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Pierre Richaud

Publications and source records attributed to Pierre Richaud.

9 recordsLinked to original sources
PubMed2005

HMA1, a new Cu-ATPase of the chloroplast envelope, is essential for growth under adverse light conditions.

Although ions play important roles in the cell and chloroplast metabolism, little is known about ion transport across the chloroplast envelope. Using a proteomic approach specifically targeted to the Arabidopsis chloroplast envelope, we have identified HMA1, which belongs to the metal-transporting P1B-type ATPases family. HMA1 is mainly expressed in green tissues, and we validated its chloroplast envelope localization. Yeast expression experiments demonstrated that HMA1 is involved in copper homeostasis and that deletion of its N-terminal His-domain partially affects the metal transport. Characterization of hma1 Arabidopsis mutants revealed a lower chloroplast copper content and a diminution of the total chloroplast superoxide dismutase activity. No effect was observed on the plastocyanin content in these lines. The hma1 insertional mutants grew like WT plants in standard condition but presented a photosensitivity phenotype under high light. Finally, direct biochemical ATPase assays performed on purified chloroplast envelope membranes showed that the ATPase activity of HMA1 is specifically stimulated by copper. Our results demonstrate that HMA1 offers an additional way to the previously characterized chloroplast envelope Cu-ATPase PAA1 to import copper in the chloroplast.

Adenosine Triphosphatases↗
PubMed2005

Heavy metal transport by AtHMA4 involves the N-terminal degenerated metal binding domain and the C-terminal His11 stretch.

The Arabidopsis thaliana AtHMA4 is a P1B-type ATPase that clusters with the Zn/Cd/Pb/Co subgroup. It has been previously shown, by heterologous expression and the study of AtHMA4 knockout or overexpressing lines in Arabidopsis , that AtHMA4 is implicated in zinc homeostasis and cadmium tolerance. Here, we report the study of the heterologous expression of AtHMA4 in the yeast Saccharomyces cerevisiae. AtHMA4 expression resulted in an increased tolerance to Zn, Cd and Pb and to a phenotypic complementation of hypersensitive mutants. In contrast, an increased sensitivity towards Co was observed. An AtHMA4::GFP fusion protein was observed in endocytic vesicles and at the yeast plasma membrane. Mutagenesis of the cysteine and glutamate residues from the N-ter degenerated heavy metal binding domain impaired the function of AtHMA4. It was also the case when the C-ter His11 stretch was deleted, giving evidence that these amino acids are essential for the AtHMA4 binding/translocation of metals.

Adenosine Triphosphatases↗
PubMed2004

Overexpression of AtHMA4 enhances root-to-shoot translocation of zinc and cadmium and plant metal tolerance.

AtHMA4 is an Arabidopsis thaliana P1B-ATPase which transports Zn and Cd. Here, we demonstrate that AtHMA4 is localized at the plasma membrane and expressed in tissues surrounding the root vascular vessels. The ectopic overexpression of AtHMA4 improved the root growth in the presence of toxic concentrations of Zn, Cd and Co. A null mutant exhibited a lower translocation of Zn and Cd from the roots to shoot. In contrast, the AtHMA4 overexpressing lines displayed an increase in the zinc and cadmium shoot content. Altogether, these results strongly indicate that AtHMA4 plays a role in metal loading in the xylem.

Adenosine Triphosphatases↗
PubMed2004

AtHMA3, a plant P1B-ATPase, functions as a Cd/Pb transporter in yeast.

The Arabidopsis thaliana AtHMA3 protein belongs to the P(1B)-adenosine triphosphatase (ATPase) transporter family, involved in heavy metal transport. Functional expression of AtHMA3 phenotypically complements the Cd/Pb-hypersensitive yeast strain Deltaycf1, but not the Zn-hypersensitive mutant Deltazrc1. AtHMA3-complemented Deltaycf1 cells accumulate the same amount of cadmium as YCF1-complemented Deltaycf1 cells or wild-type cells, suggesting that AtHMA3 carries out an intracellular sequestration of Cd. A mutant of AtHMA3 altered in the P-ATPase phosphorylation domain did not complement Deltaycf1, suggesting that metal transport rather than chelation is involved. The fusion protein AtHMA3::green fluorescent protein (GFP) is localized at the vacuole, consistent with a role in the influx of cadmium into the vacuolar compartment. In A. thaliana, the mRNA of AtHMA3 was detected mainly in roots, old rosette leaves and cauline leaves. The expression levels were not affected by cadmium or zinc treatments.

Adenosine Triphosphatases↗
PubMed2004

[Prostatic cancer].

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Antineoplastic Agents↗
PubMed2003

[Effect of bicalutamide 150 mg, after 3 years of median follow-up, in non-metastatic prostatic cancer].

OBJECTIVE: To determine the efficacy and safety of bicalutamide, at the dose of 150 mg per day, as first-line monotherapy or as curative adjuvant therapy in patients with non-metastatic prostate cancer, and to investigate the possibility of a greater benefit for certain patient subgroups. MATERIAL AND METHODS: This article recalls the preliminary results of an international endocrine therapy programme comprising three double-blind placebo-controlled clinical trials in patients with non-metastatic prostate cancer (T1-T4. Nx/N0/N1, M0). Patients were randomized to receive either 150 mg/day of bicalutamide, or placebo, as an adjuvant to radical prostatectomy, external beam radiotherapy or in the context of watchful waiting. The main endpoints were the time to objective clinical progression and overall survival. The combined data of the three trials were submitted to intent-to-treat analysis. The authors also report the results of exploratory studies performed as a function of the type of treatment and prognostic factors. RESULTS: After a median follow-up of 3 years of a sample size of 8,113 patients, objective clinical progression was observed in 9% of patients of the bicalutamide group (4,052 patients) and in 13.8% of patients of the placebo group (4,061 patients), corresponding to a 42% relative risk reduction (RR: 0.58; p << 0.0001). Reduction of the risk of disease progression was observed for the entire study population regardless of primary treatment, stage of disease or usual prognostic factors. This reduction was more marked for patients presenting poor prognostic factors. Data concerning overall survival are not available due to insufficient follow-up. Treatment was well tolerated. The adverse effects most frequently reported in the bicalutamide group were gynaecomastia and breast pain. CONCLUSION: After a median follow-up of three years, bicalutamide, as first-line monotherapy or as curative adjuvant therapy, significantly reduced the risk of objective clinical disease progression in patients with non-metastatic prostate cancer. Exploratory analyses demonstrate that the benefit of bicalutamide appeared to be greater for patient with poor prognostic factors. Survival data are not yet available.

Adult↗
PubMed2002

Surgical resection and radiotherapy for primary retroperitoneal soft tissue sarcoma.

METHODS AND MATERIALS: Forty-five patients were consecutively treated for primary retroperitoneal soft tissue sarcoma with surgery in combination with radiation therapy in the same institution. The median follow-up time was 53 months (7-108). RESULTS: Seventeen (38%) patients had clear microscopic margins (R0 resection), 26 patients (58%) had gross complete surgical excision (R1 resection) and two patients (4%) had a macroscopic residual disease (R2 resection). External radiotherapy doses ranged from 40.8 to 59.4 Gy (mean and median: 49 Gy). Seventeen patients underwent intraoperative radiation therapy (IORT). Moreover, 11 patients received chemotherapy. The overall 1-, 2-, and 5-year survival for all 45 patients were 93, 85 and 60%, respectively. The 1-, 2-, and 5-year locoregional relapse-free rate for the whole group was 91, 70 and 40%, respectively. In univariate analysis, quality of surgery was the only variable to show a significant effect for overall survival (P=0.0386) and for local control (P=0.0059). Tumor size and tumor grade had no statistically significant effect. For the patients receiving IORT+external beam radiation therapy, no difference was observed for survival or locoregional control. The most frequent acute side effects treatment complications were radiation-induced nausea or vomiting (42%) and moderate enteritis (30%). Significant late morbidity was observed for two patients. CONCLUSIONS: This study confirms the feasibility of external postoperative radiotherapy with an acceptable level of toxicity. However, the high rate of local relapses (especially in field of radiation) does not demonstrate the usefulness of radiotherapy at the level of dose used and further preferably randomized studies should be planned.

Adult↗