Date: Friday, 27 November 2020

Venue: Cheung Kung Hai Lecture Theatre 1, G/F, William M.W. Mong Block, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong

Time: 5:00 p.m. - 6:00 p.m.
 

Time: 5:00 p.m.
Speaker: Mr. Hoi Chun FONG  (MPhil candidate)
Primary Supervisor: Dr. Alan Siu Lun WONG
Presentation Title: Developing a screening system for high-throughput engineering of base editor
Abstract: 
CRISPR/Cas-based base editor has been developed to enable precise genome editing. Engineering of base editor has been largely relied on a one-by-one testing approach to improve its targeting range and reduce off-target editing. Here we develop a screening system that allows rapid detection of base editing events at up to single-nucleotide resolution. This system utilizes Restriction Fragment Length Polymorphism (RFLP) induced by base editor and can be coupled with high-throughput DNA sequencing to quantify base editing efficiency. With the creation or destruction of specific restriction enzyme sites via base editing, edited samples can be differentiated from unedited ones within a pooled screening library. With this system, we will systematically explore the effects of adding different genetic elements to and amino acid modifications on base editor for engineering its activity.

Time: 5:30 p.m. 
Speaker: Miss Sik Yin HO (PhD candidate)
Primary Supervisor: Dr. Ralf JAUCH
Presentation Title: Directed evolution of enhanced and lineage-biased SOX17 for reprogramming and directed differentiation
Abstract: 
Human transcription factor SRY-Box Transcription Factor 17 (hSOX17) is a key molecular switch directing endoderm and germ cell specification. We have previously shown that molecular design leads to engineered SOX17 (eSOX17) bestowed with the ability to induce pluripotency in somatic cells. In order to elucidate how SOX17 directs human lineage specification and to devise methods for the faithful forward program of human pluripotent cells, we aim to identify engineered SOX17 variants that exclusively specify germ cells and endoderm from human embryonic stem cells.

Four saturation mutagenesis eSOX17 libraries have been designed based on computational analyses. To benchmark the existing screening and selection system, new eSOX17 libraries have been subjected to pooled screens using inducible expression and phenotypic selection in pluripotency reprogramming. It was found that the existing pipeline leads to emergence of a large number of positive hits facilitating the identification of potent eSOX17 factors that induce pluripotency. Culturing conditions for defining the definitive endoderm and the primordial germ cells are also being established.

The discovery of eSOX17 variants that promote either endoderm or germ specification will help to contextualise pathways, molecular partnerships and regulatory targets of SOX17 in early development and hESC differentiation, and facilitate the generation of stem cell models for use in personalized medicine.

Date: Friday, 4 Decemeber 2020

Time: 5:00 p.m. - 6:00 p.m.

Zoom link: https://hku.zoom.us/j/95852511100?pwd=M2pDQ2FJV3BSUGZDU3VzeHhabUF1UT09

Meeting ID: 958 5251 1100

Password: 906063

Time: 5:00 p.m. 
Speaker: Ms. Haoqing HU (PhD candidate)
Primary Supervisor: Dr. Ralf JAUCH
Presentation Title: Collaboration and competition of SOX17 with beta-catenin in stem cell engineering and oncogenesis
Abstract: 
The Sry-related box transcription factor 17 (SOX17) plays an important role in germ cells and endoderm development. SOX17 also serves as a tumor suppresser by antagonizing Wnt/β-catenin signaling. Our group has applied protein design techniques to identify engineered SOX17 variants (eSOX17) that drive pluripotency and neural lineage reprogramming better than the classic reprogramming factor SOX2. Here, we test the hypothesis that the trans-activation capacity and potential interactions with β-catenin underpin the outstanding performance of eSOX17. By applying the small molecules modulating Wnt signaling pathway in pluripotency and neural lineage reprogramming, it was found that the long-term perturbation of β-catenin signaling has an obvious inhibitory effect on both systems. Through detailed structure-function analyses, I identified dispensable and essential fragments for eSOX17 mediated reprogramming. The eSOX17 variants will also be applied in oncogenesis assays and the interaction between SOX17 and β-catenin will be evaluated. Through this study, how SOX17 orchestrates gene expression programs will be elucidated and the findings will guide us to optimized strategies to generate cells for precision and regenerative medicine and contribute to the advances in β-catenin mediated cancer treatment.

Time: 5:30 p.m.
Speaker: Miss Yunying HUANG (PhD candidate)
Primary Supervisor: Prof. Pengtao LIU
Presentation Title: Investigation of P53 Function in using Human Expanded Potential Stem Cells
Abstract: 
The tumor suppressor protein p53 is involved in a number of cellular activities such as proliferation, apoptosis, and DNA damage response. Recent advances such as genomic profiling of embryonic stem cells have uncovered the importance of p53 functions in cell differentiation and development. Our lab has recently established a new type of stem cells called expanded potential stem cells (EPSCs) from several species, including human. Unlike pluripotent stem cells, EPSCs can efficiently generate all cell types, including the embryonic and extraembyonic cell lineages. Due to ethical concerns and technical limitation, a little is known about p53 functions in early human embryo development. Using human EPSCs as a novel in vitro model, we try to uncover the role and mechanism of p53 functions through CRISPR-CAS9 technology.

ALL ARE WELCOME

Should you have any enquiries, please feel free to contact Miss Cecilia Chan at 3917 9493.