Genetic studies on congenital heart disorders

Aparicio Sánchez, José Juan (2020) Genetic studies on congenital heart disorders. PhD thesis, University of Nottingham.

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Abstract

Congenital heart defects represent the most common form of congenital abnormality. These developmental disorders affect at least 4000 new-borns each year in the UK, and present an incidence of approximately one in every 100 babies born. The most common cause for CHDs are genetic mutations that are inherited or arise de novo during embryogenesis, and even though we have gained great insight into the CHD-causative genes during these last decades, we are still far from understanding the whole picture. In this PhD thesis, my main goal is to contribute to the genetics of congenital heart disorders by discovering and characterizing new factors involved in cardiac development and in the onset of CHD. During this thesis, I have worked on three different projects whose results have ultimately contributed to this field.

In the first part of this thesis, I report that acetyltransferases KAT2A and KAT2B associate with TBX5, a T-box transcription factor whose mutations are causative of Holt-Oram syndrome, a rare genetic condition that affects the development of the heart and upper limbs. KAT2A and KAT2B acetylate TBX5 at Lys339, and this acetylation potentiates its transcriptional activity and is required for TBX5 nuclear retention. Both morpholino-mediated knockdown and CRISPR-Cas-mediated knockout of kat2a and kat2b in zebrafish perturbs heart and limb development, mirroring thus the tbx5a loss-of-function phenotype.

In the second part, I performed a characterization of CHD4 mutations found in syndromic-CHD patients. Interactional studies revealed that none of these mutations affect CHD4 interaction with other NuRD subunits, and immunofluorescence staining showed that they localized properly to the nucleus. However, functional assays revealed that four of these mutants have a lower activity than their WT counterpart, whereas one of them appears to be a gain-of-function variant.

Last but not least, in the final chapter of this thesis I carried out the preliminary characterization of two transgenic mouse lines carrying null mutations for two genes which have been recently discovered to be involved in CHD: CHD4 and CDK13. These two lines were recently acquired by our laboratory, and following colony expansion and characterization, they were used for heart morphology studies using high-resolution episcopic microscopy.

All in all, the results presented in this thesis expand our understanding and knowledge of the genes and factors involved in the regulation of cardiac development as well as in the onset of CHDs, and help defining the complete set of genes responsible for CHDs.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Brook, David
Loose, Matthew
Keywords: Genetics, Congenital heart disorders
Subjects: Q Science > QH Natural history. Biology > QH426 Genetics
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 60106
Depositing User: Aparicio Sánchez, José
Date Deposited: 16 Jul 2021 09:42
Last Modified: 16 Jul 2021 09:42
URI: http://eprints.nottingham.ac.uk/id/eprint/60106

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