Clin Exp Reprod Med.  2023 Sep;50(3):170-176. 10.5653/cerm.2023.05876.

Repopulation of autophagy-deficient stromal cells with autophagy-intact cells after repeated breeding in uterine mesenchyme-specific Atg7 knockout mice

• Oh JE
• Kwon S
• Byun H
• Song H
• Lim HJ

• KMID: 2545466
• DOI: http://doi.org/10.5653/cerm.2023.05876

Abstract

Objective
Autophagy is highly active in ovariectomized mice experiencing hormone deprivation, especially in the uterine mesenchyme. Autophagy is responsible for the turnover of vasoactive factors in the uterus, which was demonstrated in anti-Müllerian hormone receptor type 2 receptor (Amhr2)-Cre-driven autophagy-related gene 7 (Atg7) knockout (Amhr-Cre/Atg7^f/f mice). In that study, we uncovered a striking difference in the amount of sequestosome 1 (SQSTM1) accumulation between virgin mice and breeder mice with the same genotype. Herein, we aimed to determine whether repeated breeding changed the composition of mesenchymal cell populations in the uterine stroma.
Methods
All female mice used in this study were of the same genotype. Atg7 was deleted by Amhr2 promoter-driven Cre recombinase in the uterine stroma and myometrium, except for a triangular stromal region on the mesometrial side. Amhr-Cre/Atg7^f/f female mice were divided into two groups: virgin mice with no mating history and aged between 11 and 12 months, and breeder mice with at least 6-month breeding cycles with multiple pregnancies and aged around 12 months. The uteri were used for Western blotting and immunofluorescence staining.
Results
SQSTM1 accumulation, representing Atg7 deletion and halted autophagy, was much higher in virgin mice than in breeders. Breeders showed reduced accumulation of several vasoconstrictive factors, which are potential autophagy targets, in the uterus, suggesting that the uterine stroma was repopulated with autophagy-intact cells during repeated pregnancies.
Conclusion
Multiple pregnancies seem to have improved the uterine environment by replacing autophagy-deficient cells with autophagy-intact cells, providing evidence of cell mixing.

Keyword

Atg7; Autophagy; Breeder; Mesoderm; Uterus