TRPV1 activation impedes foam cell formation by inducing autophagy in oxLDL-treated vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) are an important origin of foam cells besides macrophages. The mechanisms underlying VSMC foam cell formation are relatively little known. Activation of transient receptor potential vanilloid subfamily 1 (TRPV1) and autophagy have a potential role in regulating foam cell formation. Our study demonstrated that autophagy protected against foam cell formation in oxidized low-density lipoprotein (oxLDL)-treated VSMCs; activation of TRPV1 by capsaicin rescued the autophagy impaired by oxLDL and activated autophagy–lysosome pathway in VSMCs; activation of TRPV1 by capsaicin impeded foam cell formation of VSMCs through autophagy induction; activation of TRPV1 by capsaicin induced autophagy through AMP-activated protein kinase (AMPK) signaling pathway. This study provides evidence that autophagy plays an important role in VSMC foam cell formation and highlights TRPV1 as a promising therapeutic target in atherosclerosis.     

盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

Impaired substrate utilization in mitochondria from strain 129 dystrophic mice

Mitochondria from skeletal muscle, heart and liver of strain 129/ReJ-dy dystrophic mice and their littermate controls were characterized with respect to their respiratory and phosphorylating activities. Skeletal muscle mitochondria from dystrophic mice showed significantly lower state 3 respiratory rates than controls with both pyruvate + malate and succinate as substrates (P < 0.01). ADP/O and Ca²⁺/O ratios were found to be normal. A decreased rate of NADH oxidation (0.01 <P < 0.05) by sonicated mitochondrial suspensions from dystrophic mice was also seen. High respiratory rates with ascorbate + phenazine methosulfate as substrates indicated that cytochrome oxidase was not rate limiting in the oxidation of either pyruvate + malate or succinate. Skeletal muscle mitochondria from dystrophic mice showed no deficiency in any of the cytochromes or coenzyme Q. Mg²⁺-stimulated ATPase activity was higher in dystrophic muscle mitochondria than in controls, but basal and oligomycin-insensitive activities were virtually identical to those of controls. A significant reduction in the intramitochondrial NAD⁺ content (0.01 <P < 0.02) was seen in dystrophic skeletal muscle as compared to controls. Heart mitochondria from dystrophic mice showed similar, though less extensive abnormalities while liver mitochondria were essentially normal. We concluded from these results that skeletal muscle mitochondria from strain 129 dystrophic mice possess impairments in substrate utilization which may result from (1) an abnormality in the transfer of electrons on the substrate side of coenzyme Q in the case of succinate oxidation; (2) a defect on the path of electron flow from NADH to cytochrome c, and (3) a deficiency of NAD⁺ in the case of NAD⁺-linked substrates.     

Approaching the multifaceted nature of energy metabolism: inactivation of the cytosolic creatine kinases via homologous recombination in mouse embryonic stem cells

To study the physiological role of the creatine kinase/phosphocreatine (CK/PCr) system in cells and tissues with a high and fluctuating energy demand we have concentrated on the site-directed inactivation of the B- and M-CK genes encoding the cytosolic CK protein subunits. In our approach we used homologous recombination in mouse embryonic stem (ES) cells from strain 129/Sv. Using targeting constructs based on strain 129/Sv isogenic DNA we managed to ablate the essential exons of the B-CK and M-CK genes at reasonably high frequencies. ES clones with fully disrupted B-CK and two types of M-CK gene mutations, a null (M-CK^–) and leaky (M-CK¹) mutation, were used to generate chimaeric mutant mice via injection in strain C57BL/6 derived blastocysts. Chimaeras with the B-CK null mutation have no overt abnormalities but failed to transmit the mutation to their offspring. For the M-CK^– and M-CK¹ mutations successful transmission was achieved and heterozygous and homozygous mutant mice were bred. Animals deficient in MM-CK are phenotypically normal but lack muscular burst activity. Fluxes through the CK reaction in skeletal muscle are highly impaired and fast fibres show adaptation in cellular architecture and storage of glycogen. Mice homozygous for the leaky M-CK allele, which have 3-fold reduced MM-CK activity, show normal fast fibres but CK fluxes and burst activity are still not restored to wildtype levels.     

膜翅目精子结构研究新进展

根据观察,膜翅目昆虫精子由顶体,精核,中部,尾部四个主要部分构成。顶体具顶体丝,中部具轴丝,中部与精核间具线粒体衍生物。本文同时对膜翅目,分别隶属12个科,10个总科中的2个亚目昆虫精子的顶体、精核、线粒体衍生物、轴丝等结构的研究状况进行概括,并应用精子结构特征对上述类群的系统发育状况进行讨论。     

Fine structure and metabolism of multiply innervated fast muscle fibres in teleost fish

Summary Both the fast and slow muscle fibres of advanced teleost fish are multiply innervated. The fraction of slow-fibre volume occupied by mitochondria is 31.3%, 25.5% and 24.6%, respectively, for the myotomal muscles of brook trout (Salvelinus fontinalis), crucian carp (Carassius carassius), and plaice (Pleuronectes platessa), respectively. The corresponding figures for the fast muscles of these species are 9.3%, 4.6% and 2.0%, respectively. Cytochrome-oxidase and citrate-synthetase activities in the fast muscles of 9 species of teleost range from 0.20–0.93 moles substrate utilised, g wet weight muscle^-1 min^-1 (at 15° C) or around 4–17% of that of the corresponding slow fibres. Ultrastructural analyses reveal a marked heterogeneity within the fast-fibre population. For example, the fraction of fibres with <1% or >10% mitochondria is 0,4,42% and 36, 12 and 0%, respectively, for trout, carp and plaice. In general, small fibres (<500 m²) have the highest and large fibres (>1,500 m²) the lowest mitochondrial densities. The complexity of mitochondrial cristae is reduced in fast compared to slow fibres.Hexokinase activities range from 0.4–2.5 in slow and from 0.08–0.7 moles, g wet weight^-1 min^-1 in fast muscles, indicating a wide variation in their capacity for aerobic glucose utilisation. Phosphofructokinase activities are 1.2 to 3.6 times higher in fast than slow muscles indicating a greater glycolytic potential. Lactate dehydrogenase activities are not correlated with either the predicted anaerobic scopes for activity or the anoxic tolerances of the species studied. The results indicate a considerable variation in the aerobic capacities and principal fuels supporting activity among the fast muscles of different species. Brook trout and crucian carp are known to recruit fast fibres at low swimming speeds. For these species the aerobic potential of the fast muscle is probably sufficient to meet the energy requirements of slow swimming.     

Selective detection of UCP 3 expression in skeletal muscle: effect of thyroid status and temperature acclimation

A novel peptide antibody to UCP 3 is characterized which is sensitive and discriminatory for UCP 3 over UCP 2, UCP 1 and other mitochondrial transporters. The peptide antibody detects UCP 3 expression in E. coli, COS cells and yeast expression systems. The peptide antibody detects a single ∼33 kDa protein band in mitochondria from isolated rat skeletal muscle, mouse and rat brown adipose tissue, and in whole muscle groups (soleus and extensor digitorum longus) from mice. No 33 kDa band is detectable in isolated mitochondria from liver, heart, brain, kidney and lungs of rats, or gastrocnemius mitochondria from UCP 3 knock-out mice. From our data, we conclude that the peptide antibody is detecting UCP 3 in skeletal muscle, skeletal muscle mitochondria and brown adipose tissue mitochondria. It is also noteworthy that the peptide antibody can detect human, mouse and rat forms of UCP 3. Using the UCP 3 peptide antibody, we confirm and quantify the increased (2.8-fold) UCP 3 expression observed in skeletal muscle mitochondria isolated from 48-h-starved rats. We show that UCP 3 expression is increased (1.6-fold) in skeletal muscle of rats acclimated over 8 weeks to 8 °C and that UCP 3 expression is decreased (1.4-fold) in rats acclimated to 30 °C. Furthermore, UCP 3 expression is increased (2.3-fold) in skeletal muscle from hyperthyroid rats compared to euthyroid controls. In addition, we show that UCP 3 expression is only coincident with the mitochondrial fraction of skeletal muscle homogenates and not peroxisomal, nuclear or cytosolic and microsomal fractions.