Johns Hopkins School of Medicine

 Mechanisms of differentiation and degeneration in the nervous system

The nervous system consists of a great variety of neurons and glia that together form the components and circuits necessary for nervous system function. Neuronal and glial diversity are generated through a series of highly orchestrated events that control cell numbers, subtype identity, cell morphology and axonal projection patterns.  Although glial cells remain proliferative throughout life, the number of neurons remains largely finite, with the exception of small pockets of adult neurogenesis in the brain. Loss of neurons through injury or disease consequently leads to abnormal circuit function, and depending upon the site of loss, corresponding deficits in cognition, motor function and sensory processing.

Questions we are interested in answering encompass both development and disease. Specific questions include:

 What are the molecular mechanisms that regulate neuronal and glial differentiation during development?

What are the pathways that keep neurons alive and how might they be impacted in neurodegenerative diseases?

Are the same or different pathways altered in distinct neurodegenerative diseases such as ALS (Lou Gehrig’s disease) or Alzheimer’s disease (AD)?

To solve these questions, we utilize an integrated approach that includes in vivo models, imaging, molecular biology, cell biology, biochemistry, developmental biology, genetics and behavior. The major focus of the lab is the study of a new family of six-transmembrane proteins (6-TM GDEs) that play key roles in regulating cellular differentiation and survival in the spinal cord. We recently discovered that the 6-TM GDEs release GPI-anchored proteins from the cell surface through cleavage of the GPI-anchor. This discovery identifies 6-TM GDEs as the first membrane bound GPI-anchor cleaving enzymes in vertebrates that work at the cell surface to regulate GPI-anchored protein function. Current work in the lab studies how the 6-TM GDEs regulate signaling events that control neuronal and glial differentiation during development, together with a new major focus on how GDE dysfunction relates to the onset and progression of neurodegeneration with relevance to ALS and AD.