Effect of Phoneutria nigriventer venom on the expression of junctional protein and P-gp efflux pump function in the blood-brain barrier.
Phoneutria nigriventer spider venom (PNV) contains Ca(2+), K(+) and Na(+) channel-acting peptides that affect neurotransmitter release and causes excitotoxicity in PNS and CNS. It has been demonstrated that PNV causes blood-brain barrier (BBB) breakdown of hippocampal microvessels time-dependently through enhanced microtubule-mediated vesicular transport. Herein, it is hypothesized that PNV can cause BBB breakdown in the hippocampus and cerebellum time-dependently through other molecular mechanisms. The BBB integrity was assessed through the analysis of expression of Poly-glycoprotein (P-gp) efflux transporter protein, laminin from basement membrane and endothelial tight junctional and adhesion junctional (TJ/AJ) proteins. Phosphatase and tensin homolog (PTEN) and protein phosphatase 2A (PP2A) expression, which are known to have a role in the phosphorylation of junctional proteins and BBB opening, were also investigated. Astrocytes P-gp activity was determined by flow cytometry. The study demonstrated temporary decreased expression of laminin, TJ and AJ proteins (ZO1//occludin//claudin-5//beta-catenin) and P-gp (more prominently in hippocampus), which was completely or partially resolved between 2 and 5 h (and more quickly for cerebellum). PNV inhibited P-gp activity in astrocytes. PP2A phosphorylation, which inhibits the enzyme activity, was increased in both regions (15-45 min); however the phosphorylation level returned to baseline after 2 h. In conclusion, PNV disrupts paracellular transport in the BBB and possesses substrates for the active P-gp efflux transporter located in the BBB complex. Further studies into cellular mechanisms of astrocyte/endothelial interactions, using PNV as tool, may identify how astrocytes regulate the BBB, a characteristic that may be useful for the temporary opening of the BBB.
Departamento de Histologia e Embriologia, Instituto de Biologia, C.P. 6109, Universidade Estadual de Campinas, Campinas, SP 13087-130, Brazil.
Catarina
C
Rapôso
Paulo Alexandre Miranda
PA
Odorissi
Alexandre L R
AL
Oliveira
Hiroshi
H
Aoyama
Carmen Verissima
CV
Ferreira
Liana
L
Verinaud
Karina
K
Fontana
Roberta R
RR
Ruela-de-Sousa
Maria Alice
MA
da Cruz-Höfling
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007797:Laminin / Q000096:biosynthesis; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D020258:Neurotoxicity Syndromes / Q000378:metabolism / Q000503:physiopathology; D009498:Neurotoxins / Q000494:pharmacology*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology*; D013112:Spiders / Q000737:chemistry*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007797:Laminin; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; D013111:Spider Venoms