Estrogen Regulates Mitochondrial Morphology through Phosphorylation of Dynamin-related Protein 1 in MCF7 Human Breast Cancer Cells

Estrogen affects mitochondrial function in various tissues, but the precise mechanism remains unclear. We, therefore investigated the effect on estrogen-regulated mitochondrial morphology by dynamin-related protein 1 (Drp1) and its Ser616-phosphorylated derivative (pDrp1(Ser616)) are involved in mitochondrial fission. MCF7 human breast cancer cells were treated with 17β-estradiol (E(2)), an estrogen receptor (ER) α and β antagonist (ICI 182, 780), an ERα antagonist (MPP), and an ERβ antagonist (PHTPP) for 24 hr. The expression of Drp1 and pDrp1(Ser616) was analyzed by western blotting and immunohistochemistry. Mitochondrial morphology was analyzed by transmission electron microscopy (TEM). In control cells, Drp1 was detected in the cytoplasm of all cells while pDrp1 was observed in the cytoplasm of 3.4 ± 1.0% of the total population. After E(2) treatment, pDrp1(Ser616)-positive cells comprised 30.6 ± 5.6% of the total population, 10.5 ± 1.7% after E(2) + ICI treatment, 12.4 ± 4.2% after E(2) + MPP treatment, and 24.0 ± 2.2% after E(2) + PHTPP treatment. In ERα knockdown MCF7 cells, pDrp1 expression was decreased after E(2) treatment compared to E(2)-treated wild type cells. Tubular pattern mitochondria were found in the control cells but the number of short and small pattern mitochondria (< 0.5 μm(2)) was significantly increased after E(2) treatment (as observed by TEM). We, therefore concluded that the phosphorylation of Drp1 is important for E(2)-dependent mitochondrial morphological changes through ERα.