Type 2 diabetes mellitus (T2DM) is a risk factor for male infertility, but the underlying molecular mechanisms remain unclear. Advanced glycation end products (AGEs) are pathogenic molecules for diabetic vascular complications. Here, we investigated the effects of DNA-aptamer raised against AGEs (AGE-Apt) on testicular and sperm abnormalities in a T2DM mouse model. KK-Ay (DM) and wild-type (non-DM) 4- and 7-week-old male mice were sacrificed to collect the testes and spermatozoa for immunofluorescence, RT-PCR, and histological analyses. DM and non-DM 7-week-old mice were subcutaneously infused with AGE-Apt or control aptamer for 6 weeks and then sacrificed. Plasma glucose, testicular AGEs, and RAGE gene expression in 4-week-old DM mice and plasma glucose, testicular AGEs, oxidative stress, and pro-inflammatory gene expressions in 7-week-old DM mice were higher than those in age-matched non-DM mice; the latter of which was associated with seminiferous tubular dilation. AGE-Apt did not affect glycemic parameters, but it inhibited the seminiferous tubular dilation, reduced the number of testicular macrophages and apoptotic cells, and restored the decrease in sperm concentration, motility, and viability of 13-week-old DM mice. Our findings suggest that AGEs-Apt may improve sperm abnormality by suppressing the AGE–RAGE-induced oxidative stress and inflammation in the testes of DM mice.

The expedited development of drugs targeting gene products associated with insulin resistance holds the potential to enhance our comprehension of type 2 diabetes mellitus (T2DM). The virtual screening based on a three-dimensional (3D) protein structure has been expected as potential technique to accelerate a development of molecular target drugs. Among the targets implicated in insulin resistance, genetic characterization and protein function of Grb14 have been clarified without contradiction. The Grb14 gene displays notable variations in T2DM, and its gene product known to inhibit the function of the insulin receptor (IR) by directly binding to the tyrosine kinase domain. In the present study, a virtual screening, based on 3D structure of IR tyrosine kinase domain (IRβ) in complex with part of Grb14, was conducted to find compounds that can disrupt the complex formation between Grb14 and IRβ. First, ten compounds were selected from 154,118 compounds via hierarchical in silico structure-based drug screening, composed of grid docking-based and genetic algorithm-based programs. The experimental validations suggested that the one compound can affect blood glucose level. The molecular dynamics simulations and co-immunoprecipitation analysis showed that the compound did not completely suppress the protein–protein interaction between Grb14 and IR, though competitively bound to IR with the tyrosine kinase pseudosubstrate region in Grb14.