Effect of genetic variation in a Drosophila model of diabetes-associated misfolded human proinsulin

Bin Z. He, Michael Z. Ludwig, Desiree A. Dickerson, Levi Barse, Bharath Arun, Bjarni J. Vilhjálmsson, Pengyao Jiang, Soo Young Park, Natalia A. Tamarina, Scott B. Selleck, Patricia J. Wittkopp, Graeme I. Bell, Martin Kreitman

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22 Scopus citations

Abstract

The identification and validation of gene-gene interactions is a major challenge in human studies. Here, we explore an approach for studying epistasis in humans using a Drosophila melanogaster model of neonatal diabetes mellitus. Expression of the mutant preproinsulin (hINSC96Y) in the eye imaginal disc mimics the human disease: it activates conserved stress-response pathways and leads to cell death (reduction in eye area). Dominant-acting variants in wild-derived inbred lines from the Drosophila Genetics Reference Panel produce a continuous, highly heritable distribution of eye-degeneration phenotypes in a hINSC96Y background. A genome-wide association study (GWAS) in 154 sequenced lines identified a sharp peak on chromosome 3L, which mapped to a 400-bp linkage block within an intron of the gene sulfateless (sfl). RNAi knockdown of sfl enhanced the eye-degeneration phenotype in a mutant-hINS-dependent manner. RNAi against two additional genes in the heparan sulfate (HS) biosynthetic pathway (ttv and botv), in which sfl acts, also modified the eye phenotype in a hINSC96Y-dependent manner, strongly suggesting a novel link between HS-modified proteins and cellular responses to misfolded proteins. Finally, we evaluated allele-specific expression difference between the two major sfl-intronic haplotypes in heterozygtes. The results showed significant heterogeneity in marker-associated gene expression, thereby leaving the causal mutation(s) and its mechanism unidentified. In conclusion, the ability to create a model of human genetic disease, map a QTL by GWAS to a specific gene, and validate its contribution to disease with available genetic resources and the potential to experimentally link the variant to a molecular mechanism demonstrate the many advantages Drosophila holds in determining the genetic underpinnings of human disease.

Original languageEnglish (US)
Pages (from-to)557-567
Number of pages11
JournalGenetics
Volume196
Issue number2
DOIs
StatePublished - Feb 2014

All Science Journal Classification (ASJC) codes

  • Genetics

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    He, B. Z., Ludwig, M. Z., Dickerson, D. A., Barse, L., Arun, B., Vilhjálmsson, B. J., Jiang, P., Park, S. Y., Tamarina, N. A., Selleck, S. B., Wittkopp, P. J., Bell, G. I., & Kreitman, M. (2014). Effect of genetic variation in a Drosophila model of diabetes-associated misfolded human proinsulin. Genetics, 196(2), 557-567. https://doi.org/10.1534/genetics.113.157800