On Nov 4, 2016, Prof. William Prinz visited Institute of Biophysics, CAS and gave a lecture entitled “Lipotoxicity and intracellular lipid transport”. The lecture was hosted by Prof. Hong Zhang, and was part of the special lecture series named “Shizhang Bei Lecture” of Institute of Biophysics. 

Many lipid intermediates are toxic to cells. Ceramide is a key intermediate for synthesis of sphingolipids, and also is an important second messenger in signal transduction. However, overproduction of ceramide triggers apoptosis and causes cell death.  Prof. William Prinz`s lab aimed to investigate the role of MCSs in non-vesicular ceramide transfer between the ER and Golgi. They screened for proteins that could serve as potential tethers or facilitate non-vesicular lipid transport. One promising candidate they identified is Nvj2. They found that the yeast protein Nvj2p is an ER-Golgi tether that generates close contacts between these compartments and promotes the nonvesicular transfer of ceramides to the Golgi complex.  Nvj2 normally resides at contacts between the ER and other organelles. Upon ER stress, it relocalizes to and increases ER-Golgi contacts.  ER-Golgi contacts fail to form during ER stress in cells lacking Nvj2p. These findings demonstrate that cells regulate ER-Golgi contacts in response to stress and reveal that nonvesicular ceramide transfer out of the ER prevents the build up of toxic amounts of ceramides. 

Taken together, they have identified a novel mechanism by which cells prevent the toxic accumulation of ceramides; Nvj2 promotes non-vesicular ceramide transfer from the ER to the Golgi complex, where ceramides are converted to complex sphingolipids. Importantly, Nvj2 is conserved in higher eukaryotes and may share a similar function in ER-to-Golgi transport of ceramide, an intriguing possibility that warrants further investigation.  

Prof. William Prinz gave the lecture with vivid words, rigorous logic and great passion, which can be a lively lesson for the audience. Investigators from Institute of Biophysics attending the lecture included Dr. Pingsheng Liu, Chang Chen and Pingying Xu. After the lecture, Prof. William Prinz and the audience shared their views on the issues of common interest.