Regulation of dichloroacetate biotransformation in rat liver and extrahepatic tissues by GSTZ1 expression and chloride concentration

Jahn, Stephan C.; Smeltz, Marci; Hu, Zhiwei; Rowland‐Faux, Laura; Zhong, Guo; Lorenzo, Ryan J.; Cisneros, Katherine V.; Stacpoole, Peter W.; James, Margaret O.

doi:10.1016/j.bcp.2018.04.001

Cited by 8 publications

(20 citation statements)

References 35 publications

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“…On the 9 th day the animals were sacrificed and the liver, kidney, heart, and brain organs were collected and used to prepare cytosolic and mitochondrial subcellular fractionations as previously described (Li et al, 2011). We selected the rat DCA dose of 100 mg/kg because it was calculated to be therapeutically similar to the human dose of 25 mg/kg/day after species scaling (Boxenbaum, 1980), and sodium acetate was chosen as control since it is a similar molecule to DCA that was previously shown to have no effect on GSTZ1 expression or activity (Jahn et al, 2018;Smeltz et al, 2019). Four and 52 week-old rats were used to model children or adults around the ages of 2 and 30 years, respectively (Quinn, 2005), and a treatment period of 8 days was chosen as studies in humans and rats show a steady state reduction in GSTZ1 is achieved between 5 and 7 days (Schultz and Sylvester, 2001;Saghir and Schultz, 2005;Shroads et al, 2012).…”

Section: Chemicalsmentioning

confidence: 99%

“…Each 100 µL reaction was performed at pH 7.6 and contained 100 mM HEPES, 0.2 mM [ 14 C]-DCA, and either 1 mM GSH (cytosol), 5 mM GSH (liver mitochondria), or 10 mM GSH (kidney mitochondria). Since GSH is consumed by gamma-glutamyl transpeptidase activity in rat kidney mitochondria (Jahn et al, 2018), we utilized 10 mM GSH in the current work to maintain GSH saturation for all kidney mitochondria incubations. The reactions were initiated at 37C by the addition of dialyzed protein (0.1 to 1.0 mg) for 10 to 30 minutes for liver samples and up to 120 minutes for extrahepatic tissue samples.…”

Section: Gstz1 Protein Expression Gstz1 Protein Expression Was Assesmentioning

confidence: 99%

“…Although liver is the main site of GSTZ1 expression and activity, extrahepatic tissues also express GSTZ1 (Board et al, 1997;Lantum, Baggs, et al, 2002;Jahn et al, 2018). Therefore, elimination and disposition of DCA can be influenced by extrahepatic metabolism.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, elimination and disposition of DCA can be influenced by extrahepatic metabolism. It was shown that a single dose of a therapeutic concentration of DCA to female rats reduced GSTZ1 expression and activity in liver to a greater extent than in kidney, brain, and heart (Jahn et al, 2018), such that DCA metabolism was more prominent in these extrahepatic tissues than liver after the single dose. DCA is given on a daily basis under therapeutic conditions, however, the role of extrahepatic tissues in metabolism of DCA, MAA, and MA following repeated doses of DCA that mimic therapy has not been studied.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Multiple Doses of Dichloroacetate on GSTZ1 Expression and Activity in Liver and Extrahepatic Tissues of Young and Adult Rats

et al. 2020

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GSTZ1, expressed in liver and several extrahepatic tissues, catalyzes dechlorination of dichloroacetate (DCA) to glyoxylate. DCA inactivates GSTZ1, leading to auto-inhibition of its metabolism. DCA is an investigational drug for treating several congenital and acquired disorders of mitochondrial energy metabolism, including cancer. The main adverse effect of DCA, reversible peripheral neuropathy, is more common in adults treated long-term than in children, who metabolize DCA more quickly after multiple doses. One dose of DCA to Sprague Dawley rats reduced GSTZ1 expression and activity more in liver than extrahepatic tissues, however the effects of multiple doses of DCA that mimic its therapeutic use have not been studied. Here, we examined the expression and activity of GSTZ1 in cytosol and mitochondria of liver, kidney, heart, and brain 24 hours after completion of 8-days oral dosing of 100 mg/kg/day sodium DCA to juvenile and adult Sprague Dawley rats. Activity was measured with DCA and with 1,2-epoxy-3-(4-nitrophenoxy)propane (EPNPP), reported to be a GSTZ1-selective substrate. In DCA-treated rats, liver retained higher expression and activity of GSTZ1 with DCA than other tissues, irrespective of rodent age. DCA-treated juvenile rats retained more GSTZ1 activity with DCA than adults. Consistent with this finding, there was less measurable DCA in tissues of juvenile than adult rats. DCA-treated rats retained activity with EPNPP, despite losing over 98% of GSTZ1 protein. These data provide insight into the differences between children and adults in DCA elimination under a therapeutic regimen and confirm that the liver contributes more to DCA metabolism than other tissues.

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Section: Chemicalsmentioning

confidence: 99%

Section: Gstz1 Protein Expression Gstz1 Protein Expression Was Assesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Multiple Doses of Dichloroacetate on GSTZ1 Expression and Activity in Liver and Extrahepatic Tissues of Young and Adult Rats

et al. 2020

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“…GSTZ1 mRNA expression in humans was highest in liver among all tested tissues (Uhlén et al, 2015). Based on studies in rodents, hepatic cytosol is the major protein expression site of GSTZ1 (Lantum et al, 2002a;Jahn et al, 2018). Aside from cytosol, GSTZ1 was expressed in the hepatic mitochondrial matrix in both humans and rats, but at a lower level compared with cytosol (Li et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Age-Related Changes in Expression and Activity of Human Hepatic Mitochondrial Glutathione Transferase Zeta1

et al. 2018

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Glutathione transferase zeta1 (GSTZ1) catalyzes glutathione (GSH)-dependent dechlorination of dichloroacetate (DCA), an investigational drug with therapeutic potential in metabolic disorders and cancer. GSTZ1 is expressed in both hepatic cytosol and mitochondria. Here, we examined the ontogeny and characterized the properties of human mitochondrial GSTZ1. GSTZ1 expression and activity with DCA were determined in 103 human hepatic mitochondrial samples prepared from livers of donors aged 1 day to 84 years. DNA from each sample was genotyped for three common GSTZ1 functional single nucleotide polymorphisms. Expression of mitochondrial GSTZ1 protein increased in an age-dependent manner to a plateau after age 21 years. Activity with DCA correlated with expression, after taking into account the somewhat higher activity of samples that were homo- or heterozygous for GSTZ1A. In samples from livers with the GSTZ1C variant, apparent enzyme kinetic constants for DCA and GSH were similar for mitochondria and cytosol after correcting for the loss of GSH observed in mitochondrial incubations. In the presence of 38 mM chloride, mitochondrial GSTZ1 exhibited shorter half-lives of inactivation compared with the cytosolic enzyme ( = 0.017). GSTZ1 protein isolated from mitochondria was shown by mass spectrometry to be identical to cytosolic GSTZ1 protein in the covered primary protein sequence. In summary, we report age-related development in the expression and activity of human hepatic mitochondrial GSTZ1 does not have the same pattern as that reported for cytosolic GSTZ1. Some properties of cytosolic and mitochondrial GSTZ1 differed, but these were not related to differences in amino acid sequence or post-translationally modified residues.

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Mitochondrial Glutathione Transferase Zeta 1 Is Inactivated More Rapidly by Dichloroacetate than the Cytosolic Enzyme in Adult and Juvenile Rat Liver

Smeltz

Zhong

et al. 2019

Chem. Res. Toxicol.

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Dichloroacetate (DCA) has potential for treating mitochondrial disorders and cancer by activating the mitochondrial pyruvate dehydrogenase complex. Repeated dosing of DCA results in reduced drug clearance due to inactivation of glutathione transferase ζ1 (GSTZ1), its metabolizing enzyme. We investigated the time-course of inactivation of GSTZ1 in hepatic cytosol and mitochondria after one oral dose of 100 mg/kg DCA to female Sprague− Dawley rats aged 4 weeks (young) and 52 weeks (adult) as models for children and adults, respectively. GSTZ1 activity with both DCA and an endogenous substrate, maleylacetone (MA), as well as GSTZ1 protein expression were rapidly reduced in cytosol from both ages following DCA treatment. In mitochondria, loss of GSTZ1 protein and activity with DCA were even more rapid. The cytosolic in vivo half-lives of the loss of GSTZ1 activity with DCA were 1.05 ± 0.03 and 0.82 ± 0.02 h (mean ± S.D., n = 6) for young and adult rats, respectively, with inactivation significantly more rapid in adult rats, p < 0.001. The mitochondrial inactivation half-lives were similar in young (0.57 ± 0.02 h) and adult rats (0.54 ± 0.02 h) and were significantly (p < 0.0001) shorter than cytosolic inactivation half-lives. By 24 h after DCA administration, activity and expression remained at 10% or less than control values. The in vitro GSTZ1 inactivation half-lives following incubation with 2 mM DCA in the presence of physiological chloride (Cl − ) concentrations (cytosol = 44 mM, mitochondria = 1−2 mM) exhibited marked differences between subcellular fractions, being 3 times longer in the cytosol than in the mitochondria, regardless of age, suggesting that the lower Cl − concentration in mitochondria explained the faster degradation of GSTZ1. These results demonstrate for the first time that rat mitochondrial GSTZ1 is more readily inactivated by DCA than cytosolic GSTZ1, and cytosolic GSTZ1 is inactivated more rapidly in adult than young rats.

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Regulation of dichloroacetate biotransformation in rat liver and extrahepatic tissues by GSTZ1 expression and chloride concentration

Cited by 8 publications

References 35 publications

Effects of Multiple Doses of Dichloroacetate on GSTZ1 Expression and Activity in Liver and Extrahepatic Tissues of Young and Adult Rats

Effects of Multiple Doses of Dichloroacetate on GSTZ1 Expression and Activity in Liver and Extrahepatic Tissues of Young and Adult Rats

Age-Related Changes in Expression and Activity of Human Hepatic Mitochondrial Glutathione Transferase Zeta1

Mitochondrial Glutathione Transferase Zeta 1 Is Inactivated More Rapidly by Dichloroacetate than the Cytosolic Enzyme in Adult and Juvenile Rat Liver

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