Emily H.Y. Cheng
Department of Medicine
Memorial Sloan-Kettering Cancer Center
1275 York Ave.
New York, NY 10065
2005 Searle Scholar
of apoptotic signaling cascades and the mitochondrion-dependent
Our research focuses on dissecting the
molecular mechanisms of programmed cell death. Apoptosis is
essential for the successful development and maintenance of tissue
homeostasis in all metazoans. Deregulation of apoptosis contributes
to a variety of pathologic processes including cancer,
neurodegenerative disorders, and autoimmune disease.
The BCL-2 family constitutes a crucial checkpoint in apoptosis and
consists of both anti-apoptotic and pro-apoptotic members.
Pro-apoptotic BCL-2 members can be further subdivided into more
fully conserved, "multidomain" members or "BH3-only"
members. Using genetic and biochemical approaches, we have helped
delineate the core apoptotic pathway in mammals. The "BH3-only"
molecules activate "multidomain" pro-apoptotic BAX and BAK to
trigger a mitochondrion-dependent cell death pathway. Conversely,
anti-apoptotic BCL-2/BCL-XL sequesters translocated "BH3-only"
molecules in stable mitochondrial complexes, thus preventing the
activation of BAX/BAK. Loss of function studies revealed that the
absence of pro-apoptotic BAX and BAK creates a profound block in
apoptosis triggered by diverse death signals. Thus, activation of a
"multidomain" member, BAX or BAK, appears to be an essential
gateway to the mitochondrion-mediated cell death program. However,
how cells keep the potentially lethal BAX and BAK in check and how
"BH3-only" molecules activate BAX and BAK remain unclear. Using
protein cross-linking in conjunction with serial protein
chromatographic purification steps, we have identified VDAC2 as a
negative regulator of BAK activation.
We are currently investigating how "BH3-only" molecules
integrate specific death signals to activate "multidomain" BAX/BAK
and utilizing a proteomic approach to identify higher order
multi-protein complexes that regulate apoptosis and mitochondrial
homeostasis. Mouse genetic approaches are undertaken to define the
physiologic roles of death regulators in development. The apoptotic
machinery is a promising target of cancer therapy since cancer cells
often have defects in the apoptotic pathways. Our ultimate goal is
to apply the information obtained from the studies of programmed
cell death to develop novel anti-cancer therapeutics.