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Decapping is the enzymatic removal of 5′ cap structures from mRNAs in eukaryotic cells. Cap structures normally enhance mRNA translation and stability, and their excision commits an mRNA to complete 5′–3′ exoribonucleolytic digestion and generally ends the physical and functional cellular presence of the mRNA. Decapping plays a pivotal role in eukaryotic cytoplasmic mRNA turnover and is a critical and highly regulated event in multiple 5′–3′ mRNA decay pathways, including general 5′–3′ decay, nonsense‐mediated mRNA decay (NMD), AU‐rich element‐mediated mRNA decay, microRNA‐mediated gene silencing, and targeted transcript‐specific mRNA decay. In the yeast Saccharomyces cerevisiae, mRNA decapping is carried out by a single Dcp1‐Dcp2 decapping enzyme in concert with the accessory activities of specific regulators commonly known as decapping activators or enhancers. These regulatory proteins include the general decapping activators Edc1, 2, and 3, Dhh1, Scd6, Pat1, and the Lsm1‐7 complex, as well as the NMD‐specific factors, Upf1, 2, and 3. Here, we focus on in vivo mRNA decapping regulation in yeast. We summarize recently uncovered molecular mechanisms that control selective targeting of the yeast decapping enzyme and discuss new roles for specific decapping activators in controlling decapping enzyme targeting, assembly of target‐specific decapping complexes, and the monitoring of mRNA translation. Further, we discuss the kinetic contribution of mRNA decapping for overall decay of different substrate mRNAs and highlight experimental evidence pointing to the functional coordination and physical coupling between events in mRNA deadenylation, decapping, and 5′–3′ exoribonucleolytic decay. [ABSTRACT FROM AUTHOR]

The major aim of the present study was to explore the effects of cullin 4B (CUL4B) on the proliferation and invasion of human gastric cancer cells. Gastric tumor tissues and paired adjacent non‑tumor tissues were obtained from 21 gastric cancer patients, and gastric cancer cell lines (AGS, MGC‑803, KATO‑III, MKN‑45, SGC‑7901, BGC‑823 and MKN‑74) were cultured. BGC‑823 cells were transfected with CUL4B small interfering (si)RNA or control siRNA. Reverse transcription‑quantitative polymerase chain reaction analysis was performed to detect the mRNA expression of CUL4B. Western blot analysis was performed to measure the protein levels of Wnt, β‑catenin, glutathione synthase kinase (GSK)‑3β, caspase‑3 and cyclin E. MTT and Transwell assays were performed to examine cell proliferation and invasion following CUL4B knockdown. In addition, the effect of CUL4B knockdown on the cell cycle and apoptosis of BGC‑823 cells was evaluated by flow cytometric analysis. The results indicated that compared with the adjacent non‑tumor tissues and a normal gastric epithelial cell line, gastric cancer tissues and cell lines exhibited significantly higher expression of CUL4B. Knockdown of CUL4B in gastric cancer cells suppressed cell proliferation, caused G1 arrest and inhibited cell invasion. Silencing of CUL4B also resulted in decreased Wnt and β‑catenin expression, but increased expression of GSK‑3β, caspase‑3 and cyclin E. These results indirectly demonstrate that CUL4B enhances the proliferation and invasion abilities of gastric cancer cells by upregulating the constituent factors Wnt and β‑catenin, as well as by negatively regulating the mRNA and protein expression of GSK‑3β, caspase‑3 and cyclin E. The potential mechanism of CUL4B highlighted in the present study may be helpful for the treatment of patients with gastric cancer. [ABSTRACT FROM AUTHOR]

Nonsense-mediated mRNA decay (NMD) is generally thought to be a eukaryotic mRNA surveillance pathway tasked with the elimination of transcripts harboring an in-frame premature termination codon (PTC). As presently conceived, NMD acting in this manner minimizes the likelihood that potentially toxic polypeptide fragments would accumulate in the cytoplasm. This notion is to be contrasted to the results of systematic RNA-Seq and microarray analyses of NMD substrates in multiple model systems, two different experimental approaches which have shown that many mRNAs identified as NMD substrates fail to contain a PTC. Our recent results provide insight into, as well as a possible solution for, this conundrum. By high-resolution profiling of mRNAs that accumulate in yeast when the principal NMD regulatory genes ( UPF1, UPF2, and UPF3) are deleted, we identified approximately 900 NMD substrates, the majority of which are normal-looking mRNAs that lack PTCs. Analyses of ribosomal profiling data revealed that the latter mRNAs tended to manifest elevated rates of out-of-frame translation, a phenomenon that would lead to premature translation termination in alternative reading frames. These results, and related observations of heterogeneity in mRNA isoforms, suggest that NMD should be reconsidered as a probabilistic mRNA quality control pathway that is continually active throughout an mRNA's life cycle. [ABSTRACT FROM AUTHOR]

Nonsense-mediated mRNA decay (NMD) is a eukaryotic surveillance mechanism that monitors cytoplasmic mRNA translation and targets mRNAs undergoing premature translation termination for rapid degradation. From yeasts to humans, activation of NMD requires the function of the three conserved Upf factors: Upf1, Upf2, and Upf3. Here, we summarize the progress in our understanding of the molecular mechanisms of NMD in several model systems and discuss recent experiments that address the roles of Upf1, the principal regulator of NMD, in the initial targeting and final degradation of NMD-susceptible mRNAs. We propose a unified model for NMD in which the Upf factors provide several functions during premature termination, including the stimulation of release factor activity and the dissociation and recycling of ribosomal subunits. In this model, the ultimate degradation of the mRNA is the last step in a complex premature termination process. [ABSTRACT FROM AUTHOR]

Abstract: Cytochrome P450c17-II (cyp17-II) gene is an important factor affecting the growth, gonad differentiation and development, and other reproductive traits of fish. There are three CpG rich regions in the coding region of cyp17-II gene in Japanese flounder (Paralichthys olivaceus). The aim of this study was to understand whether mutations in exons of the cyp17-II gene occured at CpG sites, and mutations and methylation status of those CpG sites were involved in regulation of the expression level of cyp17-II gene and the reproductive endocrine of Japanese flounder. The results showed that three single nucleotide polymorphisms (SNPs) were identified. SNP1 [(c. G594A (p.Gly 188Arg)] located in exon 4 of L1 locus, and SNP2 (c.A939G) and SNP3 (c.C975T) of L2 locus located in CpG rich region of the exon 6 of cyp17-II gene. Furthermore, the A to G transition at 939bp position added a new methylation site to the cyp17-II coding region. According to multiple-comparison analysis, two loci (L1 and L2) were significantly associated with serum testosterone (T) level (P< 0.05) and the expression of cyp17-II in ovary (P< 0.01). Intriguingly, individuals with GG genotype of L2 locus containing eight CpG methylation sites had significantly lower serum testosterone level and cyp17-II mRNA expression than those with AA genotype containing seven CpG methylation sites. Moreover, the CpG site was highly methylated (⩾77.8%) at 938bp position of individuals with GG genotype of L2 locus. These implied that the mutation and methylation status of the coding region of cyp17-II could influence the gene expression and the reproductive endocrine levels in female Japanese flounder and L2 locus could be regarded as a candidate genetic or epigenetic marker for Japanese flounder breeding programs. [Copyright &y& Elsevier]

A correction to the article "Conserved mRNA-granule component Scd6 targets Dhh1 to repress translation initiation and activates Dcp2-mediated mRNA decay in vivo" which appeared in the previous is presented.

Upstream open reading frames (uORFs) play important roles in regulating the main coding DNA sequences (CDSs) via translational repression. Despite their prevalence in the genomes, uORFs are overall discriminated against by natural selection. However, it remains unclear why in the genomes there are so many uORFs more conserved than expected under the assumption of neutral evolution. Here, we generated genome-wide maps of translational efficiency (TE) at the codon level throughout the life cycle of Drosophila melanogaster. We identified 35,735 uORFs that were expressed, and 32,224 (90.2%) of them showed evidence of ribosome occupancy during Drosophila development. The ribosome occupancy of uORFs is determined by genomic features, such as optimized sequence contexts around their start codons, a shorter distance to CDSs, and higher coding potentials. Our population genomic analysis suggests the segregating mutations that create or disrupt uORFs are overall deleterious in D. melanogaster. However, we found for the first time that many (68.3% of) newly fixed uORFs that are associated with ribosomes in D. melanogaster are driven by positive Darwinian selection. Our findings also suggest that uORFs play a vital role in controlling the translational program in Drosophila. Moreover, we found that many uORFs are transcribed or translated in a developmental stage-, sex-, or tissue-specific manner, suggesting that selective transcription or translation of uORFs could potentially modulate the TE of the downstream CDSs during Drosophila development. [ABSTRACT FROM AUTHOR]

Highlights: [•] GnRH treatment of gonadotrope-derived cells causes remodeling of ribosome content. [•] Enrichment of mRNA in non-translating RNP complexes is associated with activation of EIF2AK3/PERK. [•] Enrichment of mRNA in active polyribosome complexes is associated with activation of ERK. [•] Dusp1 mRNA, a factor important for the regulatory feedback of ERK, is enriched in polyribosomes. [•] The mRNA binding protein ELAV1 binds the DUSP1 3′UTR and confers resistance to translational suppression induced by GNRH. [ABSTRACT FROM AUTHOR]

Abstract: This paper revealed the expression pattern of ERα in the ovoviviparous teleost, Sebastes schlegeli. In this paper, we isolated the cDNA encoding for estrogen receptor alpha of black rockfish (S. schlegeli) from its ovary, named as black rockfish ERα (brfERα). The cDNA sequence of brfERα consists of 2972bp with an open reading frame encoding a 624 amino acid putative protein which exhibits high identities with other teleosts’. The tissue distribution of brfERα mRNA was examined using RT-PCR. BrfERα showed generally expressions in most tissues of female black rockfish, besides, the higher degree of expressions were seen in ovary, liver, duodenum and fat, whereas it had a more restricted distribution in male fish. In ovary, the expression level of brfERα was as similar as the serum levels of E2 and P in female. However, it was a different situation in male, where the serum concentration of E2 showed higher levels after spermiation and Serum concentration of P did not show any significant changes during a year. Based on the present study, it is supposed that brfERα plays an important role in ovary and other target organs during the reproductive cycle, Further studies will focus on the transcriptional regulation and localization of brfERα in gonad in order to get a better understand of the physiological function of brfERα in ovoviviparous teleost. This study indicates that the black rockfish may be a good candidate for understanding the mechanism of estrogen in ovoviviparous fish. [Copyright &y& Elsevier]

Background: We have demonstrated that growth differentiation factor 9 (GDF9) enhances activin A-induced inhibin βB-subunit mRNA levels in human granulosa-lutein (hGL) cells by regulating receptors and key intracellular components of the activin signaling pathway. However, we could not exclude its effects on follistatin (FST) and follistatin-like 3 (FSTL3), well recognized extracellular inhibitors of activin A. Methodology: hGL cells from women undergoing in vitro fertilization (IVF) treatment were cultured with and without siRNA transfection of FST, FSTL3 or GDF9 and then treated with GDF9, activin A, FST, FSTL3 or combinations. FST, FSTL3 and inhibin βB-subunit mRNA, and FST, FSTL3 and inhibin B protein levels were assessed with real-time RT-PCR and ELISA, respectively. Data were log transformed before ANOVA followed by Tukey's test. Principal Findings: GDF9 suppressed basal FST and FSTL3 mRNA and protein levels in a time- and dose-dependent manner and inhibited activin A-induced FST and FSTL3 mRNA and protein expression, effects attenuated by BMPR2 extracellular domain (BMPR2 ECD), a GDF9 antagonist. After GDF9 siRNA transfection, basal and activin A-induced FST and FSTL3 mRNA and protein levels increased, but changes were reversed by adding GDF9. Reduced endogenous FST or FSTL3 expression with corresponding siRNA transfection augmented activin A-induced inhibin βB-subunit mRNA levels as well as inhibin B levels (P values all <0.05). Furthermore, the enhancing effects of GDF9 in activin A-induced inhibin βB-subunit mRNA and inhibin B production were attenuated by adding FST. Conclusion: GDF9 decreases basal and activin A-induced FST and FSTL3 expression, and this explains, in part, its enhancing effects on activin A-induced inhibin βB-subunit mRNA expression and inhibin B production in hGL cells. [ABSTRACT FROM AUTHOR]

Summary: Bowman–Birk trypsin inhibitors (BBIs) play important roles in animal and plant immunity, but how these protease inhibitors are involved in the immune system remains unclear. Here, we show that the rice (Oryza sativa) BBI protein APIP4 is a common target of a fungal effector and an NLR receptor for innate immunity. APIP4 exhibited trypsin inhibitor activity in vitro and in vivo. Knockout of APIP4 in rice enhanced susceptibility, and overexpression of APIP4 increased resistance to the fungal pathogen Magnaporthe oryzae. The M. oryzae effector AvrPiz‐t interacted with APIP4 and suppressed APIP4 trypsin inhibitor activity. By contrast, the rice NLR protein Piz‐t interacted with APIP4, enhancing APIP4 transcript and protein levels, and protease inhibitor activity. Our findings reveal a novel host defence mechanism in which a host protease inhibitor targeted by a fungal pathogen is protected by an NLR receptor. [ABSTRACT FROM AUTHOR]

Scd6 protein family members are evolutionarily conserved components of translationally silent mRNA granules. Yeast Scd6 interacts with Dcp2 and Dhh1, respectively a subunit and a regulator of the mRNA decapping enzyme, and also associates with translation initiation factor eIF4G to inhibit translation in cell extracts. However, the role of Scd6 in mRNA turnover and translational repression in vivo is unclear. We demonstrate that tethering Scd6 to a GFP reporter mRNA reduces mRNA abundance via Dcp2 and suppresses reporter mRNA translation via Dhh1. Thus, in a dcp2Δ mutant, tethered Scd6 reduces GFP protein expression with little effect on mRNA abundance, whereas tethered Scd6 has no impact on GFP protein or mRNA expression in a dcp2Δ dhh1Δ double mutant. The conserved LSm domain, but not the RGG domain, of Scd6 is required for translational repression and mRNA turnover by tethered Scd6. Both functions are enhanced in a ccr4Δ mutant, suggesting that the deadenylase function of Ccr4-Not complex interferes with a more efficient repression pathway enlisted by Scd6. Ribosome profiling and RNA-Seq analysis of scd6Δ and dhh1Δ mutants suggests that Scd6 cooperates with Dhh1 in translational repression and turnover of particular native mRNAs, with both processes dependent on Dcp2. Our results suggest that Scd6 can (i) recruit Dhh1 to confer translational repression and (ii) activate mRNA decapping by Dcp2 with attendant degradation of specific mRNAs in vivo, in a manner dependent on the Scd6 LSm domain and modulated by Ccr4. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a critical public health and socioeconomic problem worldwide. The herb pair Astragali Radix (AR)-Radix Angelica Sinensis (RAS) is a common prescribed herbal formula or is added to other Chinese medicine prescriptions for traumatic brain injury (TBI) treatment. However, the underlying mechanisms are unclear. In this study, we aimed to explore the active ingredients and action targets of AR-RAS based on the combined methods of network pharmacology prediction and experimental verification. Furthermore, the corresponding potential mechanisms of “multicomponents, multitargets, and multipathways” were disclosed. Methods. A network pharmacology approach including ADME (absorption, distribution, metabolism, and excretion) filter analysis, target prediction, known therapeutic targets collection, Gene Ontology (GO), pathway enrichment analysis, and network construction was used in this study. Further verification experiments were performed to reveal the therapeutic effects of AR-RAS in a rat model of TBI. Results. The comprehensive systematic approach was to successfully identify 14 bioactive ingredients in AR-RAS, while 33 potential targets hit by these ingredients related to TBI. Based on GO annotation analysis, multiple biological processes were significantly regulated by AR-RAS. In addition, 89 novel signaling pathways (P<0.05) underlying the effects of AR-RAS for TBI treatment were identified by DAVID. The neurotrophin signaling pathway was suggested as the major related pathway targeted by AR-RAS to improve axonal growth. The animal experiment confirmed that AR-RAS significantly induced tissue recovery and improved neurological deficits on the 14th day (P<0.01). Treatment with AR-RAS markedly reduced the protein and mRNA expression level of NogoA in the hippocampus of TBI rats. Conclusion. Our work illuminates the “multicompounds, multitargets, and multipathways” curative action of AR-RAS in the treatment of TBI by network pharmacology. The animal experiment verifies the effects of AR-RAS on neurological function improvement and axonal outgrowth via downregulation of NogoA expression, providing a theoretical basis for further research on treatment of TBI. [ABSTRACT FROM AUTHOR]

To study the expression of four estrogen receptor genes ( erα1, erα2, erβ1, erβ2 ) of female rainbow trout ( Oncorhynchus mykiss ) during first ovarian development, trouts were sampled from different ovarian stages. Serum E 2 (estradiol) was measured by ELISA and estrogen receptors mRNA expression were examined by qRT-PCR. Our results showed a close association between increased erα1 and vitellogenin mRNA expression during ovarian maturation and increased erα2 mRNA expression in mature ovarian stages. Correlation analysis revealed that a negative relationship between serum E 2 and ovarian erβ1 (or hepatic erβ2 ), but ovarian erβ2 mRNA expression was relatively unchanged during first ovarian development. Trout were also reared in different densities as stocking density 1, 2 and 3 (SD1, 4.6–31.1 kg/m 3 ; SD2, 6.6–40.6 kg/m 3 ; SD3, 8.6–49.3 kg/m 3 ) to elucidate effects of high density on estrogen receptor expression. Histology observation showed ovarian development of trout in higher densities were retard with a relatively early stage and fewer vitellogenin accumulation. Trout in high densities showed significantly decreased serum E 2 , erα mRNA expression and increasing trends of erβ mRNA expression. A noticeable increase of ovarian erβ2 mRNA expression was seen in trout when density is approaching to 50 kg/m 3 . In conclusion, we may hypothesize that increased erβ mRNA expression triggered by high density result in decreased erα mRNA expression and vitellogenesis. As a result, ovarian development in higher densities was retard. [ABSTRACT FROM AUTHOR]

A correction to the article "Degradation of YRA1 Pre-mRNA in the Cytoplasm Requires Translational Repression, Multiple Modular Intronic Elements, Edc3p, and Mex67p" that was published in the previous issue, is presented.

X-linked lymphoproliferative disease type 1 (XLP1) is a rare primary immunodeficiency characterized by a clinical triad consisting of severe EBV-induced hemophagocytic lymphohistiocytosis, B-cell lymphoma, and dysgammaglobulinemia. Mutations in SH2D1A gene have been revealed as the cause of XLP1. In this study, a pregnant woman with recurrence history of birthing immunodeficiency was screened for pathogenic variant because the proband sample was unavailable. We aimed to clarify the genetic diagnosis and provide prenatal testing for the family. Next-generation sequencing (NGS)-based multigene panel was used in carrier screening of the pregnant woman. Variants of immunodeficiency related genes were analyzed and prioritized. Candidate variant was verified by using Sanger sequencing. The possible influence of the identified variant was evaluated through RNA assay. Amniocentesis, karyotyping, and Sanger sequencing were performed for prenatal testing. We identified a novel de novo frameshift SH2D1A pathogenic variant (c.251_255delTTTCA) in the pregnant carrier. Peripheral blood RNA assay indicated that the mutant transcript could escape nonsense-mediated mRNA decay (NMD) and might encode a C-terminal truncated protein. Information of the variant led to success prenatal diagnosis of the fetus. In conclusion, our study clarified the genetic diagnosis and altered disease prevention for a pregnant carrier of XLP1. [ABSTRACT FROM AUTHOR]

Upf1, Upf2, and Upf3 are the principal regulators of nonsense-mediated mRNA decay (NMD), a cytoplasmic surveillance pathway that accelerates the degradation of mRNAs undergoing premature translation termination. These three proteins interact with each other, the ribosome, the translation termination machinery, and multiple mRNA decay factors, but the precise mechanism allowing the selective detection and degradation of nonsense-containing transcripts remains elusive. Here, we have determined the crystal structure of the N-terminal mIF4G domain from Saccharomyces cerevisiae Upf2 and identified a highly conserved region in this domain that is essential for NMD and independent of Upf2's binding sites for Upf1 and Upf3. Mutations within this conserved region not only inactivate NMD but also disrupt Upf2 binding to specific proteins, including Dbp6, a DEAD-box helicase. Although current models indicate that Upf2 functions principally as an activator of Upf1 and a bridge between Upf1 and Upf3, our data suggest that it may also serve as a platform for the association of additional factors that play roles in premature translation termination and NMD. [ABSTRACT FROM AUTHOR]

Cytochrome P450 aromatase (P450arom) is an enzyme responsible for the conversion of androgen into oestrogen. To study the role of ovarian aromatase (Cyp19a1a) in sex differentiation, the novel c DNA clone encoding ovarian aromatase (Cyp19a1a) was identified from the ovary of the black rockfish ( Sebastes schlegeli). The cloned c DNA is 1868 bp in length with 79 bp 5′U TR, 209 bp 3′UTR [excluding poly (A)] and contains 1550 bp ORF, encoding a protein of 516 amino acids. Alignment and phylogenetic analysis showed that the black rockfish ovarian aromatase (Cyp19a1a) shared 61-89% sequence identity with those of other seven fish species. The cyp19a1a transcript was found more highly abundant in ovary, but not detected in the testis, brain, liver, spleen, kidney, muscle, skin, heart, head kidney, gill, intestine and eyes by semi-quantitative reverse transcription ( RT)- PCR. The cyp19a1a gene is not equivalent in tissue-specific expression in the female and male, showed the possibility of distinct promoters and regulatory mechanisms. The expression level of cyp19a1a in ovary declined with the ovary development, but was higher than that in testis in all phases. These results indicated that cyp19a1a might be involved in gonadal development in S. schlegeli. [ABSTRACT FROM AUTHOR]

Background/Aims: Water channels, also named aquaporins (AQPs), play crucial roles in cellular water homeostasis. Methods: RT-PCR indicated the mRNA expression of AQPs 1-5, 7, 9, and 11-12, but not AQPs 0, 6, 8, and 10 in the 2∼8-cell stage human embryos. AQP3 and AQP7 were further analyzed for their mRNA expression and protein expression in the oocyte, zygote, 2-cell embryo, 4-cell embryo, 8-cell embryo, morula, and blastocyst from both human and mouse using RT-PCR and immunofluorescence, respectively. Results: AQP3 and AQP7 were detected in all these stages. Knockdown of either AQP3 or AQP7 by targeted siRNA injection into 2-cell mouse embryos significantly inhibited preimplantation embryo development. However, knockdown of AQP3 in JAr spheroid did not affect its attachment to Ishikawa cells. Conclusion: These data demonstrate that multiple aquaporins are expressed in the early stage human embryos and that AQP3 and AQP7 may play a role in preimplantation mouse embryo development. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The objective of this study was to explore whether hyperandrogenism induces epigenetic alterations of peroxisome proliferator-activated receptor gamma 1 (PPARG1), nuclear corepressor 1 (NCOR1), and histone deacetylase 3 (HDAC3) genes in granulosa cells (GCs) of polycystic ovary syndrome (PCOS) women and whether these alterations are involved in the ovarian dysfunction induced by hyperandrogenism. Thirty-two infertile PCOS women and 147 infertile women with tubal blockage were recruited. PCOS women were divided into the hyperandrogenism (HA) PCOS group ( n = 13) and nonhyperandrogenism (N-HA) PCOS group ( n = 19). Sixty female Sprague-Dawley rats were used for PCOS model establishment. In GCs of HA PCOS women, PPARG1 mRNA expression was lower, whereas NCOR1 and HDAC3 mRNA expression were higher than N-HA PCOS women and controls ( P < 0.05). When all women were divided into successful and failed pregnancy subgroups according to the following clinical pregnancy outcome, we found lower PPARG1 mRNA levels and higher NCOR1 and HDAC3 mRNA levels in the failed subgroup of HA PCOS ( P < 0.05). Two hypermethylated CpG sites in the PPARG1 promoter and five hypomethylated CpG sites in the NCOR1 promoter were observed only in HA PCOS women ( P < 0.01 to P < 0.0005). The acetylation levels of histone H3 at lysine 9 and p21 mRNA expression were decreased in human GCs treated with dihydrotestosterone in vitro ( P < 0.05). PCOS rat models also showed alterations of PPARG1, NCOR1, and HDAC3 mRNA expression and methylation changes of PPARG1 and NCOR1, consistent with the results from humans. Hyperandrogenism induces the epigenetic alterations of PPARG1, NCOR1, and HDAC3 in GCs, which are involved in the ovarian dysfunction of HA PCOS. [ABSTRACT FROM AUTHOR]

Background/Aims: Aquaporin-3 (AQP3), one isoform of water channel family, has been found to be expressed in mouse oocytes. The present study aimed to investigate whether functional AQP3 was expressed in oocytes induced by controlled ovarian hyperstimulation (COH), and whether altered oocyte AQP3 expression was associated with changes in fertilization rate. Methods: Sixty ICR female mice were divided into two groups: COH and control. AQP3 mRNA expression of mouse metaphase II (MII) oocytes was quantified by real-time RT-PCR. The water permeability of oocytes was assessed with cell swelling test. The fertilization profiles of oocytes were generated via in vitro fertilization. Results: AQP3 mRNA was expressed in both natural and COH-induced mouse oocytes. COH significantly reduced AQP3 mRNA expression. The volume of oocytes was significantly increased after exposure to hypotonic medium and pretreatment with HgCl2 attenuated hypotonic medium-induced increase in oocyte volume and water permeability coefficient (Pf). Furthermore, the expression of AQP3, Pf and the fertilization rate were significantly lower in COH oocytes than those in control. Conclusion: AQP3 might play an important role in controlling oocyte quality and a low in vitro fertilization rate of COH mice might, in part, result from reduced AQP3 expression and water permeability in mouse oocytes. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Summary: Autoregulatory loops often provide precise control of the level of expression of specific genes that encode key regulatory proteins. Here we have defined a pathway by which Yra1p, a yeast mRNA export factor, controls its own expression. We show that YRA1 exon 1 sequences in cis and Yra1p in trans inhibit YRA1 pre-mRNA splicing and commit the pre-mRNA to nuclear export. Mex67p and Crm1p jointly promote YRA1 pre-mRNA export, and once in the cytoplasm, the pre-mRNA is degraded by a 5′ to 3′ decay mechanism that is dependent on the decapping activator Edc3p and on specific sequences in the YRA1 intron. These results illustrate how common steps in the nuclear processing, export, and degradation of a transcript can be uniquely combined to control the expression of a specific gene and suggest that Edc3p-mediated decay may have additional regulatory functions in eukaryotic cells. [Copyright &y& Elsevier]