Elevated postmortem striatal t-DARPP expression in schizophrenia and associations with DRD2/ANKK1 polymorphism.

Area of Science:

• Neuroscience
• Molecular Psychiatry
• Genetics

Background:

• Dopamine- and cAMP-regulated phosphoprotein of molecular weight 32 kDa (DARPP-32) and calcineurin (CaN) integrate dopamine and glutamate signaling, implicating them in schizophrenia pathogenesis.
• These proteins are primarily expressed in the striatum, but their specific role in schizophrenia remains under-investigated.

Purpose of the Study:

• To investigate the expression of DARPP-32 isoforms (full-length and truncated) and calcineurin in the striatum of schizophrenia patients.
• To examine the correlation between these protein expressions and the A1 allele of the Taq1A genotype in the dopamine D2 receptor (DRD2)/ankyrin-repeat containing kinase 1 (ANKK1) gene.

Main Methods:

• Utilized immunoblotting techniques on postmortem striatal tissue from schizophrenia patients and healthy controls.
• Assessed expression levels of FL-DARPP, t-DARPP, and CaN.
• Correlated protein expression with DRD2/ANKK1 Taq1A genotype and antemortem psychiatric symptom scores.

Main Results:

• Mean t-DARPP expression was significantly higher in the caudate nucleus of schizophrenia patients compared to controls.
• The A1 allele of the DRD2/ANKK1 Taq1A genotype was significantly associated with elevated t-DARPP expression in the caudate.
• A significant correlation was observed between the A1 allele and the total score of antemortem psychiatric symptoms.

Conclusions:

• Elevated t-DARPP expression in the striatum may represent a key molecular mechanism in schizophrenia.
• The DRD2/ANKK1 Taq1A polymorphism and its association with t-DARPP could contribute to schizophrenia pathogenesis.