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Jan 18th, Seminar - Haoxing Xu

 Ion Channels in the Lysosome:

Opening the Gate to the Cell’s Recycling Center

Haoxing Xu, Ph. D.

Associate Professor, Department of MCDB,

University of Michigan


Dr. Haoxing Xu received his bachelor in Biochemistry at Peking University in 1992, and then moved to Georgia State University and obtained his Ph. D. degree in Biochemistry.  He did his postdoc in Harvard Medical School mentored by Dr. David Clapham from 2001-2006.  Then he started his laboratory at University of Michigan, and now is an Associate Professor in Department of Molecular, Cellular, & Developmental Biology, University of Michigan.



Lysosomes are acidic compartments filled with more than 60 different types of hydrolases. They mediate the degradation of extracellular particles from endocytosis and of intracellular components from autophagy. The digested products are transported out of the lysosome via specific catabolite exporters or via vesicular membrane trafficking. Lysosomes also contain more than 50 membrane proteins and are equipped with the machinery to sense nutrient availability, which determines the distribution, number, size, and activity of lysosomes to control the specificity of cargo flux and timing (the initiation and termination) of degradation. Defects in degradation, export, or trafficking result in lysosomal dysfunction and lysosomal storage diseases (LSDs). Lysosomal channels and transporters mediate ion flux across perimeter membranes to regulate lysosomal ion homeostasis, membrane potential, catabolite export, membrane trafficking, and nutrient sensing. Dysregulation of lysosomal channels underlies the pathogenesis of many LSDs and possibly that of metabolic and common neurodegenerative diseases. In order to study ion channels in the lysosome, we have recently developed a modified patch-clamp technique to directly record lysosomal membranes, and also established a fluorescence imaging method to specifically measure lysosomal Ca(2+) release using lysosome-targeted Genetically-Encoded Ca(2+) Indicators, such as GCaMP3. Using these approaches, we were able to "open" the gate to the "black box" of the cell's recycling center and discovered several novel ion channels in the lysosome. We are currently characterizing these new lysosome channels and investigating their cell biological functions.


Time: Jan. 18th, 2016, 16:00

Venue: New Biology Building, Room 143

Host: Prof. Yichang Jia



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