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Alex Leo Kolodkin, Ph.D.

Headshot of Alex Leo Kolodkin
  • Deputy Director, Institute for Basic Biomedical Sciences
  • Professor of Neuroscience

Research Interests

Neuronal regeneration; Developmental biology; Cell biology; Neural development more


Dr. Alex Kolodkin is a professor of neuroscience at the Johns Hopkins University School of Medicine and deputy director of the Institute for Basic Biomedical Sciences. His research is focused on understanding how neuronal connectivity is established during development. As a postdoctoral fellow, Dr. Kolodkin discovered and cloned the first semaphorin gene in the grasshopper. More recently, his team decoded the activity of protein signals involved in muscle-nerve connections in fruit flies.

His team is investigating how families of invertebrate and vertebrate guidance cues orchestrate neuronal wiring during embryogenesis and later in neural development, using Drosophila and the mouse as model systems.

Dr. Kolodkin received his undergraduate degree in biology from Wesleyan University. He earned his Ph.D. in molecular biology and genetics from the University of Oregon. He completed his postdoctoral fellowship at the University of California, Berkeley. Dr. Kolodkin joined the Johns Hopkins faculty in 1995.

He serves on the editorial board of Neuron. His work has been recognized with various awards, including the Javits Neuroscience Investigator Award from the National Institute of Neurological Disorders and Stroke in 2004. more


  • Deputy Director, Institute for Basic Biomedical Sciences
  • Professor of Neuroscience
  • Joint Appointment in Molecular Biology and Genetics

Departments / Divisions

Centers & Institutes


Additional Training

  • University of California, Berkeley, Berkeley, CA, 1994, Molecular and Cellular Biology

Research & Publications

Research Summary

Alex Kolodkin is a neuroscientist whose laboratory works to understand how neuronal connectivity is established, maintained, and modulated.

His team investigates the function of extrinsic guidance cues and their receptors on axonal guidance, dendritic morphology, and synapse formation and function.

For several years, they've investigated how neural circuits are formed and maintained through the action of guidance cues that include semaphorin proteins, their classical plexin and neuropilin receptors, and also novel receptors. They employ a cross-phylogenetic approach, using both invertebrate and vertebrate model systems, to understand how guidance cues regulate neuronal pathfinding, morphology and synaptogenesis. They also explore how these signals are transduced to cytosolic effectors. Though broad in scope, their interrogation of the roles played by semaphorin guidance cues provides insight into the regulation of neural circuit assembly and function. Their current work includes a relatively new interest in understanding the origins of laminar organization in the CNS. They have identified guidance cues that regulate both specific and general aspects of neurite stratification in the mouse retina, in addition to the targeting of retinal ganglion cell axons to retinorecipient midbrain targets. These observations have prompted them to look for cellular and molecular mechanisms that regulate laminar organization in the mouse neocortex.

Selected Publications

Riccomagno MM, Sun LO, Brady CM, Alexandropoulos K, Seo S, Kurokawa M, Kolodkin AL. "Cas adaptor proteins organize the retinal ganglion cell layer downstream of integrin signaling." Neuron. 2014 Feb 19;81(4):779-86. doi: 10.1016/j.neuron.2014.01.036.

Sun LO, Jiang Z, Rivlin-Etzion M, Hand R, Brady CM, Matsuoka RL, Yau KW, Feller MB, Kolodkin AL. "On and off retinal circuit assembly by divergent molecular mechanisms." Science. 2013 Nov 1;342(6158):1241974. doi: 10.1126/science.1241974.

Jeong S, Juhaszova K, Kolodkin AL. "The Control of semaphorin-1a-mediated reverse signaling by opposing pebble and RhoGAPp190 functions in drosophila." Neuron. 2012 Nov 21;76(4):721-34. doi: 10.1016/j.neuron.2012.09.018.

Riccomagno MM, Hurtado A, Wang H, Macopson JG, Griner EM, Betz A, Brose N, Kazanietz MG, Kolodkin AL. "The RacGAP β2-Chimaerin selectively mediates axonal pruning in the hippocampus." Cell. 2012 Jun 22;149(7):1594-606. doi: 10.1016/j.cell.2012.05.018.

Lloyd TE, Machamer J, O'Hara K, Kim JH, Collins SE, Wong MY, Sahin B, Imlach W, Yang Y, Levitan ES, McCabe BD, Kolodkin AL. "The p150(Glued) CAP-Gly domain regulates initiation of retrograde transport at synaptic termini." Neuron. 2012 Apr 26;74(2):344-60. doi: 10.1016/j.neuron.2012.02.026.

Contact for Research Inquiries

Johns Hopkins University
725 North Wolfe St.
The Solomon H. Snyder Department of Neuroscience
Baltimore, MD 21205 map
Phone: 410-614-9499
Fax: 410-614-8423

Email me

Academic Affiliations & Courses

Graduate Program Affiliation

Neuroscience Graduate Program

Biological Chemistry and Molecular Biology Graduate Program

Activities & Honors


  • Fund for Medical Discovery Award, Johns Hopkins University Medical School, 1998
  • Javits Neuroscience Investigator Award, National Institute of Neurological Disorders and Stroke, 2004
  • Jane Coffin Childs, NIH NRSA and A.C.S. Postdoctoral Fellowships (declined), 1987
  • Kirsch Investigator Award, 2002
  • McKnight Neuroscience Investigator Award, 2000
  • Johns Hopkins Center for ALS Research Investigator, 2000
  • Whitehall Research Award, 1995
  • Searle Scholar Award, 1996
  • Klingenstein Fellowship Award in the Neurosciences, 1995
  • McKnight Neuroscience Scholars Award, 1995
  • Alfred P. Sloan Research Fellow, 1995
  • Postdoctoral Fellowship, Damon Runyon-Walter Winchell , 1987

Professional Activities

  • Advisory Board, New York State Spinal Cord Injury Research Foundation, 2001
  • Associate Professor Promotions Committee, The Johns Hopkins University School of Medicine
  • Chair, The Johns Hopkins University School of Medicine
  • Chair, The Johns Hopkins University School of Medicine
  • Editorial Board, Neuron, 2000
  • Grant Review Committee, Institute for Basic Biomedical Sciences
  • Institutional Research Grant Project Committee, The Johns Hopkins University School of Medicine
  • MD, The Johns Hopkins University School of Medicine
  • Medical Scientist Training Program Steering Committee, The Johns Hopkins University School of Medicine
  • Reviewer, National Institutes of Health, 2002
  • Reviewer, National Institutes of Health, 2001
  • Reviewer, National Institutes of Health, 2001
  • Reviewer, National Institutes of Health, 2000
  • Reviewer, National Institutes of Health, 1998
  • Summer Academic Research Experience (SARE) Program, The Johns Hopkins University
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