RESUMO
Kidneys play an especial role in copper redistribution in the organism. The epithelial cells of proximal tubules perform the functions of both copper uptake from the primary urine and release to the blood. These cells are equipped on their apical and basal membrane with copper transporters CTR1 and ATP7A. Mosaic mutant mice displaying a functional dysfunction of ATP7A are an established model of Menkes disease. These mice exhibit systemic copper deficiency despite renal copper overload, enhanced by copper therapy, which is indispensable for their life span extension. The aim of this study was to analyze the expression of Slc31a1 and Slc31a2 genes (encoding CTR1/CTR2 proteins) and the cellular localization of the CTR1 protein in suckling, young and adult mosaic mutants. Our results indicate that in the kidney of both intact and copper-injected 14-day-old mutants showing high renal copper content, CTR1 mRNA level is not up-regulated compared to wild-type mice given a copper injection. The expression of the Slc31a1 gene in 45-day-old mice is even reduced compared with intact wild-type animals. In suckling and young copper-injected mutants, the CTR1 protein is relocalized from the apical membrane to the cytoplasm of epithelial cells of proximal tubules, the process which prevents copper transport from the primary urine and, thus, protects cells against copper toxicity.
Assuntos
Transportador de Cobre 1 , Cobre , Células Epiteliais , Túbulos Renais Proximais , Síndrome dos Cabelos Torcidos , Animais , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Membrana Celular/genética , Membrana Celular/metabolismo , Cobre/metabolismo , Cobre/toxicidade , Transportador de Cobre 1/genética , Transportador de Cobre 1/metabolismo , ATPases Transportadoras de Cobre/genética , ATPases Transportadoras de Cobre/metabolismo , Citoplasma/genética , Citoplasma/metabolismo , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Expressão Gênica , Túbulos Renais Proximais/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Síndrome dos Cabelos Torcidos/etiologia , Síndrome dos Cabelos Torcidos/genética , Síndrome dos Cabelos Torcidos/metabolismo , Camundongos , Transporte Proteico/genética , Transporte Proteico/fisiologia , RNA Mensageiro/metabolismo , Proteínas SLC31/genética , Proteínas SLC31/metabolismoRESUMO
Hyperaccumulators typically refer to plants that absorb and tolerate elevated amounts of heavy metals. Due to their unique metal trafficking abilities, hyperaccumulators are promising candidates for bioremediation applications. However, compared to bacteria-based bioremediation systems, plant life cycle is long and growing conditions are difficult to maintain hindering their adoption. Herein, we combine the robust growth and engineerability of bacteria with the unique waste management mechanisms of plants by using a more tractable platform-the common baker's yeast-to create plant-like hyperaccumulators. Through overexpression of metal transporters and engineering metal trafficking pathways, engineered yeast strains are able to sequester metals at concentrations 10-100 times more than established hyperaccumulator thresholds for chromium, arsenic, and cadmium. Strains are further engineered to be selective for either cadmium or strontium removal, specifically for radioactive Sr90. Overall, this work presents a systematic approach for transforming yeast into metal hyperaccumulators that are as effective as their plant counterparts.