BREVIPEDICELLUS and ERECTA control the expression of AtPRX17 to prevent Arabidopsis callus browning.

Efficient in vitro callus generation is required for tissue culture propagation, a process that allows for plant regeneration and transgenic breeding for desired phenotypes. Identifying genes and regulatory elements that prevent impaired callus growth and callus browning is essential for the development of in vitro callus systems. Here, we show that the BREVIPEDICELLUS and ERECTA pathways in Arabidopsis calli converge to prevent callus browning, and positively regulate the expression of the isoperoxidase gene AtPRX17 in rapidly growing calli. Loss-of-function mutations in both BREVIPEDICELLUS and ERECTA resulted in markedly increased callus browning. Transgenic lines expressing 35S pro::AtPRX17 in the bp-5 er105 double mutant background fully rescued this phenotypic abnormality. Using in vivo (chromatin immunoprecipitation-PCR and transient expression) and in vitro (electrophoretic mobility shift assays) assays, we observed that the BREVIPEDICELLUS protein binds directly to the upstream sequence of AtPRX17 to promote its transcription during callus growth. ERECTA is a ubiquitous factor required for cell proliferation and growth. We show that ERECTA positively regulates the expression of the transcription factor WRKY6, which directly binds to a separate site on the AtPRX17 promoter, further increasing its expression. Our data reveal an important molecular mechanism involved in the regulation of peroxidase isozyme expression to reduce Arabidopsis callus browning.

Transcriptomic Analysis of the Interaction Between FLOWERING LOCUS T Induction and Photoperiodic Signaling in Response to Spaceflight.

Spaceflight has an impact on the growth and development of higher plants at both the vegetative stage and reproductive stage. A great deal of information has been available on the vegetative stage in space, but relatively little is known about the influence of spaceflight on plants at the reproductive stage. In this study, we constructed transgenic Arabidopsis thaliana plants expressing the flowering control gene, FLOWERING LOCUS T (FT), together with the green fluorescent protein gene (GFP) under control of a heat shock-inducible promoter (HSP17.4), by which we induced FT expression inflight through remote controlling heat shock (HS) treatment. Inflight photography data showed that induction of FT expression in transgenic plants in space under non-inductive short-day conditions could promote flowering and reduce the length of the inflorescence stem in comparison with that of wild-type plants under the same conditions. Whole-genome microarray analysis of gene expression changes in leaves of wild-type and these transgenic plants grown under the long-day and short-day photoperiod conditions in space indicated that the function of the photoperiod-related spaceflight responsive genes is mainly involved in protein synthesis and post-translation protein modulation, notably protein phosphorylation. In addition, changes of the circadian component of gene expression in response to spaceflight under different photoperiods indicated that roles of the circadian oscillator could act as integrators of spaceflight response and photoperiodic signals in Arabidopsis plants grown in space.

The association study between CYP24A1 gene polymorphisms and risk of liver, lung and gastric cancer in a Chinese population.

Recently, four single nucleotide polymorphisms (rs2585428, rs4809960, rs6022999 and rs6068816) in CYP24A1 gene were extensively studied for their associations with cancer risk. However, these studies included only a few types of cancer, which calls for further investigations. In view of this, we here conducted a case-control study to explore the associations between these four CYP24A1 gene polymorphisms and risk of liver, lung and gastric cancer in a Chinese population. A total of 480 liver cancer patients, 550 lung cancer patients, 460 gastric cancer patients and 800 normal controls were recruited in this study. The genotyping of CYP24A1 gene polymorphisms was applied with Sanger sequencing assay. Single-locus analysis demonstrated that rs6022999 was significantly associated with risk of liver and lung cancer, while rs6068816 was significantly associated with the risk of gastric cancer. Haplotype analysis revealed that haplotype GTAT was associated with an increased risk of liver cancer and a decreased risk of lung cancer, and haplotype ATGC was associated with a decreased risk of lung cancer. The further meta-analysis of rs6068816 and lung cancer risk showed that rs6068816 was not associated with lung cancer risk in Chinese population, which confirmed our present finding. Conclusively, rs6022999 may be a genetic biomarker for liver and lung cancer susceptibility in Chinese population, and rs6068816 may be used to predict gastric cancer risk in Chinese population.

The POLR2E rs3787016 polymorphism is strongly associated with the risk of female breast and cervical cancer.

The rs3787016 polymorphism, in polymerase II polypeptide E (POLR2E), was previously identified as being associated with the risk for prostate cancer, esophageal cancer, breast cancer, papillary thyroid carcinoma and liver cancer, suggesting that rs3787016 may server as a common genetic factor to affect individual susceptibility to cancer. To prove the hypothesis, we here performed a case-control study to explore the association between rs3787016 and cervical cancer risk, and to confirm the association between rs3787016 and breast cancer in a central Chinese population, which was followed by a meta-analysis to precisely estimate the association between rs3787016 and risk of female breast and cervical cancer. The genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by sequencing. Our results indicated that rs3787016 was associated with the risk of both breast cancer and cervical cancer, and stratified analysis indicated that the association remained particularly for ≤60 years old females who smoke and drink. Moreover, after grouping breast cancer and cervical cancer together, our meta-analysis demonstrated that rs3787016 was associated with overall cancer risk and breast cancer risk. Collectively, the POLR2E rs3787016 polymorphism may be a valuable biomarker for female breast and cervical cancer predisposition.

Long non-coding RNA POLR2E rs3787016 is associated with the risk of papillary thyroid carcinoma in Chinese population.

Long non-coding RNAs (LncRNAs) have been shown to be involved in cancer tumorigenesis and progression. Single nucleotide polymorphisms (SNPs) in the lncRNAs also play a vital role in carcinogenesis. We here explored the association between POLR2E rs3787016 and risk of papillary thyroid carcinoma (PTC) in a Chinese population, which was followed by a meta-analysis of POLR2E rs3787016 and cancer risk in Chinese population. A total of 409 PTC patients and 800 healthy individuals were enrolled in the present study. The POLR2E rs3787016 was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and was confirmed by sequencing. The POLR2E rs3787016T allele increased the PTC risk in Chinese population, particular in Chinese females. The meta-analysis further revealed that POLR2E rs3787016T allele was associated with an increased cancer risk in Chinese population. Collectively, the POLR2E rs3787016 may be used as a genetic biomarker to predict cancer risk in Chinese population.