Lab Personnel

Dr. Hartzell

Criss Hartzell, PhD
Professor and PI 
Email Dr. Hartzell
Tel: 404-727-0444

I am curious how things work and have always been intrigued by mechanics. As a kid, I loved to take apart motors to see how they worked, but I rarely succeeded reassembling them in a fully functional state. Inevitably there was a pesky screw left over that I could not place and - sooner or later - I would learn why that screw was important. This isn’t so different from how I now study ion channels, proteins that form the basis of the cell’s electrical and plumbing systems. Ion channels are essentially enzymes that lower the free energy of a water-loving ions to cross fatty cell membranes. We have worked on many different kinds of ion channels, but most recently we have struggled to place the pesky screws that determine how chloride channels transport chloride in preference to other ions and how they open and close. Just like the spigot in your kitchen sink, ion channels open and close on demand, controlled by specific cellular signals. We have learned a lot how ion channels are gated by G-proteins, phosphorylation, voltage, and other things. The chloride channels that we now are studying (bestrophins and anoctamins) are opened by increases in intracellular calcium. In the last few years, the atomic structures of these channels were published and we were excited that they confirmed much of what we guessed from functional studies. The physiological importance of ion channels is evident from the large number of human diseases caused by ion channel dysfunction and the many drugs on the market that target them. Although understanding how ion channels do their “housekeeping” functions – like powering the neuronal action potential, cardiac contraction, kidney function, and epithelial secretion – has been our bread and butter, ion channels have lives outside of the world of being the cell’s electricians and plumbers. One of the channels we study, ANO1/TMEM16A, is overexpressed in many cancers and we think that it may be involved in the genesis of the primary cilium. A paralog of ANO1, ANO6/TMEM16F, is implicated in membrane organization and trafficking. What business do “chloride channels” have with cancer, ciliogenesis, and membrane lipids? Is ion transport necessary for these non-conventional channel functions? Do ANOs have a dual function as channels and as phospholipid scramblases or are these functions independent? In diseases that are linked to mutations in the ANOs, like limb-girdle muscular dystrophy 2L, is the culprit defective chloride transport, defective phospholipid scrambling, neither, or both? These are the questions that my lab will be investigating over the next few years.


KuaiKuai Yu
Staff Scientist
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Steven FoltzSteven Foltz
Postdoctoral Fellow
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Jarred Whitlock
PhD Candidate
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SkylarSkylar Fisher
PhD Candidate
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YuanYuan CuiYuanYuan Cui
Senior Research Specialist
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LucasLucas Encarnacion-Rivera 
Undergraduate Student
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