HDAC6-dependent deacetylation of NGF dictates its ubiquitination and maintains primordial follicle dormancy

Rationale: Primordial follicles are limited in number and cannot be regenerated, dormant primordial follicles cannot be reversed once they enter a growth state.Therefore, the length of the female reproductive lifespan depends on the orderly progression and selective activation of primordial follicles, the mechanism of which remains unclear.Methods: We used human ovarian cortical biopsy specimens, granulosa cells from diminished ovarian reserve (DOR) patients, Hdac6-overexpressing transgenic mouse model, and RNA sequencing to analyze the crucial roles of histone deacetylase 6 (HDAC6) in fertility preservation and primordial follicle activation.Results: In the present study, we found that HDAC6 was highly expressed in most dormant primordial follicles.The HDAC6 expression was reduced accompanying reproductive senescence in human and mouse ovaries.Overexpression of Hdac6 delayed the rate of primordial follicle activation, thereby prolonging the mouse reproductive lifespan.Short-term inhibition of HDAC6 promoted primordial follicle activation and follicular development in humans and mice.Mechanism studies revealed that HDAC6 directly interacted with NGF, reducing acetylation modification of NGF and thereby accelerating its ubiquitination degradation.Consequently, the reduced NGF protein level maintained the dormancy of primordial follicles. Conclusions:The physiological significance of the high expression of HDAC6 in most primordial follicles is to reduce NGF expression and prevent primordial follicle activation to maintain female fertility.Reduced HDAC6 expression increases NGF expression in primordial follicles, activating their development and contributing to reproduction.Our study provides a clinical reference value for fertility preservation.