Characterisation of MESP1 binding partners and their use in the production of cardiac progenitor cells

Abstract

The transcription factor, Mesoderm posterior 1 (Mesp1), is essential for mesoderm formation in the early embryo. Overexpression in an embryonic stem cell (ESC) model leads to cardiac differentiation. However dependent upon conditions, Mesp1 overexpression can also induce skeletal muscle and haematopoietic lineages. The mechanism by which Mesp1 induces these different phenotypes is unknown but could be due to different interacting partners. Identifying if such interactions play a role in the differentiation of stem cells into cardiac progenitor cells (CPCs), as well as if we can use these factors to reprogram somatic cells into CPCs is the pivotal question to be answered in order to provide a novel CPC production pathway. The ability to produce a pure CPC population would allow us to make a breakthrough in their use in regenerative medicine, opening up new avenues of treatment for heart failure patients.

To investigate this, we identified MESP1 and its binding partners through mass spectrometry of mouse embryonic stem cells (mESC) isolated at mesoderm stage of cardiac differentiation. Our analysis has identified 7 putative binding partners that have similar expression patterns to Mesp1 in mESCs undergoing cardiac differentiation. Furthermore, we have verified that 2 of these putative binding partners, Eomesodermin and Methyl- CpGbinding domain protein 3, interact with MESP1 when co-expressed in human embryonic kidney cells (HEK). Furthermore, using literature-based evidence, we have identified 1 other potential binding partner, WD Repeat Domain 5. Utilising mESCs, we have identified that these binding partners have an effect on cardiac differentiation, and other binding partner expression patterns, that previously observed in Mesp1 knockout mESCs. We further ascertained the effects of these binding partners in the reprogramming of cells. Overexpression in 3T3 fibroblasts has identified morphological and genetic changes, including inducing the expression of cardiac genes.

Date of Award	1 Jun 2021
Original language	English
Awarding Institution	King's College London
Supervisor	Fiona Wardle (Supervisor) & Georgina Ellison (Supervisor)