Downregulation of aldose reductase is responsible for developmental abnormalities of the silkworm purple quail-like mutant (q-lp)

Aldose reductase (AR) is a rate-limiting enzyme in the polyol pathway and is also the key enzyme involved in diabetic complications. The silkworm purple quail-like mutant (q-lp) exhibits pigmented dots on its epidermis. The q-lp mutant also shows developmental abnormalities and decreased vitality. In this study, fat bodies from the q-lp mutant and the wildtype 932VR strain were subjected to two-dimensional gel electrophoresis (2-DE) analysis, and the Bombyx mori AR (BmAR) protein was found to be significantly downregulated in the q-lp mutant. The expression of BmAR at the mRNA level was also significantly downregulated, as verified through quantitative reverse transcription PCR (qRT-PCR). Knockdown of the expression of BmAR via RNAi resulted in a reduction of silkworm weight. The sorbitol level in q-lp was significantly lower than in the wildtype. These results suggested that the BmAR gene is closely related to the development of the q-lp mutant. Investigation of the cause of BmAR downregulation in the q-lp mutant could contribute to revealing the function of AR in insects and offers a new method of identifying AR inhibitors for the treatment of diabetic complications.