The Yeast-Fermented Garlic and a Balance of Spermine/Spermidine Activates Autophagy via EGR1 Transcriptional Factor

Spermine (SPM) and spermidine (SPD) are polyamines found in all organisms, and their concentrations can be regulated by ingestion. We demonstrated that yeast-fermented garlic (YF) extract significantly increased autophag flux in OUMS-36T-1 and HeLa cells expressing the fluorescent probe (GFP-LC3-RFP-LC3ΔG). YF-induced increase of autophagy occurred independently of mTORC1 signaling, and RNA-sequencing analysis revealed that EGR1 was the most significantly altered gene in YF-treated OUMS-36T-1 cells. YF-treated EGR1-deficient HAP1 cells displayed reduced autophagic flux (p < 0.05). YF-induced increasing of autophagic flux occurred via a specific SPM/SPD ratio. HAP1 cells treated with equivalent amounts of SPD or SPM as that found in YF did not increase autophagic flux (p > 0.05); however, treatment with SPD and SPM in the same ratio as that found in YF increased autophagic flux (p < 0.05). This specific SPM/SPD ratio reduced MG132-induced proteostress via EGR1-dependent pathways (p < 0.05). Thus, the SPM/SPD balance may regulate autophagy via EGR1-dependent pathways, and controlling this balance may provide a strategy to maintain cellular homeostasis.