Mitochondrial translocation and interaction of cofilin and Drp1 are required for erucin-induced mitochondrial fission and apoptosis

Abstract

Cofilin is a member of the actin-depolymerizing factor (ADF) family protein, which plays an essential role in regulation of the mitochondrial apoptosis. It remains unclear how cofilin regulates the mitochondrial apoptosis. Here, we report for the first time that natural compound 4-methylthiobutyl isothiocyanate (erucin) found in consumable cruciferous vegetables induces mitochondrial fission and apoptosis in human breast cancer cells through the mitochondrial translocation of cofilin. Importantly, cofilin regulates erucin-induced mitochondrial fission by interacting with dynamin-related protein (Drp1). Knockdown of cofilin or Drp1 markedly reduced erucin-mediated mitochondrial translocation and interaction of cofilin and Drp1, mitochondrial fission, and apoptosis. Only dephosphorylated cofilin (Ser 3) and Drp1 (Ser 637) are translocated to the mitochondria. Cofilin S3E and Drp1 S637D mutants, which mimick the phosphorylated forms, suppressed mitochondrial translocation, fission, and apoptosis. Moreover, both dephosphorylation and mitochondrial translocation of cofilin and Drp1 are dependent on ROCK1 activation. In vivo findings confirmed that erucin-mediated inhibition of tumor growth in a breast cancer cell xenograft mouse model is associated with the mitochondrial translocation of cofilin and Drp1, fission and apoptosis. Our study reveals a novel role of cofilin in regulation of mitochondrial fission and suggests erucin as a potential drug for treatment of breast cancer.

Mitochondrial Fission Inhibitors Suppress Endothelin-1-Induced Artery Constriction

“…Recent works found that mitochondrial translocation of Drp1 were dependent on ROCK activation [39], and ROCK mediated mitochondrial fission by promoting dynamin-related protein-1 (Drp1) recruitment to the mitochondria [14]. These findings suggest that ROCK inhibitor Y-27632 should be a type of mitochondrial fission inhibitor.…”

ROCK1/Drp1-mediated aberrant mitochondrial fission is crucial for dopaminergic nerve cell apoptosis

“…5a). ROCK1 activation is reportedly involved in the regulation of mitochondrial translocation of Drp1 and mitochondrial fission through its dephosphorylation at Ser 637 in human breast cancer cells 19 . As shown in Fig.…”

“…Once Drp1 is activated, it translocates from the cytosol to the outer mitochondrial membrane and forms a ring structure around the mitochondria, resulting in fission of mitochondria followed by Cyto C release and caspase activation, eventually leading to apoptosis 38 . Additionally, dephosphorylation/activation of Drp1 at Ser 637 in human has been showed to promote its translocation from the cytosol to mitochondria and mitochondrial fission 19,29,39,40 . Consistent with these reports, our data revealed that dephosphorylated Drp1 at Ser 656/600 (rat/mouse) (corresponding to Ser 637 in human Drp1 isoform 1) increased mitochondrial translocation of Drp1 and leads to mitochondrial fission and nerve cell apoptosis in both in vitro and in vivo models of PD.…”

“…ROCK1 is highly expressed in a variety of cancer tissues 42 , and plays an important role in the regulation of apoptosis in various types of cancer cells 43 . In human breast cancer cells, Drp1 has been reported to be an important ROCK1 substrate, and the dephosphorylation of Drp1 induced by ROCK1 stimulates its mitochondrial fission activity 19 . Moreover, the specific ROCK1 activation inhibitor Y-27632 has also been reported to be able to inhibit dopaminergic nerve cell death in the PD substantia nigra 21 .…”

“…In the field of cancer research, ROCK1 has been reported to be cleaved into activated ROCK1 with a molecular weight of 130 kDa through proteolytic cleavage of its C-terminal auto-inhibitory domain, which eventually leads to apoptosis 18 . Importantly, activated ROCK1 has been found to play an important role in regulating mitochondrial fission via dephosphorylation/activation of Drp1 in human breast cancer cells 19 . Additionally, there are also reports in the central nervous system that the specific ROCK1 activation inhibitor Y-27632 decreases dopaminergic nerve cell death in mice and primary neuron-glia cultures 20,21 , but the mechanisms remain elusive.…”