A hallmark of the Warburg effect - which describes the shifting metabolic program in proliferating cancer cell—is a radical increase in glucose uptake and use of aerobic glycolysis over oxidative phosphorylation. Cancer cells exploit this metabolic shift to shunt glycolytic intermediates into fatty-acid and amino-acid synthesis pathways, thus providing building blocks for rapid proliferation. Inhibiting this unique glucose metabolic shift is thus a promising strategy for anti-cancer therapies. One potent glycolytic inhibitor, 2-deoxyglucose (2DG), is a toxic analog of glucose and has been evaluated in clinical trials. 2DG does kill cancer cells, however, these cancerous cells can evolve resistance over time through poorly described mechanisms. Yeast are a terrific model for this kind of glycolytic shift, as they prefer to ferment glucose via glycolysis rather than use oxidative phosphorylation, even in the presence of oxygen. This similar metabolic profile allows us to perform robust genetic screens to define factors that when mutated lead to 2DG resistance. We and others have recently identified 2DG-resistance mutations in S. cerevisiae that fall into six different genes, each of which impinge on a common pathway to regulate glucose metabolism. My research will focus on two distinct aspects of 2DG resistance metabolism: i) mutations in the hexokinase II (Hxk2) enzyme that converts 2DG to 2DG-6P, a dead end metabolite in the glycolytic pathway, and ii) regulation of the a-arrestins, a class of protein trafficking adaptor needed to regulate the abundance of glucose transporters through which 2DG enters the cell. I will make synergistic use of computational modeling and advanced cell-biology methods to provide a deep mechanistic understanding of how Hxk2 and a-arrestin function contributes to 2DG resistance and regulation of glucose homeostasis. My work will advance our understanding of the strategies cancer cells deploy to evade 2DG, enabling more effective anti-cancer drug design.
Is Cortical ER Important for TMEM16a Kinetics?- Kayla Komondor
The calcium-activated chloride channel TMEM16a is endogenously expressed in the Xenopus laevis oocyte and egg membrane, and plays a crucial role in depolarizing the egg at fertilization. Fertilization in X. laevis eggs rapidly activates TMEM16a via an IP3-induced endoplasmic reticulum (ER) release of calcium, and this depolarizes the egg. The fertilization-signaled depolarization serves as the fast block to polyspermy and protects the nascent zygote from penetration by additional sperm. This almost instant IP3-activation of TMEM16a at fertilization is not what is seen in immature oocytes, where it takes closer to 1.2 seconds between increased intracellular IP3 and measurement of TMEM16a-conducted current. During the development of an immature oocyte into a fertilization-competent egg, the ER undergoes a significant reorganization moving from distant from the plasma membrane, to immediately next to it. We therefore hypothesized the location of the endoplasmic reticulum relative to the plasma membrane plays a role in the kinetics of IP3-induced TMEM16a activation.