Decreased expression of GRAF1/OPHN-1-L in the X-linked alpha thalassemia mental retardation syndrome

Abstract

BackgroundATRX is a severe X-linked disorder characterized by mental retardation, facial dysmorphism, urogenital abnormalities and alpha-thalassemia. The disease is caused by mutations in ATRX gene, which encodes a protein belonging to the SWI/SNF DNA helicase family, a group of proteins involved in the regulation of gene transcription at the chromatin level. In order to identify specific genes involved in the pathogenesis of the disease, we compared, by cDNA microarray, the expression levels of approximately 8500 transcripts between ATRX and normal males of comparable age.MethodscDNA microarray was performed using total RNA from peripheral blood mononuclear cells of ATRX and normal males. Microarray results were validated by quantitative real-time polymerase chain reaction.ResultscDNA microarray analysis showed that 35 genes had a lower expression (30-35% of controls) while 25 transcripts had a two-fold higher expression in comparison to controls. In the microarray results the probe for oligophrenin-1, a gene known for its involvement in mental retardation, showed a decreased hybridization signal. However, such gene was poorly expressed in blood mononuclear cells and its decrease was not confirmed in the quantitative real-time RT-PCR assay. On the other hand, the expression of an homologous gene, the GTPase regulator associated with the focal adhesion kinase 1/Oligophrenin-1-like (GRAF1/OPHN-1-L), was relatively high in blood mononuclear cells and significantly decreased in ATRX patients. The analysis of the expression pattern of the GRAF1/OPHN-1-L gene in human tissues and organs revealed the predominant brain expression of a novel splicing isoform, called variant-3.ConclusionsOur data support the hypothesis of a primary role for altered gene expression in ATRX syndrome and suggest that the GRAF1/OPHN-1-L gene might be involved in the pathogenesis of the mental retardation. Moreover a novel alternative splicing transcript of such gene, predominantly expressed in brain tissues, was identified.

GRAF1 deficiency blunts sarcolemmal injury repair and exacerbates cardiac and skeletal muscle pathology in dystrophin-deficient mice

“…Whether GRAF1, like dysferlin, also mediates the release of chemotactic molecules will be an important focus of future studies. Importantly, variations of GRAF1 expression are common in the human population and are associated with many diseases ranging from X-linked alpha-thalassemia mental retardation syndrome [ 57 ] to adenocarcinomas and myelodysplastic syndrome [ 58 – 61 ]. Our findings indicate that the extent to which GRAF1 variations modify the onset and/or severity of muscle or heart phenotypes in dystrophic patients warrants further study.…”

Modulation of Pro-Oxidant and Pro-Inflammatory Activities of M1 Macrophages by the Natural Dipeptide Carnosine

“…Amplification conditions and fluorescence data collection included: one cycle at 95 • C for 15 min, 50 cycles at 94 • C (15 s each), one annealing step at 56 • C for 30 s, and one cycle at 72 • C for 30 s. The negative control consisted of a reaction in absence of cDNA (5 µL PCR Master Mix + 1 µL specific primers + 4 µL of Tris-EDTA buffer) indicated as NTC (no template control). The relative RNA expression level for each sample was calculated using the 2 −∆∆CT method (threshold cycle (CT) value of the gene of interest vs. CT value of the housekeeping gene) [40,41]. For accurate gene expression measurements with qRT-PCR, the results were normalized to the GAPDH housekeeping gene, selected using the geNorm Housekeeping Gene Selection Kit.…”

Two BRM promoter polymorphisms predict poor survival in patients with hepatocellular carcinoma

“…Several SWI/SNF components have been implicated in neurological and developmental disorders, cardiovascular conditions, and cancer, particularly the BRM and BRG1 genes . BRG1 heterozygous mice universally develop breast cancer, supporting the notion that BRG1 may act as tumor suppressor.…”

“…10 The key ATP catalytic subunit of the SWI/SNF complex is either Brahma (BRM) or the brahma-related gene 1 product (BRG1), which drives the translocation of SWI/SNF along the nucleosome complex eventually leading to gene expression activation. 11 Several SWI/SNF components have been implicated in neurological 12 and developmental disorders, 13,14 cardiovascular conditions, 15 and cancer, 5,16 particularly the BRM and BRG1 genes. 5,17 BRG1 heterozygous mice universally develop breast cancer, 18 supporting the notion that BRG1 may act as tumor suppressor.…”