Understanding renal intrinsic repair by FANCD2

Massachusetts General Hospital, Boston MA

Investigators

Abstract

Project Summary Chronic kidney disease (CKD) affects up to 13.4% of the global population, imposing significant economic burdens on healthcare systems. While kidney tubular cells can self-repair, severe or repetitive damage may lead to degenerative fibrosis, revealing critical gaps in understanding adaptive cellular repair mechanisms. Our recent work has identified unique molecular profiles in repairing tubules, indicating that FANCD2, a key protein in the Fanconi anemia pathway and crucial for interstrand crosslink (ICL) repair, may regulate adaptive repair. Despite extensive studies on FANCD2 in DNA repair and cancer, its role in the kidneys and CKD is poorly understood. No studies have reported the kidney phenotype of FANCD2 knockout (KO) mice; however, data from the International Mouse Phenotypic Consortium (IMPC) suggest kidney degenerative changes in heterozygous KO males. Furthermore, clinical studies indicate an association between Fanconi anemia and CKD, emphasizing the relevance of this research. Our investigation revealed a unique pan-nuclear distribution of FANCD2 in proximal tubules, distinct from typical DNA repair foci. Additionally, chromatin immunoprecipitation sequencing (ChIP-seq) analysis showed FANCD2 binding to the promoters of multiple genes, including those involved in kidney development. In cisplatin-induced acute kidney injury (AKI) mouse models, we observed protective effects of inhibiting FANCD2's canonical pathway. These findings suggest FANCD2 has multifaceted roles beyond its ICL repair, significantly impacting kidney development and repair through non-canonical pathways. Specific Aim 1 is to define the non-canonical role of FANCD2 as a transcriptional regulator in nephron epithelia. We will use diverse models, including conditional FANCD2 KO mice, transgenic human kidney organoids, and patient samples, employing techniques such as immunohistochemistry, 3D imaging, western blotting, qPCR, RNA-seq, and ChIP-seq. These integrative analyses will assess FANCD2 chromatin binding and transcriptional regulation. Specific Aim 2 is to investigate FANCD2’s roles in AKI and CKD through both canonical and non-canonical pathways using in vivo and in vitro models. We will employ genetic and pharmacological approaches to uncover these roles. Our evaluation will include nephron epithelial integrity, fibrosis, DNA damage and repair, and other processes through single cell analyses, providing insights into FANCD2’s pathways as a potential therapeutic target. These aims utilize diverse models to rigorously test our hypothesis and provide evidence for potential CKD interventions. Our comprehensive approach aims to enhance understanding of FANCD2-mediated kidney repair mechanisms. Unraveling the non-canonical roles of FANCD2 in CKD may lead to targeted therapies that halt fibrotic progression and improve renal function in CKD patients.