Decreased gene expression activity as a result of a mutation in the calreticulin gene promoter in a family case of schizoaffective disorder

Accumulating evidence of population association studies support the hypothesis that the high heritability of major psychiatric disorders is a combination of relatively common alleles of modest effect, and rare alleles some with relatively larger effects. We have previously reported low frequency mutations in the proximal promoter of the human calreticulin (CALR) gene that co-occur with the spectrum of major psychiatric disorders. One of those mutations at -205C>T (rs556992558) was detected in an isolate case of schizoaffective disorder. In the current study, the functional implication of mutation -205T is studied in the human neuronal cell lines LAN-5, BE(2)-C and HEK-293. In contrast with other mutations in the promoter region which increase gene expression activity, the -205T mutation significantly decreased gene expression in those cell lines in comparison with the wild-type -205C nucleotide (p < 0.000001, p < 0.0005, and p < 0.017, respectively). Treatment of the cell lines with the mood-stabilizing drug, valproic acid (VPA) resulted in differential gene expression activity in the mutant -205T versus the wild-type -205C construct. VPA increased gene expression activity in both constructs, while a significantly higher expression activity was observed in the mutant construct (p < 0.01), indicative of the creation of a positive effector binding site for VPA as a result of the -205T mutation. We conclude that deviation from normalcy in the level of CALR in either direction is associated with major psychiatric disorders.

Differential Binding of Creb, Usf, and c-myc to the Calreticulin Human Specific –220c May Be Linked with the Evolution of Higher Brain Functions in Human

Introduction

We have previously reported a human-specific nucleotide in the promoter sequence of the calreticulin (CALR) gene at position –220C, which is the site of action of valproic acid.

Objectives

Reversion of this nucleotide to the ancestral type, –220A, co-occurs with severe deficit in higher brain cognitive functions.

Aims

In the current study, we compare the pattern of protein binding between –220C and –220A.

Methods

Antibodies reactive against transcription factors CREB, USF, and c-Myc were used to identify the specific proteins involved in complexes with DNA using electrophoretic mobility shift assay (EMSA).

Results

Significant increase was observed in the overall protein complexes binding to the –220 C allele vs. –220A. The transcription factors, CREB, USF, and c-Myc, were differentially bound to –220C, represented by supershifts.

Conclusions

We propose that differential binding of CREB, USF, and c-Myc to CALR nucleotide –220C may be linked with the evolution of higher brain functions in human.

Disclosure of interest

The author has not supplied his/her declaration of competing interest.