Biomedical subjects

Anna A Gybina

Publications and source records attributed to Anna A Gybina.

5 recordsLinked to original sources

PubMed2006

Copper transport protein (Ctr1) levels in mice are tissue specific and dependent on copper status.

Studies were conducted to determine distribution of the copper transporter, Ctr1, a transmembrane protein responsible for cellular copper uptake, in adult mice and in suckling mice nursed by either copper-adequate (Cu+) or copper-deficient (Cu-) dams. Western immunoblot analyses, using immunopurified antibody, detected monomeric (23 kDa) and oligomeric forms of Ctr1 in the membrane fraction of several mouse organs. Immunohistochemical analyses detected abundant Ctr1 protein in liver canaliculi; kidney cortex tubules; small intestinal enterocytes; the choroid plexus and capillaries of brain; intercalated disks of heart; mature spermatozoa; epithelium of mammary ducts; and the pigment epithelium, outer limiting membrane, and outer plexiform layer of the retina. Duodenal Ctr1 distribution was different in the adult compared with suckling mice; adult mice demonstrated strong intracellular staining of the enterocyte, whereas apical staining predominated in suckling mice. In Cu- mice at postnatal d 16 (P16), Ctr1 staining was augmented in kidney, duodenum, and choroid plexus, compared with Cu+ mice. Brain immunoblot data indicated that Ctr1 protein in membrane fractions of Cu- mice was 56% higher than Cu+ mice. Cu- mice had lower hemoglobin (56% of Cu+), and lower copper concentration (% of Cu+) in liver (15%), brain (26%), and kidney (65%). These results suggest that Ctr1 protein is expressed in multiple tissues and found in higher levels in selected organs after perinatal copper deficiency. Enhanced Ctr1 levels and redistribution might compensate in part for the decrease in copper supply. Mechanisms for the enhancement in Ctr1 staining remain to be established.

Animals↗

PubMed2005

Peptidylglycine-alpha-amidating monooxygenase activity and protein are lower in copper-deficient rats and suckling copper-deficient mice.

Peptidylglycine-alpha-amidating monooxygenase (PAM) is a copper-dependent enzyme involved in peptide posttranslational activation. Dietary Cu deficiency (Cu-) was studied to determine if lower PAM activity was due to reduction in protein or cofactor limitation. PAM activity was lower in cardiac atria of Cu- rats than Cu-adequate (Cu+) rats and there was a 50% equivalent reduction in PAM protein. No reduction in Cu- rat midbrain PAM protein was detected although PAM activity was reduced 40%. In 12-day-old (P12) mouse pups derived from dams that began Cu deficiency on day 7 of gestation, there was a parallel reduction in brain PAM activity and protein of 40-50%. PAM mRNA levels assessed in atria and brains from Cu+ and Cu- rats and mice were not altered by dietary treatment, suggesting a posttranscriptional mechanism for lower PAM protein when Cu is limiting in the cell, perhaps due to enhanced apoprotein turnover.

Animals↗

PubMed2005

Rat brain iron concentration is lower following perinatal copper deficiency.

Experiments performed with Holtzman rats demonstrated that brain iron (Fe) was lower by postnatal day 13 (P13) in pups born and nursed by dams that began copper-deficient (-Cu) treatment at embryonic day 7. Transcardial perfusion of P24-P26 males and females to remove blood Fe contamination revealed that brain Fe was still 20% lower in -Cu than +Cu rats. Estimated blood content of brain for -Cu rats was greater than for +Cu rats; for all groups, values ranged between 0.43 and 1.03%. Using group-specific data and regression analyses, r = 0.99, relating blood Fe to hemoglobin, brain Fe in non-perfused rats in a replicate study was lower by 33% at P13 and 39% at P24 in -Cu rats. Brain extracts from these rats and from P50 rats from a post-weaning model were compared by immunoblotting for transferrin receptor (TfR1). P24 brain -Cu/+Cu TfR1 was 3.08, suggesting that brains of -Cu rats were indeed Fe deficient. This ratio in P13 rats was 1.44, p < 0.05. No change in P50 -Cu rat brain TfR1 or Fe content was detected despite a 50% reduction in plasma Fe. The results suggest that brain Fe accumulation depends on adequate Cu nutriture during perinatal development.

Animals↗

PubMed2004

Intracellular copper transport in mammals.

Copper is an essential cofactor for approximately a dozen cuproenzymes in which copper is bound to specific amino acid residues in an active site. However, free cuprous ions react readily with hydrogen peroxide to yield the deleterious hydroxyl radical. Therefore, copper homeostasis is regulated very tightly, and unbound copper is extremely low in concentration. Copper imported by the plasma membrane transport protein Ctr1 rapidly binds to intracellular copper chaperone proteins. Atox1 delivers copper to the secretory pathway and docks with either copper-transporting ATPase ATP7B in the liver or ATP7A in other cells. ATP7B directs copper to plasma ceruloplasmin or to biliary excretion in concert with a newly discovered chaperone, Murr1, the protein missing in canine copper toxicosis. ATP7A directs copper within the transgolgi network to the proteins dopamine beta-monooxgenase, peptidylglycine alpha-amidating monooxygenase, lysyl oxidase, and tyrosinase, depending on the cell type. CCS is the copper chaperone for Cu,Zn-superoxide dismutase; it delivers copper in the cytoplasm and intermitochondrial space. Cox17 delivers copper to mitochondria to cytochrome c oxidase via the chaperones Cox11, Sco1, and Sco2. Other copper chaperones may exist and might include metallothionein and amyloid precursor protein (APP). Genetic and nutritional studies have illustrated the essential nature of these copper-binding proteins; alterations in their levels are associated with severe pathology.

Adenosine Triphosphatases↗

PubMed2003

Increased rat brain cytochrome c correlates with degree of perinatal copper deficiency rather than apoptosis.

Reductions in copper due to dietary restriction or transporter deficiency in brindled mice or humans with Menkes disease lead to reduced cuproenzyme activities, mitochondrial abnormalities, neurodegeneration and early mortality. The mechanisms for observed neuropathology remain unknown. Some researchers studying mutant mice suggest brain apoptosis as a possible factor based on changes in transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and increased cytosolic cytochrome c and decreased Bcl-2 levels. Perinatal copper deficiency was induced in Holtzman rats during late gestation and lactation to investigate the role of apoptosis in the developing brain. Analysis of 13- and 24-d-old (P13 and P24) brains from male copper-deficient and copper-adequate rats revealed no difference in cytosolic cytochrome c or total Bcl-2 levels. Cerebellar TUNEL staining and caspase-3 activity were higher in the P12 copper-deficient than in the copper-adequate pups. However, TUNEL staining decreased and caspase-3 activity was not detected at P24 even though pups were more copper deficient based on cortex copper, Cu, Zn-superoxide dismutase and cytochrome c oxidase activities. This suggests that neuronal apoptosis is not enhanced by dietary copper deficiency in the brain. Lower Bcl-2 levels were detected in the copper-deficient rat hearts, consistent with apoptotic processes in mice reported by others. A robust enhancement of cytochrome c was observed in the total brain extracts and purified brain mitochondria of copper-deficient pups. Higher cytochrome c appeared to be correlated with the degree of copper deficiency and seemed to be associated with increased mitochondrial mass, because higher levels of voltage-dependent anion channel and mitochondrial complex I were also detected. The biochemical mechanisms for elevated cytochrome c are not known nor are the physiological consequences.

Animals↗