Dynamin superfamily proteins mediate mitochondrial fusion in fungi and animals. A new study expands the taxonomic reach of this superfamily and provides insights into the roles these proteins play by investigating MfnL, a family member involved in trypanosomal mitochondrial dynamics. Importantly, MfnL occurs widely in eukaryotes and prokaryotes.

• MeSH
• dynaminy * metabolismus   genetika   MeSH
• mitochondriální dynamika * fyziologie   MeSH
• mitochondriální proteiny metabolismus   genetika   MeSH
• mitochondrie metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dynaminy * MeSH
• mitochondriální proteiny MeSH

Specific patterns of mitochondrial dynamics have been repeatedly reported to promote drug resistance in cancer. However, whether targeting mitochondrial fission- and fusion-related proteins could be leveraged to combat multidrug-resistant pediatric sarcomas is poorly understood. Here, we demonstrated that the expression and activation of the mitochondrial fission mediator DRP1 are affected by chemotherapy exposure in common pediatric sarcomas, namely, rhabdomyosarcoma and osteosarcoma. Unexpectedly, decreasing DRP1 activity through stable DRP1 knockdown neither attenuated sarcoma drug resistance nor affected growth rate or mitochondrial network morphology. The minimal impact on sarcoma cell physiology, along with the up-regulation of fission adaptor proteins (MFF and FIS1) detected in rhabdomyosarcoma cells, suggests an alternative DRP1-independent mitochondrial fission mechanism that may efficiently compensate for the lack of DRP1 activity. By exploring the upstream mitophagy and mitochondrial fission regulator, AMPKα1, we found that markedly reduced AMPKα1 levels are sufficient to maintain AMPK signaling capacity without affecting chemosensitivity. Collectively, our findings challenge the direct involvement of DRP1 in pediatric sarcoma drug resistance and highlight the complexity of yet-to-be-characterized noncanonical regulators of mitochondrial dynamics.

• MeSH
• chemorezistence * genetika   MeSH
• dynaminy * metabolismus   genetika   MeSH
• GTP-fosfohydrolasy metabolismus   genetika   MeSH
• lidé MeSH
• membránové proteiny metabolismus   genetika   MeSH
• mitochondriální dynamika * účinky léků   MeSH
• mitochondriální proteiny * metabolismus   genetika   MeSH
• mitochondrie * metabolismus   účinky léků   MeSH
• mitofagie účinky léků   genetika   MeSH
• nádorové buněčné linie MeSH
• osteosarkom metabolismus   patologie   farmakoterapie   genetika   MeSH
• proteiny asociované s mikrotubuly metabolismus   genetika   MeSH
• protinádorové látky farmakologie   MeSH
• rhabdomyosarkom metabolismus   genetika   patologie   MeSH
• sarkom * metabolismus   genetika   farmakoterapie   patologie   MeSH
• signální transdukce účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNM1L protein, human MeSH Prohlížeč
• dynaminy * MeSH
• FIS1 protein, human MeSH Prohlížeč
• GTP-fosfohydrolasy MeSH
• membránové proteiny MeSH
• Mff protein, human MeSH Prohlížeč
• mitochondriální proteiny * MeSH
• proteiny asociované s mikrotubuly MeSH
• protinádorové látky MeSH

The 3-mercaptopyruvate sulfurtransferase (MPST) is a protein persulfidase, occurring mainly in mitochondria. Although function of this protein in cancer cells has been already studied, no clear outcome can be postulated up to now. Therefore, we focused on the determination of function of MPST in colon (HCT116 cells)/colorectal (DLD1 cells) cancers. In silico analysis revealed that in gastrointestinal cancers, MPST together with its binding partners can be either of a high risk or might have a protective effect. Silencing of MPST gene resulted in decreased ATP, while acetyl-CoA levels were elevated. Increased apoptosis was detected in cells with silenced MPST gene, which was accompanied by decrease in mitochondrial membrane potential, but no changes in IP3 receptor's protein. Mitochondria underwent activation of fission and elevated DRP1 expression after MPST silencing. Proliferation and migration of DLD1 and HCT116 cells were markedly affected, showing the importance of MPST protein in colon/colorectal cancer development.

• Klíčová slova
• 3- mercaptopyruvate sulfurtransferase, Colon/colorectal cancer, Fission, Mitochondria,
• MeSH
• apoptóza MeSH
• dynaminy metabolismus   genetika   MeSH
• HCT116 buňky MeSH
• kolorektální nádory * metabolismus   patologie   enzymologie   genetika   MeSH
• lidé MeSH
• membránový potenciál mitochondrií MeSH
• mitochondrie metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádory tračníku metabolismus   patologie   genetika   enzymologie   MeSH
• pohyb buněk MeSH
• proliferace buněk MeSH
• sulfurtransferasy * metabolismus   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 3-mercaptopyruvate sulphurtransferase MeSH Prohlížeč
• DNM1L protein, human MeSH Prohlížeč
• dynaminy MeSH
• sulfurtransferasy * MeSH

The diverse GTPases of the dynamin superfamily play various roles in the cell, as exemplified by the dynamin-related proteins (DRPs) Mgm1 and Opa1, which remodel the mitochondrial inner membrane in fungi and metazoans, respectively. Via an exhaustive search of genomic and metagenomic databases, we found previously unknown DRP types occurring in diverse eukaryotes and giant viruses (phylum Nucleocytoviricota). One novel DRP clade, termed MidX, combined hitherto uncharacterized proteins from giant viruses and six distantly related eukaryote taxa (Stramenopiles, Telonemia, Picozoa, Amoebozoa, Apusomonadida, and Choanoflagellata). MidX stood out because it was not only predicted to be mitochondria-targeted but also to assume a tertiary structure not observed in other DRPs before. To understand how MidX affects mitochondria, we exogenously expressed MidX from Hyperionvirus in the kinetoplastid Trypanosoma brucei, which lacks Mgm1 or Opa1 orthologs. MidX massively affected mitochondrial morphology from inside the matrix, where it closely associates with the inner membrane. This unprecedented mode of action contrasts to those of Mgm1 and Opa1, which mediate inner membrane remodeling in the intermembrane space. We speculate that MidX was acquired in Nucleocytoviricota evolution by horizontal gene transfer from eukaryotes and is used by giant viruses to remodel host mitochondria during infection. MidX's unique structure may be an adaptation for reshaping mitochondria from the inside. Finally, Mgm1 forms a sister group to MidX and not Opa1 in our phylogenetic analysis, throwing into question the long-presumed homology of these DRPs with similar roles in sister lineages.

• Klíčová slova
• Nucleocytoviricota, Mgm1, Opa1, dynamin superfamily, mitochondria, protists,
• MeSH
• dynaminy genetika   metabolismus   MeSH
• fylogeneze MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondrie genetika   metabolismus   MeSH
• obří viry * genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dynaminy MeSH
• mitochondriální proteiny MeSH

SH3P2 (At4g34660), an Arabidopsis thaliana SH3 and Bin/amphiphysin/Rvs (BAR) domain-containing protein, was reported to have a specific role in cell plate assembly, unlike its paralogs SH3P1 (At1g31440) and SH3P3 (At4g18060). SH3P family members were also predicted to interact with formins-evolutionarily conserved actin nucleators that participate in microtubule organization and in membrane-cytoskeleton interactions. To trace the origin of functional specialization of plant SH3Ps, we performed phylogenetic analysis of SH3P sequences from selected plant lineages. SH3Ps are present in charophytes, liverworts, mosses, lycophytes, gymnosperms, and angiosperms, but not in volvocal algae, suggesting association of these proteins with phragmoplast-, but not phycoplast-based cell division. Separation of three SH3P clades, represented by SH3P1, SH3P2, and SH3P3 of A. thaliana, appears to be a seed plant synapomorphy. In the yeast two hybrid system, Arabidopsis SH3P3, but not SH3P2, binds the FH1 and FH2 domains of the formin FH5 (At5g54650), known to participate in cytokinesis, while an opposite binding specificity was found for the dynamin homolog DRP1A (At5g42080), confirming earlier findings. This suggests that the cytokinetic role of SH3P2 is not due to its interaction with FH5. Possible determinants of interaction specificity of SH3P2 and SH3P3 were identified bioinformatically.

• Klíčová slova
• cell plate, cytokinesis, evolution, formin, interaction specificity, phylogeny,
• MeSH
• Arabidopsis MeSH
• cytokineze * MeSH
• dynaminy metabolismus   MeSH
• fylogeneze MeSH
• molekulární evoluce * MeSH
• proteiny huseníčku klasifikace   genetika   metabolismus   MeSH
• transportní proteiny klasifikace   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dynaminy MeSH
• proteiny huseníčku MeSH
• SH3P2 protein, Arabidopsis MeSH Prohlížeč
• transportní proteiny MeSH

Dynamins and dynamin-like proteins (DLPs) belong to a family of large GTPases involved in membrane remodelling events. These include both fusion and fission processes with different dynamin proteins often having a specialised function within the same organism. Trypanosoma brucei is thought to have only one multifunctional DLP (TbDLP). While this was initially reported to function in mitochondrial division only, an additional role in endocytosis and cytokinesis was later also proposed. Since there are two copies of TbDLP present in the trypanosome genome, we investigated potential functional differences between these two paralogs by re-expressing either protein in a TbDLP RNAi background. These paralogs, called TbDLP1 and TbDLP2, are almost identical bar a few amino acid substitutions. Our results, based on cell lines carrying tagged and RNAi-resistant versions of each protein, show that overexpression of TbDLP1 alone is able to rescue the observed endocytosis and growth defects in the mammalian bloodstream form (BSF) of the parasite. While TbDLP2 shows no rescue in our experiments in BSF, this might also be due to lower expression levels of the protein in this life stage. In contrast, both TbDLP proteins apparently play more complementary roles in the insect procyclic form (PCF) since neither TbDLP1 nor TbDLP2 alone can fully restore wildtype growth and morphology in TbDLP-depleted parasites.

• MeSH
• buněčné linie MeSH
• dynaminy chemie   genetika   metabolismus   MeSH
• protozoální proteiny chemie   genetika   metabolismus   MeSH
• RNA interference MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• Trypanosoma brucei brucei metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dynaminy MeSH
• protozoální proteiny MeSH

BACKGROUND: Mitochondria of opisthokonts undergo permanent fission and fusion throughout the cell cycle. Here, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, in the anaerobic protist parasite Giardia intestinalis, a member of the Excavata supergroup of eukaryotes. The mitosomes have abandoned typical mitochondrial traits such as the mitochondrial genome and aerobic respiration and their single role known to date is the formation of iron-sulfur clusters. RESULTS: In live experiments, no fusion events were observed between the mitosomes in G. intestinalis. Moreover, the organelles were highly prone to becoming heterogeneous. This suggests that fusion is either much less frequent or even absent in mitosome dynamics. Unlike in mitochondria, division of the mitosomes was absolutely synchronized and limited to mitosis. The association of the nuclear and the mitosomal division persisted during the encystation of the parasite. During the segregation of the divided mitosomes, the subset of the organelles between two G. intestinalis nuclei had a prominent role. Surprisingly, the sole dynamin-related protein of the parasite seemed not to be involved in mitosomal division. However, throughout the cell cycle, mitosomes associated with the endoplasmic reticulum (ER), although none of the known ER-tethering complexes was present. Instead, the ER-mitosome interface was occupied by the lipid metabolism enzyme long-chain acyl-CoA synthetase 4. CONCLUSIONS: This study provides the first report on the dynamics of mitosomes. We show that together with the loss of metabolic complexity of mitochondria, mitosomes of G. intestinalis have uniquely streamlined their dynamics by harmonizing their division with mitosis. We propose that this might be a strategy of G. intestinalis to maintain a stable number of organelles during cell propagation. The lack of mitosomal fusion may also be related to the secondary reduction of the organelles. However, as there are currently no reports on mitochondrial fusion in the whole Excavata supergroup, it is possible that the absence of mitochondrial fusion is an ancestral trait common to all excavates.

• MeSH
• biologická evoluce MeSH
• dynaminy metabolismus   MeSH
• endoplazmatické retikulum metabolismus   MeSH
• Giardia lamblia cytologie   metabolismus   MeSH
• interfáze MeSH
• koenzym A-ligasy metabolismus   MeSH
• mastná kyselina s dlouhým řetězcem-CoA-ligasa MeSH
• mitochondriální dynamika * MeSH
• mitochondrie metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dynaminy MeSH
• koenzym A-ligasy MeSH
• mastná kyselina s dlouhým řetězcem-CoA-ligasa MeSH