Melamine induces autophagy in mesangial cells via enhancing ROS level.

CONTEXT

Melamine, as an industrial chemical, was blended illegally with infant formula to counterfeit the illusion of more abundant protein content in 2008. Due to its nephrotoxicity, thousands of children underwent kidney disease.

OBJECTIVE

It was to investigate whether melamine could affect autophagy in mesangial cells (MCs) via oxidative stress and whether autophagy played a positive role in protecting MCs impaired by melamine.

MATERIALS AND METHODS

MCs were used as a mesangium model. The cell viability was measured by MTT assay. Intracellular hydrogen peroxide (H2O2) was assessed by using H2O2 assay kit. The Western blot assay was employed to measure the expression of autophagy-related proteins.

RESULTS

MTT assay showed that melamine induced MCs death in a concentration-dependent and time-dependent manner. The measurement of H2O2 demonstrated that melamine decreases H2O2 level of MCs. Meaningfully, treatment of a type of ROS scavenger formulation named N-(mercaptopropionyl)-glycine (N-MPG) could inhibit MCs death induced by melamine. Meanwhile, Western blot analysis indicated that melamine enhanced the ratio of LC3-II/LC3-I and Beclin-1 level in MCs, and N-MPG down-regulated autophagy in melamine-treated MCs. The cell viability of MCs with melamine and an autophagy inhibitor named 3-methyladenine (3-MA) showed that autophagy could protect melamine-treated MCs.

CONCLUSIONS

The study showed that melamine-enhanced autophagy by increasing ROS levels in MCs, and autophagy could protect melamine-treated MCs. Improving autophagy may become a new potential clinical application to relieve melamine-induced renal injury.