Purificació, caracterització i regulació de la metal.lotioneïna III (o "growth inhibitory factor") de cervell de rata. Comparació amb la MT-III humana i implicacions per a patologies neurodegenerative

Metallothionens (MT) are a family of low molecular-weight, cysteine-rich, heavy metal (Zn, Cu) binding proteins. Based in the order of elution in ion-exchange chromatography, MTs have been known as MT-I and MT-II, but recently a new isoform has been discovered, the so called MT-III or growth inhibitory factor (GIF), which is expressed only in the nervous system. This isoform has the capacity for decreasing the survival and formation of neurites of cortical neurons incubated "in vitro" in the presence of brain extracts obtained from patients with Alzheimer disease. Data just published, however, demonstrate that human MT-III (and also MT-I) promotes the survival of neurons "in vitro" in the absence of brain extracts, and challenge previous results that suggested a down-regulation of the MT-III gene in Alzheimer disease. The neurotrophic potential of these proteins, and its putative relatio