967C Poster - 15. Models of human disease
Saturday April 09, 1:30 PM - 3:30 PM

Authors:
John Pleinis ²; Kevin Hope ¹; Danielle DaCrema ¹; Clement Chow ¹; Aylin Rodan ²

Affiliations:
1) Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT; 2) Department of Internal Medicine, Division of Nephrology and Hypertension, and Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT

Keywords:
k. developmental disorders; j. endoplasmic reticulum

NGLY1 deficiency is a rare disorder caused by loss of function mutations in the NGLY1 gene and often presents with developmental delay, liver dysfunction, and seizures. One of the most consistent and defining disease phenotypes is the reduced ability to make tears, sweat, and saliva. Therapies that could treat these secretory problems could have a profound effect on quality of life for these patients. To study salivary gland dysfunction in adult flies, we developed a “rock candy” assay, which measures the consumption of a solid blue sugar. Consumption, as measured by blue dye, is correlated with salivary gland function. Ablation of the salivary gland results in little to no consumption of the blue sugar. To model NGLY1-induced salivary gland dysfunction, we used RNAi to knockdown NGLY1 (Pngl in flies) expression in the salivary glands of adult flies and found that this reduces consumption by nearly 50%. We previously showed that the Na-K-Cl cotransporter, NKCC1 (Ncc69 in flies), is an enzymatic target of NGLY1 and a modifier of NGLY1 deficiency in flies. NKCC1 regulates ion flux in secretory cells like those in the salivary gland. We generated salivary gland-specific knockdown of NKCC1 and found a severe consumption defect. To test whether the defects we observed in either single knockdown was due to a genetic interaction, we generated salivary gland-specific double knockdown. The double knockdown had a severe consumption defect similar to what we observed in the single NKCC1 knockdown, suggesting that the defects observed are due to a genetic interaction between NGLY1 and NKCC1. We also demonstrate that drugs that alter NGLY1 or NKCC1 activity can rescue the consumption phenotype in NGLY1 knockdown. Together, these data indicate that the fly is a powerful model for studying salivary gland dysfunction in NGLY1 deficiency and may help develop life changing therapies.