Mitochondrial modulation is involved in the hepatoprotection of Limonium sinense extract against liver damage in mice

AIM OF THE STUDY

Limonium sinense (Girard) Ktze is a Chinese folk medicine used to treat fever, hemorrhage, hepatitis, and other disorders. The present research focused on the protective effects of L. sinense extracts (LSE) against liver damage.

MATERIALS AND METHODS

In this study the extract from the root of Limonium sinense was used. Aminotransferase activity detection, electron microscopy, mitochondrial function evaluation, RT-PCR and western blot were used to evaluate the hepatoprotection of LSE in LPS/d-GalN-intoxicated mice.

RESULTS

Pretreatment with 100, 200 or 400mg/kg LSE significantly blocked the increase in both serum aspartate aminotransferase (sAST) and serum alanine aminotransferase (sALT) levels induced by treatment with LPS plus d-GalN (LPS/d-GalN). Ultrastructural observation by electron microscopy showed reduced hepatocyte nuclear condensation and less lipid deposition. The decrease in both the mitochondrial membrane potential (14.6%) and sensitivity to mitochondrial swelling induced by Ca(2+) (45.9%) observed in the liver of LPS/d-GalN-treated mice were prevented by pretreatment with LSE. In addition, different doses of LSE increased both the transcription and the translation of voltage-dependent anion channels (VDAC), which was down-regulated by LPS/d-GalN treatment.

CONCLUSIONS

In summary, LSE protects livers against LPS/d-GalN-induced damage, possibly by mitochondrial mechanisms related to increased expression of VDAC.

Different effects of maternal parity, cold exposure and nutrient restriction in late pregnancy on the abundance of mitochondrial proteins in the kidney, liver and lung of postnatal sheep

Adaptation to the extrauterine environment at birth relies upon the onset of postnatal function and increased metabolism in the lungs, liver and kidney, mediated partly by activation of mitochondrial proteins such as the voltage-dependent anion channel (VDAC), cytochrome c and, in the lung only, uncoupling protein (UCP)2. The magnitude of adaptation is dependent on the maternal metabolic and endocrine environment. We, therefore, examined the influence of maternal cold exposure (MCE) induced by winter shearing of pregnant sheep in conjunction with nutrient restriction (NR; 50% reduction in maternal food intake from 110 days gestation up to term). The effect of parity was also examined, as the offspring of nulliparous mothers are growth restricted compared with multiparous offspring. All sheep were twin bearing. One twin was sampled after birth and its sibling at 30 days. In the lung, both MCE and maternal nulliparity enhanced UCP2 abundance. However, whilst VDAC abundance was decreased in both the offspring of nulliparous mothers and by NR, it was transiently raised by MCE. Kidney VDAC abundance was reduced by MCE and nulliparity, adaptations only influenced by NR in multiparous mothers. Cytochrome c abundance was raised by MCE and by NR in multiparous controls and raised in offspring of nulliparous mothers. Liver VDAC and cytochrome c abundance were transiently reduced by MCE and persistently lower in offspring of nulliparous mothers. In conclusion, changes in the maternal metabolic environment have marked tissue-specific effects on mitochondrial protein abundance in the lungs, liver and kidney that may be important in enabling the newborn to effectively adapt to the extrauterine environment.

A targeted proteomic approach for the analysis of rat liver mitochondrial outer membrane proteins with extensive sequence coverage

Membrane proteins play an important role in cellular function. However, their analysis by mass spectrometry often is hindered by their hydrophobicity and/or low abundance. In this article, we present a method for the mass spectrometric analysis of membrane proteins based on the isolation of the resident membranes, isolation of the proteins by gel electrophoresis, and electroelution followed by enzymatic digestion by both trypsin and proteinase K. With this method, we have achieved 82-99% sequence coverage for the membrane proteins carnitine palmitoyltransferase-I (CPT-I), long-chain acyl-CoA synthetase (LCAS), and voltage-dependent anion channel (VDAC), isolated from rat liver mitochondrial outer membranes, including the transmembrane domains of these integral membrane proteins. This high sequence coverage allowed the identification of the isoforms of the proteins under study. This methodology provides a targeted approach for examining membrane proteins in detail.

Tissue-specific effects of leptin administration on the abundance of mitochondrial proteins during neonatal development

Many tissues undergo a rapid transition after birth, accompanied by dramatic changes in mitochondrial protein function. In particular, uncoupling protein (UCP) abundance increases at birth in the lung and adipose tissue, to then gradually decline, an adaptation that is important in enabling normal tissue function. Leptin potentially mediates some of these changes and is known to promote the loss of UCP1 from brown fat but its effects on UCP2 and related mitochondrial proteins (i.e. voltage-dependent anion channel (VDAC) and cytochrome c) in other tissues are unknown. We therefore determined the effects of once-daily jugular venous administration of ovine recombinant leptin on mitochondrial protein abundance as determined by immunoblotting in tissues that do (i.e. the brain and pancreas) and do not (i.e. liver and skeletal muscle) express UCP2. Eight pairs of 1-day-old lambs received either 100 mug leptin or vehicle daily for 6 days, before tissue sampling on day 7. Administration of leptin diminished UCP2 abundance in the pancreas, but not the brain. Leptin administration had no affect on the abundance of VDAC or cytochrome c in any tissue examined. In leptin-administered animals, but not controls, UCP2 abundance in the pancreas was positively correlated with VDAC and cytochrome c content, and UCP2 abundance in the brain with colonic temperature. In conclusion, leptin administration to neonatal lambs causes a tissue-specific loss of UCP2 from the pancreas. These effects may be important in the regulation of neonatal tissue development and potentially for optimising metabolic control mechanisms in later life.