PKC delta Impaired Vessel Formation and Angiogenic Factor Expression in Diabetic Ischemic Limbs
DIABETES
Authors: Lizotte, Farah; Pare, Martin; Denhez, Benoit; Leitges, Michael; Guay, Andreanne; Geraldes, Pedro
Abstract
Decreased collateral vessel formation in diabetic peripheral limbs is characterized by abnormalities of the angiogenic response to ischemia. Hyperglycemia is known to activate protein kinase C (PKC), affecting the expression and activity of growth factors such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). The current study investigates the role of PKC delta in diabetes-induced poor collateral vessel formation and inhibition of angiogenic factors expression and actions. Ischemic adductor muscles of diabetic Prkcd(+/+) mice exhibited reduced blood reperfusion, vascular density, and number of small vessels compared with nondiabetic Prkcd(+/+) mice. By contrast, diabetic Prkcd(-/-) mice showed significant increased blood flow, capillary density, and number of capillaries. Although expression of various PKC isoforms was unchanged, activation of PKC delta was increased in diabetic Prkcd(+/+) mice. VEGF and PDGF mRNA and protein expression were decreased in the muscles of diabetic Prkcd(+/+) mice and were normalized in diabetic Prkcd(-/-) mice. Furthermore, phosphorylation of VEGF receptor 2 (VEGFR2) and PDGF receptor-beta (PDGFR-beta) were blunted in diabetic Prkcd(-/-) mice but elevated in diabetic Prkcd(-/-) mice. The inhibition of VEGFR2 and PDGFR-beta activity was associated with increased SHP-1 expression. In conclusion, our data have uncovered the mechanisms by which PKC delta activation induced poor collateral vessel formation, offering potential novel targets to regulate angiogenesis therapeutically in diabetic patients.
De novo mutations implicate novel genes in systemic lupus erythematosus
HUMAN MOLECULAR GENETICS
Authors: Pullabhatla, Venu; Roberts, Amy L.; Lewis, Myles J.; Mauro, Daniele; Morris, David L.; Odhams, Christopher A.; Tombleson, Philip; Liljedahl, Ulrika; Vyse, Simon; Simpson, Michael A.; Sauer, Sascha; de Rinaldis, Emanuele; Syvanen, Ann-Christine; Vyse, Timothy J.
Abstract
The omnigenic model of complex disease stipulates that the majority of the heritability will be explained by the effects of common variation on genes in the periphery of core disease pathways. Rare variant associations, expected to explain far less of the heritability, may be enriched in core disease genes and thus will be instrumental in the understanding of complex disease pathogenesis and their potential therapeutic targets. Here, using complementary whole-exome sequencing, high-density imputation, and in vitro cellular assays, we identify candidate core genes in the pathogenesis of systemic lupus erythematosus (SLE). Using extreme-phenotype sampling, we sequenced the exomes of 30 SLE parent-affected-offspring trios and identified 14 genes with missense de novo mutations (DNM), none of which are within the >80 SLE susceptibility loci implicated through genome-wide association studies. In a follow-up cohort of 10, 995 individuals of matched European ancestry, we imputed genotype data to the density of the combined UK10K-1000 genomes Phase III reference panel across the 14 candidate genes. Gene-level analyses indicate three functional candidates: DNMT3A, PRKCD, and C1QTNF4. We identify a burden of rare variants across PRKCD associated with SLE risk (P = 0.0028), and across DNMT3A associated with two severe disease prognosis sub-phenotypes (P = 0.0005 and P = 0.0033). We further characterise the TNF-dependent functions of the third candidate gene C1QTNF4 on NF-kappa B activation and apoptosis, which are inhibited by the p.His198Gln DNM. Our results identify three novel genes in SLE susceptibility and support extreme-phenotype sampling and DNM gene discovery to aid the search for core disease genes implicated through rare variation.