Mitochondrial Calcium-Triggered Oxidative Stress and Developmental Defects in Dopaminergic Neurons Differentiated from Deciduous Teeth-Derived Dental Pulp Stem Cells with MFF Insufficiency

• Main Authors: Xiao Sun (Author), Shuangshan Dong (Author), Hiroki Kato (Author), Jun Kong (Author), Yosuke Ito (Author), Yuta Hirofuji (Author), Hiroshi Sato (Author), Takahiro A. Kato (Author), Yasunari Sakai (Author), Shouichi Ohga (Author), Satoshi Fukumoto (Author), Keiji Masuda (Author)
• Format: Book
• Published: MDPI AG, 2022-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antiox11071361; 2076-3921
• Keywords: EMPF2; mitochondrial calcium; mitochondrial fission factor; reactive oxygen species; stem cells from human exfoliated deciduous teeth; Therapeutics. Pharmacology; RM1-950
• Source: Antioxidants, Vol 11, Iss 7, p 1361 (2022)

Mitochondrial fission factor (MFF) is an adapter that targets dynamin-related protein 1 from the cytosol to the mitochondria for fission. Loss-of-function MFF mutations cause encephalopathy due to defective mitochondrial and peroxisomal fission 2 (EMPF2). To elucidate the molecular mechanisms that were involved, we analyzed the functional effects of MFF depletion in deciduous teeth-derived dental pulp stem cells differentiating into dopaminergic neurons (DNs). When treated with MFF-targeting small interfering RNA, DNs showed impaired neurite outgrowth and reduced mitochondrial signals in neurites harboring elongated mitochondria. MFF silencing also caused mitochondrial Ca²⁺ accumulation through accelerated Ca²⁺ influx from the endoplasmic reticulum (ER) via the inositol 1,4,5-trisphosphate receptor. Mitochondrial Ca²⁺ overload led DNs to produce excessive reactive oxygen species (ROS), and downregulated peroxisome proliferator-activated receptor-gamma co-activator-1 alpha (PGC-1α). MFF was co-immunoprecipitated with voltage-dependent anion channel 1, an essential component of the ER-mitochondrial Ca²⁺ transport system. Folic acid supplementation normalized ROS levels, PGC-1α mediated mitochondrial biogenesis, and neurite outgrowth in MFF depleted DNs, without affecting their mitochondrial morphology or Ca²⁺ levels. We propose that MFF negatively regulates the mitochondrial Ca²⁺ influx from the ER. MFF-insufficiency recapitulated the EMPF2 neuropathology with increased oxidative stress and suppressed mitochondrial biogenesis. ROS and mitochondrial biogenesis might be potential therapeutic targets for EMPF2.