Common variation of the NSD1 gene is associated with susceptibility to Hirschsprung's disease in Chinese Han population.

BACKGROUND: Hirschsprung's disease (HSCR) is the most common congenital cause of intestinal obstruction in children. Sotos syndrome (SoS) is an overgrowth disorder with constipation and sometimes accompanied by HSCR. NSD1 gene mutation is the main cause of SoS. We aimed to investigate association of NSD1 common single nucleotide polymorphisms (SNPs) with HSCR susceptibility in Chinese Han population. METHOD: We genotyped 15 SNPs encompassing NSD1 gene region in 420 HSCR patients and 1665 controls on Fludigm EP1 platform. Association analysis was performed between cases and controls. RESULT: Rs244709 was the most associated SNP with HSCR susceptibility of the sample set (PAllelic = 9.69 × 10-5, OR = 1.37, 95% CI: 1.17-1.61). Gender stratification analysis revealed that NSD1 SNPs were associated with HSCR in males, but not in females. The nonsynonymous coding SNP rs28932178 in NSD1 exon 5 represented the most significant signal in males (PAllelic = 6.43 × 10-5, OR = 1.42, 95% CI: 1.20-1.69). The associated SNPs were expression quantitative trait loci (eQTLs) of nearby genes in multiple tissues. NSD1 expression levels were higher in aganglionic colon tissues than ganglionic tissues (P = 3.00 × 10-6). CONCLUSION: NSD1 variation conferred risk to HSCR in males, indicating SoS and HSCR may share common genetic factors. IMPACT: This is the first study to reveal that NSD1 variation conferred risk to Hirschsprung's disease susceptibility in males of Chinese Han population, indicating Sotos syndrome and Hirschsprung's disease may share some common genetic background. This study indicates more attention should be paid to the symptom of constipation in patients with Sotos syndrome. Our results raise questions about the role of NSD1 in the development of enteric nervous system and the pathogenesis of Hirschsprung's disease.

Association Analysis of Variants of DSCAM and BACE2 With Hirschsprung Disease Susceptibility in Han Chinese and Functional Evaluation in Zebrafish.

Hirschsprung disease (HSCR) has a higher incidence in children with Down syndrome (DS), which makes trisomy 21 a predisposing factor to HSCR. DSCAM and BACE2 are close together on the HSCR-associated critical region of chromosome 21. Common variants of DSCAM and rare variants of BACE2 were implicated to be associated with sporadic HSCR. However, the submucosal neuron defect of DS mouse model could not be rescued by normalization of Dscam. We aimed to explore the contribution of DSCAM and BACE2 to the development of the enteric nervous system (ENS) and HSCR susceptibility. We genotyped 133 tag single-nucleotide polymorphisms (SNPs) in DSCAM and BACE2 gene region in 420 HSCR patients and 1,665 controls of Han Chinese. Expression of DSCAM and BACE2 homologs was investigated in the developing gut of zebrafish. Overexpression and knockdown of the homologs were performed in zebrafish to investigate their roles in the development of ENS. Two DSCAM SNPs, rs430255 (P Addtive = 0.0052, OR = 1.36, 95% CI: 1.10-1.68) and rs2837756 (P Addtive = 0.0091, OR = 1.23, 95% CI: 1.05-1.43), showed suggestive association with HSCR risk. Common variants in BACE2 were not associated with HSCR risk. We observed dscama, dscamb, and bace2 expression in the developing gut of zebrafish. Knockdown of dscama, dscamb, and bace2 caused a reduction of enteric neurons in the hindgut of zebrafish. Overexpression of DSCAM and bace2 had no effects on neuron number in the hindgut of zebrafish. Our results suggested that common variation of DSCAM contributed to HSCR risk in Han Chinese. The dysfunction of both dscams and bace2 caused defects in enteric neuron, indicating that DSCAM and BACE2 might play functional roles in the occurrence of HSCR. These novel findings might shed new light on the pathogenesis of HSCR.

Association of Variants in PLD1, 3p24.1, and 10q11.21 Regions With Hirschsprung's Disease in Han Chinese Population.

Background and Aims: Hirschsprung's disease (HSCR) is a rare genetically heterogeneous congenital disorder. A recent study based on whole genome sequencing demonstrated that common variants at four novel loci, which contained two intronic variants on CASQ2 and PLD1, and intergenic variants located between SLC4A7 and EOMES at 3p24.1, and between LINC01518 and LOC283028 at 10q11.21, were associated with HSCR susceptibility. To validate these associations with HSCR susceptibility, we performed a case-control study in a Han Chinese sample set. Methods: We selected four previously identified single nucleotide polymorphisms (SNPs) for replication, along with tag SNPs to cover the four associated regions. In total, 61 SNPs were genotyped in 420 HSCR patients and 1,665 healthy controls from the Han Chinese population. Results: None of the 14 tag SNPs in the CASQ2 gene region, including the previously associated rs9428225, showed an association with HSCR. Among the 24 tag SNPs from the SLC4A7-EOMES region at 3p24.1, rs2642925 [odds ratio (OR) = 1.41, 95% confidence interval (95% CI) = 1.10-1.79; P Additive = 0.007] and the previously associated SNP rs9851320 showed a suggestive association (OR = 1.22, 95% CI = 1.01-1.47; P Additive = 0.042). A non-synonymous SNP, rs2287579, in PLD1 showed a suggestive association with HSCR susceptibility (OR = 1.71, 95% CI = 1.18-2.46; P Additive = 0.004). Additionally, the previously associated PLD1 SNP rs12632766 showed a suggestive significance (OR = 1.20, 95% CI = 1.01-1.42, P Additive = 0.038). In the LINC01518-LOC283028 region at 10q11.21, three SNPs meet the study-wide significance threshold. Rs17153309 was the most associated SNP (OR = 1.60, 95% CI = 1.34-1.90; P Additive = 1.13 × 10-7). The previously associated SNP rs1414027 also showed significant association (OR = 1.43, 95% CI = 1.20-1.70, P Additive = 3.92 × 10-5). Two associated SNPs at 10q11.21 (rs1414027 and rs624804) were expression quantitative trait loci in digestive tract tissues from GTEx databases. Conclusions: Our results confirmed that variants of the LINC01518-LOC283028 region were associated with HSCR in the Han Chinese population. Additionally, the susceptibility of SNPs in the LINC01518-LOC283028 region were associated with the expression levels of nearby genes. These results provide new insight into the pathogenesis of HSCR.

Association of common variation in ADD3 and GPC1 with biliary atresia susceptibility.

Biliary atresia (BA) is an idiopathic neonatal cholestatic disease. Recent genome-wide association study (GWAS) revealed that common variation of ADD3, GPC1, ARF6, and EFEMP1 gene was associated with BA susceptibility. We aimed to evaluate the association of these genes with BA in Chinese population. Twenty single nucleotide polymorphisms (SNPs) in these four genes were genotyped in 340 BA patients and 1,665 controls. Three SNPs in ADD3 were significantly associated with BA, and rs17095355 was the top SNP (PAllele = 3.23×10-6). Meta-analysis of published data and current data indicated that rs17095355 was associated with BA susceptibility in Asians and Caucasians. Three associated SNPs were expression quantitative trait loci (eQTL) for ADD3. Two GPC1 SNPs in high linkage disequilibrium (LD) showed nominal association with BA susceptibility (PAllele = 0.03 for rs6707262 and PAllele = 0.04 for rs6750380), and were eQTL of GPC1. Haplotype harboring these two SNPs almost reached the study-wide significance (P = 0.0035). No association for ARF6 and EFEMP1 was found with BA risk in the current population. Our study validated associations of ADD3 and GPC1 SNPs with BA risk in Chinese population and provided evidence of epistatic contributions of genetic factors to BA susceptibility.

Emodin protects against oxidative stress and apoptosis in HK-2 renal tubular epithelial cells after hypoxia/reoxygenation.

The aim of the present study was to determine the effects of emodin, a natural compound with antioxidant properties, on oxidative stress and apoptosis induced by hypoxia/reoxygenation (H/R) in HK-2 human renal tubular cells. In HK-2 cells subjected to H/R, it was observed that pre-treatment with emodin lead to an increase in cellular viability and a reduction in the rate of apoptosis and the B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 ratio. H/R alone caused a significant increase in the levels of reactive oxygen species and malondialdehyde (P<0.05) and a significant decrease in the activities of superoxide dismutase, catalase and glutathione peroxidase (P<0.05), relative to normoxic cells. In turn, parameters of oxidative stress were improved by emodin pre-treatment. In addition, emodin pre-treatment significantly inhibited the phosphorylation of extracellular signal-regulated protein kinase and c-Jun N-terminal kinase mitogen-activated protein kinases (MAPKs) induced by H/R (P<0.05). These data suggest that emodin may prevent H/R-induced apoptosis in human renal tubular cells through the regulation of cellular oxidative stress, MAPK activation and restoration of the Bax/Bcl-2 ratio.

Functional characterization of GmBZL2 (AtBZR1 like gene) reveals the conserved BR signaling regulation in Glycine max.

Brassinosteroids (BRs) play key roles in plant growth and development, and regulate various agricultural traits. Enhanced BR signaling leads to increased seed number and yield in Arabidopsis bzr1-1D (AtBZR1(P234L), gain-of-function mutant of the important transcription factor in BR signaling/effects). BR signal transduction pathway is well elucidated in Arabidopsis but less known in other species. Soybean is an important dicot crop producing edible oil and protein. Phylogenetic analysis reveals AtBZR1-like genes are highly conserved in angiosperm and there are 4 orthologues in soybean (GmBZL1-4). We here report the functional characterization of GmBZL2 (relatively highly expresses in flowers). The P234 site in AtBZR1 is conserved in GmBZL2 (P216) and mutation of GmBZL2(P216L) leads to GmBZL2 accumulation. GmBZL2(P216L) (GmBZL2*) in Arabidopsis results in enhanced BR signaling; including increased seed number per silique. GmBZL2* partially rescued the defects of bri1-5, further demonstrating the conserved function of GmBZL2 with AtBZR1. BR treatment promotes the accumulation, nuclear localization and dephosphorylation/phosphorylation ratio of GmBZL2, revealing that GmBZL2 activity is regulated conservatively by BR signaling. Our studies not only indicate the conserved regulatory mechanism of GmBZL2 and BR signaling pathway in soybean, but also suggest the potential application of GmBZL2 in soybean seed yield.