Abnormal isoaspartyl residues in erythrocyte membranes from psoriatic patients

Spontaneous protein deamidation of labile asparagines (Asn), generating abnormal isoaspartyl residues (IsoAsp), is associated with cell aging and enhanced by an oxidative microenvironment. The presence of isopeptide bonds impairs protein structure/function and can trigger autoimmune responses. To mi...

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Bibliographic Details
Published in:Archives of Dermatological Research 2012-08, Vol.304 (6), p.475-479
Main Authors: D’Angelo, Stefania, Lembo, Serena, Flora, Filomena, De Bonis, Maria Luigia, Balato, Anna, Ayala, Fabio, Balato, Nicola, Galletti, Patrizia, Zappia, Vincenzo
Format: Article
Language:English
Subjects:
Adult
Aged
Dermatology
Erythrocyte Membrane - chemistry
Female
Humans
Isoaspartic Acid - analysis
Male
Medicine
Medicine & Public Health
Middle Aged
Psoriasis - blood
Short Communication
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Summary:Spontaneous protein deamidation of labile asparagines (Asn), generating abnormal isoaspartyl residues (IsoAsp), is associated with cell aging and enhanced by an oxidative microenvironment. The presence of isopeptide bonds impairs protein structure/function and can trigger autoimmune responses. To minimize the damage, IsoAsp can be “repaired” by a specific l -isoaspartate-( d -aspartate)-protein- O -methyltransferase. The condition of chronic oxidative stress reported in psoriatic patients, and the potential etiological role of unknown self-antigens, prompted us to investigate Asn deamidation in psoriatic tissues. Erythrocytes (RBC) were selected as the model system since, lacking protein synthesis apparatus, they are unable to replace damaged proteins. Blood samples were obtained from 36 patients and 34 controls. l -isoAsp content was highly increased in RBC membrane proteins from psoriatic patients. Deamidated species included ankyrin, band 4.1, band 4.2 and the integral membrane protein band 3. A functional analysis demonstrated that this result was unrelated to a reduced efficiency of the S -adenosylmethionine-dependent repair system suggesting an increased protein instability at Asn sites, responsible for IsoAsp accumulation in psoriatic patients.
ISSN:0340-3696
1432-069X
DOI:10.1007/s00403-012-1247-z