Iron and copper metabolism

Arredondo, Miguel; Núñez, Marco T.

doi:10.1016/j.mam.2005.07.010

Cited by 432 publications

(304 citation statements)

References 84 publications

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“…Cu + is highly toxic to living cells (37). Organisms need to maintain copper homeostasis for many processes such as energy transduction, iron mobilization, and oxidative stress responses (38). High copper levels cause lignin accumulation in plants (39,40), and copper deficiency decreases plant lignin content (41).…”

Section: Discussionmentioning

confidence: 99%

Ptr-miR397a is a negative regulator of laccase genes affecting lignin content in Populus trichocarpa

Wei

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

337

338

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Laccases, as early as 1959, were proposed to catalyze the oxidative polymerization of monolignols. Genetic evidence in support of this hypothesis has been elusive due to functional redundancy of laccase genes. An Arabidopsis double mutant demonstrated the involvement of laccases in lignin biosynthesis. We previously identified a subset of laccase genes to be targets of a microRNA (miRNA) ptr-miR397a in Populus trichocarpa. To elucidate the roles of ptr-miR397a and its targets, we characterized the laccase gene family and identified 49 laccase gene models, of which 29 were predicted to be targets of ptr-miR397a. We overexpressed PtrMIR397a in transgenic P. trichocarpa. In each of all nine transgenic lines tested, 17 PtrLACs were down-regulated as analyzed by RNAseq. Transgenic lines with severe reduction in the expression of these laccase genes resulted in an ∼40% decrease in the total laccase activity. Overexpression of Ptr-MIR397a in these transgenic lines also reduced lignin content, whereas levels of all monolignol biosynthetic gene transcripts remained unchanged. A hierarchical genetic regulatory network (GRN) built by a bottom-up graphic Gaussian model algorithm provides additional support for a role of ptr-miR397a as a negative regulator of laccases for lignin biosynthesis. Full transcriptome-based differential gene expression in the overexpressed transgenics and protein domain analyses implicate previously unidentified transcription factors and their targets in an extended hierarchical GRN including ptr-miR397a and laccases that coregulate lignin biosynthesis in wood formation. Ptr-miR397a, laccases, and other regulatory components of this network may provide additional strategies for genetic manipulation of lignin content.L ignin, an abundant biological polymer affecting the ecology of the terrestrial biosphere, is vital for the integrity of plant cell walls, the strength of stems, and resistance against pests and pathogens (1). Lignin is also a major barrier in the pulping and biomass-to-ethanol processes (2-4). For extracting cellulose (pulping) or for enzymatic degradation of cellulose for bioethanol, harsh chemical or physical treatments are used to reduce interactions with lignin or other cell wall components (2-4). Reducing lignin content or altering lignin structure to reduce its recalcitrance are major goals for more efficient processing.Lignin is polymerized primarily from three monolignol precursors, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol (1, 5). Over five decades, efforts have been made to understand the biosynthesis of the primary monolignols and to modify the quantity or composition of lignin. The polymerization of monolignols into a lignin polymer has long been thought to occur through oxidative polymerization catalyzed by either laccases or peroxidases (6). The mechanisms and specificity of the roles of the oxidative enzymes in lignin polymerization have been controversial (7).Laccases (EC. 1.10.3.2) are multicopper oxidoreductases. Plant laccase was the first enzyme sh...

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Section: Discussionmentioning

confidence: 99%

Ptr-miR397a is a negative regulator of laccase genes affecting lignin content in Populus trichocarpa

Wei

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

337

338

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“…Fe is an essential element involved in several biological processes ranging from electron transport to ATP production, heme and DNA synthesis (Eisenstein, 2000;Arredondo and Nunez, 2005). However, low tissue Fe isn't expected at tissues surrounding a tumor, as literature suggests that excessive Fe is associated with adverse effects resulted from oxidative stress induced (Reddy and Clark, 2004).…”

Section: Discussionmentioning

confidence: 99%

Serum Levels of Trace Elements in Patients with Prostate Cancer

Kaba¹,

Pirinççi²,

Yüksel³

et al. 2014

Asian Pacific Journal of Cancer Prevention

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Background: Trace elements are major components of biological structures; however, excessive levels of these elements can be toxic. Materials and Methods: In the present study, serum levels of trace elements were measured in 30 patients with newly diagnosed as prostate cancer and 32 healthy volunteer by using furnace atomic absorption spectrophotometry. Results: It was found that there was an increase in serum levels of Co, Cu, Mg and Pb (p<0.05), whereas a decrease in serum levels of Fe, Mn, and Zn levels in patients with prostate cancer (p<0.05). Conclusions: These changes may be important in the pathogenesis of prostate cancers; however, further prospective studies are needed to identify relationships between prostate cancer and trace elements.

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“…Although a number of new, larger copper binding proteins have recently been identified in mammalian cells, most of these are bound to intracellular membranes or the plasma membrane (ATP7A and B; hephaestin; DMT1; CTR1) (Arredondo & Nunez 2005;Linder 2002;Puig & Thiele 2002). Prior studies had indicated it was larger than 100 kDa.…”

Section: Discussionmentioning

confidence: 99%

Copper binding components of blood plasma and organs, and their responses to influx of large doses of 65Cu, in the mouse

et al. 2008

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To establish for the first time how mice might differ from rats and humans in terms of copper transport, excretion, and copper binding proteins, plasma and organ cytosols from adult female C57CL6 mice were fractionated and analyzed by directly coupled size exclusion HPLC-ICP-MS, before and after i.p. injection of large doses of 65 Cu. Plasma from untreated mice had different proportions of Cu associated with transcuprein/macroglobulin, ceruloplasmin and albumin than in humans and rats, and two previously undetected copper peaks (Mr 700k and 15k) were observed. Cytosols had Cu peaks seen previously in rat liver (Mr >1000k, 45k and 11k) plus one of 110kDa. 65 Cu (141 μg) administered over 14h, initially loaded plasma albumin and mainly entered liver and kidney (especially 28kDa and 11kDa components). Components of other organs were less, but still significantly enriched. 63 Cu/ 65 Cu ratios returned almost to normal by 14d, indicating a robust system for excreting excess copper. We conclude that there are significant differences but also strong similarities in copper metabolism between mice, rats and humans; that the liver is able to buffer enormous changes in copper status; and that a large number of mammalian copper proteins remain to be identified.

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Iron and copper metabolism

Cited by 432 publications

References 84 publications

Ptr-miR397a is a negative regulator of laccase genes affecting lignin content in Populus trichocarpa

Ptr-miR397a is a negative regulator of laccase genes affecting lignin content in Populus trichocarpa

Serum Levels of Trace Elements in Patients with Prostate Cancer

Copper binding components of blood plasma and organs, and their responses to influx of large doses of 65Cu, in the mouse

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