Date: Wednesday, 10 November 2021

Venue: Cheung Kung Hai Lecture Theatre 3, 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.

5:00 p.m.

Speaker:   Dr. Tiffany Yuen Kwan AU (Post-doctoral Fellow)
Primary Supervisor: Prof. Kathryn Song Eng CHEAH
Presentation Title: Integrating transcriptomes of in vivo and in vitro models for a molecular understanding of the notochord lineage during intervertebral disc development
Abstract: The nucleus pulposus (NP) in the core of the intervertebral disc (IVD) is critical for maintaining shock-absorbing function, protecting the spine from injury and degeneration. The NP originates from the embryonic notochord, that emerges soon after gastrulation and acts as the early axial skeleton. As the vertebrae form, the notochord undergoes remodeling, and segmentation to form the NP. Little is known of the molecular control/changes that occur during the transition from the notochord to NP. Here we developed two systems to provide insights into the transition : a double transgenic mouse model Foxa2^mNE-Cre/Z/EG  for lineage tracing of  notochordal cells and an ex-vivo model system of notochord development. Using these systems we confirmed the contribution of notochordal cells to the mature NP.  Further, to understand the molecular dynamics of the transition, we studied the global transcriptomic changes that occur, as the notochord transitions to the early NP and matures down to single cell resolution. The knowledge gained from the transcriptomes aided a robust protocol for directed in vitro differentiation of  mouse embryonic stem cells (mESC) to the notochordal lineage and provided new insights into the differentiation process. Furthermore using the Foxa2^mNE-Cre/Z/EG model, we implicate the transformation of notochordal descendants to a fibroblastic state in injury induced disc degeneration.

5:30 p.m. 

Speaker: Dr. Zhongyang LIN (Post-doctoral Fellow)
Primary Supervisor: Prof. Michael Shing Yan HUEN
Presentation Title: Dissecting the cellular mechanism of de novo centromere and artificial chromosome formation in Caenorhabditis elegans embryos
Abstract: The centromere is a specialized region on each chromosome that attaches to spindle microtubules to orchestrate chromosome segregation during cell division. Ectopic formation of new centromeres has been implicated in promoting chromosome instability and tumorigenesis. However, the process of new centromere establishment has been challenging to observe in various cell models. In this study, we utilized microinjection of foreign DNA into C. elegans gonads to conduct studies on de novo centromere formation. Our results reveal the in vivo stepwise biological processes of how exogenously introduced DNA fragments spontaneously concatemerize into a larger fragment, then assembles into a chromosome, and finally centromerizes to become a stably propagated artificial chromosome. Using this C. elegans platform, we are able to compare how de novo centromeres are established on artificial chromosomes to how existing centromeres are maintained on endogenous chromosomes for the very first time.

ALL ARE WELCOME

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