The mitochondrial contact site and cristae organization system (MICOS) is a multiprotein complex responsible for cristae formation. Even though cristae are found in all mitochondria capable of oxidative phosphorylation, only Mic10 and Mic60 appear to be conserved throughout eukaryotes. The remaining 4 or 5 known MICOS subunits are specific to the supergroup Opisthokonta, which includes yeast and mammals that are the only organisms in which this complex has been analyzed experimentally. We have isolated the MICOS from Trypanosoma brucei, a member of the supergroup Excavata that is profoundly diverged from opisthokonts. We show that it is required for the maintenance of the unique discoidal cristae that typify excavates, such as euglenids and kinetoplastids, the latter of which include trypanosomes. The trypanosome MICOS consists of 9 subunits, most of which are essential for normal growth. Unlike in opisthokonts, it contains two distinct Mic10 orthologs and an unconventional putative Mic60 that lacks a mitofilin domain. Interestingly, one of the essential trypanosomatid-specific MICOS subunits called TbMic20 is a thioredoxin-like protein that appears to be involved in import of intermembrane space proteins, including respiratory chain complex assembly factors. This result points to trypanosome MICOS coordinating cristae shaping and population of its membrane with proteins involved in respiration, the latter via the catalytic activity of TbMic20. Thus, trypanosome MICOS allows us to define which of its features are conserved in all eukaryotes and decipher those that represent lineage-specific adaptations.
In this study, we report for the first time concurrent measurements of membrane potential and dynamics and respiratory chain activities in rat heart mitochondria, as well as calcium transients in the hearts of rats in an early phase of streptozotocin diabetes, not yet accompanied with diabetes-induced complications. Quantitative relationships among these variables were assessed. The mitochondria from diabetic rats exhibited decreased fluorescence anisotropy values of diphenylhexatriene. This indicates that hydrophobic core of the membranes was more fluid compared with controls (p<0.05). We discuss the changes in fluidity as having been associated with augmented energy transduction through the diabetic membranes. Reduced ratio of JC-1 fluorescence (aggregates to monomers) in the mitochondria from diabetic hearts reflected descendent transmembrane potential. A significant negative association between membrane fluidity and potential in the diabetic group was found (p<0.05; r=0.67). Further, we observed an increase in calcium transient amplitude (CTA) in the diabetic cardiomyocytes (p=0.048). We conclude that some of the calcium-induced regulatory events that dictate fuel selection and capacity for ATP production in diabetic heart occur at the membrane level. Our findings offer new insight into acute diabetes-induced changes in cardiac mitochondria.
- MeSH
- experimentální diabetes mellitus metabolismus patofyziologie MeSH
- financování organizované MeSH
- fluidita membrány MeSH
- kardiomyocyty metabolismus MeSH
- krysa rodu rattus MeSH
- kultivované buňky MeSH
- membránový potenciál mitochondrií MeSH
- mitochondriální membrány fyziologie MeSH
- myokard metabolismus MeSH
- oxidativní fosforylace MeSH
- potkani Wistar MeSH
- spotřeba kyslíku MeSH
- srdce patofyziologie MeSH
- srdeční komory cytologie MeSH
- srdeční mitochondrie fyziologie MeSH
- vápník fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
Undecanesulfonate is transported by uncoupling protein-1. Its inability to induce H+ uniport with reconstituted uncoupling protein-1 supports fatty acid cycling hypothesis. Rial et al. [Rial, E., Aguirregoitia, E., Jimenez-Jimenez, J., & Ledesma, A. (2004). Alkylsulfonates activate the uncoupling protein UCP1: Implications for the transport mechanism. Biochimica et Biophysica Acta, 1608, 122-130], have challenged the fatty acid cycling by observing uncoupling of brown adipose tissue mitochondria due to undecanesulfonate, interpreted as allosteric activation of uncoupling protein-1. We have estimated undecanesulfonate effects after elimination of endogenous fatty acids by carnitine cycle in the presence or absence of bovine serum albumin. We show that the undecanesulfonate effect is partly due to fatty acid release from albumin when undecanesulfonate releases bound fatty acid and partly represents a non-specific uncoupling protein-independent acceleration of respiration, since it proceeds also in rat heart mitochondria lacking uncoupling protein-1 and membrane potential is not decreased upon addition of undecanesulfonate without albumin. When the net fatty acid-induced uncoupling was assayed, the addition of undecanesulfonate even slightly inhibited the uncoupled respiration. We conclude that undecanesulfonate does not allosterically activate uncoupling protein-1 and that fatty acid cycling cannot be excluded on a basis of its non-specific effects.
- MeSH
- alkylsulfonany farmakologie metabolismus MeSH
- biologické modely MeSH
- biologický transport účinky léků MeSH
- hnědá tuková tkáň metabolismus účinky léků MeSH
- iontové kanály MeSH
- iontový transport účinky léků MeSH
- křečci praví MeSH
- krysa rodu rattus MeSH
- mastné kyseliny metabolismus MeSH
- membránové potenciály účinky léků MeSH
- membránové proteiny metabolismus MeSH
- mitochondriální membrány fyziologie účinky léků MeSH
- mitochondriální proteiny MeSH
- mitochondrie metabolismus účinky léků MeSH
- protony MeSH
- sérový albumin hovězí farmakologie MeSH
- spotřeba kyslíku účinky léků MeSH
- srdeční mitochondrie metabolismus účinky léků MeSH
- transportní proteiny metabolismus MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
The interaction between retinoids and transforming growth factor-beta1 (TGF-beta1) leading to regulation of proliferation, differentiation and apoptosis is not still fully understood. In this study, we demonstrated that a combination treatment with all-trans retinoic acid (ATRA) and TGF-beta1 led to the enhancement of ATRA-induced suppression of cell proliferation, which is accompanied by inhibition of ATRA-induced apoptosis in human leukemia HL-60 cells. This effect was preceded by the arrest of cells in G0/G1 cell cycle phase linked with pRb protein dephosphorylation, continuous accumulation of p21 and transiently increased level of p27, inhibitors of cyclin-dependent kinases. Inhibition of ATRA-induced apoptosis by TGF-beta1 was associated with an increased level of Mcl-1 protein, an anti-apoptotic member of Bcl-2 family, but not with inhibition of mitochondrial membrane depolarization. Levels of other Bcl-2 family proteins (Bcl-2, Bcl-X(L), Bad, Bak, Bax) were unaffected by simultaneous ATRA and TGF-beta1 treatment, when compared to ATRA alone. Upregulation of c-FLIP(L) protein, an inhibitor of apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), correspond with inhibition of ATRA-induced (autocrine TRAIL-mediated) caspase-8 activation and apoptosis. These results suggest that apoptosis inhibition associated with proliferation block could depend on modulation of the TRAIL apoptotic pathway and regulation of the Mcl-1 protein level. In summary, we demonstrate that the balance of processes leading to regulation of proliferation and differentiation of myeloid cells can modulate cell sensitivity to apoptosis-inducing stimuli.
- MeSH
- aktivace enzymů účinky záření MeSH
- antigeny CD11b fyziologie účinky léků MeSH
- buněčná diferenciace účinky léků MeSH
- buněčný cyklus účinky léků MeSH
- FLIP (buněčný) MeSH
- fosforylace MeSH
- G0 fáze účinky léků MeSH
- G1 fáze účinky léků MeSH
- granulocyty fyziologie účinky léků MeSH
- HL-60 buňky MeSH
- inhibitor p21 cyklin-dependentní kinasy biosyntéza účinky léků MeSH
- intracelulární signální peptidy a proteiny farmakologie metabolismus MeSH
- kaspasa 3 MeSH
- kaspasa 8 MeSH
- kaspasy metabolismus účinky léků MeSH
- lidé MeSH
- membránové glykoproteiny farmakologie metabolismus MeSH
- mitochondriální membrány fyziologie účinky léků MeSH
- nádorové buňky kultivované MeSH
- nádorové proteiny metabolismus účinky léků MeSH
- proliferace buněk účinky léků MeSH
- protein TRAIL MeSH
- protein X asociovaný s bcl-2 metabolismus účinky léků MeSH
- proteiny regulující apoptózu farmakologie metabolismus MeSH
- protoonkogenní proteiny c-bcl-2 metabolismus účinky léků MeSH
- reaktivní formy kyslíku metabolismus MeSH
- retinoblastomový protein metabolismus účinky léků MeSH
- synergismus léků MeSH
- TNF-alfa farmakologie metabolismus MeSH
- transformující růstový faktor beta farmakologie MeSH
- transformující růstový faktor beta1 MeSH
- tretinoin antagonisté a inhibitory farmakologie MeSH
- viabilita buněk účinky léků MeSH
- Check Tag
- lidé MeSH
- MeSH
- apoptóza imunologie účinky léků MeSH
- cytochromy c farmakologie fyziologie účinky léků MeSH
- kaspasy farmakologie fyziologie MeSH
- klinické zkoušky jako téma MeSH
- laktalbumin farmakologie imunologie terapeutické užití MeSH
- lékařská onkologie dějiny metody trendy MeSH
- lidé MeSH
- mateřské mléko imunologie MeSH
- mitochondriální membrány fyziologie imunologie MeSH
- molekulární biologie metody trendy MeSH
- nenasycené mastné kyseliny izolace a purifikace metabolismus MeSH
- papilom farmakoterapie MeSH
- permeabilita buněčné membrány fyziologie účinky léků MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Švédsko MeSH
