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Molecular mechanisms of copper uptake and
distribution
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Copper-binding proteins
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Cu is also a potent cytotoxin when allowed to
accumulate in excess of cellular needs.
Cu readily participates in reactions that result
in the production of highly reactive oxygen
species (ROS) including hydroxyl radical
Cu
Cu2
Cu displacing other metal cofactors from their
natural ligands in key cellular signalling
proteins.
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Pathway of copper in the body
Copper imbalances in humans lead to serious
diseases such as Menkes syndrome or Wilson disease
Additionally , copper has been strongly
implicated in amyotropic lateral sclerosis
(FALS), Alzheimers disease and prion disease of
neuronal spongiform encephalopathy
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Model for human Cu absorbtion

• Two possible candidate proteins responsible for
  the absorption of dietary copper have emerged
• divalent metal transport 1 (DMT1)
• copper transport 1 (Ctr1)

? reductase
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hCtr1 and its role in body copper homeostasis
ScCtr1, ScCtr3 S. cereviasiae Ctr SpCtr4,
SpCtr5 S. pombe Ctr h/m Ctr1 human and mouse
Ctr1 AtCopt1 A. thaliana copper transport
Proposed topological structure of the Ctr family
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mucosal
serosal
hCtr1
?
Cu
Cu
DMT1
Stomach and small intestine cells
Menkes disease
Copper efflux across the basolateral surface of
the enterocytes into the portal circulation is
defective in Menkes disease patients and result
in accumulation of copper in the enterocytes and
overall copper deficiency in the body
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Menkes Cu-ATPase (ATP7A/MNK)
ATP7A mRNA is expressed in the muscle, kidney,
lung and brain, but only a trace amount in liver
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The cellular pathways of copper
mucosal
serosal
hCtr1
ATP7A
Cu efflux
Cu
Cu
Apo-lysyl oxidase
Lysyl oxidase
metallothioneine
Small intestine cells
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Wilson disease
Most of the newly absorbed copper is normally
taken up by the liver. In cases of copper
overload, excess copper is excreted in the bile
and this process is blocked in Wilson disease, as
is the delivery of copper to ceruloplasmin.
Wilson Cu-ATPase (ATP7B/WND)
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The normal copper transport pathway
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Homology modelling of ATP7B based on the known
structure of SERCA1a. Actuator domain (A)
N-terminal metal-binding domain (M)
nucleotide-binding domain (N) phosphorylation
domain (P).
The proposed catalytic cycle of copper transport
by ATP7B based on models proposed for classical
ATPases and functional studies to date.
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Copper and prion disease
The primary structure of the human prion protein
(PrPc)
The prion protein at the synapse
The prion protein and copper binding
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Obiettivi

• Analisi dei fenomeni di trasporto cellulare del
  rame, nonché i principali meccanismi regolatori
  del trasporto e delle eventuali interazioni con
  substrati chelanti il rame come cuprizone,
• aminoacidi e dipeptidi.

• Analisi dellassorbimento intestinale ed al
  trasporto a livello di cellule nervose, valutando
  anche gli aspetti legati allanomalo accumulo o
  deplezione intracellulare di rame correlabili a
  malfunzionamento dei trasportatori.

• Studio della regolazione da parte del rame dei
  meccanismi di endocitosi di proteine prioniche
  non patogene allo scopo di comprendere la
  funzione della proteina prionica cellulare ed
  eventualmente dei meccanismi patogenetici della
  malattia prionica.

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Intestinal copper transport
serosal
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Conclusione

• I primi dati suggeriscono che
• Il cuprizone non è in grado di attraversare la
  parete intestinale dellileo di ratto suggerendo
  che i suoi effetti neuro-tossici ottenuti per via
  alimentare siano mediati da carenze indotte di
  rame
• 2) Leccesso o la carenza di rame a livello di
  cellule di neuroblastoma indotta dal cuprizone o
  da un idrolizzato proteico è in grado di
  modificare lespressione del mRNA codificante per
  PrPC