The Children's Hospital of Philadelphia Abramson Research Center, Room 816C
267-425 ?2124

Research Interest:
The research of the lab aims to understand intracellular membrane trafficking and Calcium-Regulated Exocytosis in eukaryotic cells.

Cell Biology, Membrane Trafficking, Exocytosis, Membrane fusion, SNAREs, Lipid Microdomain.

Research Details:
In particular we are focused in two main projects. One project investigates the molecular machinery required for membrane fusion during the cytotoxic immune response. The cell-mediated killing is a fundamental process in immunity that involves the fusion of the lytic granules at a specific area of the plasma membrane known as immunological synapse. To study how this process is achieved we utilize multidisciplinary approaches including biochemical reconstitution, proteomics, biophysical analysis, live cell imaging and Total Internal Reflection Microscopy. In addition, we are developing novel simplified fusion assays that will help us to elucidate the molecular mechanism of how lytic granule exocytosis is controlled in time and space. The second project in the lab focuses in the development of methodologies to study lipid localization and dynamics within the Golgi complex. To this end, we utilize fluorescently-labeled protein domains or peptides that bind specific lipids to visualize them in living cells. The information we obtain using these probes will help us distinguish between two long-standing models for how proteins are transported through the Golgi stack, and to understand the influence of membrane lipid composition on protein sorting.

Rotational Projects (2015-2016):
Study the role of Syntaxin 11 on lytic granule fusion using live-cell imaging techniques
Investigate by Super Resolution Microscopy (STED) the distribution patterns of fluorescently labeled SNAREs during the cytotoxic immune response.
Test the effect of different regulatory proteins (Munc18-2, Munc13-4) on SNARE mediated fusion using reconstituted fusion assays.
Study the dynamics of sphingomyelin in eukaryotic cells and its influence on protein sorting.

Lab Personnel:
Waldo A. Spessott (Postdoctoral Fellow)
Margaret McCormick (Research Technician)
Maria L. Sanmillan (Research Technician)
Melanie Santos-Marrero (IGG- Graduate Student)

Assistant Professor of Pathology and Laboratory Medicine at University of Pennsylvania School of Medicine (2012– present)
Ph.D., Chemical Sciences, National University of Cordoba - Argentina (2002)
M.S., Chemistry, National University of Cordoba - Argentina (1997)
B.A.., Biochemist, National University of Cordoba - Argentina (1996)
Selected Publications
Shi L, Kümmel D, Melia TJ, Coleman J, Giraudo CG. Dual roles of Munc18-1 rely on distinct binding modes of the central cavity with Syntaxin 1 H3 domain and SNARE complex.. Mol. Biol. Cell. Vol 22. 2011 November:4150.
Krishnakumar SS, Radoff DT, Kümmel D, Giraudo CG, Li F, Khandan L, Baguley SW, Coleman J, Reinisch KM, Pincet F, Rothman JE. A conformational switch in complexin is required for synaptotagmin to trigger synaptic fusion.. Nat Struct Mol Biol.. Vol 18(8) . 2011 July:934-40.
Kümmel D, Krishnakumar SS, Radoff DT, Li F, Giraudo CG, Pincet F, Rothman JE, Reinisch KM. Complexin cross-links prefusion SNAREs into a zigzag array.. Nat. Struct. Mol. Biol.. Vol 18(8) . 2011 July:927-33.
Li F, Pincet F, Perez E, Giraudo CG, Tareste D, Rothman JE. Complexin activates and clamps SNAREpins by a common mechanism involving an intermediate energetic state. Nat Struct Mol Biol.. Vol 18(8) . 2011 July:941-6.
Quinteros CA, Giraudo CG, Villareal M, Montich G and Maccioni HJ. Identificatification of a site in Sar1 involved in the interaction with the Cts of Glycolipid Glycosyltransferases.. J. Biol. Chem. Vol 285. 2010 September:30340-6.
Giraudo CG, Garcia-Diaz A, Eng WS, Chen Y, Hendrickson W, Melia TJ, Rothman JE. Alternative zippering as an On-Off switch of SNARE-mediated membrane fusion.. Science. Vol 323. 2009 January:21211-21219.
Giraudo CG, Garcia-Diaz A, Eng WS, Yamamoto A, Melia TJ, Rothman JE. Distinct domains of complexins bind SNARE complexes and clamp fusion in vitro. J Biol Chem. Vol 283. 2008 July:21211-21219.