Impact on fatty acid metabolism and differential localization of FATP1 and FAT/CD36 proteins delivered in cultured human muscle cells

2005 ◽  
Vol 288 (6) ◽  
pp. C1264-C1272 ◽  
Author(s):  
Cèlia García-Martínez ◽  
Mario Marotta ◽  
Rodrigo Moore-Carrasco ◽  
Maria Guitart ◽  
Marta Camps ◽  
...  

We compared the intracellular distribution and regulatory role of fatty acid transporter protein (FATP1) and fatty acid translocase (FAT/CD36) on muscle cell fatty acid metabolism. With the use of adenoviruses, FATP1 and FAT genes were delivered to primary cultured human muscle cells. FATP1 and FAT moderately enhanced palmitate and oleate transport evenly at concentrations of 0.05, 0.5, and 1 mM. Long-term (16 h) consumption of palmitate and oleate from the media, and particularly incorporation into triacylglyceride (TAG), was stimulated equivalently by FATP1 and FAT at all fatty acid concentrations tested. In contrast, long-term CO2 production was reduced by FATP1 and FAT at all doses of palmitate and at the lower concentrations of oleate. Neither FATP1 nor FAT markedly altered the production of acid-soluble metabolic intermediates from palmitate or oleate. The intracellular localization of fusion constructs of FATP1 and FAT with enhanced green fluorescent protein (EGFP) was examined. Independently of fatty acid treatment, FATPGFP was observed throughout the cytosol in a reticular pattern and concentrated in the perinuclear region, partly overlapping with the Golgi marker GM-130. FATGFP was found in the extracellular membrane and in cytosolic vesicles not coincident with GM-130. Neither FATP1 nor FAT proteins colocalized with lipid droplets in oleate-treated cells. We conclude that whereas FAT is localized on the extracellular membrane, FATP1 is active in the cytosol and imports fatty acids into myotubes. Overall, both FATP1 and FAT stimulated transport and consumption of palmitate and oleate, which they channeled away from complete oxidation and toward TAG synthesis.

2006 ◽  
Vol 27 (3) ◽  
pp. 187-200 ◽  
Author(s):  
Colin Selman ◽  
Nicola D. Kerrison ◽  
Anisha Cooray ◽  
Matthew D. W. Piper ◽  
Steven J. Lingard ◽  
...  

Caloric restriction (CR) increases healthy life span in a range of organisms. The underlying mechanisms are not understood but appear to include changes in gene expression, protein function, and metabolism. Recent studies demonstrate that acute CR alters mortality rates within days in flies. Multitissue transcriptional changes and concomitant metabolic responses to acute CR have not been described. We generated whole genome RNA transcript profiles in liver, skeletal muscle, colon, and hypothalamus and simultaneously measured plasma metabolites using proton nuclear magnetic resonance in mice subjected to acute CR. Liver and muscle showed increased gene expressions associated with fatty acid metabolism and a reduction in those involved in hepatic lipid biosynthesis. Glucogenic amino acids increased in plasma, and gene expression for hepatic gluconeogenesis was enhanced. Increased expression of genes for hormone-mediated signaling and decreased expression of genes involved in protein binding and development occurred in hypothalamus. Cell proliferation genes were decreased and cellular transport genes increased in colon. Acute CR captured many, but not all, hepatic transcriptional changes of long-term CR. Our findings demonstrate a clear transcriptional response across multiple tissues during acute CR, with congruent plasma metabolite changes. Liver and muscle switched gene expression away from energetically expensive biosynthetic processes toward energy conservation and utilization processes, including fatty acid metabolism and gluconeogenesis. Both muscle and colon switched gene expression away from cellular proliferation. Mice undergoing acute CR rapidly adopt many transcriptional and metabolic changes of long-term CR, suggesting that the beneficial effects of CR may require only a short-term reduction in caloric intake.


Author(s):  
Jolita Ciapaite ◽  
Nicole M. van den Broek ◽  
Heleen te Brinke ◽  
Klaas Nicolay ◽  
Jeroen A. Jeneson ◽  
...  

2006 ◽  
Vol 31 (4) ◽  
pp. 467-476 ◽  
Author(s):  
Hakam Alkhateeb ◽  
Adrian Chabowski ◽  
Arend Bonen

Skeletal muscle metabolism has been examined in perfused hindlimb muscles and in isolated muscle preparations. While long-term viability of the fast-twitch epitrochlearis has been documented with respect to glucose transport, it appears that long-term incubated soleus muscles are less stable when incubated ex vivo for many hours. Therefore, in the present study, we have examined whether the isolated soleus muscle remains metabolically viable for up to 18 h with respect to maintaining ATP and phosphocreatine (PCr) concentrations, carbohydrate and fatty-acid metabolism, insulin signalling, and protein expression. Soleus muscles were incubated in well-oxygenated Medium 199 (M199) supplemented with low concentrations of insulin (14.3 µU/mL) for 0, 6, 12, and 18 h. During this incubating period the concentrations of ATP and PCr were stable, indicating that oxygenation and substrate supply were being maintained. In addition, the concentrations of proglycogen and macroglycogen were not altered, whereas an increase (+30%) in intramuscular triacylglycerol concentration was observed at the end of 18 h of incubation (p < 0.05). Complex molecular processes in the long-term incubated muscles were also stable. This was shown by maintenance of basal as well as insulin-stimulated rates of 3-O-methyl glucose transport, and by the maintenance of protein expression of the glucose transporter GLUT4 and the fatty acid transporters FAT/CD36 and FABPpm. In addition, the insulin-stimulated translocation of GLUT4 to the plasma membrane, which involves a complex signalling cascade, was fully preserved. In conclusion, in well-oxygenated soleus muscles maintained in M199 supplemented with extremely low concentrations of insulin, ATP and PCr concentrations, carbohydrate and fatty acid metabolism, insulin signalling, and protein expression were stably maintained for up to 18 h. This provides for opportunities to examine muscle metabolic function under very highly controlled conditions.


2006 ◽  
Vol 30 (5) ◽  
pp. 324 ◽  
Author(s):  
Yong jik Lee ◽  
Zheng Shan Zhao ◽  
Soo Kyung Kim ◽  
Hae Jin Kim ◽  
Wan Sub Shim ◽  
...  

Hepatology ◽  
1994 ◽  
Vol 19 (5) ◽  
pp. 1272-1281
Author(s):  
Stephan Krähenbühl ◽  
Christine Talos ◽  
Jürg Reichen

2005 ◽  
Vol 289 (1) ◽  
pp. E151-E159 ◽  
Author(s):  
Bong-Soo Cha ◽  
Theodore P. Ciaraldi ◽  
Kyong-Soo Park ◽  
Leslie Carter ◽  
Sunder R. Mudaliar ◽  
...  

The impact of type 2 diabetes on the ability of muscle to accumulate and dispose of fatty acids and triglycerides was evaluated in cultured muscle cells from nondiabetic (ND) and type 2 diabetic (T2D) subjects. In the presence of 5 μM palmitate, T2D muscle cells accumulated less lipid than ND cells (11.5 ± 1.2 vs. 15.1 ± 1.4 nmol/mg protein, P < 0.05). Chronic treatment (4 days) with the peroxisome proliferator-activated receptor-γ (PPARγ) agonist troglitazone increased palmitate accumulation, normalizing uptake in T2D cells. There were no significant differences between groups with regard to the relative incorporation of palmitate into neutral lipid species. This distribution was also unaffected by troglitazone treatment. β-Oxidation of both long-chain (palmitate) and medium-chain (octanoate) fatty acids in T2D muscle cells was reduced by ∼40% compared with ND cells. Palmitate oxidation occurred primarily in mitochondrial (∼40–50% of total) and peroxisomal (20–30%) compartments. The diabetes-related defect in palmitate oxidation was localized to the mitochondrial component. Both palmitate and octanoate oxidation were stimulated by a series of thiazolidinediones. Oxidation in T2D muscle cells was normalized after treatment. Troglitazone increased the mitochondrial component of palmitate oxidation. Skeletal muscle cells from T2D subjects express defects in free fatty acid metabolism that are retained in vitro, most importantly defects in β-oxidation. These defects can be corrected by treatment with PPARγ agonists. Augmentation of fatty acid disposal in skeletal muscle, potentially reducing intramyocellular triglyceride content, may represent one mechanism for the lipid-lowering and insulin-sensitizing effects of thiazolidinediones.


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