Abstract: PO1516
FPC, TFAP2B, and MCM3 Function in a Species-Specific Regulome That Modulates Myc/MYC Expression: Implications for ARPKD
Session Information
- Cystic Kidney Diseases: Mechanisms, Genetics, and Treatment
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1001 Genetic Diseases of the Kidneys: Cystic
Authors
- Harafuji, Naoe, Center for Translational Research, Children’s National Medical Center, Washington, District of Columbia, United States
- Yang, Chaozhe, Center for Translational Research, Children’s National Medical Center, Washington, District of Columbia, United States
- Odinakachukwu, Maryanne, Center for Translational Research, Children’s National Medical Center, Washington, District of Columbia, United States
- Wu, Maoqing, Center for Translational Research, Children’s National Medical Center, Washington, District of Columbia, United States
- Caldovic, Ljubica, Center for Genetic Medicine Research, Children’s National Medical Center, Washington, District of Columbia, United States
- Guay-Woodford, Lisa M., Center for Translational Research, Children’s National Medical Center, Washington, District of Columbia, United States
Background
Mutations in PKHD1 cause human ARPKD (MIM 263200), but mouse Pkhd1 mutants have limited or no renal cystic disease. We previously showed that MYC is overexpressed in human ARPKD kidneys but not in mouse Pkhd1 mutant kidneys, and that mouse FPC C-terminal domain (FPC-CTD) activates Myc (ASN 2018). Trudel (2019) has reported that Myc is a central driver in Pkd1-induced pathogenesis. Relevant to the current study, mice express three TFAP2B isoforms while humans express only one, which is most similar to mouse isoform TFAP2B1. Here, we describe a species-specific regulatory framework (regulome) in which FPC-CTD, TFAP2B, and MCM3 regulate Myc/MYC in renal collecting duct (CD) cells.
Methods
Human and mouse CD cell lines, Myc-tagged TFAP2B, Tfap2b1, and Tfap2b2, V5-tagged human and mouse FPC-CTD constructs, and Cys1, Pkhd1 and Myc/MYC promoter constructs were used to perform dual luciferase and co-IP assays.
Results
In mouse cells, TFAP2B1 & 2 positively regulated expression of Pkhd1 and Cys1 while Myc was positively regulated by TFAP2B2 but negatively regulated by TFAP2B1. TFAP2B1 negative regulation of Myc was epistatic over FPC-CTD activation. MCM3, previously identified as a FPC-CTD binding partner, positively regulated Myc promoter activity. Human MYC was activated by FPC-CTD and negatively regulated by TFAP2B.
Conclusion
We show that in both mouse and human, FPC-CTD and TFAP2B regulate Myc/MYC expression. Notably, mouse TFAP2B isoforms differentially regulate Myc expression, while humans lack a MYC activating isoform. Based on our data, we propose a model in which a regulome that includes FPC-CTD, TFAP2B, and MCM3 modulates Myc/MYC expression in CD cells in a species-specific fashion. Species-specific renal phenotypes could be attributable to differences in constituent proteins, isoform diversity, and epistatic interactions within the proposed regulome. We speculate that this model may explain the differential effects of PKHD1/Pkhd1 deficiency on renal cystogenesis and provide initial clues for putative renoprotective mechanisms in Pkhd1 mutant mice.
Funding
- NIDDK Support