Probing the Tumour Suppressor Function of BAP1 in CRISPR-engineered Human Liver Organoids

ABSTRACT: The deubiquitinating enzyme BAP1 is a tumour suppressor, amongst others involved in cholangiocarcinoma. BAP1 has many proposed molecular targets, while its Drosophila homolog is known to deubiquitinate Histone H2AK119. Here, we mutate BAP1 by CRISPR/Cas9 in normal human liver organoids. We find that BAP1 controls the expression of junctional/cytoskeleton components by regulating chromatin accessibility. Consequently, we observe loss of multiple epithelial characteristics, while motility increases. Importantly, restoring the catalytic activity of BAP1 in the nucleus rescues these cellular and molecular changes. We engineer human liver organoids to combine four common cholangiocarcinoma mutations (TP53, PTEN, SMAD4, NF1). In this genetic background, BAP1 loss results in acquisition of malignant features upon xenotransplantation. Thus, control of epithelial identity through the regulation of chromatin accessibility appears a key aspect of BAP1’s tumour suppressor function. Organoid technology combined with CRISPR/Cas9 provides an experimental platform for mechanistic studies of cancer gene function in a human context.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cholangiocyte, Liver

DISEASE(S): Cholangiocarcinoma

SUBMITTER: Rik Lindeboom  

LAB HEAD: Hans Clevers

PROVIDER: PXD013353 | Pride | 2019-05-22

REPOSITORIES: Pride