Genetic variations at the human growth hormone receptor (GHR) gene locus are associated with idiopathic short stature.

GH plays an essential role in the growing child by binding to the growth hormone receptor (GHR) on target cells and regulating multiple growth promoting and metabolic effects. Mutations in the GHR gene coding regions result in GH insensitivity (dwarfism) due to a dysfunctional receptor protein. However, children with idiopathic short stature (ISS) show growth impairment without GH or GHR defects.

No association of type 1 diabetes with a functional polymorphism of the LRAP gene.

Aims/hypothesis: In a recent linkage analysis of genome-wide gene-expression patterns in lymphoblastoid lines, the gene encoding the leukocyte-derived arginine aminopeptidase (LRAP) was identified as having its expression levels modulated by one of the most pronounced effects in cis, mapping to a single-nucleotide polymorphism (rs2762). As this enzyme has an important role in processing antigenic peptides for the HLA I molecules, a variant that drastically modulates its expression levels might affect risk of autoimmunity. This study was designed to confirm that LRAP expression in B-cell derived lines is controlled by a haplotype marked by rs2762 and to see whether this would be the basis of an association with type 1 diabetes (T1D).

Dexamethasone inhibits the action of TNF on ENaC expression and activity.

We have reported that TNF, a proinflammatory cytokine present in several lung pathologies, decreases the expression and activity of the epithelial Na(+) channel (ENaC) by approximately 70% in alveolar epithelial cells. Because dexamethasone has been shown to upregulate ENaC mRNA expression and is well known to downregulate proinflammatory genes, we tested if it could alleviate the effect of TNF on ENaC expression and activity. In cotreatment with TNF, we found that dexamethasone reversed the inhibitory effect of TNF and upregulated alpha, beta, and gammaENaC mRNA expression.

The insulin-like growth factor-II receptor gene is associated with type 1 diabetes: evidence of a maternal effect.

Susceptibility to type 1 diabetes (T1D) is a complex trait, involving several loci. One of these putative loci, insulin-dependent diabetes mellitus-8 (IDDM8) at 6q, has been found to be subject to parental effects, suggesting the involvement of an imprinted gene. IGF-II receptor (IGF2R), the best-studied imprinted gene in the IDDM8 region, encodes the IGF-2 receptor, a protein involved in many biological processes, including immune function and beta-cell regeneration.

Downregulation of ENaC activity and expression by TNF-alpha in alveolar epithelial cells.

Sodium absorption by an amiloride-sensitive channel is the main driving force of lung liquid clearance at birth and lung edema clearance in adulthood. In this study, we tested whether tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine involved in several lung pathologies, could modulate sodium absorption in cultured alveolar epithelial cells. We found that TNF-alpha decreased the expression of the alpha-, beta-, and gamma-subunits of epithelial sodium channel (ENaC) mRNA to 36, 43, and 16% of the controls after 24-h treatment and reduced to 50% the amount of alpha-ENaC protein in these cells.