The function and mechanism of aldh9a1b in diabetes

Reactive aldehydes such as 4-HNE, MDA and acrolein are implicated in the pathological development of diabetes as their widespread and universally exposed characteristics. Trans, trans-2,4-decadienal (tt-DDE) come from lipid peroxidation of omega-6 and is most abundant aldehyde in cooking oil fumes, while, its role in diabetes remained unknown. Aldh9a1 is a cytosolic enzyme that catalyze the NAD+-dependent oxidation of a variety of aldehydes and has its homology aldh9a1b in zebrafish. To investigate the function of endogenous and exogenous tt-DDE, aldh9a1b knockout zebrafish are established using CRISPR/Cas9 technology. TT-DDE was confirmed to act as substrate for aldh9a1b and a series of experiments are performed on a histological, metabolomic and transcriptomic level in aldh9a1b-/- zebrafish. Both aldh9a1b-/- larvae and adult fish displayed abnormal retinal vasculature and impaired glucose homeostasis, which are caused by tt-DDE induced downregulated insulin signaling pathway. Furthermore, the abnormal hyaloid vasculature in the fish can be reversed by insulin receptor sensitizer and metformin exhibited strongest effects among them. Altogether, these results identified tt-DDE as the preferred substrate for aldh9a1b, which subsequently causes microvascular damage and impaired glucose metabolism by insulin resistance. Overall design: A CRISPR based knockout ofaldh9a1b was created in zebrafish. The development of the fish was analyzed, as well as organ specific glucose metabolism in skeletal muscle and liver. Imaging studies of Retina, kidney, liver and skeletal muscle were conducted. RNA sequencing was performed on the larvae of aldh9a1b+/+, aldh9a1b-/- and tt-DDE treating aldh9a1b+/+ by BGI .