ABSTRACT
In a recent study on multiple sclerosis (MS), we observed additive effects and epistatic interactions between variants of four genes that converge to induce T-cell hyperactivity by altering Asn-(N)-linked protein glycosylation: namely, the Golgi enzyme MGAT1, cytotoxic T-lymphocyte antigen 4 (CTLA-4), interleukin-2 receptor-α (IL2RA) and interleukin-7 receptor-α (IL7RA). As the CTLA-4, IL2RA and IL7RA variants are associated with type 1 diabetes (T1D), we examined for joint effects in T1D. Employing a novel conditional logistic regression for family-based data sets, epistatic and additive effects were observed using 1423 multiplex families from the Type 1 Diabetes Genetic Consortium data set. The IL2RA and IL7RA variants had univariate association in MS and T1D, whereas the MGAT1 and CTLA-4 variants associated with only MS or T1D, respectively. However, similar to MS, the MGAT1 variant haplotype interacted with CTLA4 (P=0.03), and a combination of IL2RA and IL7RA (P=0.01). The joint effects of MGAT1, CTLA4, IL2RA, IL7RA and the two interactions using a multiple conditional logistic regression were statistically highly significant (P<5 × 10(-10)). The MGAT1-CTLA-4 interaction was replicated (P=0.01) in 179 trio families from the Genetics of Kidneys in Diabetes study. These data are consistent with defective N-glycosylation of T cells contributing to T1D pathogenesis.
Subject(s)
CTLA-4 Antigen/genetics , Diabetes Mellitus, Type 1/genetics , Epistasis, Genetic , Family , Genetic Variation/immunology , Interleukin-2 Receptor alpha Subunit/genetics , N-Acetylglucosaminyltransferases/genetics , Receptors, Interleukin-7/genetics , CTLA-4 Antigen/immunology , Datasets as Topic , Diabetes Mellitus, Type 1/immunology , Epistasis, Genetic/immunology , Female , Humans , Interleukin-2 Receptor alpha Subunit/immunology , Male , N-Acetylglucosaminyltransferases/immunology , Receptors, Interleukin-7/immunologyABSTRACT
The identification and characterization of multipotent neural precursors open the possibility of transplant therapies, but this approach is complicated by the widespread pathology of many degenerative diseases. Activation of endogenous precursors that support regenerative mechanisms is a possible alternative. We have previously shown that Notch ligands promote stem cell survival in vitro. Here, we show that there is an intimate interaction between insulin and Notch receptor signaling. Notch ligands also expand stem cell numbers in vivo with correlated benefits in brain ischemia. We now show that insulin promotes recovery of injured dopamine neurons in the adult brain. This response suggests that activating survival mechanisms in neural stem cells will promote recovery from progressive degenerative disease.
