Welcome to the Sever Lab

Basic Science Research with Clinical Relevance

  • biochemistry
  • genetics
  • cell biology
  • live-cell imaging

bottom Click to learn more

Research Overview

Approximately 16% of Americans suffer from chronic kidney diseases. That number is expected to increase with the rising incidence of obesity and type 2 diabetes. Currently there is no cure. In order to define the molecular mechanisms underlying proteinuric kidney diseases our laboratory employs a combination of biochemistry, cell biology, live-cell imaging, and mouse models thereby enabling analysis at the RNA, protein, cellular, and physiological level. Current investigations concern the structure and function of podocytes, focusing on regulation of the actin cytoskeleton, the GTPase dynamin, and clathrin-mediated endocytosis. A better understanding of podocyte pathobiology will pave the way for developing a cure for kidney diseases.

Biochemistry

Among standard techniques used in the laboratory are the GTPase assays, actin polymerization assays using recombinant proteins or cell extracts, protein expression and purification using bacteria, insect cells and mammalian tissue culture.

Genetics

We use a number of genetic murine models of chronic kidney diseases, such as Actinin4 transgenic mice and BTBR Ob/Ob mutant mice.

Cell Biology

We utilize diverse cell lines in culture including mouse and human podocytes. Standardly used techniques are immunofluorescence, immunoprecipitations, motility assays, ELISA, Western blot analysis, as well as standard techniques of molecular biology.

Live-Cell Imaging

We have recently established assay that follows dynamin oligomerization in vitro and in cells in real time using fluorescence lifetime imaging microscopy (FLIM).


Scroll down further for more details!

bottom

Current Research Interests

We are currently interested in...

Podocytes are terminally differentiated cells that form the filtration barrier in the kidney. Damage or loss of podocytes is an early symptom of many kidney diseases; structural integrity of the podocyte actin cytoskeleton is critical for its proper function. A better understanding of podocyte pathobiology will pave the way for developing a cure for kidney diseases.

Our work has shown that dynamin is a unique GTPase that directly regulates actin polymerization and is thus essential for podocyte structure and function. We now seek to identify the specific role and mechanism of GTPase dynamin regulation of the actin cytoskeleton.

We have also shown that a cytoplasmic form of the protease cathepsin-L is induced in proteinuric kidney disease. Induction of cytoplasmic cathepsin-L leads to cleavage of dynamin resulting in reorganization of the podocyte actin cytoskeleton and subsequent proteinuria. We have recently elucidated the mechanism of cathepsin-L induction.
We are also interested in the role of dynamin in clathrin-mediated endocytosis. The classical view of dynamin holds that it acts as a mechanochemical enzyme or "pinchase," severing vesicles from the plasma membrane. Our work suggests an alternative model in which dynamin is a regulatory GTPase, orchestrating formation of clathrin-coated vesicles. In this view unoligomerized dynamin recruits additional proteins that drive formation of fully invaginated coated pits and subsequent budding of free vesicles.

We have established a novel assay that measures dynamin oligomerization in live cells. Our studies suggest that dynamin oligomerization may play an indirect role in endocytosis through regulation of actin. In support of our model we have identified Hsc70 and its co-chaperone auxilin as downstream effectors of dynamin activity.


Podocytes expressing dynamin mutant R725A, which increases dynamin’s propensity to oligomerize into higher-order structures such as rings. Dynamin oligomerization has been implicated in clathrin-mediated endocytosis, but here we show for the first time that its oligomerization plays an essential physiological role by directly regulating the actin cytoskeleton. This, in turn, drives the formation of foot processes that are significantly longer than those in wild-type animals and those in animals before Doxycycline treatment (used to drive expression of DynR725A). It is very rare to see such a dramatic effect on the length of the foot processes (FPs) since dominant-negative mutations of diverse proteins expressed in podocytes typically result in the loss of FPs. It should be noted that this particular dynamin mutant (DynR725A) has been published by Dr. Sever back in 1999 in Nature (Sever et al, Nature 1999). This mutant suggested that dynamin is a regulatory GTPase and not a pinchase. As you can see, this mutant has a long history.

Techniques

Details about some of the techniques we use

Description forthcoming. Section currently under construction.

Lab Members

Members of the Sever lab, present and past. Click the appropriate tabs to learn more.

Investigators

Sanja Sever, Ph.D. —

Principal Investigator, Assistant Professor of Medicine

Postdoctoral Research Fellow, The Scripps Research Institute
Ph.D. in Biochemistry, Zagreb University & Visiting graduate student, Yale University
M.S. in Molecular Biology, Zagreb University
B.S. in Molecular Biology, Zagreb University

Changkyu Gu, Ph.D. —

Instructor

Postdoctoral Research Fellow, Harvard Medical School and the Massachusetts General Hospital
Postdoctoral Research Fellow, Department of Life Science, Sookmyung Women’s University
Ph.D. in Biomedical Gerontology, Hallym University
M.S. in Biomedical Gerontology, Hallym University
B.S. in Microbiology, Hankuk University of Foreign Studies

Postdoctoral Fellows

Kamalika Mukherjee —

Postdoctoral Research Fellow

Postdoctoral Research Associate in Chemical Biology, State University of New York at Binghamton
Ph.D. in Chemistry, State University of New York at Binghamton
M.S. in Applied Microbiology, Vellore Institute of Technology University
B.S. in Biochemistry, Microbiology, and Botany, Bangalore University

Research Assistants

Garrett Garborcauskas — |

Research Assistant

B.S. in Chemistry and Classical Studies, Smith College

Postdoctoral Fellows

Marina Kasaikina, Ph.D. (2013-2015) —

Postdoctoral Fellow at Dana Farber

Postdoctoral Research Fellow, Tufts University
Ph.D. in Biochemistry, University of Nebraska-Lincoln
B.S./M.S. in Bioorganic Chemistry, Moscow State University

Valentina Shchedrina, Ph.D. (2012-2014) —

Postdoctoral Research Fellow, Brigham & Women’s Hospital
Postdoctoral Research Fellow, University of Nebraska-Lincoln
Ph.D. in Biochemistry, Moscow State University
M.S. in Chemistry, Moscow State University
B.S. in Chemistry, Moscow State University

Miroslav Sekulic, M.D./Ph.D. (2012-2013)

Pathology Resident at the University of Minnesota

M.D. University of Belgrade School of Medicine
M.A. in Medical Sciences, Boston University School of Medicine
B.S. in Physiology & Neurobiology, University of Connecticut

Suma Yaddanapudi, Ph.D. (2007-2012)

Senior Scientist at Pfizer

Ph.D. in Pharmaceutical Sciences, University of Connecticut
B.S. in Pharmacy, Osmania University

Subbulakshmi Chidambaram, Ph.D. (2007-2008)

Senior Scientist at Vision Research Foundation

Elisabetta del Re, Ph.D. (2003-2005)

Investigator and Instructor in Psychiatry at Harvard Medical School

Research Assistants

Vincent A. Pham (2013-2015) — |

Went on to Graduate School

B.S. in Neuroscience, Brown University

Eileen Kapples (2013-2015)

Went on to Medical School

B.S. in Biology (minor in Spanish), Georgetown University

Joann Chang (2011-2013)

Went on to Medical School

University of Michigan School of Law, J.D.
Cornell University, B.A.

Amanda C. Taus (2011-2013)

Smith College, B.A.

David Ko (2005-2007)

Went on to Medical School

Lavan Khandan (2005-2006)

Went on to Graduate School

Sharif Nankoe (2004-2006)

Went on to Medical School

Ithaca College, B.A.

Thomas Gilmore (2003-2005)

Went on to Medical School

Arne Christensen (2000-2003)

Went on to Graduate School

Visiting Scholars and Summer Students

Cristina Bardita, 2014

Visiting Scholar (Rush University)

Karina Thieme, 2013

Visiting Scholar (University of São Paulo)

Filip Miletic, 2009

Summer Student (University of Connecticut)

Tim Marinelli, 2008

Summer Student (Williams College)

Elena Bukanova, 2004

Summer Student (Brown University)

Lab group photo 2015

Lab 2013

The Sever Lab celebrating MGH being voted #1 best hospital in U.S. News and World Reports

Left to right: Changkyu, Garrett, Vincent, Eileen


Lab 2013

By the water near our lab in Charlestown

Left to right: Changkyu, Eileen, Vincent, Marina, Garrett, Sanja


Lab 2013

At lunch at Pier 6

Left to right: Marina, Changkyu, Vincent, Eileen, Garrett


Lab group photo 2013

Lab 2013

Left to right: Miro, Changkyu, Amanda, Joann, Marina, Valentina, Sanja


Publications

To search for Dr. Sever's publications on PubMed, please click here.

Highlighted Publications

Pharmacological targeting of actin-dependent dynamin oligomerization ameliorates chronic kidney disease in diverse animal models

Schiffer M*, Teng B*, Gu C*, Shchedrina VA, Kasaikina M, Pham VA, Hanke N, Rong S, Gueler F, Schroeder P, Tossidou I, Park J, Staggs L, Haller H, Erschow S, Hilfiker-Kleiner D, Wei C, Chen C, Tardi N, Hakroush S, Selig M, Vasilyev A, Merscher S, Reiser J, Sever S.
Nature Medicine. doi: 10.1038/nm.3843. Epub 2015 May 11.
PMID: 25962121

A Podocyte-Based Automated Screening Assay Identifies Protective Small Molecules.

Lee HW, Khan SQ, Faridi MH, Wei C, Tardi NJ, Altintas MM, Elshabrawy HA, Mangos S, Quick KL, Sever S, Reiser J, Gupta V.
J Am Soc Nephrol. 2015 Apr 9. pii: ASN.2014090859. [Epub ahead of print]
PMID: 25858967

Regulation of dynamin oligomerization in cells: the role of dynamin-actin interactions and its GTPase activity.

Gu C, Chang J, Shchedrina VA, Pham VA, Hartwig JH, Suphamungmee W, Lehman W, Hyman BT, Bacskai BJ, Sever S.
Traffic. 2014 Aug;15(8):819-38. doi: 10.1111/tra.12178. Epub 2014 Jun 24.
PMID: 24891099

Reduction of proteinuria through podocyte alkalinization.

Altintas MM, Moriwaki K, Wei C, Möller CC, Flesche J, Li J, Yaddanapudi S, Faridi MH, Gödel M, Huber TB, Preston RA, Jiang JX, Kerjaschki D, Sever S, Reiser J.
J Biol Chem. 2014 Jun 20;289(25):17454-67. doi: 10.1074/jbc.M114.568998. Epub 2014 May 9.
PMID: 24817115

Transient receptor potential channel 6 (TRPC6) protects podocytes during complement-mediated glomerular disease.

Kistler AD, Singh G, Altintas MM, Yu H, Fernandez IC, Gu C, Wilson C, Srivastava SK, Dietrich A, Walz K, Kerjaschki D, Ruiz P, Dryer S, Sever S, Dinda AK, Faul C, Reiser J.
J Biol Chem. 2013 Dec 20;288(51):36598-609. doi: 10.1074/jbc.M113.488122. Epub 2013 Nov 5.
PMID: 24194522

PCD2AP in mouse and human podocytes controls a proteolytic program that regulates cytoskeletal structure and cellular survival.

Yaddanapudi S, Altintas MM, Kistler AD, Fernandez I, Möller CC, Wei C, Peev V, Flesche JB, Forst AL, Li J, Patrakka J, Xiao Z, Grahammer F, Schiffer M, Lohmüller T, Reinheckel T, Gu C, Huber TB, Ju W, Bitzer M, Rastaldi MP, Ruiz P, Tryggvason K, Shaw AS, Faul C, Sever S, Reiser J.
J Clin Invest. 2011 Oct;121(10):3965-80. doi: 10.1172/JCI58552. Epub 2011 Sep 12. Erratum in: J Clin Invest. 2012 Feb 1;122(2):780.
PMID: 21911934

Direct dynamin-actin interactions regulate the actin cytoskeleton.

Gu C, Yaddanapudi S, Weins A, Osborn T, Reiser J, Pollak M, Hartwig J, Sever S.
EMBO J. 2010 Nov 3;29(21):3593-606. doi: 10.1038/emboj.2010.249. Epub 2010 Oct 8.
PMID: 20935625

Nucleoside diphosphate kinase Nm23-H1 regulates chromosomal stability by activating the GTPase dynamin during cytokinesis.

Conery AR, Sever S, Harlow E.
Proc Natl Acad Sci U S A. 2010 Aug 31;107(35):15461-6. doi: 10.1073/pnas.1010633107. Epub 2010 Aug 16.
PMID: 20713695

Establishment of protein delivery systems targeting podocytes.

Chiang WC, Geel TM, Altintas MM, Sever S, Ruiters MH, Reiser J.
PLoS One. 2010 Jul 29;5(7):e11837. doi: 10.1371/journal.pone.0011837.
PMID: 20686602

Synaptotagmin-mediated vesicle fusion regulates cell migration.

Colvin RA, Means TK, Diefenbach TJ, Moita LF, Friday RP, Sever S, Campanella GS, Abrazinski T, Manice LA, Moita C, Andrews NW, Wu D, Hacohen N, Luster AD.
Nat Immunol. 2010 Jun;11(6):495-502. doi: 10.1038/ni.1878. Epub 2010 May 16.
PMID: 20473299

Proteolytic processing of dynamin by cytoplasmic cathepsin L is a mechanism for proteinuric kidney disease.

Sever S, Altintas MM, Nankoe SR, Möller CC, Ko D, Wei C, Henderson J, del Re EC, Hsing L, Erickson A, Cohen CD, Kretzler M, Kerjaschki D, Rudensky A, Nikolic B, Reiser J.
J Clin Invest. 2007 Aug;117(8):2095-104.
PMID: 17671649

Dynasore puts a new spin on dynamin: a surprising dual role during vesicle formation.

Nankoe SR, Sever S.
Trends Cell Biol. 2006 Dec;16(12):607-9. Epub 2006 Oct 24.
PMID: 17064900

Physical and functional connection between auxilin and dynamin during endocytosis.

Sever S, Skoch J, Newmyer S, Ramachandran R, Ko D, McKee M, Bouley R, Ausiello D, Hyman BT, Bacskai BJ.
EMBO J. 2006 Sep 20;25(18):4163-74. Epub 2006 Aug 31.
PMID: 16946707

The low density lipoprotein receptor-related protein (LRP) is a novel beta-secretase (BACE1) substrate.

von Arnim CA, Kinoshita A, Peltan ID, Tangredi MM, Herl L, Lee BM, Spoelgen R, Hshieh TT, Ranganathan S, Battey FD, Liu CX, Bacskai BJ, Sever S, Irizarry MC, Strickland DK, Hyman BT.
J Biol Chem. 2005 May 6;280(18):17777-85. Epub 2005 Mar 4.
PMID: 15749709

Assays and functional properties of auxilin-dynamin interactions.

Sever S, Skoch J, Bacskai BJ, Newmyer SL.
Methods Enzymol. 2005;404:570-85.
PMID: 16413301

Auxilin-dynamin interactions link the uncoating ATPase chaperone machinery with vesicle formation.

Newmyer SL, Christensen A, Sever S.
Dev Cell. 2003 Jun;4(6):929-40.
PMID: 12791276

Expression, purification, and functional assays for self-association of dynamin-1.

Damke H, Muhlberg AB, Sever S, Sholly S, Warnock DE, Schmid SL.
Methods Enzymol. 2001;329:447-57. No abstract available.
PMID: 11210565

Dynamin:GTP controls the formation of constricted coated pits, the rate limiting step in clathrin-mediated endocytosis.

Sever S, Damke H, Schmid SL.
J Cell Biol. 2000 Sep 4;150(5):1137-48.
PMID: 10974001

Impairment of dynamin's GAP domain stimulates receptor-mediated endocytosis.

Sever S, Muhlberg AB, Schmid SL.
Nature. 1999 Apr 8;398(6727):481-6.
PMID: 10206643

Transfer RNA identity contributes to transition state stabilization during aminoacyl-tRNA synthesis.

Ibba M, Sever S, Praetorius-Ibba M, Söll D.
Nucleic Acids Res. 1999 Sep 15;27(18):3631-7.
PMID: 10471730

Interactions between tRNA identity nucleotides and their recognition sites in glutaminyl-tRNA synthetase determine the cognate amino acid affinity of the enzyme.

Ibba M, Hong KW, Sherman JM, Sever S, Söll D.
Proc Natl Acad Sci U S A. 1996 Jul 9;93(14):6953-8.
PMID: 8692925

Escherichia coli tryptophanyl-tRNA synthetase mutants selected for tryptophan auxotrophy implicate the dimer interface in optimizing amino acid binding.

Sever S, Rogers K, Rogers MJ, Carter C Jr, Söll D.
Biochemistry. 1996 Jan 9;35(1):32-40.
PMID: 8555191

The grand challenge of nephrology.

Trachtman H, Benzing T, Sever S, Harris RC, Reiser J.
Front Med (Lausanne). 2014 Sep 18;1:28. doi: 10.3389/fmed.2014.00028. eCollection 2014.
PMID: 25593903

Signal transduction in podocytes--spotlight on receptor tyrosine kinases.

Reiser J, Sever S, Faul C.
Nat Rev Nephrol. 2014 Feb;10(2):104-15. doi: 10.1038/nrneph.2013.274. Epub 2014 Jan 7.
PMID: 24394191

Dynamin rings: not just for fission.

Sever S, Chang J, Gu C.
Traffic. 2013 Dec;14(12):1194-9. doi: 10.1111/tra.12116. Epub 2013 Sep 19.
PMID: 23980695

Is there clinical value in measuring suPAR levels in FSGS?

Sever S, Trachtman H, Wei C, Reiser J.
Clin J Am Soc Nephrol. 2013 Aug;8(8):1273-5. doi: 10.2215/CJN.06170613. Epub 2013 Jul 25.
PMID: 23886567

Podocyte biology and pathogenesis of kidney disease.

Reiser J, Sever S.
Annu Rev Med. 2013;64:357-66. doi: 10.1146/annurev-med-050311-163340. Epub 2012 Nov 26. Review.
PMID: 23190150

AP-2 makes room for rivals.

Sever S.
Dev Cell. 2003 Oct;5(4):530-2.
PMID: 14536052

Dynamin and endocytosis.

Sever S.
Curr Opin Cell Biol. 2002 Aug;14(4):463-7.
PMID: 12383797

Garrotes, springs, ratchets, and whips: putting dynamin models to the test.

Sever S, Damke H, Schmid SL.
Traffic. 2000 May;1(5):385-92.
PMID: 11208124

Substrate selection by aminoacyl-tRNA synthetases.

Ibba M, Thomann HU, Hong KW, Sherman JM, Weygand-Durasevic I, Sever S, Stange-Thomann N, Praetorius M, Söll D.
Nucleic Acids Symp Ser. 1995;(33):40-2. Review.
PMID: 8643392

Positions

We are hiring! See below for available positions.

  • Postdoctoral Fellow

    • Job Description


      General Overview

      The Massachusetts General Hospital Division of Nephrology studies chronic kidney disease and the mechanism of associated proteinuria. General aims of the program include targeting the regulatory pathways leading to glomerular failure, bridging the gap between scientific discovery and drug development, and developing novel techniques for drug discovery and therapeutics.

      The Sever laboratory investigates the role of the GTPase dynamin in the regulation of actin dynamics and endocytosis after having identified a connection between these processes and podocyte pathobiology. We are currently interested in uncovering the molecular mechanisms by which dynamin directly regulates actin polymerization in general and actin dynamics in endocytosis in particular. The research will involve experimental approaches from protein biochemistry, mammalian tissue culture, cell biology and, ‘state of the art' microscopy such as fluorescence lifetime imaging microscopy (FLIM), TIRFM and single-molecule imaging. Novel concepts are tested for their physiological relevance using animal mouse.



      Qualifications

      This position offers an unparalleled opportunity to work with both a congenial tight-knit group and with the support of a world-renowned institute. Ideal candidates will have a Ph.D. in the life sciences with a strong background in molecular biology, cell biology, biochemistry, or pharmacology. Candidates must also have a first-author paper published in a well-recognized peer-reviewed journal.
      Experience with live-cell imaging or protein biochemistry is desired.
      Candidates must be independent, enthusiastic, self-motivated and willing to collaborate as part of a team.


      To Apply

      Interested candidates should send a letter of intent, resume, and a list of three references to Dr. Sanja Sever, Ph.D. (sever.lab.at.mgh@gmail.com).

    apply Now
  • Research Assistant/Technician

    • Job Description


      General Description


      A research assistant position is available at Harvard Medical School and the Massachusetts General Hospital, Nephorlogy Division, to study the molecular mechanisms underlying chronic kidney diseases such as diabetic nephropathy. Research in the laboratory focuses on molecular events involved in the pathobiology of podocytes, which are terminally differentiated cells that are part of the kidney filter.


      We have uncovered connections between intracellular membrane trafficking, the actin cytoskeleton, and podocyte pathobiology. Research on podocytes is currently considered one of the hotspots in nephrology, as they form the most important layer of the renal filtration barrier. Podocyte damage or loss is the early symptom of many kidney diseases. Better understanding of podocyte pathobiology will definitely pave the way for developing a cure for kidney diseases in the future.


      Qualifications

      Candidates with a strong background in molecular biology, biochemistry, and cell biology are encouraged to apply.


      To Apply

      Interested candidates should send a cover letter, resume, and a list of three references to Dr. Sanja Sever, Ph.D. (sever.lab.at.mgh@gmail.com).

    apply Now
where are we located?
click to open map

Traveling Directions

Click on a method of transportation to expand detailed directions.

From the MBTA Green Line, go to North Station. Here, you may board the free MGH/Partners shuttle bus (located at the intersection of Causeway Street and Haverhill Street) to the Charlestown Navy Yard, MGH East Research Building 149. The Sever Lab is on the 8th floor. The shuttle goes every 15 minutes during working hours (less often on weekends and holidays).

From the MBTA Red Line, go to Charles/MGH. Here you may board the free MGH/Partners shuttle bus to the Charlestown Navy Yard, MGH East Research Building 149. The bus stops behind the MGH Jackson building and on Staniford St. behind the Whole Foods. The Sever Lab is on the 8th floor. The shuttle goes every 15 minutes during working hours (less often on weekends and holidays).
At the end of Storrow Drive, just beyond the MGH Main Campus, take a left onto the McGrath-O'Brien Highway. The Museum of Science will be on your left. At the first set of lights, proceed right onto the Gilmore Bridge, then at the next lights take a right onto Rutherford Avenue. Turn left at the second lights onto Chelsea Street. The Navy Yard and the U.S.S. Constitution will be on your right. Continue on Chelsea Street through three sets of traffic lights (about 1 mile). At the fourth set of lights take a right and the MGH East Navy Yard Research Building (Bldg. 149) will be one block away on the right. Take the first left to the MGH Parking Garage, which is connected to the Research Building by overhead walkways.
Take I-90 to Route 93 North through downtown Boston and over the Zakim/Bunker Hill Bridge. Take the Sullivan Square exit. Go right at the bottom of the ramp and take the second exit off the Sullivan Square rotary towards Charlestown (keep Schrafft building on your left). At the first intersection, take a left onto Medford Street. At the end of Medford Street, take a left and an immediate right into the Navy Yard. The MGH East Navy Yard Research Building (Bldg. 149) will be one block away on your right. Take the first left to the Parking Garage, which is connected to the Research Building by overhead walkways.

Once you have arrived please call us at (617) 724-8922. You will have to check in with Security before we can escort you to the lab, so please bring your driver’s license or other government-issued identification.

MGH at the Charlestown Navy Yard

Building 149, Room 8113

13th Street, Charlestown, MA 02129