Organizer : Young Hye Kim (Korea Basic Science Institute, Korea)
The “Proteomics for stem cell medicine” session will be addressed by three distinguished scientists and will focus on the current progress and future prospects of proteomic application in the field of stem cell research.
South University of Science and Technology of China, China
Title
Ultra-sensitive proteomics technology for deep proteome profiling of stem cells and cell microenvironment
Abstract
Stem cells and related niche microenvironment provide novel means to study early human development and also hold strong therapeutic potentials. However, our understanding of the biological mechanisms involved in stem cells developmental processes, such as differentiation into bone and blood, is limited. Mass spectrometry-based proteomics has been developed as a systems biology approach to explore gene functions at the post-transcriptional level. Some of the major challenges for these global scale studies are: (1) limited number of stem cells are available for the analysis; (2) not only limited to the stem cell niche, cell microenvironment in general provides a higher level of regulation for various molecular mechanisms; However, functional proteomic approaches for understanding cell microenvironment are largely missing. In this talk, I will present our recent effort for developing new proteomic approaches for addressing the emerging biological questions in dental stem cells and immunological synapse fields.
Regulation of stemness via post-translational modification of Oct4
Abstract
Embryonic stem cells (ESCs) are not only promising sources for regenerative medicine but also important tools to study the processes of cell-fate conversion. Upon differentiation, ESCs lose pluripotency and acquire new epigenetic and metabolic features of destinated cells. These processes are elaborately co-ordinated by transcriptional factors and signals networks, however, the detailed mechanisms should be uncovered. Among transcriptional factors governing pluripotency, Oct4 (also known as Pou5f1) is known to be a key factor. Previously we showed that the transcriptional activity of Oct4 was not strictly co-related with its protein level, implicating post-translational regulation of Oct4 activity. Using mass spectrometry analysis, we and others identified various post-translational modifications (PTMs) on Oct4. To uncover the physiological role of each PTMs, we substituted each PTM-defective Oct4 for endogenous Oct4 and investigated their effect on ESC self-renewal. Several PTMs, that are seemingly important for self-renewal, were scrutinized. Our results showed that post-translational modifications regulates various fuctions of Oct4 including transcriptional activity, maintenance of stemness, lineage determination, and soon. Detailed results will be presented at the seminar.
While many sophisticated membrane protein identification methods have been employed to identify cell-surface proteins, these methods may not reflect functional changes in cell-surface phenotype of a dynamic cell state. Recently, we have established a mammalian cell-based antibody selection/antigen discovery platform, which takes full advantage of the functional capabilities of active cell state. The platform includes selection of target-specific antibodies recognizing the native comfirmation of exposed cell-surface proteins and subsequent in-vitro cell-surface crosslinking procedure for individual antibody with target cells for antigen identification. By using the platform, we have demonstrated that our novel antibody/antigen discovery screening method enables concurrent identification of a panel of antibody/antigen pairs. It is possible to isolate antibodies to the surface of MD-MBA453 derived cancer stem cells, resulting in a panel of antibodies epitoping to the native structural confirmation of exposed cell-surface proteins as well as a panel of specific MD-MBA453 cancer stem cell markers. We believe that the panel of antibody/antigen pairs would be useful resources for the development of therapeutic interventions since discovered disease-specific surface proteins in native complex conformation can be directly targeted by conformational epitope-specific antibodies.
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