Activation of Tyrosine Phosphorylation Signaling in Erythrocytes of Patients with Alzheimer's Disease.

• In erythrocytes of AD patients the anion transporter band3 is highly phosphorylated. • Activation of lyn kinase and downregulation of tyrosine phosphatase occur. • Band3 phosphorylation correlates negatively with the cognitive status of patients. • Treatment of erythrocytes with Aβ1–42 peptide induces both band3 phosphorylation and lyn activation. Alzheimer's disease (AD) is the most prevalent type of dementia affecting older people. The identification of biomarkers is increasingly important and would be crucial for future therapy. Here, we demonstrated that in AD erythrocytes: (i) the anion transporter band3 is highly phosphorylated; (ii) the lyn kinase is phosphorylated and activated; (iii) the tyrosine phosphatase activity is downregulated, with a significant inverse correlation between band3 phosphorylation and disease progression, as revealed by Mini Mental State Examination score. Finally, we showed that in normal erythrocytes, treated in vitro with Aβ1–42 peptide, both band3 phosphorylation and lyn activation occurs. These results suggest that modulation of tyrosine phosphorylation signaling may be evaluated as a potential peripheral marker in AD. [ABSTRACT FROM AUTHOR]