Cell growth and survival depend on a delicate balance between energy production and synthesis of metabolites. Here, we provide evidence that an alternative mitochondrial complex II (CII) assembly, designated as CIIlow, serves as a checkpoint for metabolite biosynthesis under bioenergetic stress, with cells suppressing their energy utilization by modulating DNA synthesis and cell cycle progression. Depletion of CIIlow leads to an imbalance in energy utilization and metabolite synthesis, as evidenced by recovery of the de novo pyrimidine pathway and unlocking cell cycle arrest from the S-phase. In vitro experiments are further corroborated by analysis of paraganglioma tissues from patients with sporadic, SDHA and SDHB mutations. These findings suggest that CIIlow is a core complex inside mitochondria that provides homeostatic control of cellular metabolism depending on the availability of energy.

• MeSH
• biosyntetické dráhy fyziologie   MeSH
• energetický metabolismus fyziologie   MeSH
• fyziologický stres * MeSH
• genový knockout MeSH
• HEK293 buňky MeSH
• kontrolní body fáze S buněčného cyklu fyziologie   MeSH
• lidé MeSH
• malá interferující RNA metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• mutace MeSH
• myši inbrední BALB C MeSH
• myši nahé MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• paragangliom genetika   patologie   MeSH
• respirační komplex II genetika   metabolismus   MeSH
• sukcinátdehydrogenasa genetika   metabolismus   MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• malá interferující RNA MeSH
• respirační komplex II MeSH
• respiratory complex II MeSH Prohlížeč
• SDHA protein, human MeSH Prohlížeč
• SDHB protein, human MeSH Prohlížeč
• sukcinátdehydrogenasa MeSH

Lipophilic bisphosphonium salts are among the most promising antiprotozoal leads currently under investigation. As part of their preclinical evaluation we here report on their mode of action against African trypanosomes, the etiological agents of sleeping sickness. The bisphosphonium compounds CD38 and AHI-9 exhibited rapid inhibition of Trypanosoma brucei growth, apparently the result of cell cycle arrest that blocked the replication of mitochondrial DNA, contained in the kinetoplast, thereby preventing the initiation of S-phase. Incubation with either compound led to a rapid reduction in mitochondrial membrane potential, and ATP levels decreased by approximately 50% within 1 h. Between 4 and 8 h, cellular calcium levels increased, consistent with release from the depolarized mitochondria. Within the mitochondria, the Succinate Dehydrogenase complex (SDH) was investigated as a target for bisphosphonium salts, but while its subunit 1 (SDH1) was present at low levels in the bloodstream form trypanosomes, the assembled complex was hardly detectable. RNAi knockdown of the SDH1 subunit produced no growth phenotype, either in bloodstream or in the procyclic (insect) forms and we conclude that in trypanosomes SDH is not the target for bisphosphonium salts. Instead, the compounds inhibited ATP production in intact mitochondria, as well as the purified F1 ATPase, to a level that was similar to 1 mM azide. Co-incubation with azide and bisphosphonium compounds did not inhibit ATPase activity more than either product alone. The results show that, in T. brucei, bisphosphonium compounds do not principally act on succinate dehydrogenase but on the mitochondrial FoF1 ATPase.

• Klíčová slova
• FoF1 ATPase, Mitochondrion, Phosphonium salt, SDH complex, Succinate dehydrogenase, Trypanosoma brucei,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• azidy farmakologie   MeSH
• buněčné linie MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondrie účinky léků   genetika   metabolismus   MeSH
• organofosforové sloučeniny chemie   farmakologie   MeSH
• protonové ATPasy metabolismus   MeSH
• RNA interference MeSH
• sukcinátdehydrogenasa metabolismus   MeSH
• trypanocidální látky farmakologie   MeSH
• Trypanosoma brucei brucei cytologie   účinky léků   růst a vývoj   MeSH
• trypanozomóza africká parazitologie   MeSH
• vápník metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfát MeSH
• azidy MeSH
• mitochondriální DNA MeSH
• organofosforové sloučeniny MeSH
• protonové ATPasy MeSH
• sukcinátdehydrogenasa MeSH
• trypanocidální látky MeSH
• vápník MeSH