Estradiol Ameliorates Postmenopausal Bladder Dysfunction by Restoring Mitophagy via the miRNA-200/KLF4/mTOR Signaling...

Postmenopausal ovarian hormone deficiency (OHD) contributes to overactive bladder (OAB) through oxidative stress, mitochondrial dysfunction, and dysregulated estrogen receptor (ER) signaling. This study investigated whether estradiol (E2) alleviates dysfunction by modulating the ER/Smad/miRNA-200/KLF4/mTOR signaling pathway to restore mitochondrial quality control. Thirty female Sprague-Dawley rats were initially allocated to Sham, Ovariectomy (OVX) and OVX + E2 group; after attrition during the 12-month protocol, six surviving animals per group were included in the principal analyses. The OVX + E2 group received daily intramuscular E2 (IM, 30 μg/kg/day) for one month. Bladder function was assessed via micturition volume and frequency by metabolic cages, cystometrograms, and contractility assays. Mechanisms were analyzed using immunofluorescence, Western blotting, transmission electron microscopy (TEM), and miRNA sequencing. OVX rats exhibited significant overactivity and compromised contractility, accompanied by upregulated ERα and downregulated ERβ/GPER. Molecularly, OHD was associated with the upregulation of the miRNA-200 family (miRNA-200a-3p, miRNA-200b-3p and miRNA-200b-5p), which was accompanied by reduced levels of KLF4 and autophagy proteins (ATG7, ATG12 and Beclin-1), as well as elevated p-mTOR expression. TEM revealed the accumulation of damaged mitochondria with ultrastructural features associated with impaired mitophagy. However, E2 treatment ameliorated these abnormalities. These improvements were associated with the restoration of TGF-β/Smad signaling, downregulation of selected miRNA-200 family members, recovery of KLF4 level, and increased expression of autophagy-related markers, accompanied by improved mitochondrial ultrastructural integrity. This cellular restoration might be correlated with improved urodynamic parameters. E2 might exert therapeutic effects by improving mitochondrial quality, potentially via the ER/Smad/miRNA-200/KLF4 signaling pathway. These findings provided mechanistic insights into estrogen-mediated protection and highlight this proposed signaling pathway as a therapeutic target for postmenopausal OAB.