Pyridine Nucleotide Cycling and Control of Intracellular Redox State in Relation to Poly (ADP-Ribose) Polymerase Activity and Nuclear Localization of Glutathione during Exponential Growth of Arabidopsis Cells in Culture

Abstract

Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione (GSH) to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly (ADP-ribose) polymerase (PARP) activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form (NAD)-plus-nicotinamide adenine dinucleotide, reduced form (NADH) pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form (NADP)-plus-nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is maintained by interplay of the major redox pyridine nucleotides, glutathione, and ascorbate pools. The correlation between PARP expression and activity and GSH accumulation and the finding that GSH can be recruited to the nucleus suggest a relationship between redox regulation and nuclear enzyme activity.

Ectopic phytocystatin expression increases nodule numbers and influences the responses of soybean (Glycine max) to nitrogen deficiency

“…Real-time (qPCR) was performed essentially as described previously by Pellny et al (2009). RNA was extracted from the three plants representing each line (OCI-1, OCI-2 and wild-type control) previously used for cysteine protease activity measurement.…”

The Transcription Factor ABI4 Is Required for the Ascorbic Acid–Dependent Regulation of Growth and Regulation of Jasmonate-Dependent Defense Signaling Pathways inArabidopsis

“…Ascorbate has functions distinct from those of glutathione in the control of cell proliferation (Noctor et al, 2000;Potters et al, 2002;Pellny et al, 2009;Diaz Vivancos et al, 2010a, 2010b. Ascorbate also participates in the synthesis (Sommer-Knudsen et al, 1998) and cross-linking of cell wall components (Smirnoff, 2000;Pellny et al, 2009) and thus participates in the redox regulation of cell expansion (Esaka, 1998;Kato and Esaka, 2000).…”

Defects in a New Class of Sulfate/Anion Transporter Link Sulfur Acclimation Responses to Intracellular Glutathione Levels and Cell Cycle Control

“…Our finding that glutathione overaccumulates in smt15-1 but not in sac mutants is a possible clue for understanding the cell cycle defects in this mutant. Glutathione levels and subcellular localization have been linked to cell cycle control in both plants and animals (Markovic et al, 2007;Pallardó et al, 2009;Pellny et al, 2009;Diaz Vivancos et al, 2010a, 2010b, although its specific impact on cell cycle-related processes is not completely understood. Changing the redox state of cell cycle regulators through glutathionylation has also been shown to influence the cell cycle (Chiu and Dawes, 2012).…”