Metabolic pathway of 4-pyridone-3-carboxamide-1ß-d-ribonucleoside and its effects on cellular energetics.

4-pirydone-3-carboxamide-1ß-d-ribonucleoside (4PYR) is an endogenous nucleoside that could be converted to triphosphates, diphosphates, monophosphates and an analogue of NAD - 4PYRAD. Elevated level of these compounds have been reported in chronic renal failure, cancer and active HIV infection. However, little is known about the effect on cell functionality and the metabolic pathways. This study tested effects of 4PYR in different cell types on nucleotide, energy metabolism and clarified enzymes that are involved in conversions of 4PYR. We have found that human neuroblastoma cells, human malignant melanoma cells, human adipose-derived stem cells, human bone marrow-derived stem cells, human dermal microvascular endothelial cells and human embryonic kidney cells, were capable to convert 4PYR into its derivatives. This was associated with deterioration of cellular energetics. Incubation with 4PYR did not affect mitochondrial function, but decreased glycolytic rate (as measured by extracellular acidification) in endothelial cells. Silencing of adenosine kinase, cytosolic 5'-nucleotidase II and nicotinamide nucleotide adenylyltransferase 3, blocked metabolism of 4PYR. Incubation of endothelial cells with 4PYR decreased AMP deaminase activity by 40%. The main finding of this paper is that human cells (including cancer type) are capable of metabolizing 4PYR that lead to deterioration of energy metabolism, possibly as the consequence of inhibition of glycolysis. This study, it was also found that several enzymes of nucleotide metabolism could also contribute to the 4PYRconversions.

Metallothioneins 1 and 2, but not 3, are regulated by nutritional status in rat white adipose tissue.

BACKGROUND: Cumulating evidence underlines the role of adipose tissue metallothionein (MT) in the development of obesity and type 2 diabetes. Fasting/refeeding was shown to affect MT gene expression in the rodent liver. The influence of nutritional status on MT gene expression in white adipose tissue (WAT) is inconclusive. The aim of this study was to verify if fasting and fasting/refeeding may influence expression of MT genes in WAT of rats. RESULTS: Fasting resulted in a significant increase in MT1 and MT2 gene expressions in retroperitoneal, epididymal, and inguinal WAT of rats, and this effect was reversed by refeeding. Altered expressions of MT1 and MT2 genes in all main fat depots were reflected by changes in serum MT1 and MT2 levels. MT1 and MT2 messenger RNA (mRNA) levels in WAT correlated inversely with serum insulin concentration. Changes in MT1 and MT2 mRNA levels were apparently not related to total zinc concentrations and MTF1 and Zn transporter mRNA levels in WAT. Fasting or fasting/refeeding exerted no effect on the expression of MT3 gene in WAT. Addition of insulin to isolated adipocytes resulted in a significant decrease in MT1 and MT2 gene expressions. In contrast, forskolin or dibutyryl-cAMP (dB-cAMP) enhanced the expressions of MT1 and MT2 genes in isolated adipocytes. Insulin partially reversed the effect of dB-cAMP on MT1 and MT2 gene expressions. CONCLUSIONS: This study showed that the expressions of MT1 and MT2 genes in WAT are regulated by nutritional status, and the regulation may be independent of total zinc concentration.

Progesterone-induced down-regulation of hormone sensitive lipase (Lipe) and up-regulation of G0/G1 switch 2 (G0s2) genes expression in inguinal adipose tissue of female rats is reflected by diminished rate of lipolysis.

Decreased lipolytic activity in adipose tissue may be one of the reasons behind excess accumulation of body fat during pregnancy. The aim of this study was to analyze the effect of progesterone on the expression of: (a) Lipe (encoding hormone-sensitive lipase, HSL), (b) Pnpla2 (encoding adipose triglyceride lipase, ATGL), (c) abhydrolase domain containing 5 (Abhd5), and (d) G0/G1 switch 2 (G0s2) genes in white adipose tissue (WAT), as potential targets for progesterone action during the course of pregnancy. Administration of progesterone to female rats, which was reflected by approximately 2.5-fold increase in circulating progesterone concentration, is associated with a decrease in Lipe gene expression in the inguinal WAT. The expression of Pnpla2 gene in all main fat depots of females and males remained unchanged after progesterone administration. Administration of progesterone resulted in an increase in the expression of Abhd5 gene (whose product increases ATGL activity) and G0s2 gene (whose product decreases ATGL activity) in the inguinal WAT of female rats. Mifepristone, a selective antagonist of progesterone receptor, abolished the effect of progesterone on Lipe, Abhd5 and G0s2 genes expression in the inguinal WAT. The decrease in Lipe and the increase in Abhd5 and G0s2 genes expression was associated with lower rate of stimulated lipolysis. Administration of progesterone exerted no effect on Lipe, Abhd5 and G0s2 genes expression and stimulated lipolysis in the retroperitoneal WAT of females, as well as in the inguinal, epididymal and retroperitoneal WAT of males. In conclusion, our findings suggest that progesterone decreases the rate of lipolysis in the inguinal WAT of female rats, inhibiting the activity of both ATGL (by stimulating synthesis of G0S2 - specific inhibitor of the enzyme) and HSL (due to inhibition of Lipe gene expression).

Decreased serum platelet derived growth factor BB levels in acute and increased in chronic pancreatitis.

AIM: To examine circulating growth factor concentrations in patients with acute pancreatitis (AP) and chronic pancreatitis (CP), and walled-off pancreatic necrosis (WOPN). METHODS: Forty patients with mild AP, 40 patients with alcoholic CP, 33 patients with WOPN and 40 healthy subjects were examined. Serum concentrations of platelet derived growth factor BB (PDGF-BB), transforming growth factor ß-1 (TGFß-1), chemerin and high-mobility group box chromosomal protein 1 (HMBG1) were assayed by enzyme linked immunosorbent assay. RESULTS: Patients with mild AP and those with WOPN had significantly lower serum levels of PDGF-BB compared to healthy subjects (4.0 ± 0.61 ng/mL vs 6.2 ± 0.76 ng/mL, P = 0.027, and 1.60 ± 0.31 ng/mL vs 6.2 ± 0.76 ng/mL, P < 0.001, respectively), while CP was associated with higher serum levels of PDGF-BB (12 ± 1.3 ng/mL vs 6.2 ± 0.76 ng/mL, P < 0.001). Circulating TGFß-1 and chemerin levels were elevated in CP patients (57 ± 3.6 ng/mL vs 39 ± 3.6 ng/mL, P < 0.001 and 73 ± 7.2 ng/mL vs 48 ± 2.3 ng/mL, P < 0.001, respectively), but not in patients with AP and WOPN. No significant changes in serum HMBG1 levels were found either in patients with AP, WOPN or CP. CONCLUSION: The serum levels of some growth factors and cytokines differ significantly in AP, WOPN and CP. These data suggest that selected growth factors and cytokines may be considered as potential diagnostic biomarkers in patients with pancreatic diseases.