Mitochondrial division inhibitor 1 reduces dynamin-related protein 1 and mitochondrial fission activity

Abstract

The purpose of our study was to better understand the effects of mitochondrial-division inhibitor 1 (Mdivi-1) on mitochondrial fission, mitochondrial biogenesis, electron transport activities, and cellular protection. In recent years, researchers have found excessive mitochondrial fragmentation and reduced fusion in a large number of diseases with mitochondrial dysfunction. Therefore, several groups have developed mitochondrial division inhibitors. Among these, Mdivi-1 was extensively studied and was found to reduce Drp1 levels and excessive mitochondrial fission, enhance mitochondrial fusion activity and protect cells. However, a recent study by Bordt et al. (2017) (1) questioned earlier findings of the beneficial, inhibiting effects of Mdivi-1. In the current study, we studied the protective effects of Mdivi-1 by studying the following: mRNA and protein levels of electron transport chain (ETC) genes, mitochondrial dynamics and biogenesis genes, enzymatic activities of ETC complexes I, II, III and IV, the mitochondrial network, mitochondrial size & number, Drp1 GTPase enzymatic activity and mitochondrial respiration 1) in N2a cells treated with Mdivi-1, 2) overexpressed with full-length Drp1+Mdivi-1-treated N2a cells and 3) Drp1 RNA silenced+Mdivi-1-treated N2a cells. We found reduced levels of the fission genes Drp1 and Fis1 levels; increased levels of the fusion genes Mfn1, Mfn2, and Opa1; and the biogenesis genes PGC1α, Nrf1, Nrf2, and TFAM. Increased levels mRNA and protein levels were found in ETC genes of complexes I, II and IV genes. Immunoblotting data agreed with mRNA changes. Transmission electron microscopy analysis revealed reduced numbers of mitochondria and increased length of mitochondria 1) in N2a cells treated with Mdivi-1, 2) cells overexpressed with full-length Drp1+ Mdivi-1-treated N2a cells and 3) Drp1 RNA silenced+Mdivi-1-treated N2a cells. Immunofluorescence analysis revealed that mitochondrial network was increased. Increased levels of complex I, II and IV enzymatic activities were found in all 3 groups of cells treated with low concentration of Mdivi-1. Mitochondrial function was increased and GTPase-Drp1 activity was decreased in all 3 groups of N2a cells. These observations strongly suggest that Mdivi-1 is a Drp1 inhibitor and directly reduces mitochondrial fragmentation and further, Mdivi-1 is a promising molecule to treat human diseases with ETC complexes, I, II and IV.

Drp1 overexpression induces desmin disassembling and drives kinesin-1 activation promoting mitochondrial trafficking in skeletal muscle

“…* vs WT mice (*P < 0.05, **P < 0.01, ***P < 0.001). [54], several lines of evidence support this activity [41,55,56] showing that Mdivi-1 reduces Drp1 levels, prevents mitochondrial fragmentation, enhances fusion and promotes the formation of mitochondrial network and we confirm these findings. In agreement with mitochondrial improvements, Mdivi-1 ameliorated also desmin pattern in Drp/MC muscle, decreasing the accumulation of insoluble sarcoplasmic tetramers and consistently its phosphorylation in Ser-31.…”

“…S4C) supporting a role of Drp1 only in the maintenance of normal mitochondria positioning and in the regulation of mitochondrial trafficking. Accordingly to Manczak et al [41], we found a significant Mdivi-1-dependent drop of Drp1 levels in muscle (Fig. 4b).…”

The prospective curative role of lipoxin A4 in induced gastric ulcer in rats: Possible involvement of mitochondrial dynamics signaling pathway

“…The results of the present study revealed that LXA 4 significantly improved mitochondrial functions via restoration of complex‐I activity with subsequent suppression of ROS production and hence improved the mitochondrial ΔΨm collapse. The exact mechanism by which LXA 4 improved mitochondrial complex‐I activity is not well clear, but it might be due to improvement of the mitochondrial dynamics, as proved in these results. It was noticed, in these results, that Omez significantly suppress mitochondrial ROS production with subsequent elevation of mitochondrial ΔΨm and inhibition of apoptosis and oxidative stress of gastric mucosa.…”

Repeated hypoglycemia blunts the responsiveness of glucose-inhibited GHRH neurons by remodeling neural inputs and disrupting mitochondrial structure and function

“…To address whether maintaining mitochondrial structure could preserve sensitivity to low glucose in cells treated with multiple episodes of low glucose, we used the small molecule DRP1 inhibitor, mitochondrial division inhibitor-1 (mdivi-1). Mdivi-1 inhibits mitochondrial fission in a diverse range of mammalian cells (28). Mdivi-1 maintained mitochondrial length ( Fig 10A) and preserved low glucose induced depolarization in N38 cells treated with repeated glucose deprivation ( Fig 10B).…”