Purification of a novel aminopeptidase from the pollen of Parietaria judaica that alters epithelial integrity and degrades neuropeptides.
BACKGROUND
Parietaria judaica pollen is a common cause of pollinosis in the Mediterranean area.


OBJECTIVE
This study sought to purify and characterize the peptidase responsible for the majority of proteolytic activity present in the pollen extract of P judaica, and to investigate its contribution to the allergic response.


METHODS
A serial of chromatographic steps was applied to isolate the peptidase from P judaica's pollen, and its biochemical properties were determined. Bioactive peptides present in the airways were incubated with the peptidase, and their degradation was visualized by direct protein sequencing. In addition, we measured the cellular detachment, by methylene blue binding assay, of an airway-derived epithelial cell line (A549) in the presence of the peptidase, and visualized, by Western blot, the degradation of proteins from intercellular junctions.


RESULTS
We purified a 98-kDa peptidase from the pollen of P judaica that was classified as an aminopeptidase on the basis of its biochemical properties and internal amino acid sequence. The aminopeptidase was able to degrade bioactive peptides. Moreover, the aminopeptidase caused cellular detachment of A549 cell line and degradation of occludin and E-cadherin.


CONCLUSIONS
Our results suggest that the P judaica aminopeptidase can alter the integrity of the epithelium barrier by degrading occludin as well as E-cadherin. In addition, P judaica aminopeptidase can degrade bioactive peptides, which can exacerbate the overall bronchoconstrictive effect detected in asthmatic lungs.


CONCLUSIONS
The novel aminopeptidase described here could constitute a relevant therapeutic target in the treatment of allergic disorders induced by the pollen of P judaica.
Cortes
Luísa
L
Center for Neurosciences and Cell Biology, University of Coimbra, Portugal.
Carvalho
Ana Luísa
AL
Todo-Bom
Ana
A
Faro
Carlos
C
Pires
Euclides
E
Veríssimo
Paula
P
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000302:isolation & purification* / Q000494:pharmacology / Q000502:physiology*; D015820:Cadherins / Q000187:drug effects; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000187:drug effects; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000187:drug effects; D062793:Occludin; D032403:Parietaria / Q000737:chemistry* / Q000276:immunology; D011058:Pollen / Q000737:chemistry* / Q000276:immunology
D015820:Cadherins; D008565:Membrane Proteins; D009479:Neuropeptides; C568985:OCLN protein, human; D062793:Occludin; D000626:Aminopeptidases; C515152:Pj-peptidase, Parietaria judaica