NbCycB2 represses Nbwo activity via a negative feedback loop in tobacco trichome development.

The transcription factor Woolly (Wo) and its downstream gene CycB2 have been shown to regulate trichome development in tomato (Solanum lycopersicum). It has been demonstrated that only the gain-of-function allele of Slwo (SlWoV, the Slwo woolly motif mutant allele) can increase the trichome density; however, it remains unclear why the two alleles function differently in trichome development. In this study, we used Nicotiana benthamiana as a model and cloned the homologues of Slwo and SlCycB2 (named Nbwo and NbCycB2). We also constructed a Nbwo gain-of-function allele with the same mutation site as SlWoV (named NbWoV). We found that both Nbwo and NbWoV directly regulate NbCycB2 and their own expression by binding to the promoter of NbCycB2 and their own genomic sequences. As form of a feedback regulation, NbCycB2 negatively regulates trichome formation by repressing Nbwo activity at the protein level. We also found that mutations in the Nbwo woolly motif can prevent repression of NbWoV by NbCycB2, which results in a significant increase in the amount of active Nbwo proteins and in increases in trichome density and the number of branches. Our results reveal a novel reciprocal regulation mechanism between NbCycB2 and Nbwo during trichome formation in N. benthamiana.

Genetic susceptibility to ulcerative colitis in the Chinese Han ethnic population: association with TNF polymorphisms.

BACKGROUND: Tumor necrosis factor alpha (TNFalpha) is an important proinflammatory cytokine that has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Recent studies have evaluated the role of TNF promoter polymorphisms in IBD, whereas the data are inconsistent. Trans-racial mapping in an ethnically distinct but homogenous population may help clarify these associations. We investigate the association between TNF promoter polymorphisms and susceptibility to ulcerative colitis (UC) in the Chinese Han ethnic population. METHODS: We studied 110 unrelated UC patients and 292 healthy controls from Zhejiang Province, China. Genotyping for 6 common TNF promoter polymorphisms (TNF -1031T/C, -863C/A, -857C/T, -380G/A, -308G/A, -238G/A) was carried out by polymerase chain reaction sequence-specific primers (PCR-SSP). RESULTS: TNF -308A was associated with disease (allele frequency patients 14.6% vs controls 8.9%, P = 0.02). TNF -857T was increased in patients but without statistical significance (allele frequency 17.3% vs 12.2%, P = 0.06). Haplotype analysis revealed 6 haplotypes including two (H5 and H3), which contained TNF -308A. H5 was associated with disease (haplotype frequency patients -12.3% vs controls 7.5%, P = 0.03). Of note the rare haplotype H3 has not previously been identified in Caucasian populations. Homozygosity for the haplotype H4 comprising the common alleles at each TNF promoter single-nucleotide polymorphism (SNP) was negatively associated with disease (patients vs controls 24.5% vs 34.9%, P < 0.05). CONCLUSIONS: We report the association with TNF -308A polymorphisms in Chinese patients with ulcerative colitis. The functional study in Chinese Han ethnic population is now required.

[NOD2/CARD15 gene polymorphisms and susceptibility to Crohn's disease in Chinese Han population].

OBJECTIVE: Previous studies have shown NOD2/CARD15 gene is the first susceptibility gene to Crohn's disease (CD), three single nucleotide polymorphisms (SNPs) of the gene have been identified to be associated with CD in the Caucasians, but not in the Japanese. Here we have evaluated the NOD2/CARD gene polymorphisms in Chinese patients to determine whether the gene is associated with susceptibility to CD in Chinese Han population. METHODS: Blood samples were obtained from 32 patients with CD, 110 patients with ulcerative colitis, and 292 healthy controls in Zhejiang location. Genotyping for 3 common NOD2/CARD15 (Arg702Trp, Gly908Arg, Leu1007fsinsC) polymorphisms was carried out using polymerase chain sequence with specific primer. RESULTS: None of the patients with CD had heterozygous or homozygous SNPs variants. Similarly none of the ulcerative colitis or health controls. CONCLUSION: The common variants in NOD2/CARD15 found in Caucasians with CD are not associated with CD in the Chinese Han population.