Aikaterini Kontrogianni-Konstantopoulos, PhD

URL of My Bibliography:  http://www.ncbi.nlm.nih.gov/sites/myncbi/aikaterini.kontrogianni-konstantopoulos.1/bibliography/41140460/public/?sort=date&direction=ascending

Honors and Professional Memberships 
1988-1990             Award for Excellence in Academic Performance, Institute of National Scholarships, Greece

1993-1994             Graduate Student Scholarship, Department 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, School of Medicine, Division of Hematology, Dept. of Medicine, Baltimore, MD

2000                  Research Fellow Investigator Award (one of the five finalists among one hundred and sixty-nine participants), Research Retreat, Johns Hopkins University, School of Medicine, Division of Hematology, Dept. of Medicine, Baltimore, MD

2000-2002             American Heart Association, Mid-Atlantic Post-doctoral Fellowship

2001-2002             National Institute of Health (NIH) Training Grant, University of Maryland Baltimore, School of Medicine, Interdisciplinary Training Program in Muscle Biology

2003-pres.            Journal Reviewer

2004-pres.            Grant Reviewer (NIH, AHA, NSF, MDA etc.)

2009-2011             Lead Guest Editor, Journal of Biomedicine and Biotechnology; Series of special issues: Advances in Muscle Physiology and Pathophysiology

2010-2018             Interdisciplinary Training Program in Muscle Biology; Member of steering committee

2011                  American Society of Cell Biology, Discussion Focus Group

2011-2012             Biophysical Society, Programming Committee

2012                  FASEB-Experimental Biology Meeting, Session: Cell Motility in Health and Disease, Chair

2013-2014             Lead Guest Editor, Frontiers in Physiology

2016                  Satellite workshop on Titin, Myosin Binding Protein-C and Obscurin; co-Organizer and Moderator, Chicago, IL

2017-pres             Scientific Advisory Board Member; European Union Actin cytoskeleton in striated muscle function in Health And Disease-EU AHEAD project (coordinator: Dr. Marie-Louise Bang)

2017-pres             Member, Appointments, Promotion & Tenure (APT) Committee, Dept. of Biochemistry and Molecular Biology, UMSOM

2017-pres             Scientific Reports: Cell Biology; Editorial Advisory Panel Member

2018                   Woman Scientist of the Year, Greece

2018                   Dr. Patricia Sokolove Outstanding Mentor Award, University of Maryland Graduate School

2018                   Session Chair; European Muscle Conference, Session: Muscle development, regeneration and disease

2018-2019              Co-director; Interdisciplinary Training Program in Muscle Biology

2018-pres.             Vice Chair; Heart Failure SFRN Oversight Advisory Committee

2019                    Session Chair; 63rd Biophysical Society Meeting, Myosin and skeletal/smooth muscle mechanics, structure and regulation

2019                    Session Chair; AHA Basic Cardiovascular Sciences Meeting; Session: Rare genetic diseases in the heart

2019-pres.              UMSOM; Preclerkship working group/Curriculum Reform group

2019-2020               NIH-Cardiac Contractility and Heart Failure Study section; Regular member

2019-onwards            Director; Interdisciplinary Training Program in Muscle Biology

2019-onwards            Member, American Heart Association Research Leaders Academy Planning Committee

2020-2021               Member, Scientific Committee 2nd Olympiad in Cardiovascular Medicine

2020-2022               Member, American Heart Association Basic Cardiovascular Sciences (BCVS) Specialty Conference Program Committee-BCVS Council

2021-2025               NIH-Integrative Muscle Physiology and Pathophysiology-A Study Section; Chair & Regular Member

• R01AR076373 (Kontrogianni-Konstantopoulos, A.)         

          NIH/NIAMS      09/01/20-08/31/25                                                       

         “Novel MYBPC1 mutations cosegregate with a myopathy associated with muscle weakness, hypotonia and tremor”

• R01AR077106 (Kontrogianni-Konstantopoulos, A & Bloch, RJ, Multi-PI)   

          NIH/NIAMS       08/01/20-07/31/25                                                          

          “Cytoskeletal regulation of SERCA in muscle”

• Research Grant (Kontrogianni-Konstantopoulos, A.)                                                                                                                                   

         Muscular Dystrophy Association       02/01/19-01/31/22

         “Novel mutations in MYBPC1 resulting in myopathy with tremor”

• T32 AR007592 (Kontrogianni-Konstantopoulos, A.; Program Director since 07/19)                                    NIH/NIAMS        05/01/96-04/30/26

         “Interdisciplinary Training Program in Muscle Biology”

Contributions to Science

General note on our 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 ~20 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 deletion and knock-in models.

Below please see three major areas of research on obscurins that we are currently pursuing.

1. Obscurin in heart pathophysiology

Giant obscurins are multidomain proteins expressed in striated muscles that intimately surround sarcomeres at the level of M-bands and Z-disks. Manipulation of the expression levels of obscurins, either in vitro or in vivo, has shown that they play key roles in myofibrillogenesis, the cytoskeletal alignment of the SR membranes, and the subsarcolemmal organization of microtubules, highlighting their importance in striated muscle structure and function. This is further highlighted by the identification of mutations in the OBSCN gene that are directly linked to the development of hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and left ventricular noncompaction (LVNC) in humans. To study the roles of obscurins in cardiac pathophysiology, my laboratory has generated knock-in and deletion mouse models expressing mutant obscurins that carry disease-associated mutations and truncated obscurins that lack binding modules, respectively. Our studies indicate a direct involvement of obscurins in Ca²⁺ cycling through the regulation of SERCA activity and mechanotransduction pathways through their interaction with titins. Our research focuses on the detailed mechanistic characterization of the molecular, biochemical, and cellular alterations taking placing in myocardia and skeletal muscles expressing mutant or truncated obscurins.

2. Obscurin-Kinase Activity at the Intercalated Disc

            Two main 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 Kin1 and Kin2 that belong to the myosin light chain kinase (MLCK) family. Contrary to obscurin A, obscurin B is also present at the intercalated disk (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 Kin1 and Kin2 in obscurin B was discovered more than a decade ago, their enzymatic activity, catalytic substrates and (patho)physiological roles have remained elusive. It is only recently that our group demonstrated that both Kin1 and Kin2 are enzymatically active. In particular, Kin1 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 Kin1 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. Given the involvement of obscurins in cardiac (patho)physiology, the pivotal roles of MLCK/MLCK-like kinases in cardiac structure & function, and the development of severe and lethal cardiomyo-pathies due to deregulated ICD proteins, our studies are of high (patho)physiological significance and relevance.

3. Giant Obscurins in Breast Cancer Development and Metastasis

Recent evidence has unexpectedly implicated OBSCN in cancer development due to the high mutational prevalence it exhibits in different types of cancer, including breast cancer, leading to significant reduction of the obscurin transcript levels. In light of this observation, we began to unravel the roles of the OBSCN gene in breast cancer formation and progression^1-3. 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 (EMT). More importantly, obscurin-KD, but not scramble control, breast epithelial cells expressing an active form of K-Ras form extensive local (primary) tumors and lung metastases in vivo. We thus hypothesize that loss of giant obscurins correlates with the tumorigenic and metastatic propensity of breast tumors, and propose to establish giant obscurins (or lack thereof) as a novel prognostic biomarker for metastatic breast cancer, and to elucidate the molecular and cellular alterations due to their loss. More importantly, restoration of the expression and/or functionality of obscurins in obscurin-deficient breast cancer cells using genome editing and peptide therapy approaches are major goals of my lab. Thus, our research has important clinical implications in the establishment of obscurin as novel prognostic biomarker for metastatic breast cancer and the development of new, more effective, targeted therapies.

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 muscle¹. Given the molecular complexity, differential phosphorylation, key structural and regulatory roles, and direct involvement of MyBP-C slow in Distal Arthrogryposis and a new form of distal myopathy characterized by muscle weakness and tremor, the biology of the MyBP-C slow subfamily has become a major project in my laboratory.

4. 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 (c), slow skeletal (s) and fast skeletal (f). During the last forty years, numerous studies have focused on elucidating the mechanisms that modulate the activities of cMyBP-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 cMyBP-C. Our group has been studying the slow skeletal form of MyBP-C aiming to understand its regulation and activities^1-5. Using molecular tools, we have shown that the MYBPC1 gene, encoding sMyBP-C, 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 sMyBP-C undergoes extensive phosphorylation mediated by PKA and PKC. In particular, we have identified four phosphorylation sites in the NH₂-terminus of the protein, with one of them located within an alternatively spliced region. Recently, mutations in MYBPC1 slow were directly associated with the development of different forms of arthrogryposis: Distal Arthrogryposis Type 1 and 2 (DA1 and DA2), which are severe autosomal dominant disorders that selectively affect the distal limbs, Lethal Congenital Contractural Syndrome Type 4 (LCCS4), a neonatal lethal autosomal recessive syndrome, and a novel distal myopathy accompanied by muscle weakness, hypotonia, tremor and facial/body deformities. We therefore propose that sMyBP-C 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 sMyBP-C during myofibrillogenesis and in adulthood in both slow and fast twitch muscles, and to examine how these are compromised in disease.