Vesicular transport mediates the uptake of cytoplasmic proteins into mitochondria in Drosophila melanogaster

Abstract

Mitochondrial aging, which results in mitochondrial dysfunction, is strongly linked to many age-related diseases. Aging is associated with mitochondrial enlargement and transport of cytosolic proteins into mitochondria. The underlying homeostatic mechanisms that regulate mitochondrial morphology and function, and their breakdown during aging, remain unclear. Here, we identify a mitochondrial protein trafficking pathway in Drosophila melanogaster involving the mitochondria-associated protein Dosmit. Dosmit induces mitochondrial enlargement and the formation of double-membraned vesicles containing cytosolic protein within mitochondria. The rate of vesicle formation increases with age. Vesicles originate from the outer mitochondrial membrane as observed by tracking Tom20 localization, and the process is mediated by the mitochondria-associated Rab32 protein. Dosmit expression level is closely linked to the rate of ubiquitinated protein aggregation, which are themselves associated with age-related diseases. The mitochondrial protein trafficking route mediated by Dosmit offers a promising target for future age-related mitochondrial disease therapies.

SNARE-dependent mitochondria-lysosome contacts regulate glial mitochondrial dynamics and dopaminergic neuron survival

“…These results indicate that Drp1 and Marf are epistatically downstream of glial VAMP7 in controlling mitochondrial fission and fusion. Interestingly, endogenous protein levels of Fission, mitochondrial 1 (Fis1), Drp1, Marf, and Optic astrophy 1 (Opa1) were not affected by the absence of glial VAMP7, suggesting that VAMP7 does not regulate glial mitochondrial dynamics via tuning fission/fusion proteins levels (29) (Figures S2A-S2H). These results suggest that glial VAMP7 acts upstream of these mitochondrial factors in regulating mitochondrial fission/fusion; mitochondrial elongation caused by the lack of glial VAMP7 is potentially due to a change in the dynamic or balance of fission and fusion.…”

UQCRC1 engages cytochrome c for neuronal apoptotic cell death

“…Adult fly tissues, indirect flight muscles, and larval imaginal discs were dissected, fixed, immunostained, mounted and imaged following Lien et al (2020) and Chen et al (2020) with minor modifications for incubation and wash times. SH-SY5Y cells were fixed, immunostained, mounted and imaged following Tzou et al (2021).…”

“…The protein levels were measured by Bradford assay per manufacturer's instructions (Bio-Rad). Transmission electron microscopy of mitochondria in fly tissues TEM images of mitochondria in L2 ventral ganglion and indirect flight muscle were performed according to Chen et al (2020). Briefly, each L2 larva or fly thorax was dissected in 0.1 M cacodylate buffer and fixed in 1% glutaraldehyde and 4% paraformaldehyde in 0.1 M cacodylate buffer overnight at 4 C. After washing with 0.1 M cacodylate buffer, the samples were treated with 1% OsO4 for 1 h at 4 C. After washing with ddH2O, samples were dehydrated in a gradient series using 30%, 50%, 70%, 95%, and 100% ethanol solutions at RT.…”

“…Mitochondria extraction in each experiment was isolated from the thorax of 20 flies using the Mitochondria Isolation Kit for Tissue (ThermoFisher, USA), according to the manufacturer's protocol. While the fraction contains mitochondria, it may also potentially contain ER and other membranes (Chen et al, 2020).…”

Visualizing, quantifying, and manipulating mitochondrial DNA in vivo

“…It remains possible that mtDNA is metabolized to some extent within mitochondria, in the absence of mitophagy or preceding it. Mitochondria can contain lysosome-like organelles ( 139 ) and vesicles containing cytosolic components ( 140 ). Whether these intramitochondrial organelles or other factors within mitochondria play roles in mtDNA metabolism remains to be resolved.…”