Bidirectional Transport of Spermine Across the Inner Membrane of Liver Mitochondria

Toninello, Antonio; Siliprandi, D.; Castagnini, P.; Novello, Maria Cristina; Siliprandi, N.

doi:10.1007/978-1-4684-5637-0_43

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…Polyamine transport by mitochondria has been relatively little studied. Only for liver mitochondria has uptake been demonstrated directly (Toninello et al, 1985(Toninello et al, , 1988). The specificity of this uptake system was not extensively examined, but possibly involves co-transport of spermine (in the bivalent form) with phosphate.…”

Section: Mechanism Of the Activation Of Pdh Activity By Polyamines Wimentioning

confidence: 99%

Regulation of pyruvate dehydrogenase by insulin and polyamines within electropermeabilized fat-cells and isolated mitochondria

Rutter

Diggle

Denton

1992

Biochemical Journal

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1. Regulation of the mammalian pyruvate dehydrogenase (PDH) complex by insulin and polyamines has been examined by using electropermeabilized rat epididymal fat-cells and isolated mitochondria. The complex could be regulated within the permeabilized cells not only by insulin, but also by certain low-M(r) species, including Ca2+ and the polyamine spermidine. 2. Both spermine and spermidine increased the level of active dephosphorylated PDH (PDHa) in isolated adipose-tissue mitochondria 2-3-fold, with half-maximal effects at 0.9 mM and 1.7 mM respectively. By contrast, PDH activity in rat heart mitochondria was essentially insensitive to the effects of these polyamines. 3. The effects on PDH activity of incubation of adipose-tissue mitochondria with spermine persisted through re-isolation and re-incubation of the mitochondria in the absence of the polyamine. 4. No evidence was found of any increase in the concentration of spermine associated with purified mitochondrial fractions prepared from insulin-treated tissue. 5. Overall, the data provide further evidence against a role for polyamines in the rapid stimulation of PDH by insulin, but suggest that polyamines may be important in mediating longer-term changes in the activity of the complex.

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Section: Mechanism Of the Activation Of Pdh Activity By Polyamines Wimentioning

confidence: 99%

Regulation of pyruvate dehydrogenase by insulin and polyamines within electropermeabilized fat-cells and isolated mitochondria

Rutter

Diggle

Denton

1992

Biochemical Journal

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“…Many of these effects of spermine on mitochondrial integrity may be explained by the recent finding that spermine inhibits the permeability transition of isolated mitochondria [31]. Toninello et al [32,33] have presented evidence for the electrophoretic transport of spermine into energized rat liver mitochondria. Spermine has been shown to activate the mitochondrial ATP synthase [34] and the ADP/ATP translocator [35].…”

Section: Discussionmentioning

confidence: 99%

Activation of hepatic glutaminase by spermine

Kovačević

Day

Collett

et al. 1995

Biochemical Journal

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Glutaminase activity in intact mitochondria from rat liver is activated by spermine, as indicated both by increased glutamate production from glutamine and by increased respiration with glutamine as sole substrate. Glutaminase activity assayed in membranes from frozen-thawed mitochondria, is activated by spermine about 6-fold at physiological concentrations of its other effectors (NH4+ at 0.7 mM, Pi 5 mM) and at pH 7.4. Spermine decreased the apparent Km for glutamine from 38 to 15 mM at 5 mM Pi, and increased the sensitivity of the enzyme for phosphate activation so that the concentration required for 50% stimulation decreased from 15 to 4 mM. Half-maximal spermine effects occurred at 0.15 mM, which is in the physiological range. Spermine was effective in the presence of physiological concentrations of Mg2+. We suggest that spermine may be a physiological activator of hepatic glutaminase.

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Bidirectional fluxes of spermine across the mitochondrial membrane

et al. 2013

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The polyamine spermine is transported into the mitochondrial matrix by an electrophoretic mechanism having as driving force the negative electrical membrane potential (DW). The presence of phosphate increases spermine uptake by reducing DpH and enhancing DW. The transport system is a specific uniporter constituted by a protein channel exhibiting two asymmetric energy barriers with the spermine binding site located in the energy well between the two barriers. Although spermine transport is electrophoretic in origin, its accumulation does not follow the Nernst equation for the presence of an efflux pathway. Spermine efflux may be induced by different agents, such as FCCP, antimycin A and mersalyl, able to completely or partially reduce the DW value and, consequently, suppress or weaken the force necessary to maintain spermine in the matrix. However this efflux may also take place in normal conditions when the electrophoretic accumulation of the polycationic polyamine induces a sufficient drop in DW able to trigger the efflux pathway. The release of the polyamine is most probably electroneutral in origin and can take place in exchange with protons or in symport with phosphate anion. The activity of both the uptake and efflux pathways induces a continuous cycling of spermine across the mitochondrial membrane, the rate of which may be prominent in imposing the concentrations of spermine in the inner and outer compartment. Thus, this event has a significant role on mitochondrial permeability transition modulation and consequently on the triggering of intrinsic apoptosis.

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Bidirectional Transport of Spermine Across the Inner Membrane of Liver Mitochondria

Cited by 6 publications

References 15 publications

Regulation of pyruvate dehydrogenase by insulin and polyamines within electropermeabilized fat-cells and isolated mitochondria

Regulation of pyruvate dehydrogenase by insulin and polyamines within electropermeabilized fat-cells and isolated mitochondria

Activation of hepatic glutaminase by spermine

Bidirectional fluxes of spermine across the mitochondrial membrane

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