Carla B. Green
Circadian control of neuroendocrine genes
The work in the Green lab is focused on several aspects of molecular regulation of cell function with an emphasis on the molecular mechanisms involved in circadian control of cell physiology. Although the lab has used the vertebrate retina as a model system over the past few years, recent work has made it obvious that many types of cells contain the molecular mechanisms that can drive daily rhythmicity. Non-neuronal cell types of many kinds, including transformed cells of many varieties show intrinsic rhythmicity of gene expression and other cellular phenomena. They have made use of several of the core facilities, including the Biomolecular Research Facility, the Flow Cytometry Facility, and the Tissue Culture Facility.
The lab studies the transcriptional and post-transcriptional control of genes involved in this time-keeping function. For example, they have identified promoter elements critical for appropriate temporal and spatial expression of clock-controlled genes. One of these genes, nocturnin, is a highly rhythmic gene that they recently have shown encodes a novel enzyme that acts as a deadenylase - an enzyme that specifically removes polyA tails from mRNAs, presumably as a first step in targeting these RNAs for turnover. They are currently studying the role of this enzyme, both within the circadian clock mechanism itself, and also in the general regulation of proper cell function.
The circadian clock mechanism also is comprised of a number of proteins with wide-ranging cellular functions. These include kinases (casein kinase I epsilon/delta, GSK3, etc.), proteins with evolutionary relationships to DNA repair enzymes (cryptochromes, nocturnin) and others. Their lab is currently carrying out structure/function studies on several of these key players and these studies have taken them beyond their specific roles in timing and into many other aspects of cell signaling.