A multi-phenotypic GWA screen for renal function in Drosophila

Li, Keqin (2025) A multi-phenotypic GWA screen for renal function in Drosophila. PhD thesis, University of Glasgow.

Abstract

Renal function plays a critical role in maintaining water-salt homeostasis and survival of most animal species. Impaired renal function has been associated with kidney stone disease, with evidence linking compromised tubular secretion to the progression of renal dysfunction in humans. Moreover, substantial genetic contributions have been identified in both kidney stone formation and tubular transport of endogenous solutes and xenobiotics. Therefore, understanding the genetic basis of nephrolithiasis and tubular transport may provide valuable insights into the mechanisms underlying nephrolithiasis, impaired tubular secretion, and their contributions to renal function decline. Genome-wide association studies in humans have reported several sequence variants associated with kidney function and kidney stone disease. Calcium-based urinary stones account for more than 80% of all kidney stones, and tubular transport represents another important renal functional parameter apart from glomerular
filtration. Despite this, only a handful of genes implicated in calcium nephrolithiasis and tubular transport have been identified. The genetic basis of variation in susceptibility to kidney stones and renal tubular secretion remains largely unclear. While association studies are powerful and unbiased tools for identifying risk loci, several challenges persist in human studies.

The Malpighian tubules of Drosophila, functional analogues of human kidneys, have been demonstrated to be an excellent model for studying human renal function and disease. The Drosophila melanogaster genetic reference panel serves as a valuable genetic resource for investigating the genetic basis of complex traits. In this study, we utilized inbred, fully sequenced lines from the panel to identify genetic variants influencing kidney stone formation and the secretion capacity of renal tubules. Calcium crystals were quantified in the renal tubules of fly lines subjected to a lithogenic diet, and the fluid secretion capacity of the dissected tubules was measured. Furthermore, the genetic basis of neuroendocrine regulation of secretion was explored using two neuropeptides targeting distinct cell types. We found considerable and reproducible phenotypic variation in both crystal formation and fluid secretion ability. Interestingly, no correlation was observed between the development of renal crystals and basal fluid secretion rates, despite low urine volume being a recognized risk factor for kidney stone disease.

Association studies were conducted to identify genetic variants associated with the observed phenotypic variation. A total of 68 polymorphisms corresponding to 41 genes were associated with crystal formation, while 155 polymorphisms corresponding to 92 genes were linked to basal secretion rate. Candidate genes harbouring these polymorphisms were functionally validated through RNAimediated knockdown. Interactions between candidate genes and their physically and genetically interacting genes were extracted from curated databases. Functional enrichment analysis of the clustered gene networks revealed that biological processes, including the Wnt signalling pathway and extracellular acidification, were associated with the gene networks identified in the analysis of stone formation. Additionally, processes such as the electron transport chain, aerobic respiration, and mitochondrial ATP synthesis were linked to variation in basal secretion rate.

In conclusion, this study presents the first genome-wide association analysis of renal crystal formation and tubular fluid secretion in Drosophila, identifies multiple candidate loci and pathways, and helps to prioritise human genes and pathways as potential therapeutic targets for kidney stone disease and impaired tubular transport. This study has thus demonstrated the utility of a systematic, unbiased screen in identifying genes of interest in renal function in both insects and humans.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Funding from the China Scholarship Council and BBSRC.
• Subjects: Q Science > QH Natural history > QH345 Biochemistry
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Funder's Name: China Scholarship Council, Biotechnology and Biological Sciences Research Council (BBSRC)
• Supervisor's Name: Dow, Professor Julian A.T.
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85363
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 31 Jul 2025 07:23
• Last Modified: 20 Feb 2026 16:29
• Thesis DOI: 10.5525/gla.thesis.85363
• URI: https://theses.gla.ac.uk/id/eprint/85363