Gina E. Sosinsky, Ph.D.
Gina E. Sosinsky, Ph.D. is an adjunct professor at UCSD and assistant director for the NCMIR.
Dr. Sosinsky is dedicated to exploring the molecular structure of gap junctions and other structures of cell-cell junctions. These studies are being conducted using high-resolution electron microscopy (EM). Gap junctions are one of the primary ways that cells communicate with each other. They are specialized cell contact areas that contain hundreds to thousands of channels. These channels allow for the passage of molecules from one cell’s cytoplasm to another, thereby providing a fast and efficient means of signaling and cooperation. They are found in almost all tissues in which cells abut each other. Connexin26 (Cx26) is the smallest of the gap junction protein family and is also one of the most functionally important. It is found in significant quantities in many major organ systems including brain, liver and intestine.
The Sosinsky laboratory has isolated Cx26 gap junctions as in situ ordered two-dimensional crystals for analysis by electron microscopy (EM) structure determination, atomic force microscope imaging (AFM) and biochemical studies. The focus is on structure and functional dynamics of Cx26 gap junction channels. Using high resolution AFM, the group has been able to visualize conformational changes at submolecular resolution (10 Å laterally, 2Å vertically).
In a closely related line of study, Dr. Sosinsky is looking at the cellular organization of gap junctions and identifying structural intermediates in connexin trafficking by specific labeling and electron tomography. Gap junctions are unique in that the channels are rapidly being assembled and degraded by multiple mechanisms; not all of the channels within the same junctional plaque are active at the same time. Research efforts are aimed at understanding how the connexin organizes into and functions within the gap structure and how the connexins organize and interact with other cellular components. The primary tool used is the electron microscope which provides excellent resolution to determine the molecular structure of gap junction proteins as well as their arrangements within and between cells. Multiple microscopies such as confocal and atomic force microscopy in addition to electron microscopy are used to better understand gap junction dynamics.
Dr. Sosinsky’s group is able to chronicle protein dynamics in living systems followed by direct visualization of individual macromolecules in situ in the same preparation, with minimal need for tissue treatments that negatively impact ultrastructure. Using this approach, the Sosinsky laboratory was able for the first time to unequivocally determine that new gap junction proteins are added to the periphery and removed from the central region of plaques in cells. This work was described in a paper published in Science in 2002.
In complementary studies, Dr. Sosinsky continues to explore the nodes of Ranvier and their relationship to gap junction structure. Nodes of Ranvier are sites on myelinated axons where the insulating layers of myelin are interrupted. Myelinated axons and their nodes of Ranvier represent an important evolutionary advance for vertebrates that permit very rapid propagation of action potentials without large increases in axonal diameter. Studies are aimed at examining the possible mechanisms of interaction between axons and myelinating glia to understand more about how the nodal complex manages and modulates propagation of the nerve impulse.
The Sosinsky group hypothesizes that functions residing in specific subcomponents of this extremely complex system regulate nodal physiological properties and therefore, play a critical role in governing subtle but important phenomena such as shifts in axonal conduction velocity. They are specifically involved in gathering and extracting new information about the structural organization of the node using molecular labeling and electron tomographic imaging. The group uses novel methods of selective staining and tomography for obtaining accurate and high resolution information about the three dimensional structure in situ (down to the macromolecular scale) using intermediate high voltage electron tomography. The combined results will significantly increase our understanding of saltutory conduction and contribute to the development of new strategies for treatment of disorders involving myelinated axons.
In another line of research, Dr. Sosinsky is conducting studies aimed at increasing our understanding of phytoplankton synthesis at all space and time scales. This is important because phytoplankton impact climate and the biogeochemical cycling of carbon, nitrogen and sulfur. Although several models have been developed at the ecological level using bulk parameters, few models address the relationship between irradiance and photosynthesis at the cellular or subcellular level. The Sosinsky laboratory is proposing a new and innovative approach to understanding photosynthesis at the subcellular level that integrates several approaches such as electron tomography, phytoplankton optics, and computer modeling of photosynthesis parameters.
Dr. Sosinsky has a long-standing interest in software technology. Her combined strengths in science and technology complement each other perfectly. She serves as Project Coordinator for the development and implementation of software for automated data collection of tomographic datasets. She also works on a related project to develop improved software for obtaining images for molecular imaging.
Dr. Sosinsky serves as Principal Investigator and was the project originator of the Electron Microscopy Outreach Program. This is a joint project between the National Center for Microscopy and Imaging (NCMIR) and the San Diego Supercomputer Center (NPACI/SDSC). This project seeks to produce and promote a centralized resource for investigators who want to know about techniques within or outside of their own scientific disciplines.
Teaching involvement includes her role as Liaison for the National Partnership for Advanced Computing Infrastructure (NPACI) Education, Outreach and Training to Telescience and Neuroscience Thrust Areas. In this capacity she coordinates help integration of technology from the computer scientists at SDSC and the researchers who are part of NPACI with educational programs for K-12 such as Envision for Kids program and a neuroscience curriculum in development at the Preuss School.
Outside professional activities include serving as Editor for Microscopy Research and Technique, and guest editor for Cell Communication and Adhesion. She has been an ad hoc reviewer for such premier publications as the J of Neuroscience, PNAS, and J of Biochemistry. Additionally, she has been a grant reviewer for NSF.
Other notable activities include her participation in the organization of several conferences key among which was her role as Chair for a poster session for Three Dimensional Electron Microscopy at the Gordon Conference in June 2003. She has presented a number of invited lectures at the national level. Until very recently she was Co-Chair of the Women in Science and Engineering Committee. She continues her membership on that committee.
View Dr. Sosinsky's curriculum vitae
