The Role of Carnitine in Cell Metabolism

Bremer, Jon

doi:10.1007/978-1-4615-6005-0_1

Cited by 84 publications

(80 citation statements)

References 175 publications

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“…Lower mitochondrial carnitine concentrations are associated with diminished activity of enzymes involved in fatty acid oxidation [9,28,29]. In addition, the rate of fatty acid oxidation and the removal of potentially toxic intracellular acyl CoA esters are dependent upon carnitine [28,30,31]. We observed that carnitine treatment elevated the total carnitine concentration that was associated with greater fatty acid oxidation.…”

Section: Discussionmentioning

confidence: 63%

Carnitine and Dehydroepiandrosterone Sulfate Induce Protein Synthesis in Porcine Primary Osteoblast-Like Cells

et al. 1999

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Abstract. Age-related bone loss eventually leads to osteopenia in men and women. The etiology of age-related bone loss is currently unknown; however, decreased osteoblast activity contributes to this phenomenon. In turn, osteoblast proliferation and function is dependent on energy production, thus the loss of energy production that occurs with age may account for the deficient osteoblast activity. Carnitine and dehydroepiandrosterone-sulfate (DHEAS), both of which decline with age, promote energy production through fatty acid metabolism. Thus, we hypothesized that carnitine and DHEAS would increase osteoblast activity in vitro. Accordingly, we measured the effect of carnitine and DHEAS on palmitic acid oxidation as a measure of energy production, and alkaline phosphatase (ALP) activity and collagen type I (COL) as indices of osteoblast function in primary porcine osteoblast-like cell cultures. Carnitine (10 −3 and 10 −1 M) but not DHEAS (10 −9 , 10 −8 , and 10 −7 M) increased carnitine levels within the cells. Carnitine alone and in combination with DHEAS increased palmitic acid oxidation. Both carnitine and DHEAS alone and in an additive fashion increased ALP activity and COL levels. These results demonstrate that in osteoblast-like cells in vitro, energy production can be increased by carnitine and osteoblast protein production can be increased by both carnitine and DHEAS. These data suggest that carnitine and DHEAS supplementation in the elderly may stimulate osteoblast activity and decrease age-related bone loss. Key words:Osteoblast -Carnitine -Dehydroepiandrosterone sulfate -Alkaline phosphatase -Collagen Type I.Bone loss is often divided into two broad mechanisms: (1) postmenopausal bone loss, characterized by increased osteoclast activity, and (2) age-related bone loss, characterized by decreased osteoblast activity. Osteoblast activity is dependent on energy production. Thus, it is plausible that the loss of energy production, which accompanies age, may account for decreased osteoblast activity. Most cells use both glucose and fatty acid oxidation pathways for ATP synthesis, although some cell types show a substrate preference. For instance, some studies have suggested that glucose is the major fuel substrate for bone [1,2]. However, more recent work indicates that cell populations enriched with osteoblast-like cells generate 40-80% of the energy demands through fatty acid oxidation [3]. Osteoblasts are responsible for bone formation and it follows that they maintain a high rate of ATP utilization to support the requisite protein synthesis. Cells with a high rate of protein synthesis generate ATP from fatty acid oxidation, the most efficient metabolic process for energy production [4][5][6]. Thus, modulation of fatty acid oxidation may regulate the amount of energy available for protein synthesis in osteoblasts.A number of factors are required for fatty acid oxidation. For example, carnitine is the requisite carrier for the transport of long-chain fatty acids across the inner mitochondrial membrane into...

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Section: Discussionmentioning

confidence: 63%

Carnitine and Dehydroepiandrosterone Sulfate Induce Protein Synthesis in Porcine Primary Osteoblast-Like Cells

et al. 1999

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“…Generally, the key point in the regulation of mitochondrial β-oxidation is thought to be CPT1, which can be inhibited by malonyl-CoA. Since the synthesis of malonyl-CoA is the first committed step in de novo fatty acid biosynthesis, the concentration-dependent inhibition of CPT1 by malonyl-CoA provides a direct mechanism to control the balance between lipogenesis and mitochondrial β-oxidation (Bremer, 1997). In addition to inhibition by malonyl-CoA, CPT1 activity is significantly regulated at the gene level as a response to nutritional stimuli such as fatty acids and feeding and fasting (Brandt et al 1998;Leone et al 1999).…”

Section: Carnitine Palmitoyl Transferasementioning

confidence: 99%

Towards Fish Lipid Nutrigenomics: Current State and Prospects for Fin-Fish Aquaculture

Leaver

Bautista

Björnsson

et al. 2008

Reviews in Fisheries Science

226

192

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Lipids are the predominant source of energy for fish. The mechanisms by which fish allocate energy from lipids, for metabolism, development, growth and reproduction are critical for understanding key life history strategies and transitions. Currently, the major lipid component in aquaculture diets is fish oil (FO), derived from wild capture fisheries that are exploited at their maximum sustainable limit. The increasing demand from aquaculture for FO will soon exceed supply and threaten the viability of aquaculture. Thus, it is essential to minimize FO use in aquaculture diets. This might be achieved by a greater understanding of lipid storage and muscle growth, or the identification of alternatives to FO in feeds. This review focuses on recent research applying molecular and genomic techniques to the study of fin-fish lipid metabolism from an aquaculture perspective. Accordingly, particular emphasis will be given to fatty acid metabolism and to highly unsaturated fatty acid (HUFA) biosynthesis, and to the transcriptional mechanisms and endocrine factors that regulate these processes in fish. Comparative studies of gene function and distribution are described which, when integrated with recent fish genome sequence information, provide insights into lipid homeostasis and the outcomes associated with the replacement of FO in fish diets.

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“…In addition, the carnitine system (which comprises carnitine, CPT I, carnitine acetyl transferase, and carnitine translocase) plays an important role in the cell-trafficking of short-chain fatty acids such as acetyl-CoA and works to maintain the acetyl-CoA/CoA ratio (Bremer, 1997).…”

Section: Shifting Of Clu Forms During Tumor Progressionmentioning

confidence: 99%