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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #216044
Title: Expression profiling of clonal lymphocyte cell cultures from Rett syndrome patients

Author
item DELGADO, IVAN - BAYLOR COLLEGE MED
item KIM, DONG - BAYLOR COLLEGE MED
item THATCHER, KAREN - UNIV CALIFORNIA
item LASALLE, JANINE - UNIV CALIFORNIA
item Van Den Veyver, Ignatia

Submitted to: BMC Medical Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2006
Publication Date: 7/21/2006
Citation: Delgado, I.J., Kim, D.S., Thatcher, K.N., LaSalle, J.M., Van den Veyver, I.B. 2006. Expression profiling of clonal lymphocyte cell cultures from Rett syndrome patients. BMC Medical Genetics [serial online]. 7:61.

Interpretive Summary: The problem addressed in this work is to determine which genes are abnormally expressed in patients who have Rett syndrome, which is caused by mutations in MECP2, a gene that encodes a factor that regulates how DNA methylation affects the function (expression) of other genes. We used gene-chips (microarrays) to perform global gene expression profiling in white blood cells of Rett syndrome patients. This is important because it will help us understand which genes are regulated by DNA methylation.

Technical Abstract: More than 85% of Rett syndrome (RTT) patients have heterozygous mutations in the X-linked MECP2 gene which encodes methyl-CpG-binding protein 2, a transcriptional repressor that binds methylated CpG sites. Because MECP2 is subject to X chromosome inactivation (XCI), girls with RTT express either the wild type or mutant MECP2 in each of their cells. To test the hypothesis that MECP2 mutations result in genome-wide transcriptional deregulation and to identify its target genes in a system that circumvents the functional mosaicism resulting from XCI, we performed gene expression profiling of pure populations of untransformed T-lymphocytes that express either a mutant or a wild-type allele. Single T lymphocytes from a patient with a c.473C>T (p.T158M) mutation and one with a c.1308-1309delTC mutation were subcloned and subjected to short term culture. Gene expression profiles of wild-type and mutant clones were compared by oligonucleotide expression microarray analysis. Expression profiling yielded 44 upregulated genes and 77 downregulated genes. We compared this gene list with expression profiles of independent microarray experiments in cells and tissues of RTT patients and mouse models with Mecp2 mutations. These comparisons identified a candidate MeCP2 target gene, SPOCK1, downregulated in two independent microarray experiments, but its expression was not altered by quantitative RT-PCR analysis on brain tissues from a RTT mouse model. Initial expression profiling from T-cell clones of RTT patients identified a list of potential MeCP2 target genes. Further detailed analysis and comparison to independent microarray experiments did not confirm significantly altered expression of most candidate genes. These results are consistent with other reported data.