Objective: This study aims to investigate the role of Insulin-like Growth Factor 2 (IGF2) deficiency in promoting obesity through suppressed testosterone synthesis in Leydig cells by modulating autophagy flux.
Methods: Conditional hepatocyte-specific Igf2 knockout mice (Igf2 ΔHep) were generated. Body weight gain, serum testosterone, and glucose-lipid metabolic indicators were compared between Igf2 ΔHep and control mice. Transcriptomic sequencing was conducted on liver samples, and a combined analysis was done on publicly available single-cell sequencing data from testicular tissues. Autophagy levels and autolysosomes changes in Leydig cells were measured via autophagy marker protein LC3 and transmission electron microscopy (TEM). Key testosterone synthesis enzymes HSD17B and CYP17A1 expressions were quantified, followed by assessing cholesterol uptake using the BODIPY-cholesterol probe.
Results: Hepatocyte-specific Igf2 deletion mice exhibited accelerated weight gain compared to controls, coupled with significantly lower serum testosterone levels. Single-cell transcriptomics and immunofluorescence confirmed predominant expression of IGF2 and IGF2R in Leydig cells within the testes. Transcriptomic analysis disclosed downregulated genes in cholesterol metabolism and steroidogenesis pathways in Igf2 ΔHep mice. Immunofluorescence assays verified reduced expression of LC3 and TEM revealed a significant decrease in autolysosomes in Leydig cells of Igf2 ΔHep mice. Fluorescent co-staining and BODIPY-cholesterol assays indicated downregulated expression of testosterone synthesis enzymes HSD17B/CYP17A1 and decreased cholesterol uptake in IGF2-deficient mice.
Conclusion: This research demonstrated that IGF2 deficiency suppresses testosterone synthesis by regulating autophagy in Leydig cells, affecting cholesterol uptake and utilization, thereby potentially lowering testosterone levels and increasing obesity risk in males.
W. Gui: None.
National Natural Science Foundation of China (82370846)
