Elevated 4-hydroxynonenal induces hyperglycaemia via Aldh3a1 loss in zebrafish and associates with diabetes progression in humans

Abstract

Increased methylglyoxal (MG) formation is associated with diabetes and its complications. In zebrafish, knockout of the main MG detoxifying system Glyoxalase 1, led to limited MG elevation but significantly elevated aldehyde dehydrogenases (ALDH) activity and aldh3a1 expression, suggesting the compensatory role of Aldh3a1 in diabetes. To evaluate the function of Aldh3a1 in glucose homeostasis and diabetes, aldh3a1 −/− zebrafish mutants were generated using CRISPR-Cas9. Vasculature and pancreas morphology were analysed by zebrafish transgenic reporter lines. Corresponding reactive carbonyl species (RCS), glucose, transcriptome and metabolomics screenings were performed and ALDH activity was measured for further verification. Aldh3a1 −/− zebrafish larvae displayed retinal vasodilatory alterations, impaired glucose homeostasis, which can be aggravated via pdx1 silencing induced hyperglycaemia. Unexpectedly, MG was not altered, but 4-hydroxynonenal (4-HNE), another prominent lipid peroxidation RCS exhibited high affinity with Aldh3a1, was increased in aldh3a1 mutants. 4-HNE was responsible for the retinal phenotype via pancreas disruption induced hyperglycaemia and can be rescued via l -Carnosine treatment. Furthermore, in type 2 diabetic patients, serum 4-HNE was increased and correlated with disease progression. Thus, our data suggest impaired 4-HNE detoxification and elevated 4-HNE concentration as biomarkers but also the possible inducers for diabetes, from genetic susceptibility to the pathological progression.

Redox changes in obesity, metabolic syndrome, and diabetes

“…Therefore, 4-HNE in VAT is related to VAT dysfunction and oxidative stress even at low BMI, leading to restricted lipid buffering function of adipose tissue and increased lipid peroxidation as a function of BMI increase. In T2DM patients, higher serum levels of 4-HNE were found to directly correlate with clinical prognostic parameters (glycated hemoglobin, fasting glucose) [ 66 ]. However, the role of 4-HNE in metabolic diseases has not yet been fully elucidated and is probably concentration-dependent.…”

Which Hyperglycemic Model of Zebrafish (Danio rerio) Suites My Type 2 Diabetes Mellitus Research? A Scoring System for Available Methods

“…The gene is available in human, mouse, and zebrafish. In zebrafish, the gene shares 61.6% to human ALDH3A1 (Lou et al, 2020 ). Lou et al ( 2020 ) revealed that aldh3a1 −/− knockout in zebrafish is accompanied with an increased whole larval glucose, retinal vasodilatory alterations, and generally impaired glucose metabolism.…”

“…In zebrafish, the gene shares 61.6% to human ALDH3A1 (Lou et al, 2020 ). Lou et al ( 2020 ) revealed that aldh3a1 −/− knockout in zebrafish is accompanied with an increased whole larval glucose, retinal vasodilatory alterations, and generally impaired glucose metabolism. They also showed a correlation between HbA1c increase and 4-hydroxynonenal (4-HNE).…”

“…They also showed a correlation between HbA1c increase and 4-hydroxynonenal (4-HNE). This specific mutant hyperglycemic state was amplified by pdx1 gene silenced mutant and achieved a higher level of free larval glucose accordingly (Lou et al, 2020 ).…”

“…It is possible to extract fructosamine from the eyes of zebrafish and consider its increase as an upregulation of non-enzymatic glycation of proteins and diabetes (Armbruster, 1987 ; Capiotti et al, 2014 ). Other compounds, such as 4-hydroxynonenal (4-HNE) (Lou et al, 2020 ) and MG (Lodd et al, 2019 ) are proposed as indicators, too.…”