Yan Qin

Seminar Details

Host: Dr. Jennifer Herman

Time: 4:00pm-5:00pm

Location: BCBP Rm 108

Seminar Abstract

Zinc ion (Zn2+) is emerging as an intracellular and intercellular signaling molecule. Genetically encoded sensors enable real-time recording of cellular signal dynamics with spatio-temporal resolutions. We therefore design and engineer genetically encoded Zn2+ probes based on a single fluorescent protein platform toprovide fluorescent readouts that are proportional to cellular Zn2+ concentrations. We have created a panel of probes including both green zinc probes (GZnPs, derived from cpGFP) and red zinc probes (RZnPs, derived from cpApple) with bright fluorescence, high dynamic range (Fmax/Fmin) and different binding affinity for cellular Zn2+. By employing GZnP3 which has unprecedented sensitivity in the sub-nanomolar range (Kd = 1.3 nM), we provide the first profound evidence that lysosomal channel TRPML1 is permeable to Zn2+ and can mobilize Zn2+ from lysosomes and late endosomes to the cytosol in hippocampal neurons. Loss of function mutations in TRPML1 are the sole genetic cause of Mucolipidosis type IV disease (MLIV). MLIV is a lysosomal storage disease with neurodevelopmental defects and neurodegenerative phenotypes evident early in childhood. Our work reveals that the zinc permeability of TRPML1 patient mutants correlates with the severity of MLIV symptoms. Recently, using mito-GZnP4, a high affinity mitochondrial sensor (Kd = 18 pM), we found that TRPML1 can mediate mitochondrial Zn2+ transport, potentially from lysosomes. We also discover that Zn2+ influx inhibits mitochondrial and lysosomal movement with IC50 of 5-10 nM.