Heads of Laboratories
Associate Professor
Laboratory of Developmental Genetics
shaham@rockefeller.edu
Research in the Shaham lab focuses on two areas: the control of programmed cell death during animal development and the roles of glial cells in nervous system development and function. The Shaham lab uses the nematode Caenorhabditis elegans in its studies and has demonstrated that underlying both areas of research are cellular programs conserved from C. elegans to humans.
Nervous systems consist of two major cell types: neurons and glia. Basic properties of neurons, and mechanisms governing neuronal development and function are well studied. However, the functions of glia, the most abundant cell type in vertebrate nervous systems, remain mostly unexplored, and few mediators of glial function are known. Glia are important in disease: 95 percent of brain malignancies are of glial character, and glial defects are associated with neurodegenerative diseases including amyotrophic lateral sclerosis and Alzheimer’s disease, suggesting that understanding glial functions, and how they go awry, is indispensable for comprehending brain functions and dysfunctions.
One explanation for the gap in understanding glia may lie in their neurotrophic properties. Glial manipulation often results in neuronal loss, precluding investigations of other effects glia may have on neuronal morphogenesis or activity. The Shaham lab has discovered that glia of the nematode Caenorhabditis elegans bear striking morphological, anatomical and molecular similarities to vertebrate glia. Importantly, C. elegans glia are not required for neuronal survival, making C. elegans a unique model for deciphering glial roles in the nervous system, and allowing, for the first time, manipulation of these cells in vivo without the complication of neuronal loss.
The Shaham lab has shown that glia are essential for neural development, promoting axon outgrowth and dendrite extension; and that glia are required for morphological plasticity of neuronal receptive endings; indeed, some sensory receptive structures fail to form in their absence. The lab has also uncovered morphology-independent roles for glia in sensory neuron function, showing that animals lacking glia exhibit profound sensory deficits. To understand the bases of these functional interactions, the Shaham lab has identified glia-enriched proteins and shown that one secreted protein, FIG-1, is required for neuronal sensory functions. Strikingly, FIG-1 shares similarities with thrombospondins, proteins released by vertebrate glia and required for synaptogenesis. These and other studies have led to the suggestion that fundamental similarities exist between sensory receptive structures and synapses. Research in the Shaham lab has also revealed that glia respond to environmental stimuli independently of neurons, and that this response may promote neuronal remodeling. Thus, glia may interpret extracellular cues to alter neuronal activity.
Although C. elegans glia do not control neuronal survival, the Shaham lab has explored the death of other C. elegans cells to understand principles by which vertebrate glia might control neuronal viability. In addition to discovering novel transcriptional and protein degradation-mediated controls of apoptotic cell death, the lab has identified a novel cell death program independent of known apoptotic regulators. The unique morphology accompanying this cell death program is conserved during development of the vertebrate nervous system. The Shaham lab identified several genes promoting this new cell death form; one, induced upon cell death initiation, encodes a polyglutamine-rich protein. Because some neurodegenerative diseases are caused by polyglutamine expansions in endogenous proteins, this work suggests possible mechanistic links with this novel death program.
CAREER
Dr. Shaham received his A.B. degree in biochemistry from Columbia University in 1989. In 1995 he graduated from the Massachusetts Institute of Technology with a Ph.D. in biology. After postdoctoral studies at the University of California, San Francisco, Dr. Shaham joined Rockefeller as assistant professor in 2001.
Dr. Shaham is a recipient of the 2005 Klingenstein Fellowship Award in the Neurosciences and the 2005 Breast Cancer Alliance
Masin Young Investigator Award. He is also the recipient of the 2004 Weill-Caulier Herschel Fellowship and was named scholar
of both the Rita Allen Foundation (2003) and the Sidney Kimmel Foundation for Cancer Research (2002). He was Brookdale
Foundation National Fellow in 1999 and a Helen Hay Whitney Foundation Postdoctoral Fellow in 1996. In 1994 he was a Glaxo
Research Institute Fellow, and in 1992 a W.M. Keck Foundation Fellow.
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