Tight genetic linkage of genes causing hybrid necrosis and pollinator isolation between young species.

The mechanisms of reproductive isolation that cause phenotypic diversification and eventually speciation are a major topic of evolutionary research. Hybrid necrosis is a post-zygotic isolation mechanism in which cell death develops in the absence of pathogens. It is often due to the incompatibility between proteins from two parents. Here we describe a unique case of hybrid necrosis due to an incompatibility between loci on chromosomes 2 and 7 between two pollinator-isolated Petunia species. Typical immune responses as well as endoplasmic reticulum stress responses are induced in the necrotic line. The locus on chromosome 2 encodes ChiA1, a bifunctional GH18 chitinase/lysozyme. The enzymatic activity of ChiA1 is dispensable for the development of necrosis. We propose that the extremely high expression of ChiA1 involves a positive feedback loop between the loci on chromosomes 2 and 7. ChiA1 is tightly linked to major genes involved in the adaptation to different pollinators, a form of pre-zygotic isolation. This linkage of pre- and post-zygotic barriers strengthens reproductive isolation and probably contributes to rapid diversification and speciation.

EIF3D promotes resistance to 5-fluorouracil in colorectal cancer through upregulating RUVBL1.

BACKGROUND: As EIF3D is oncogenic in colorectal cancer (CRC) and is associated with multidrug resistance, this study aims to investigate whether and how EIF3D regulates resistance to 5-fluorouracil (5-Fu) in CRC. METHODS: EIF3D-associated genes in CRC were predicted using bioinformatics tools. CRC cells and nude mice received 5-Fu treatment. Then, the impacts of EIF3D and the interaction between EIF3D and RUVBL1 on cell viability, colony formation, apoptosis, and DNA damage were detected through MTT, colony formation, flow cytometry, and immunofluorescence assays, and those on in vivo tumorigenesis through murine xenograft assay. IC50 value of 5-Fu for CRC cells was determined by probit regression analysis. Expressions of EIF3D, eIF4E, EIF3D-associated genes, γH2AX, Bcl-2, Bax, and Cleaved Caspase-3/Caspase-3 in CRC tissues, cells, and/or xenograft tumors were analyzed by qRT-PCR and/or Western blot. RESULTS: EIF3D and RUVBL1 were highly expressed and positively correlated with CRC tissues/cells. In CRC cells, except for eIF4E, both EIF3D and RUVBL1 levels were upregulated by 5-Fu treatment; in addition to that, RUVBL1 level was downregulated by EIF3D silencing rather than eIF4E. Meanwhile, EIF3D silencing diminished IC50 value of 5-Fu and potentiated 5-Fu-induced viability decrease, colony formation inhibition, apoptosis promotion, Bcl-2 downregulation, and γH2AX, Bax, and Cleaved Caspase-3/Caspase-3 upregulation but reversed 5-Fu-triggered RUVBL1 upregulation. RUVBL1 overexpression offsets EIF3D silencing-induced viability decrease and apoptosis promotion of 5-Fu-treated CRC cells, and tumorigenesis suppression and apoptosis promotion in 5-Fu-treated mice. CONCLUSION: EIF3D promotes resistance to 5-Fu in CRC through upregulating RUVBL1 level.

A SnRK1-ZmRFWD3-Opaque2 Signaling Axis Regulates Diurnal Nitrogen Accumulation in Maize Seeds.

Zeins are the predominant storage proteins in maize (Zea mays) seeds, while Opaque2 (O2) is a master transcription factor for zein-encoding genes. How the activity of O2 is regulated and responds to external signals is yet largely unknown. Here, we show that the E3 ubiquitin ligase ZmRFWD3 interacts with O2 and positively regulates its activity by enhancing its nuclear localization. Ubiquitination of O2 enhances its interaction with maize importin1, the α-subunit of Importin-1 in maize, thus enhancing its nuclear localization ability. We further show that ZmRFWD3 can be phosphorylated by a Suc-responsive protein kinase, ZmSnRK1, which leads to its degradation. We demonstrated that the activity of O2 responds to Suc levels through the ZmSnRK1-ZmRFWD3-O2 signaling axis. Intriguingly, we found that Suc levels, as well as ZmRFWD3 levels and the cytonuclear distribution of O2, exhibit diurnal patterns in developing endosperm, leading to the diurnal transcription of O2-regulated zein genes. Loss of function in ZmRFWD3 disrupts the diurnal patterns of O2 cytonuclear distribution and zein biosynthesis, and consequently changes the C/N ratio in mature seeds. We therefore identify a SnRK1-ZmRFWD3-O2 signaling axis that transduces source-to-sink signals and coordinates C and N assimilation in developing maize seeds.

The regulation of zein biosynthesis in maize endosperm.

KEY MESSAGE: We review the current knowledge regarding the regulation of zein storage proteins biosynthesis and protein body formation, which are crucial processes for the successful accumulation of nutrients in maize kernels. Storage proteins in the seeds of crops in the grass family (Poaceae) are a major source of dietary protein for humans. In maize (Zea mays), proteins are the second largest nutrient component in the kernels, accounting for ~ 10% of the kernel weight. Over half of the storage proteins in maize kernels are zeins, which lack two essential amino acids, lysine and tryptophan. This deficiency limits the use of maize proteins in the food and feed industries. Zeins are encoded by a large super-gene family. During endosperm development, zeins accumulate in protein bodies, which are derived from the rough endoplasmic reticulum. In recent years, our knowledge of the pathways of zein biosynthesis and their deposition within the endosperm has been greatly expanded. In this review, we summarize the current understanding of zeins, including the genes encoding these proteins, their expression patterns and transcriptional regulation, the process of protein body formation, and other biological processes affecting zein accumulation.

Eukaryotic translation initiation factor 3 subunit G promotes human colorectal cancer.

In this study, we investigated the role of eukaryotic translation initiation factor 3 subunit G (EIF3G) in colorectal cancer. Immunohistochemical analysis showed higher EIF3G expression in stage IV human colorectal cancer tissues than in adjacent normal tissues (P<0.01). EIF3G short hairpin RNA (shRNA) knockdown in HCT116 colon cancer cells reduced proliferation and increased apoptosis as compared to control. EIF3G knockdown also increased autophagy and reduced mTOR signaling, as evidenced by low phospho-AKT, phospho-S6K and phospho-4EBP1 levels. Functional experiments indicated that overexpression of EIF3G promoted HCT-116 cells proliferation, migration and xenograft tumor growth. Finally, we observed lower xenograft tumor weights and volumes with EIF3G-silenced HCT116 cells than with control cells. These findings demonstrate that EIF3G promotes colon cancer growth and is a potential therapeutic target.

The ZmbZIP22 Transcription Factor Regulates 27-kD γ-Zein Gene Transcription during Maize Endosperm Development.

Zeins are the most abundant storage proteins in maize (Zea mays) kernels, thereby affecting the nutritional quality and texture of this crop. 27-kD γ-zein is highly expressed and plays a crucial role in protein body formation. Several transcription factors (TFs) (O2, PBF1, OHP1, and OHP2) regulate the expression of the 27-kD γ-zein gene, but the complexity of its transcriptional regulation is not fully understood. Here, using probe affinity purification and mass spectrometry analysis, we identified ZmbZIP22, a TF that binds to the 27-kD γ-zein promoter. ZmbZIP22 is a bZIP-type TF that is specifically expressed in endosperm. ZmbZIP22 bound directly to the ACAGCTCA box in the 27-kD γ-zein promoter and activated its expression in wild tobacco (Nicotiana benthamiana) cells. 27-kD γ-zein gene expression was significantly reduced in CRISPR/Cas9-generated zmbzip22 mutants. ChIP-seq (chromatin immunoprecipitation coupled to high-throughput sequencing) confirmed that ZmbZIP22 binds to the 27-kD γ-zein promoter in vivo and identified additional direct targets of ZmbZIP22. ZmbZIP22 can interact with PBF1, OHP1, and OHP2, but not O2. Transactivation assays using various combinations of these TFs revealed multiple interaction modes for the transcriptional activity of the 27-kD γ-zein promoter. Therefore, ZmbZIP22 regulates 27-kD γ-zein gene expression together with other known TFs.

Eukaryotic translation initiation factor 3 subunit G (EIF3G) resensitized HCT116/5-Fu to 5-fluorouracil (5-Fu) via inhibition of MRP and MDR1.

PURPOSE: Colorectal cancer (CRC) has become a predominant cancer and accounts for approximately 10% of cancer-related mortality. Drug resistance still remains a priority mortality factor for patients due to no available therapeutic alternatives. The purpose of the present study was to investigate the underlying molecular mechanisms how eukaryotic translation initiation factor 3 subunit G (EIF3G) resensitized 5-Fu-resistant human CRC cells (HCT116/5-Fu) to 5-fluorouracil (5-Fu). METHODS: Multiple cellular and molecular biology experiments were performed in the present study, such as CCK-8, western blotting and flow cytometry. RESULTS: We found that EIF3G is highly expressed at RNA and protein levels in HCT116/5-Fu cells compared with HCT116 cells using quantitative real-time polymerase chain reaction and Western blot analysis. In addition, silencing EIF3G enhanced 5-Fu-induced apoptosis in HCT116/5-Fu cells. Moreover, EIF3G silencing decreased the activity of the drug-related proteins MDR1 and MRP levels in HCT116/5-Fu cells. Finally, the xenograft tumor model further confirmed that EIF3G resensitized HCT116/5-Fu tumors to 5-Fu. We observed that EIF3G silencing followed by 5-Fu administration had a synergistic interaction effect on HCT116/5-Fu in vitro and in vivo. CONCLUSION: These findings demonstrate that EIF3G is a targetable regulator of chemoresistance in CRC, and inhibiting EIF3G in combination with 5-Fu might be a potential therapeutic strategy for colon cancer.

Erectile Dysfunction and Associated Risk Factors in Chinese Males of Infertile Couples.

BACKGROUND: Knowledge on the occurrence of erectile dysfunction (ED) and timely ovulatory intercourse failure (TOIF) in Chinese men of infertile couples is limited. AIM: To obtain representative estimates of ED and TOIF in Chinese men of infertile couples and to analyze potential risk factors associated with ED. METHODS: 4,299 Chinese men of infertile couples with an average age of 32.85 ± 5.98 years were surveyed using the 5-item International Index of Erectile Function (IIEF-5) questionnaire for their ED occurrence. Multiple logistic regression analysis was used to disclose risk factors associated with ED. OUTCOMES: The occurrence of ED was 57.8% and that of TOIF was up to 26.2% in Chinese men of infertile couples. RESULTS: Based on IIEF-5 criteria, 34.9% of men had mild ED and only 2.6% had severe ED. Secondary infertility, infertility with known causes, and chronic prostatitis were significant risk factors associated with ED. TOIF was significantly higher (23.3%) in men of infertile couples with ED than in those without ED (8.6%), indicating that TOIF is likely a contributing factor to male infertility. CLINICAL IMPLICATIONS: Understanding the occurrence and types of ED and TOIF in men of infertile couples and their associated risk factors will help physicians treat clinical cases of male infertility more effectively. STRENGTHS AND LIMITATIONS: Large numbers of infertile outpatients from multiple hospital clinics across the country were included in this study. The concept of TOIF was raised for the 1st time and studied preliminarily in Chinese men of infertile couples. The lack of participants' psychological status, a control group of men of fertile couples, and measurement of testosterone levels was a limitation in this clinic-based study. CONCLUSION: The occurrence of ED was higher in Chinese men of infertile couples than in the general Chinese male population. Yang B, Xu P, Shi Y, et al. Erectile Dysfunction and Associated Risk Factors in Chinese Males of Infertile Couples. J Sex Med 2018;15:671-677.

High-efficiency CRISPR/Cas9 multiplex gene editing using the glycine tRNA-processing system-based strategy in maize.

BACKGROUND: CRISPR/Cas9 genome editing strategy has been applied to a variety of species and the tRNA-processing system has been used to compact multiple gRNAs into one synthetic gene for manipulating multiple genes in rice. RESULTS: We optimized and introduced the multiplex gene editing strategy based on the tRNA-processing system into maize. Maize glycine-tRNA was selected to design multiple tRNA-gRNA units for the simultaneous production of numerous gRNAs under the control of one maize U6 promoter. We designed three gRNAs for simplex editing and three multiple tRNA-gRNA units for multiplex editing. The results indicate that this system not only increased the number of targeted sites but also enhanced mutagenesis efficiency in maize. Additionally, we propose an advanced sequence selection of gRNA spacers for relatively more efficient and accurate chromosomal fragment deletion, which is important for complete abolishment of gene function especially long non-coding RNAs (lncRNAs). Our results also indicated that up to four tRNA-gRNA units in one expression cassette design can still work in maize. CONCLUSIONS: The examples reported here demonstrate the utility of the tRNA-processing system-based strategy as an efficient multiplex genome editing tool to enhance maize genetic research and breeding.

Genome-wide characterization of cis-acting DNA targets reveals the transcriptional regulatory framework of opaque2 in maize.

Opaque2 (O2) is a transcription factor that plays important roles during maize endosperm development. Mutation of the O2 gene improves the nutritional value of maize seeds but also confers pleiotropic effects that result in reduced agronomic quality. To reveal the transcriptional regulatory framework of O2, we studied the transcriptome of o2 mutants using RNA sequencing (RNA-Seq) and determined O2 DNA binding targets using chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-Seq). The RNA-Seq analysis revealed 1605 differentially expressed genes (DEGs) and 383 differentially expressed long, noncoding RNAs. The DEGs cover a wide range of functions related to nutrient reservoir activity, nitrogen metabolism, stress resistance, etc. ChIP-Seq analysis detected 1686 O2 DNA binding sites distributed over 1143 genes. Overlay of the RNA-Seq and ChIP-Seq results revealed 35 O2-modulated target genes. We identified four O2 binding motifs; among them, TGACGTGG appears to be the most conserved and strongest. We confirmed that, except for the 16- and 18-kD zeins, O2 directly regulates expression of all other zeins. O2 directly regulates two transcription factors, genes linked to carbon and amino acid metabolism and abiotic stress resistance. We built a hierarchical regulatory model for O2 that provides an understanding of its pleiotropic biological effects.

[Psychological factors and male reproductive health].

Reproductive health is a focus of the 21st century medical sciences. Researches on the correlation between psychological factors and male reproductive health may help discover the rules of the development of male diseases. This paper analyzes the social root-cause of the adverse psychological factors of men, discusses how psychological factors affect male reproductive health, and proposes some remedial measures for related psychological problems.