Presence of thiamin pyrophosphate in mammalian peroxisomes

Department of Molecular Cell Biology, Division of Pharmacology, LIPIT, Katholieke Universiteit Leuven, O&N1, Leuven, Belgium. <>
BMC Biochemistry (Impact Factor: 1.44). 02/2007; 8(1):10. DOI: 10.1186/1471-2091-8-10
Source: PubMed


Thiamine pyrophosphate (TPP) is a cofactor for 2-hydroxyacyl-CoA lyase 1 (HACL1), a peroxisomal enzyme essential for the alpha-oxidation of phytanic acid and 2-hydroxy straight chain fatty acids. So far, HACL1 is the only known peroxisomal TPP-dependent enzyme in mammals. Little is known about the transport of metabolites and cofactors across the peroxisomal membrane and no peroxisomal thiamine or TPP carrier has been identified in mammals yet. This study was undertaken to get a better insight into these issues and to shed light on the role of TPP in peroxisomal metabolism.
Because of the crucial role of the cofactor TPP, we reanalyzed its subcellular localization in rat liver. In addition to the known mitochondrial and cytosolic pools, we demonstrated, for the first time, that peroxisomes contain TPP (177 +/- 2 pmol/mg protein). Subsequently, we verified whether TPP could be synthesized from its precursor thiamine, in situ, by a peroxisomal thiamine pyrophosphokinase (TPK). However, TPK activity was exclusively recovered in the cytosol.
Our results clearly indicate that mammalian peroxisomes do contain TPP but that no pyrophosphorylation of thiamine occurs in these organelles, implying that thiamine must enter the peroxisome already pyrophosphorylated. Consequently, TPP entry may depend on a specific transport system or, in a bound form, on HACL1 translocation.

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Available from: Minne Casteels, Dec 25, 2013
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    • "Three replicates of each sample were extracted in 500 µl of 7.2% perchloric acid by sonicating for 30 min in a bath, held on ice for 15 min with periodic vortex mixing, and then cleared by centrifugation at (14000 g, 10 min). The supernatant was then analyzed for thiamin and its phosphates by oxidation to thiochrome derivatives followed by HPLC with fluorometric detection (Fraccascia et al., 2007; Goyer et al., 2013). "
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    • "In addition, TPP is involved in the í µí»¼oxidation of 3-methyl-branched and straight chain 2-hydroxy long chain fatty acids pathway functioning as coenzyme for peroxisomes. As a result TPP is a crucial cofactor for energy metabolism, antioxidation, and myelinization of nerve cells [21]. Continued high-dose cisplatin chemotherapy necessitates the investigation of strategies to decrease the doselimiting ototoxicity. "
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    ABSTRACT: Objective: The aim of this study was to evaluate the effectiveness of thiamine pyrophosphate against cisplatin-induced ototoxicity in guinea pigs. Materials and methods: Healthy guinea pigs (n = 18) were randomly divided into three groups. Group 1 (n = 6) received an intraperitoneal injection of saline solution and cisplatin for 7 days, group 2 (n = 6) received an intraperitoneal injection of thiamine pyrophosphate and cisplatin for 7 days, and group 3 (n = 6) received only intraperitoneal injection of saline for 7 days. The animals in all groups were sacrificed under anesthesia, and their cochleas were harvested for morphological and biochemical observations. Results: In group 1, receiving only cisplatin, cochlear glutathione concentrations, superoxide dismutase, and glutathione peroxidase activities significantly decreased (P < 0.05) and malondialdehyde concentrations significantly increased (P < 0.05) compared to the control group. In group 2, receiving thiamine pyrophosphate and cisplatin, the concentrations of enzymes were near those of the control group. Microscopic examination showed that outer hair cells, spiral ganglion cells, and stria vascularis were preserved in group 2. Conclusion: Systemic administration of thiamine pyrophosphate yielded statistically significant protection to the cochlea of guinea pigs from cisplatin toxicity. Further experimental animal studies are essential to determine the appropriate indications of thiamine pyrophosphate before clinical use.
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    • "However, bearing in mind that TPP is formed from thiamine in hepatic cells, we think that cisplatin also has a negative impact on various enzymatic mechanisms involved in liver cells. This is because although thiamine is reported to be metabolized very quickly to TPP, there are as yet no established data on this, and the mechanism involved at the cellular level is unclear [49, 50]. In conclusion, cisplatin causes oxidative stress in the rat liver. "
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