title: A small-molecule screen reveals that HSP90β promotes the conversion of induced pluripotent stem cell-derived endoderm to a hepatic fate and regulates HNF4A turnover.
abstract: We have previously shown that the transcription factor HNF4A is required for the formation of hepatic progenitor cells from endoderm that has been derived from human induced pluripotent stem cells (iPSCs). We reasoned that we could uncover regulatory pathways with new roles in hepatocyte differentiation by identifying cellular processes that regulate HNF4A. We therefore performed a screen of 1120 small molecules with well-characterized mechanisms of action to detect those that affect the abundance of HNF4A in iPSC-derived hepatic progenitor cells. This approach uncovered several small molecules that depleted HNF4A. Of those, we chose to focus on an inhibitor of heat shock protein 90 beta (HSP90β). We show that mutation of the gene encoding HSP90β represses hepatocyte differentiation during the formation of hepatocytes from iPSCs. We reveal that HSP90β, although dispensable for expression ofHNF4AmRNA, directly interacts with HNF4A protein to regulate its half-life. Our results demonstrate that HSP90β has an unappreciated role in controlling hepatic progenitor cell formation and highlight the efficiency of using small-molecule screens during the differentiation of iPSCs to reveal new molecular mechanisms that control hepatocyte formation.
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Basic Science Building BS657A, 173 Ashley Avenue, MSC 508, Charleston, SC 29425, USA.
authors.forename: Ran
authors.initials: R
authors.lastname: Jing
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Basic Science Building BS657A, 173 Ashley Avenue, MSC 508, Charleston, SC 29425, USA.
authors.forename: Cameron B
authors.identifier: 0000-0002-2507-7827
authors.initials: CB
authors.lastname: Duncan
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Basic Science Building BS657A, 173 Ashley Avenue, MSC 508, Charleston, SC 29425, USA duncanst@musc.edu.|Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, MSC 955, Charleston, SC 29425, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Duncan
mesh_terms: D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D004707:Endoderm / Q000166:cytology*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D006207:Half-Life; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D022781:Hepatocytes / Q000502:physiology*; D057166:High-Throughput Screening Assays / Q000379:methods; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D008099:Liver / Q000166:cytology; D011489:Protein Denaturation; D054852:Small Molecule Libraries / Q000032:analysis*
chemical_list: C496592:HNF4A protein, human; D018841:HSP90 Heat-Shock Proteins; C493165:HSP90AB1 protein, human; D051557:Hepatocyte Nuclear Factor 4; D054852:Small Molecule Libraries
keywords: Liver development; Small-molecule screening; iPSC-derived hepatocytes