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981.
W.F. Theeuwes H.R. Gosker R.C.J. Langen N.A.M. Pansters A.M.W.J. Schols A.H.V. Remels 《生物化学与生物物理学报:疾病的分子基础》2018,1864(9):2913-2926
Background
Mitochondrial biogenesis is crucial for myogenic differentiation and regeneration of skeletal muscle tissue and is tightly controlled by the peroxisome proliferator-activated receptor-γ co-activator 1 (PGC-1) signaling network. In the present study, we hypothesized that inactivation of glycogen synthase kinase (GSK)-3β, previously suggested to interfere with PGC-1 in non-muscle cells, potentiates PGC-1 signaling and the development of mitochondrial biogenesis during myogenesis, ultimately resulting in an enhanced myotube oxidative capacity.Methods
GSK-3β was inactivated genetically or pharmacologically during myogenic differentiation of C2C12 muscle cells. In addition, m. gastrocnemius tissue was collected from wild-type and muscle-specific GSK-3β knock-out (KO) mice at different time-points during the reloading/regeneration phase following a 14-day hind-limb suspension period. Subsequently, expression levels of constituents of the PGC-1 signaling network as well as key parameters of mitochondrial oxidative metabolism were investigated.Results
In vitro, both knock-down as well as pharmacological inhibition of GSK-3β not only increased expression levels of important constituents of the PGC-1 signaling network, but also potentiated myogenic differentiation-associated increases in mitochondrial respiration, mitochondrial DNA copy number, oxidative phosphorylation (OXPHOS) protein abundance and the activity of key enzymes involved in the Krebs cycle and fatty acid β-oxidation. In addition, GSK-3β KO animals showed augmented reloading-induced increases in skeletal muscle gene expression of constituents of the PGC-1 signaling network as well as sub-units of OXPHOS complexes compared to wild-type animals.Conclusion
Inactivation of GSK-3β stimulates activation of PGC-1 signaling and mitochondrial biogenesis during myogenic differentiation and reloading of the skeletal musculature. 相似文献982.
Verena Hiebl Angela Ladurner Simone Latkolik Verena M. Dirsch 《Biotechnology advances》2018,36(6):1657-1698
Nuclear receptors (NRs) represent attractive targets for the treatment of metabolic syndrome-related diseases. In addition, natural products are an interesting pool of potential ligands since they have been refined under evolutionary pressure to interact with proteins or other biological targets.This review aims to briefly summarize current basic knowledge regarding the liver X (LXR) and farnesoid X receptors (FXR) that form permissive heterodimers with retinoid X receptors (RXR). Natural product-based ligands for these receptors are summarized and the potential of LXR, FXR and RXR as targets in precision medicine is discussed. 相似文献
983.
Insung Na Shelly DeForte Bosko M. Stojanovski 《Journal of biomolecular structure & dynamics》2018,36(1):152-165
Heme biosynthesis, a complex, multistage, and tightly controlled process, starts with 5-aminolevulinate (ALA) production, which, in metazoa and certain bacteria, is a reaction catalyzed by 5-aminolevulinate synthase (ALAS), a pyridoxal 5′-phosphate (PLP)-dependent enzyme. Functional aberrations in ALAS are associated with several human diseases. ALAS can adopt open and closed conformations, with segmental rearrangements of a C-terminal, 16-amino acid loop and an α-helix regulating accessibility to the ALAS active site. Of the murine erythroid ALAS (mALAS2) forms previously engineered to assess the role of the flexible C-terminal loop versus mALAS2 function one stood out due to its impressive gain in catalytic power. To elucidate how the simultaneously introduced seven mutations of this activity-enhanced variant affected structural and dynamic properties of mALAS2, we conducted extensive molecular dynamics simulation analysis of the dimeric forms of wild-type mALAS2, hepta-variant and Rhodobacter capsulatus ALAS (aka R. capsulatus HemA). This analysis revealed that the seven simultaneous mutations in the C-terminal loop, which extends over the active site of the enzyme, caused the bacterial and murine proteins to adopt different conformations. Specifically, a new β-strand in the mutated ‘loop’ led to interaction with two preexisting β-strands and formation of an anti-parallel three-stranded β-sheet, which likely endowed the murine hepta-variant a more ‘stable’ open conformation than that of wild-type mALAS2, consistent with a kinetic mechanism involving a faster closed-to-open conformation transition and product release for the mutated than wild-type enzyme. Further, the dynamic behavior of the mALAS2 protomers was strikingly different in the two dimeric forms. 相似文献
984.
985.
Washed cells prepared from carbon-limited continuous cultures of Alcaligenes eutrophus synthesised poly-3-hydroxybutyrate (PHB) rapidly when supplied with glucose, dl-lactate or l-lactate. Unlike growing cultures, washed cells excreted significant amounts of pyruvate. The combined rates of PHB production
(qPHB) and pyruvate excretion (qPyr) were linearly related to the rate of carbon substrate utilisation (qS), showing that
washed cells behaved similarly to growing cultures when corrected for the absence of non-PHB biomass production. The addition
of formate (as a potential source of NADH and/or ATP) significantly stimulated both qPHB and qPyr, but slightly decreased
qS and substantially decreased the flux of carbon through the tricarboxylic acid cycle (qTCA). Citrate synthase activity of
broken cells was inhibited by physiological concentrations of NADH, but not of ATP, in a manner that was not reversible by
AMP. Citrate synthase was purified and shown to be a “large” form of the enzyme (M
r 227,000), comprising a single type of subunit (M
r 47,000) as found in several other gram-negative aerobes. The potential role of citrate synthase in the regulation of PHB
production via its ability to control carbon flux into the tricarboxylic acid cycle is discussed.
Received: 14 March 1997 / Accepted: 9 July 1997 相似文献
986.
Wlodzimierz Borejsza-Wysocki Ewa Borejsza-Wysocka Geza Hrazdina 《Plant cell reports》1997,16(5):304-309
Cell suspension cultures were established from germinating pea (Pisum sativum L.) seeds. This cell culture, which accumulated pisatin, consisted mostly of single cells containing a few cell aggregates. The cells responded to treatment with a yeast glucan preparation with transient accumulation of pisatin in both cells and culture media. Addition of pisatin to cell cultures resulted in increased synthesis of pisatin. Phenylalanine ammonia-lyase, chalcone synthase and isoflavone reductase activities were present in untreated cells. Upon treatment with an elicitor preparation the activities of the first two enzymes showed a rapid, transient increase up to 20 hours after treatment. Isoflavone reductase showed a major and minor peak at 16 and 36 h, respectively, after elicitor treatment. The time course of the enzyme activity and pisatin accumulation is consistent with an elicitor-mediated response.Abbreviations CHS
chalcone synthase
- 2,4-D
2,4-dichlorophenoxyacetic acid
- IBA
indole-3-butyric acid
- IFR
isoflavone reductase
- 2iP
6-(dimethylallylamino)-purine
- MS
Murashige & Skoog basal salt medium
- PAL
phenylalanine ammonia-lyase
- PMSF
phenylmethylsulfonyl fluoride
- POPOP
1,4-bis-2-(4-methyl-5-phenyloxazolyl)-benzene
- PPO
2,5-diphenyloxazole 相似文献
987.
Transfer of a grapevine stilbene synthase gene to rice (Oryza sativa L.) 总被引:17,自引:0,他引:17
P. Stark-Lorenzen B. Nelke G. Hänßler H. P. Mühlbach J. E. Thomzik 《Plant cell reports》1997,16(10):668-673
A gene derived from grapevine (Vitis vinifera) coding for stilbene synthase has been transferred into protoplasts of the commercially important japonica rice cultivar
Nipponbare using PEG-mediated direct gene transfer. Transgenic plants were regenerated from calli selected on kanamycin. Southern
blot analysis of genomic DNA isolated from regenerants and progeny plants demonstrated that the stilbene synthase gene is
stably integrated in the genome of transgenic rice plants and inherited in the offspring. The transient formation of stilbene-synthase-specific
mRNA shortly after inoculation with the fungus of the rice blast Pyricularia oryzae has demonstrated that the grapevine stilbene synthase promoter is also active in monocotyledonous plants. Preliminary results
indicate an enhanced resistance of transgenic rice to P. oryzae.
Received: 1 July 1996 / Revision received: 5 November 1996 / Accepted: 30 November 1996 相似文献
988.
B. Bisbis J.P. Billard C. Huault C. Kevers F. Le Dily T. Gaspar 《Biologia Plantarum》1997,40(4):493-497
5-Aminolevulinic acid synthase (ALAS) has been detected in a normal (auxin- and cytokinin-dependent) green sugar beet callus under light and under darkness. ALAS activity was lower when the callus was grown under light. The supply of precursors of the Shemin pathway (glycine and succinate) to dark-grown callus enhanced considerably the capacity of the 5-aminolevulinic acid (ALA) formation. Glutamate, -aminobutyrate or -ketoglutarate also increased ALA accumulation. Such an accumulation was also obtained after inhibition of polyamine synthesis. The results show that glutamate or its derivatives might feed the Shemin pathway in conditions preventing glutamate to be used through the Beale pathway. 相似文献
989.
The biosynthetic chain leading from 5-aminolevulinic acid to chlorophyll is localised to the plastid. Many of the enzymes are nuclear-encoded. NADPH-protochlorophyllide oxidoreductase (EC 1.3.1.33) is one such enzyme which is encoded by two different genes and can exist in an A and a B form. Its import into the plastid seems to be facilitated when protochlorophyllide is present in the chloroplast envelope. Within the plastid the reductase is assembled to thylakoids or prolamellar bodies. The specific properties of the reductase together with the specific properties of the lipids present in the etioplast inner membranes promote the formation of the three-dimensional regular network of the prolamellar bodies. The reductase forms a ternary complex with protochlorophyllide and NADPH that gives rise to different spectral forms of protochlorophyllide. Light transforms protochlorophyllide into chlorophyllide and this photoreaction induces a conformational change in the reductase protein which leads to a process of disaggregation of enzyme, pigment aggregates and membranes, which can be followed spectroscopically and with electron microscopy. The newly formed chlorophyllide is esterified by a membrane-bound nuclear-encoded chlorophyll synthase and the chlorophyll molecule is then associated with proteins into active pigment protein complexes in the photosynthetic machinery. 相似文献
990.
Polyamine metabolism and its regulation 总被引:21,自引:1,他引:20
Antonio F. Tiburcio Teresa Altabella Antoni Borrell Carles Masgrau 《Physiologia plantarum》1997,100(3):664-674