[Show abstract][Hide abstract] ABSTRACT: We have reported that pyrroloquinoline quinone (PQQ) improves reproduction, neonatal development, and mitochondrial function in animals by mechanisms that involve mitochondrial related cell signaling pathways. To extend these observations, the influence of PQQ on energy and lipid relationships and apparent protection against ischemia reperfusion injury are described herein. Sprague-Dawley rats were fed a nutritionally complete diet with PQQ added at either 0 (PQQ-) or 2 mg PQQ/Kg diet (PQQ+). Measurements included: 1) serum glucose and insulin, 2) total energy expenditure per metabolic body size (Wt(3/4)), 3) respiratory quotients (in the fed and fasted states), 4) changes in plasma lipids, 5) the relative mitochondrial amount in liver and heart, and 6) indices related to cardiac ischemia. For the latter, rats (PQQ- or PQQ+) were subjected to left anterior descending occlusions followed by 2 h of reperfusion to determine PQQ's influence on infarct size and myocardial tissue levels of malondialdehyde, an indicator of lipid peroxidation. Although no striking differences in serum glucose, insulin, and free fatty acid levels were observed, energy expenditure was lower in PQQ- vs. PQQ+ rats and energy expenditure (fed state) was correlated with the hepatic mitochondrial content. Elevations in plasma di- and triacylglyceride and β-hydroxybutryic acid concentrations were also observed in PQQ- rats vs. PQQ+ rats. Moreover, PQQ administration (i.p. at 4.5 mg/kg BW for 3 days) resulted in a greater than 2-fold decrease in plasma triglycerides during a 6-hour fast than saline administration in a rat model of type 2 diabetes. Cardiac injury resulting from ischemia/reperfusion was more pronounced in PQQ- rats than in PQQ+ rats. Collectively, these data demonstrate that PQQ deficiency impacts a number of parameters related to normal mitochondrial function.
PLoS ONE 01/2011; 6(7):e21779. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PQQ (pyrroloquinoline quinone) improves energy utilization and reproductive performance when added to rodent diets devoid of PQQ. In the present paper we describe changes in gene expression patterns and transcriptional networks that respond to dietary PQQ restriction or pharmacological administration. Rats were fed diets either deficient in PQQ (PQQ-) or supplemented with PQQ (approx. 6 nmol of PQQ/g of food; PQQ+). In addition, groups of rats were either repleted by administering PQQ to PQQ- rats (1.5 mg of PQQ intraperitoneal/kg of body weight at 12 h intervals for 36 h; PQQ-/+) or partially depleted by feeding the PQQ- diet to PQQ+ rats for 48 h (PQQ+/-). RNA extracted from liver and a Codelink(R) UniSet Rat I Bioarray system were used to assess gene transcript expression. Of the approx. 10000 rat sequences and control probes analysed, 238 were altered at the P<0.01 level by feeding on the PQQ- diet for 10 weeks. Short-term PQQ depletion resulted in changes in 438 transcripts (P<0.01). PQQ repletion reversed the changes in transcript expression caused by PQQ deficiency and resulted in an alteration of 847 of the total transcripts examined (P<0.01). Genes important for cellular stress (e.g. thioredoxin), mitochondriogenesis, cell signalling [JAK (Janus kinase)/STAT (signal transducer and activator of transcription) and MAPK (mitogen-activated protein kinase) pathways] and transport were most affected. qRT-PCR (quantitative real-time PCR) and functional assays aided in validating such processes as principal targets. Collectively, the results provide a mechanistic basis for previous functional observations associated with PQQ deficiency or PQQ administered in pharmacological amounts.
[Show abstract][Hide abstract] ABSTRACT: Bioactive compounds reported to stimulate mitochondrial biogenesis are linked to many health benefits, such increased longevity,
improved energy utilization, and protection from reactive oxygen species. Previously studies have shown that mice and rats
fed diets lacking in pyrroloquinoline quinone (PQQ) have reduced mitochondrial content. Therefore, we hypothesized that PQQ
can induce mitochondrial biogenesis in mouse hepatocytes. Exposure of mouse Hepa1-6 cells to 10-30 mM PQQ for 24-48 h resulted
in increased citrate synthase and cytochrome c oxidase activity, Mitotracker staining, mitochondrial DNA content, and cellular
oxygen respiration. The induction of this process occurred through the activation of cAMP response element binding protein
(CREB) and PPAR-γ-coactivator-1α (PGC-1α), a pathway known to regulate mitochondrial biogenesis. PQQ exposure stimulated
phosphorylation of CREB at serine 133, activated the promoter of PGC-1α, and increased PGC-1α mRNA and protein expression.
PQQ did not stimulate mitochondrial biogenesis following siRNA-mediated reduction in either PGC-1α or CREB expression. Consistent
with activation of the PGC-1α pathway, PQQ increased nuclear respiratory factor activation (NRF-1 and NRF-2) and Tfam, TFB1M,
and TFB2M mRNA expression. Moreover, PQQ protected cells from mitochondrial inhibition by rotenone, 3-nitropropionic acid,
antimycin A, and sodium azide. The ability of PQQ to stimulate mitochondrial biogenesis accounts in part for action of this
compound and suggests that PQQ may be beneficial in diseases associated with mitochondrial dysfunction.
Journal of Biological Chemistry 10/2009; · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bioactive compounds reported to stimulate mitochondrial biogenesis are linked to many health benefits such increased longevity, improved energy utilization, and protection from reactive oxygen species. Previously studies have shown that mice and rats fed diets lacking in pyrroloquinoline quinone (PQQ) have reduced mitochondrial content. Therefore, we hypothesized that PQQ can induce mitochondrial biogenesis in mouse hepatocytes. Exposure of mouse Hepa1-6 cells to 10-30 microm PQQ for 24-48 h resulted in increased citrate synthase and cytochrome c oxidase activity, Mitotracker staining, mitochondrial DNA content, and cellular oxygen respiration. The induction of this process occurred through the activation of cAMP response element-binding protein (CREB) and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), a pathway known to regulate mitochondrial biogenesis. PQQ exposure stimulated phosphorylation of CREB at serine 133, activated the promoter of PGC-1alpha, and increased PGC-1alpha mRNA and protein expression. PQQ did not stimulate mitochondrial biogenesis after small interfering RNA-mediated reduction in either PGC-1alpha or CREB expression. Consistent with activation of the PGC-1alpha pathway, PQQ increased nuclear respiratory factor activation (NRF-1 and NRF-2) and Tfam, TFB1M, and TFB2M mRNA expression. Moreover, PQQ protected cells from mitochondrial inhibition by rotenone, 3-nitropropionic acid, antimycin A, and sodium azide. The ability of PQQ to stimulate mitochondrial biogenesis accounts in part for action of this compound and suggests that PQQ may be beneficial in diseases associated with mitochondrial dysfunction.
Journal of Biological Chemistry 10/2009; 285(1):142-52. · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The expression of phase I and II biotransformation enzymes was examined with respect to experimental diet composition and with the addition of the bi-functional inducer flavone. Enzymatic activity and mRNA levels of cytochrome P450 monooxygenase (CYP) isoforms (CYP1A1, CYP1A2, CYP2B1/2) and glutathione-S-transferase (GST) isoforms (GSTA, GSTM, and GSTP) were used as indices for the changes in expression. An amino acid based (AA) diet and a semi-purified egg white (EW) diet were designed to include similar levels of nutrients and were compared to a standard laboratory chow (SC) diet. Rats (Sprague-Dawley) and mice (C57BL/6) were used as animal models. Animals were fed one of the three diets for 7 days prior to incorporation of flavone (2%, wt/wt). Diets with or without flavone were next fed for an additional 3 days. Enzymatic activities of the CYPs in mice and GSTs in both mice and rats were determined. In mice, the relative mRNA levels for each of the CYP and GST isoforms were also measured. The increase in phase I and II enzyme expression observed in response to flavone was most dynamic when the AA-based diet was used (often >20-fold for given isoform enzymatic activities and >200-fold for specific mRNAs), followed by the EW diet (10 to 20-fold and 100 to 200-fold, respectively). The SC diet resulted in a higher level of background expression of CYP and GST isoforms and as a consequence the observed fold increases in CYP and GST isoforms (enzymatic and mRNA levels) were substantially less (1 to 10-fold and 1 to 150-fold. respectively), when the SC diet fed group with or without flavone was compared.
Archives of Toxicology 05/2008; 82(12):893-901. · 5.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pyrroloquinoline quinone (PQQ) added to purified diets devoid of PQQ improves indices of perinatal development in rats and mice. Herein, PQQ nutritional status and lysine metabolism are described, prompted by a report that PQQ functions as a vitamin-like enzymatic cofactor important in lysine metabolism (Nature 422  832). Alternatively, we propose that PQQ influences lysine metabolism, but by mechanisms that more likely involve changes in mitochondrial content. PQQ deprivation in both rats and mice resulted in a decrease in mitochondrial content. In rats, alpha-aminoadipic acid (alphaAA), which is derived from alpha-aminoadipic semialdehyde (alphaAAS) and made from lysine in mitochondria, and the plasma levels of amino acids known to be oxidized in mitochondria (e.g., Thr, Ser, and Gly) were correlated with changes in the liver mitochondrial content of PQQ-deprived rats, but not PQQ-supplemented rats. In contrast, the levels of NAD dependent alpha-aminoadipate-delta-semialdehyde dehydrogenase (AASDH), a cytosolic enzyme important to alphaAA production from alphaAAS, was not influenced by PQQ dietary status. Moreover, the levels of U26 mRNA were not significantly changed even when diets differed markedly in PQQ and dietary lysine content. U26 mRNA levels were measured, because of U26's proposed, albeit questionable role as a PQQ-dependent enzyme involved in alphaAA formation.
Biochimica et Biophysica Acta 12/2006; 1760(11):1741-8. · 4.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: When pyrroloquinoline quinone (PQQ) is added to an amino acid-based, but otherwise nutritionally complete basal diet, it improves growth-related variables in young mice. We examined PQQ and mitochondrial function based on observations that PQQ deficiency results in elevated plasma glucose concentrations in young mice, and PQQ addition stimulates mitochondrial complex 1 activity in vitro. PQQ-deficient weanling mice had a 20-30% reduction in the relative amount of mitochondria in liver; lower respiratory control ratios, and lower respiratory quotients than PQQ-supplemented mice (2 mg PQQ/kg diet). In mice from dams fed a conventional laboratory diet, but switched at weaning to the basal diet, plasma glucose, Ala, Gly, and Ser concentrations were elevated at 4 wk (PQQ- vs. PQQ+), but not at 8 wk. The relative mitochondrial content (ratio of mtDNA to nuclear DNA) also tended (P<0.18) to be lower (PQQ- vs. PQQ+) at 4 wk, but not at 8 wk. PQQ also counters the mitochondrial complex 1 inhibitor, diphenylene iodonium (DPI). Mice were gavaged with 0, 0.4, or 4 microg PQQ/g body weight (BW) daily for 14 d. At each PQQ level, DPI was injected (i.p.) at 0, 0.4, 0.8, or 1.6 microg DPI/g BW. The PQQ-deficient mice exposed to 0.4 or 4.0 microg DPI/g lost weight and had lower plasma glucose levels than PQQ-supplemented mice (P<0.05). In addition, fibroblasts took up (3)H-PQQ added to cell cultures, and cultured hepatocytes maintained mitochondrial PQQ concentrations similar to those observed in vivo. Collectively, these results indicate that dietary PQQ can influence mitochondrial amount and function, particularly in perinatal and weanling mice.
Journal of Nutrition 03/2006; 136(2):390-6. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Infants are exposed to variable copper (Cu) intake; Cu in breast milk is low, whereas infant formulas vary in Cu content as well as the water used for their preparation. Little is known about the regulation of Cu absorption during infancy. The objectives of this study were to determine effects of Cu supplementation on Cu absorption and tissue distribution and the expression of Cu transporters in an infant rat model. Suckling rat pups were orally dosed with 0, 10, or 25 microg Cu/day. Intestine and liver were collected at days 10 and 20, and Cu concentration, Cu transporter-1 (Ctr1), Atp7A, Atp7B, and metallothionein (MT) mRNA and protein levels were measured. 67Cu absorption was measured at days 10 and 20. Total 67Cu absorption decreased, and intestinal 67Cu retention increased with increased Cu intake. At day 10, intestine Cu concentration, MT mRNA, and Ctr1 protein levels increased with supplementation, but no changes in Atp7A or Atp7B levels were observed. At day 20, intestine Cu concentration was unaffected by Cu supplementation, but Ctr1 protein and Atp7A mRNA and protein levels were higher than in controls. In liver, Cu level reflected Cu intake at days 10 and 20. There was a significant increase in Ctr1, Atp7B, and MT mRNA expression in liver at both ages with Cu supplementation. In conclusion, the ability of suckling rat pups to tolerate varying amounts of dietary Cu may be due to changes in Cu transporters, facilitated by transcriptional and posttranslational mechanisms. Despite these adaptive changes, Cu supplementation resulted in elevated alanine aminotransferase levels, suggesting a risk of Cu toxicity with supplementation during infancy.
[Show abstract][Hide abstract] ABSTRACT: Ctr1 and Atp7A are copper (Cu) transporters that may play a role in the regulation of intestinal Cu absorption; however, intestinal regulation of these transporters by Cu in vivo has not been well defined. In this study, we hypothesized that Cu supplementation would alter the expression of intestine Ctr1 and Atp7A in vivo and further documented effects of Cu exposure on Cu transport, Ctr1 and Atp7A levels and localization in enterocyte-like Caco-2 cells. Suckling rat pups were supplemented with Cu (0 and 25 microg Cu/day) for 10 days and small intestine Cu concentration, Ctr1, Atp7A and metallothionein (MT) gene expression were measured by Northern blot analysis. Caco-2 cells were treated with basal medium, or medium supplemented with 3 and 94 microM CuSO4 and 67Cu transport, Ctr1 and Atp7A levels and localization were determined. In rat pups, Cu supplementation increased intestinal Cu, Ctr1 and MT gene expression; however, Atp7A gene expression was not significantly affected. Caco-2 cells treated with 94 microM Cu had lower cellular Cu uptake and export compared to untreated cells. While Ctr1 and Atp7A gene and protein levels were unaffected, confocal microscopy indicated that Ctr1 was endocytosed and co-localized with transferrin in Cu treated cells. This study demonstrates the functional response of intestinal cells to Cu treatment and suggests that both Ctr1 and Atp7A may regulate Cu absorption.
The Journal of Nutritional Biochemistry 04/2004; 15(3):155-62. · 4.55 Impact Factor