Hypothalamic gene expression profile indicates a reduction in G protein signaling in the Wfs1 mutant mice
PHYSIOLOGICAL GENOMICS
Authors: Koks, Sulev; Soomets, Ursel; Plaas, Mario; Terasmaa, Anton; Noormets, Klari; Tillmann, Vallo; Vasar, Eero; Fernandes, Cathy; Schalkwyk, Leonard C.
Abstract
Koks S, Soomets U, Plaas M, Terasmaa A, Noormets K, Tillmann V, Vasar E, Fernandes C, Schalkwyk LC. Hypothalamic gene expression profile indicates a reduction in G protein signaling in the Wfs1 mutant mice. Physiol Genomics 43: 1351-1358, 2011. First published October 25, 2011; doi:10.1152/physiolgenomics.00117.2011.-The Wfs1 gene codes for a protein with unknown function, but deficiency in this protein results in a range of neuropsychiatric and neuroendocrine syndromes. In the present study we aimed to find the functional networks influenced by Wfs1 in the hypothalamus. We performed gene expression profiling (Mouse Gene 1.0 ST Arrays) in Wfs1-deficient mice; 305 genes were differentially expressed with nominal P value < 0.01. FDR (false discovery rate)-adjusted P values were significant (0.007) only for two genes: C4b (t = 9.66) and Wfs1 (t = -9.03). However, several genes related to G protein signaling were very close to the FDR-adjusted significance level, such as Rgs4 (regulator of G protein signaling 4) that was downregulated (-0.34, t = -5.4) in Wfs1-deficient mice. Changes in Rgs4 and C4b expression were confirmed by QRT-PCR. In humans, Rgs4 is in the locus for bipolar disease (BPD), and its expression is downregulated in BPD. C4b is a gene related to the neurodegenerative diseases. Functional analysis including the entire data set revealed significant alterations in the canonical pathway "G protein-coupled receptor signaling." The gene expression profile in the hypothalami of the Wfs1 mutant mice was significantly similar to the profiles of following biological functions: psychological disorders, bipolar disorder, mood disorder. In conclusion, hypothalamic gene expression profile resembles with some molecular pathways functionally related to the clinical syndromes in the Wolfram syndrome patients.
Genetics of hearing loss: Allelism and modifier genes produce a phenotypic continuum
ANATOMICAL RECORD PART A-DISCOVERIES IN MOLECULAR CELLULAR AND EVOLUTIONARY BIOLOGY
Authors: Mchugh, RK; Friedman, RA
Abstract
Recent genetic and genomic studies have greatly advanced our knowledge of the structure and function of genes involved in hearing loss. We are starting to recognize, however, that many of these genes do not appear to follow traditional Mendelian expression patterns and are subject to the effects of allelism and modifier genes. This review presents two genes illustrative of this concept that have varied expression pattern such that they may produce either syndromic or nonsyndromic hearing loss. One of these genes, cadherin 23, produces a spectrum of phenotypic traits, including presbycusis, nonsyndromic prelingual hearing loss (DFNB12), and syndromic hearing loss as part of Usher syndrome (Usher 1D). Missense mutations in CDH23 have been associated with presbycusis and DFNB12, whereas null alleles cause the majority of Usher 1D. Modifier gene products that interact with cadherin 23 also affect the phenotypic spectrum. Similarly, allelsim in the gene encoding wolframin (WFS1) causes either a nonsyndromic dominant low-frequency hearing loss (DFNA6/14/38) or Wolfram syndrome. Missense mutations within a defined region are associated with DFNA6/14/38, while more severe mutations spanning WFS1 are found in Wolfram syndrome patients. The phenotypic spectrum of Wolfram syndrome is also hypothesized to be influenced by modifier genes products. These studies provide increasing evidence for the importance of modifier genes in elucidating the functional pathways of primary hearing loss genes. Characterizing modifier genes may result in better treatment options for patients with hearing loss and define new diagnostic and therapeutic targets.