrMo (forged alloy), ceramics and UHMWPE (Ultra High Molecular Weight PolyEthylene). Despite application of different biocompatible materials, the ultimate material with properties of native joints has not been found to date. This project provides a comprehensive view on the problem of adverse immune reactions to implant material including immunological, genomic, reverse engineering, microbiological, epidemiological and clinical aspects. The ultimate goals of our project are to develop a novel orthopaedic implant prototype based on hypoallergenic materials and to define individual predictive and general diagnostic biomarkers for AIR.
Estonian Science Foundation Project ETF8736 01.01.2011-31.12.2014
Cellular energetic depression: basis of cardiac and skeletal muscle disorders and target of protective mechanisms.
Principal investigator: Enn Seppet/Margus Eimre (margus.eimre [ät] ut.ee)
Research staff: Kalju Paju, Ehte Orlova, Margus Eimre, Lumme Kadaja, Arno Ruusalepp, Andres Piirsoo, Tatjana Kums, Helena Gapeyeva, Mati Pääsuke, Taavi Põdramägi, Mart Roosimaa, Reedik Pääsuke
This project addresses several interrelated aspects of the role of impaired energy metabolism in the pathogenesis of disorders of muscle cells, such as (i) alterations in regulation of oxidative phosphorylation (OXPHOS) by extramitochondrial Ca2+ and (ii) changes in cross-talk between OXPHOS and glycolysis in conditions of hypoxia, cardiac failure and aging related sarcopenia. (iii) The potential of some signalling pathways (HIF-1alpha, p38, MEK/Erk, and PKB/Akt) in protection against cardiac disease and combating sarcopenia will be tested.
Figure 2. Disorders of mitochondrial ATP synthesis and energy transfer cause cellular energy depression (CED) and lead to reduced ability of muscle to work. The resulting reactive oxygen species formation and Ca2+overload further impair the mitochondria and energy transfer leading to cell death. CK – creatine kinase isoenzymes involved in energy transfer, AK – adenylate kinase, PK – pyruvate kinase, HK II – isoenzyme of hexokinase, which may in conditions of energy deficit, be bound to mitochondria as an adaptation mechanism promoting cellular energy supply. MOMP- mitochondrial outer membrane permeabilization, PT – permeability transition of mitochondrial inner membraane, Inhibitors – proteins of Bcl family and cyclosporine A, which prevent the formation of channels in the membranes of mitochondria, Aralar – aspartate/glutamate carrier, component of malate-aspartate shuttle, R.C. – respiratory chain.
Estonia-Vietnam collaboration in medical science
Principal investigator: Sulev Kõks
The aim of the DIOXMED initiative is to create a foundation for international research collaboration between universities and clinics in Estonia, the UK and Vietnam in order to increase awareness of the effects of dioxins as the cause of increasing environmental pollution problems in people’s everyday lives (developmental disorders, infertility and others), in veterinary research and the environment. In the framework of this project international research collaboration will be developed with Estonian medical researchers to raise international competitiveness in the fields of bone and joint disease and reproductive medicine among Vietnamese researchers with great research potential. Active cooperation will be developed for initiating new research projects in Vietnam’s medical education and research institutes (Hue University of Medicine and Pharmacy), Vietnamese hospitals (in Hue, Da Nang, Saigon, Hanoi), the Vietnamese Genetic Consultation and Disabled Children’s Centre and King’s College in London.
International collaboration to develop regenerative medicine (REMARK) 01.05.2012–31.08.2015
Principal investigator: Eric Tkaczyk
REMARK is a regenerative medicine grant from the Estonian Ministry of Education and Research to fund international research collaboration and the exchange of students and scientists. Domestic partners include the University of Tartu (including the Estonian Genome Center with DNA samples of 5% of the country's population), Estonian Life Sciences University. International partners include the Regenerative Medicine Coalition and Vanderbilt University. The main areas of collaboration are:
1) innovative three-dimensional cell cultures and methods from materials science;
2) non-invasive advanced imaging and optical methods;
3) biobanking, genomics and proteomics
European Commission 7-th Framework Programme Project MARMP09022R 01.01.2009-31.12.2012
MYOAGE- Understanding and combating age related muscle weakness.
Principal investigator: Enn Seppet/ Mati Pääsuke
Kalju Paju, Lumme Kadaja, Margus Eimre, Nadežda Peet, Merike Kruus, Jelena Sokk, Reedik Pääsuke, Mart Roosimaa, Helena Gapeyeva, Jaan Ereline, Tatjana Kums, Herje Aibast, Aare Märtson, Andres Piirsoo, AnuKõiveer, Tauno Koovit.
The age related changes in functions of the mitochondrial respiratory chain complexes and functional coupling of mitochondrial kinases to oxidative phosphorylation and peripheral kinases to ATPases in relation to mitochondrial capacity to accumulate Ca2+, expression of kinases, uncoupler proteins and contractile function are being studied. The relationships between the changes of energy metabolism, expression of differentiation markers and activation of signaling pathways will be tested in primary myoblasts cultured from biopsy samples of m. quadriceps. Alterations in regulation of oxidative phosphorylation by extramitochondrial Ca2+ (via glutamate-aspartate transporter: aralar system) are being studied. The role of pro- and anti-inflammatory cytokines in modulating the energy metabolism is being assessed. Genomic analyses of mitochondrial and cytoskeletal proteins in myocytes in different steps of myogenesis are being performed.
Targeted Financing Project SF0180114As08 01.01.2008-31.12.2013
Role of impaired oxidative phosphorylation and compartmentation of energy metabolism in pathophysiology of diseased and aged muscle cells.
Principal investigator: Enn Seppet/Lumme Kadaja
Research staff: Margus Eimre, Lumme Kadaja, Ehte Orlova, Kalju Paju, Arno Ruusalepp, Evelin Seppet
The aim of the project is to assess the function of the systems of energy metabolism (oxidative phosphorylation and energy transfer) in cardiac and skeletal muscle cells in conditions of heart failure, neurodegenerative diseases and ageing. The functions of the mitochondrial respiratory chain complexes and functional couplings of mitochondrial kinases to oxidative phosphorylation and peripheral kinases to ATPases in relation to mitochondrial capacity to accumulate Ca2+, expression of kinases, cytoskeletal proteins, uncoupler proteins and contractile function will be studied. In studies of ageing muscles, special attention is played to the roles of mTOR- and AMPK-mediated pathways and pro- and antiinflammatory cytokines in modulating the intracellular energy.
Estonian Science Foundation Project ETF7823 01.01.2009-31.12.2012
Dynamics of formation modular bioenergetic systems during differentiation of stem cells into myocytes and their degradation during ageing.
Principal investigator: Valdur Saks
Research staff: Toomas Tiivel, Anu Nutt, Kairi Tammoja, Kersti Tepp, Tuuli Käämbre, Peeter Sikk, Madis Metsis, Natalja Timohhin, Andres Piirsoo, Ehte Orlova, Enn Seppet, Kalju Paju, Lumme Kadaja, Karin Tamm, Minna Karu, Tiina Drell, Igor Ševtšuk, Vladimir Tšekulaje, Aleksandr Klepinin
Genomic and proteomic analyses of mitochondrial and cytoskeletal proteins in myocytes and stem cells in different steps of myogenesis are being performed.
- Roosimaa M, Põdramägi T, Kadaja L, Ruusalepp A, Paju K, Puhke R, Eimre M, Orlova E, Piirsoo A, Peet N, Gellerich FN, Seppet E (2013). Dilation of human atria: Increased diffusion restrictions for ADP, overexpression of hexokinase 2 and its coupling to oxidative phosphorylation in cardiomyocytes.Mitochondrion. 13: 399-409.
- Kõks S, Overall RW, Ivask M, Soomets U, Guha M, Vasar E, Fernandes C, Schalkwyk LC (2013).Silencing of the WFS1 gene in HEK cells induces pathways related to neurodegeneration and mitochondrial damage. Physiological genomics. 45: 182-190.
- Seppet E, Orlova E, Seene T, Gellerich FN (2012). Adaptation of cardiac and skeletal muscle mitochondria to endurance training: implications for cardiac protection. Ostadal B, Dhalla N.S (Toim.). Cardiac Adaptations (375–402). Springer.
- Ellinghaus D, Ellinghaus E, Nair RP, Stuart PE, Esko T, Metspalu A, Debrus S, Raelson JV, Tejasvi T, Belouchi M, West SL, Barker JN, Kõks S, Kingo K, Balschun T, Palmieri O, Annese V, Gieger C, Wichmann HE, Kabesch M, Trembath RC, Mathew CG, Abecasis GR, Weidinger S, Nikolaus S, Schreiber S, Elder JT, Weichenthal M, Nothnagel M, Franke A (2012). Combined Analysis of Genome-wide Association Studies for Crohn Disease and Psoriasis Identifies Seven Shared Susceptibility Loci. American Journal of Human Genetics. 6: 636-647.
- Gellerich FN, Gizatullina Z, Trumbekaite S, Korzeniewski B, Gaynutdinov T, Seppet E, Vielhaber S, Heinze HJ, Striggow F (2012). Cytosolic Ca2+ regulates the energization of isolated brain mitochondria by formation of pyruvate through the malate-aspartate shuttle. Biochem J. 443: 747–755.
- Tsoi LC, Spain SL, Knight J, Ellinghaus E, Stuart PE, Capon F, Ding J, Li Y, Tejasvi T, Gudjonsson JE, Kang HM, Allen MH, McManus R, Novelli G, Samuelsson L, Schalkwijk J, Ståhle M, Burden AD, Smith CH, Cork MJ, Estivill X, Bowcock AM, Krueger GG, Weger W, Worthington J, Tazi-Ahnini R, Nestle FO, Hayday A, Hoffmann P, Winkelmann J, Wijmenga C, Langford C, Edkins S, Andrews R, Blackburn H, Strange A, Band G, Pearson RD, Vukcevic D, Spencer CC, Deloukas P, Mrowietz U, Schreiber S, Weidinger S, Koks S, Kingo K, Esko T, Metspalu A, Lim HW, Voorhees JJ, Weichenthal M, Wichmann HE, Chandran V, Rosen CF, Rahman P, Gladman DD, Griffiths CE, Reis A, Kere J, Duffin KC, Helms C, Goldgar D, Li Y, Paschall J, Malloy MJ, Pullinger CR, Kane JP, Gardner J, Perlmutter A, Miner A, Feng BJ, Hiremagalore R, Ike RW, Christophers E, Henseler T, Ruether A, Schrodi SJ, Prahalad S, Guthery SL, Fischer J, Liao W, Kwok P, Menter A, Lathrop GM, Wise C, Begovich AB, Genetic Analysis of Psoriasis Consortium; Onoufriadis A, Weale ME, Hofer A, Salmhofer W, Wolf P, Kainu K, Saarialho-Kere U, Suomela S, Badorf P, Hüffmeier U, Kurrat W, Küster W, Lascorz J, Mössner R, Schürmeier-Horst F, Ständer M, Traupe H, Bergboer JG, Heijer Md, van de Kerkhof PC, Zeeuwen PL, Barnes L, Campbell LE, Cusack C, Coleman C, Conroy J, Ennis S, Fitzgerald O, Gallagher P, Irvine AD, Kirby B, Markham T, McLean WH, McPartlin J, Rogers SF, Ryan AW, Zawirska A, Giardina E, Lepre T, Perricone C, Martín-Ezquerra G, Pujol RM, Riveira-Munoz E, Inerot A, Naluai AT, Mallbris L, Wolk K, Leman J, Barton A, Warren RB, Young HS, Ricano-Ponce I, Trynka G, Pellett FJ, Henschel A, Aurand M, Bebo B, Gieger C, Illig T, Moebus S, Jöckel KH, Erbel R, Wellcome Trust Case Control Consortium 2; Donnelly P, Peltonen L, Blackwell JM, Bramon E, Brown MA, Casas JP, Corvin A, Craddock N, Duncanson A, Jankowski J, Markus HS, Mathew CG, McCarthy MI, Palmer CN, Plomin R, Rautanen A, Sawcer SJ, Samani N, Viswanathan AC, Wood NW, Bellenguez C, Freeman C, Hellenthal G, Giannoulatou E, Pirinen M, Su Z, Hunt SE, Gwilliam R, Bumpstead SJ, Dronov S, Gillman M, Gray E, Hammond N, Jayakumar A, McCann OT, Liddle J, Perez ML, Potter SC, Ravindrarajah R, Ricketts M, Waller M, Weston P, Widaa S, Whittaker P, Nair RP, Franke A, Barker JN, Abecasis GR, Elder JT, Trembath RC (2012). Identification of 15 new psoriasis susceptibility loci highlights the role of innate immunity. Nature Genetics. 44: 1341-1348.
- Kadaja L, Eimre M, Paju K, Roosimaa M, Põdramägi T, Kaasik P, Pehme A, Orlova E, Mudist M, Peet N, Piirsoo A, Seene T, Gellerich FN, Seppet EK (2010). Impaired oxidative phosphorylation in overtrained rat myocardium. Experimental and Clinical Cardiology. 15: e116-e127.
- Saks V, Guzun R, Timohhina N, Tepp K, Varikmaa M. Monge C, Beraud N, Käämbre T, Kuznetsov A, Kadaja L, Eimre M, Seppet E (2010). Structure - function relationships in feedback regulation of energy fluxes in vivo in health and disease: Mitochondrial Interactosome. Biochimica et Biophysica Acta. 1797: 678-697.