Gunn Lab Research
Dr. Gunn developed the theory that metabolic enzymes can use self-oligomerization to exert spatiotemporal control over activity during her postdoctoral work on the lipoprotein lipase filament. Her lab will use enzyme-dense pancreatic acinar cells to both identify and characterize enzymes that utilize quaternary structure as a form of self-regulation.
Importance of Metabolic Enzymes
Metabolic enzymes are essential for breaking down food in the digestive tract. However, these same enzymes can cause significant cellular damage by breaking down cellular components rather than food. This is what occurs during pancreatitis, which is characterized by enzymes becoming active in the pancreas rather than the intestine and eventually leaking into the blood stream, severely damaging pancreatic cells. The mechanisms to modulate enzymatic activity and prevent enzyme dysregulation in healthy pancreatic cells are not fully understood. We know some regulatory methods in acinar cells, including synthesis in an inactive zymogen form, however it is not clear how the many non-zymogen pancreatic enzymes are regulated. It is important to understand this mechanism because when non-zymogen pancreatic enzymes are secreted incorrectly, they damage surrounding cells resulting in pancreatitis. A better understanding of the link between improper trafficking and acute pancreatitis will be needed to prevent detrimental secretion of pancreatic enzymes.
Pancreatic Triacylglycerol Lipase
The lab is currently investigating pancreatic triacylglycerol lipase (PTL). Dysregulated PTL secretion is known to be a symptom of pancreatitis. PTL is also a target for treating obesity, which is a risk factor for cardiovascular disease. Our preliminary work using fluorescent microscopy suggests that PTL utilizes a quaternary structure self-regulation mechanism similar to the one Dr. Gunn discovered for LPL. This project aims to solve the structure of a novel quaternary structure form of PTL in vitro using cryogenic electron microscopy (cryoEM), while simultaneously using cryogenic electron tomography (cryoET) and fluorescence microscopy to characterize the effect of mutations on filament formation and the role of heparan sulfate proteoglycans (HSPGs) in vivo. We aim to provide a better understanding of how PTL activity is regulated that will benefit patients suffering from pancreatitis, cardiovascular disease, and heart failure.
Quaternary Structure Regulation
The Gunn Lab is centered around the theme of enzyme regulation by quaternary structure. To that end, we are interested in discovery of new enzymes that adopt inactive quaternary structures as a form of regulation. We are using pancreatic acinar cells to identify these enzymes using cell biology and biochemical techniques. We are also developing molecular tools to differentiate between active and inactive quaternary structures in vivo. We hope to use our findings to stabilize specific quaternary structures to prevent off-target enzyme activity.
