Jun Qin Lab

The Qin Laboratory is interested in understanding several intriguing biological processes, with a special emphasis on the development and application of cutting-edge mass spectrometry-based proteomics toolkits to untangle challenging biological problems.

We have a long standing interest on a concept of "network analysis proteomics." Proteins tend to assemble into multi-subunit protein complexes as the minimal biologically functional units. The execution of biological processes in the cell can be viewed as a network of ordered interactions between different protein complexes. Thus, the understanding of the basic mechanisms of cellular homeostasis relies on our ability to determine the composition of protein complexes and to decipher the interactions between these protein complex modules. Likewise, the understanding of pathogenesis ultimately depends on the knowledge of global perturbations in the protein ‘complexome’, or a cellular network of protein complex interactions during disease development. Specifically, we are analyzing the endogenous protein complexome by immunoprecipitation (IP) with primary antibody and mass spectrometry. We aim at constructing a complete human protein interactome.

As an important part of our research, we are continuously developing novel MS-based proteomic methods that will enable us to analyze dynamic changes of complex biological processes in a quantitative manner.

Protein ubiquitination is one of the major post translational modifications (PTMs) that regulate a very broad spectrum of cellular functions. Deregulation of ubiquitination is associated with many human diseases such as cancer and human neurodegenerative disorders. We are developing novel proteomics strategies to systematically profile ubiquitin proteome, and to study the regulation of such system in the biological contexts.

The cohesin complex plays a central role in genome maintenance by regulating chromosome segregation in mitosis and DNA damage response (DDR) in other phases of the cell cycle. Checkpoint kinas ATM/ATR phosphorylates SMC1 and SMC3, two core components of the cohesin complex. In addition, SMC3 is acetylated at two critical lysine residues and this modification is critical for sister chromatid cohesion and genome instability in both yeast and human. We recently showed that genome-wide binding of SMC1 and SMC3 after ionizing radiation (IR) is enhanced by reinforcing pre-existing cohesin binding sites in human cancer cells. We are now vigorously investigating the functions of sister chromatid cohesion using a combination of mass spectrometry, biochemistry and genetic manipulations.