Biochemistry and Molecular Biology
Biomedical Research Facility, 215A
Education and Training
I received my Ph.D. from Baylor College of Medicine, Houston, TX in the Department of Cell Biology. After graduating from Baylor College of Medicine, I joined the laboratory of Dr. E.J. Benz, Jr., in the Division of Hematology, Department of Medicine at Johns Hopkins University, School of Medicine in 1998, to study protein 4.1R, a peripheral membrane protein that was originally discovered in red blood cells. In 2001, I moved to the laboratory of Dr. R.J. Bloch, in the Department of Physiology, at the University of Maryland School of Medicine, as an Academic Fellow, to study a small form of ankyrin 1 (small ankyrin 1) that localizes at the sarcoplasmic reticulum membranes, and its ligands in skeletal muscle. In 2002, I was promoted to Research Associate, and 2003 to Research Assistant Professor.
In 2007, I joined the Department of Biochemistry and Molecular Biology at the University of Maryland School of Medicine as Assistant Professor in the tenure track. Using the muscle and epithelial cell as model systems, my laboratory has pioneered the molecular and functional characterization of major cytoskeletal and membrane-associated proteins as structural and signaling mediators in health and disease. My research has been funded by grants from the Muscular Dystrophy Association (MDA), the American Heart Association (AHA) and the National Institutes of Health (NIH).
My research focuses on the elucidation of the roles of cytoskeletal and membrane-associated proteins as structural and signaling mediators. Using the muscle and epithelial cell as model systems, my laboratory has pioneered the molecular and functional characterization of the obscurin subfamily and its binding partner Myosin Binding Protein-C slow in health and disease.
As evidence of the recognition of my group for its studies on cytoskeletal regulators, I have been invited to submit a review article discussing the biology of giant cytoskeletal regulators in the journal Physiological Reviews (impact factor: 29.041), and to present our work in major national and international meetings, including the American Society for Cell Biology, San Francisco, CA (12/08), the FP7-funded network on Muscle Z-disk Protein Complexes (MUZIC): from Atomic Structure to Physiological Function, Stockholm, Sweden (06/10), The International Society for Heart Research, Baltimore, MD (05/09) and San Diego, CA (06/13), the Experimental Biology Society, San Diego, CA (04/12), the Biophysical Society, Philadelphia, PA (02/13), the Myofilament Meeting, Madison, WI (06/12 and 06/14), the 20th World Congress on Advances in Oncology and 18th International Symposium of Molecular Medicine, Athens, Greece (10/15), the International Cancer Study and Therapy Conference, Baltimore, MD (02/16 and 02/17) etc. In addition, I have been invited to organize and chair symposia in the Experimental Biology Meeting, San Diego, CA (04/12), a satellite workshop focusing on “Titin, Obscurin and Myosin Binding Protein-C”, Chicago, IL (06/16) and the World Cancer Congress, Barcelona, Spain (05/17), serve as Lead Guest Editor in a series of special issues for The Journal of Biotechnology and Biomedicine, covering current “Advances of Muscle Physiology and Pathophysiology” (2010-2012), and organize a “Research Topics” section for Frontiers in Physiology focusing on striated muscle structure and function (2013-2014). I have also served as reviewer for several journals and study section panels (e.g., National Institutes of Health, National Science Foundation, American Heart Association, Muscular Dystrophy Association, Cancer Research Foundation, UK, National Cancer Science Center, PL, etc.).
Lastly, I have established a number of collaborations with prominent scientists in the general fields of cytoskeleton, muscle (patho)physiology, and epithelial cancer biology within and outside UMD, including Drs. CW Ward (UMD), J Lederer (UMD), R.J. Bloch (UMD), D. Weber (UMD), S. Martin (UMD), K. Konstantopoulos (JHU), D. Huso (JHU), J. Sellers (NHLBI), C. Gurnett (Wash U), and C. dos Remedios (U Syd, Australia).
cytoskeleton, signaling, skeletal and cardiac muscle (patho)physiology, breast cancer
- Ackermann, M.A., Hu, L.-Y. R., Bowman, A.L., Bloch, R.J. and Kontrogianni-Konstantopoulos, A., "Obscurin Interacts with a Novel Isoform of Myosin Binding Protein C-Slow at the Periphery of the M-band and Regulates the Assembly of Thick Filaments", Mol. Biol. Cell, 201 (12): 2963-78, 2009.
- Hu, L.Y. and Kontrogianni-Konstantopoulos, A., “The kinase domains of obscurin interact with intercellular adhesion proteins” FASEB Journal, 27(5), 2001-2012, 2013.
- Shriver, M., Stroka, K.M., Vitolo, M.I., Martin, S.S., Huso, D.L., Konstantopoulos, K., and Kontrogianni-Konstantopoulos A. “Loss of giant obscurins from breast epithelium promotes epithelial-to-mesenchymal transition, tumorigenicity and metastasis” Oncogene, 2014, doi: 10.1038/onc.2014.358.
- Ackermann, M.A., Ward, C., Gurnett, C., and Kontrogianni-Konstantopoulos, A., "Myosin Binding Protein-C Slow Phosphorylation is Altered in Duchenne Dystrophy and Arthrogryposis Myopathy in Fast-Twitch Skeletal Muscles”, Scientific Reports, 2015, doi: 10.1038/srep13235.
- Shriver, M. Marimuthu, S., Paul, C., Geist, J., Seale, T., Konstantopoulos, K., and Kontrogianni-Konstantopoulos, A. “Giant obscurins regulate the PI3K cascade in breast epithelial cells via direct binding to the PI3K/p85 regulatory subunit”, Oncotarget, 2016, doi: 10.18632/oncotarget.9985.
Honors & Awards
1988-1990, Award for Excellence in Academic Performance, Institute of National Scholarships, Greece
1993-1994 Graduate Student Scholarship, Dept of Cell Biology, Baylor College of Medicine, Houston, Texas
1996 Scholarship Award in Recognition of Excellence in Academic Achievement, Hellenic Professional Society of Texas
1998, 1999 Travel Award, American Society of Hematology
1999-2001 National Institute of Health (NIH) Training Grant, Johns Hopkins University, Baltimore, MD
2000 Research Fellow Investigator Award, Research Retreat, Johns Hopkins University, Baltimore, MD
2000-2002 American Heart Association, Mid-Atlantic Affiliate Post-doctoral Fellowship
2001-2002 NIH Training Grant, University of Maryland School of Medicine, Interdisciplinary Training Program in Muscle Biology
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine
2007-present Biochemistry and Molecular Biology-Graduate Recruiting Committee, Member
2011-2013 Biochemistry and Molecular Biology-School of Medicine Council, Alternate Representative
2013-present Biochemistry and Molecular Biology-Research Committee, Co-Chair
2013-present Biochemistry and Molecular Biology-Political Action Advisory Committee, Member
2015-present Biochemistry and Molecular Biology-Steering Committee, Member
2016-present Biochemistry and Molecular Biology-APT Committee, Member
University of Maryland School of Medicine
2002-2007 UMSOM Biacore Facility; Director
2007-present UMSOM Medical School Admissions & Advisory Committee, Interviewer
2010-present GPILS Governing Committee, Biochemistry Joint Graduate Program, Member
2010-present NIH/NIAMS Interdisciplinary Training Program in Muscle Biology Steering Committee, Member
2015-present Training Program in Integrative Membrane Biology Retreat & 21st Annual Mini Retreat of the Interdisciplinary Training Program in Muscle Biology, co-Organizer
2015-present: UM Graduate Council-Graduate Faculty Committee, Member
2016-present UMSOM MSTP Admissions & Advisory Committee, Member/Interviewer
University of Maryland School of Medicine, (other)
2011 UM Marlene and Stewart Greenebaum Comprehensive Cancer Center, Cancer Biology Retreat, Judge
2013 UMSOM Graduate Research Conference, Judge
2015 UMSOM Graduate Research Conference, Judge
2016 UMSOM Research Strategic Plan (2017-2021) Committee, Member
2016 UMSOM GPILS and OPS Awards Committee, Member
2016 UMSOM STRAP 20 by ’20 Faculty Recruitment Initiative Committee, Member
2006-2010 NIH/NIAMS; Special Emphasis Panel Member (Ad hoc)
2007-2008 National Science Foundation Scientific Review Panel, Study Section Member (Ad hoc)
2008-2015 American Heart Association; Peer Review Study Group, Basic Cell 3 Region II, Study Section Member
2011 American Society of Cell Biology, Discussion Focus Group, Study Section Member
2011-2013 Biophysical Society, Programming Committee, Member
2012 FASEB-Experimental Biology Meeting, Session: Cell Motility in Health and Disease, Chair
2015-present NIH/NHLBI; Cardiac Myosin Binding Protein-C: Structure, Function, & Regulation, Study Section Member (Ad hoc)
2015-present Muscular Dystrophy Association; Scientific Advisory Committee, Member
2015-present Muscular Dystrophy Association; Medical Advisory Committee, Member
2016 NIH/NIAMS; Skeletal Muscle Biology and Exercise Physiology (SMEP) study section, Study Section Member (Ad hoc)
2016 American Physiological Society, Handbook of Physiology series, Comprehensive Physiology, Invited Contributor
2016 Workshop on titin, MyBP-C and obscurin; co-Organizer & Moderator, Loyola University Chicago, IL
2016 AHA, Heart Failure Strategically Focused Network Center Grants Basic Project Review Committee-Phase I, Member
2016 AHA, Heart Failure Strategically Focused Network Center Grants Review Committee-Phase II, Member
2016-2018 AHA, Strategically Focused Heart Failure Research Network Oversight Advisory Committee, Member
2016-present Oncotarget:Gerotarget-Section on Aging & Age-related disease, Advisory Board, Member
2010 Cancer Research Foundation, United Kingdom; Biological Sciences Committee, Study Section Member
2010-2012 Journal of Biomedicine and Biotechnology, Special Volume, Lead Guest Editor
2013-2014 Frontiers in Physiology, Special Volume, Primary Editor
2013-present National Science Center, Poland; Review Panel II, Study Section Member
2015 French National Research Agency, France, Study Section Member
2015 20th World Congress on Advances in Oncology &
18th International Symposium of Molecular Medicine; Athens, Greece, Session Chair
2017 10th Annual World Cancer Congress, Barcelona, Spain; Session Chair
Contributions to Science
General note on my research focusing on the giant cytoskeletal proteins obscurins: Studying the biology of obscurins has presented us with many challenges due to their apparent large size (500-920 kDa), multifaceted nature and unique biochemical properties. Consequently, during the last ~15 years that the OBSCN gene encoding obscurins has been identified, we have developed an arsenal of experimental protocols and methodologies and generated a plethora of reagents, including a panel of highly specific antibodies, small inhibitory RNA plasmids, adenoviral overexpression vectors, and more recently partial knock-out and knock-in models. Below please see three major areas of research on obscurins that we are currently pursuing.
I. Obscurin mutations and heart disease
Giant obscurins, encoded by the single OBSCN gene, are multidomain proteins expressed in striated muscles where they play key roles in the regular assembly and integration of the contractile cytoskeleton with internal membranes and the sarcolemma. Recently, sequencing analysis of the OBSCN gene has revealed the presence of congenital mutations, which are causally linked to the development of hypertrophic and dilated cardiomyopathy (HCM & DCM) in humans. My group has focused on a particular mutation, R4344Q, which is directly linked to HCM. To decipher the molecular alterations taking place in the R4344Q mutant myocardium, we generated a Knock-In (KI) mouse model carrying the R4344Q substitution. Morphological examination and physiological measurements of sedentary KI hearts demonstrated that they develop fibrosis, tachycardia and arrhythmia. Importantly, exertion of mechanical stress via transaortic constriction further uncovered the detrimental effects of the R4344Q mutation, leading to the development of profound cardiac hypertrophy accompanied by compromised cardiac function. Our current studies focus on the elucidation of the molecular and cellular alterations taking place in the R4344Q mutant myocardium in the absence and presence of physiological and pathological stress.
II. Obscurin kinase activity at the intercalated disc
Two main giant isoforms of obscurin have been characterized to date, obscurin A (~720 kDa) and obscurin B (~870 kDa). These share the same NH2-terminal adhesion and signaling motifs, but have unique COOH-termini. While obscurin A contains a non-modular COOH-terminus, obscurin B contains two Ser/Thr kinase domains, referred to as SK1 and SK2 that belong to the myosin light chain kinase (MLCK) family. Contrary to obscurin A, obscurin B is also present at the intercalated disc (ICD), the unique microdomain of the sarcolemma that contributes to the mechanical and electrochemical coupling of neighboring cardiomyocytes. Consistent with this, the transcript levels of obscurin B dramatically increase in response to aortic stenosis and tachycardia. Although the presence of SK1 and SK2 in obscurin B was discovered more than a decade ago, their enzymatic activity, catalytic substrates and (patho)physiological roles had remained elusive. It is only recently that our group demonstrated that both SK1 and SK2 are enzymatically active. In particular, SK2 undergoes autophosphorylation, and directly binds to and phosphorylates the cytoplasmic domain of N-cadherin. N-cadherin is a major component of the ICD that plays pivotal roles in maintaining the structural integrity and synchronous beating of the myocardium. Our research aims to show that the obscurin SK2 domain plays key roles in cell-cell adhesion and communication in cardiac muscle by regulating the activities of N-cadherin via phosphorylation of its cytoplasmic domain.
III. Giant Obscurins in Breast Cancer Development and Metastasis
Recent evidence has implicated OBSCN in cancer development due to its high mutational prevalence in different types of cancer, including breast cancer. In light of this observation, we began to unravel the roles of obscurins in breast cancer formation and progression. Our studies were the first to show that giant obscurins are abundantly expressed in normal breast tissue, but are virtually absent from advanced stage human breast cancer biopsies. Normal breast epithelial cells depleted of giant obscurins exhibit dramatically increased survival, motility and invasiveness. Consistent with these findings, obscurin-knockdown (KD) breast epithelial cells fail to form adherens junctions and undergo Epithelial to Mesenchymal Transition. More importantly, obscurin-KD, but not scramble control, breast epithelial cells expressing an active form of K-Ras form extensive local tumors and lung metastases in vivo. Our goal is to establish giant obscurins (or lack thereof) as a novel prognostic biomarker for metastatic breast cancer, and to delineate the molecular and cellular alterations due to their loss in breast cancer cells. More importantly, ectopic expression of an obscurin mini-cassette (<10 kDa) in obscurin-deficient breast epithelial cells drastically diminishes their migratory, invasive and reattachment potentials. We therefore further propose to mechanistically examine the tumor- and metastasis-suppressive effects of the obscurin mini-cassette, and thus its potential as a novel therapeutic target.
General note on our research focusing on the Myosin Binding Protein-C Slow (MyBP-C slow) subfamily: We originally identified MyBP-C slow as a binding partner of giant obscurins in skeletal muscle. Given the molecular complexity, differential phosphorylation, key structural and regulatory roles, and direct involvement of MyBP-C slow in Distal Arthrogryposis Myopathies, the biology of the MyBP-C slow subfamily has become a major project in our laboratory during the past five years.
IV. MyBP-C Slow: a Multifaceted Regulator of Muscle Structure and Function
Myosin Binding Protein-C (MyBP-C) comprises a subfamily of thick filament associated proteins that has structural and regulatory roles. Three distinct isoforms have been characterized, including the cardiac, slow skeletal and fast skeletal. During the last forty years, numerous studies have focused on elucidating the mechanisms that modulate the activities of cardiac MyBP-C. On the contrary, the regulation and roles of the skeletal isoforms have remained obscure, and mainly inferred due to the structural similarity they share with cardiac MyBP-C. Our group has been studying the slow skeletal form of MyBP-C aiming to understand its regulation and activities1-5. Using molecular tools, we have shown that the MYBPC1 gene, encoding MyBP-C slow, is heavily spliced giving rise to several variants, which are expressed in different combinations and amounts during development and in adulthood, in both slow and fast twitch skeletal muscles. The slow variants share common domains, but differ by the inclusion or skipping of novel insertions located in the NH2-terminus, the FN-III C7 domain and the COOH-terminus. Both the NH2 and COOH termini can retain native myosin and actin and modulate the sliding velocity of actin filaments past myosin heads, though to different extents, and in a variant-specific manner. Moreover, using proteomic tools, we have demonstrated that MyBP-C slow undergoes extensive phosphorylation mediated by PKA and PKC. In particular, we have identified four phosphorylation sites in the NH2-terminus of the protein, with two of them located within alternatively spliced regions. Recently, mutations in MYBPC1 slow were directly associated with the development of different forms of arthrogryposis myopathy: Distal Arthrogryposis Type 1 and 2 (DA1 and DA2), which are severe autosomal dominant myopathies that selectively affect the distal limbs, and Lethal Congenital Contractural Syndrome Type 4 (LCCS4), a neonatal lethal autosomal recessive myopathy. We therefore propose, that MyBP-C slow plays important structural and regulatory roles in developing and adult skeletal muscles, via the expression of distinct variants that are differentially phosphorylated. Our goals are to delineate the roles and regulation of MyBP-C slow during myofibrillogenesis and in adulthood, in both slow and fast twitch muscles, and to examine how these are compromised in severe (DA1 and DA2) and lethal (LCCS4) forms of arthrogryposis myopathy.
- NIH/NCI R01 CA183804 (A. Kontrogianni-Konstantopoulos, Multi-PI); 05/01/15-04/30/20; "Development of High Throughput Screening Technologies in Breast Cancer"
- MDA Research Grant (A. Kontrogianni-Konstantopoulos, PI); 08/01/15-07/31/18; "Loss of actomyosin regulation in distal arthrogryposis due to mutant MyBP-C slow"
- AHA Grant-In-Aid (A. Kontrogianni-Konstantopoulos, PI); 07/01/16-06/30/18; "Obscurins: new players in the development of hypertrophic cardiomyopathy"