INVESTIGADORES
FAILLACE Maria Paula
congresos y reuniones científicas
Título:
REGULATION OF EXTRACELLULAR ATP IN THE VERTEBRATE RETINA: ECTONUCLEOTIDASES LOCALIZATION AND ACTIVITY
Autor/es:
MARIA PAULA FAILLACE, MARIA JIMENA RICATTI, PABLO J. SCHWARZBAUM AND LIONEL D. ALFIE
Lugar:
Hilton, Puerto Madero, Ciudad de Buenos Aires, Argentina
Reunión:
Congreso; XVII International Congress of Eye Research (ICER); 2006
Institución organizadora:
The International Society for Eye Research (ISER)
Resumen:
ATP released by neurons and
glia acts as a neurotransmitter and neuromodulator via specific
purinergic receptors in the nervous system. Extracellular ATP
concentrations are precisely regulated by ecto-nucleoside-triphosphate
diphosphohydrolases (ENTPDases, ectonucleotidases). ATP hydrolysis
products can also either act on specific purinergic receptors or be
further metabolized extracellularly to adenosine, a potent inhibitory
neuromodulator. We showed that two major subtypes of ectonucleotidases
(ENTPDase type 1 and 2) are expressed in zebrafish and mouse retina
both by western blot and immunohistochemistry. Both enzymes are
heterogeneously distributed among retinal layers and principally
expressed in the inner half of the retina. However, their expression
pattern overlaps only partially because ENTPDase type 2 also exhibits a
strong immunoreactivity on the outer plexiform layer. ENTPDases-like
activity was also demonstrated on retinal membranes, by using
radioactive nucleotides as substrates, in the presence of inhibitors of
all other likely present enzymes with either ATPase or phosphatase
activity. At present we are exploring ENTPDase subtypes expression on
different cell types and synaptic layers throughout mouse and zebrafish
retinas. To this end, we are comparing co-localization of
immunoreactivity for both ENTPDase subtypes and several retinal cells
and synaptic layers markers. In conclusion, the vertebrate retina
contains at least two different types of ENTPDases with ATPase
activity. These enzymes show a specific distribution on cell subtypes
and synaptic retinal layers. Since ENTPDase 1 produces AMP in a much
higher rate than ENTPDase 2, our results suggest a localized regulation
of extracellular adenosine levels as well as ATP/ADP extracellular
signaling.