Downregulation of OsAGO17 by artificial microRNA causes pollen abortion resulting in the reduction of grain yield in rice

Background: Pollen development is an important reproductive process that directly affects pollen fertility and grain yield in rice. Argonaute (AGO) proteins, the core effectors of RNA-mediated silencing, play important roles in regulating plant growth and development. However, few AGO proteins in rice were reported to be involved in pollen development. In this study, artificial microRNA technology was used to assess the function of OsAGO17 in pollen development. Results: In this study, OsAGO17, a rice-specific gene, was specifically expressed in rice pollen grains, with the highest expression in uninucleate microspores. Downregulation of OsAGO17 by artificial microRNA technology based on the endogenous osa-miRNA319a precursor was successfully achieved. It is found that downregulation of OsAGO17 could significantly affect pollen fertility and cause pollen abortion, thus suggesting that OsAGO17 functions in rice pollen development. In addition, the downregulation of OsAGO17 mainly caused a low seed-setting rate, thereby resulting in the reduction of grain yield, whereas the downregulation of OsAGO17 did not significantly affect rice vegetative growth and other agricultural traits including number of florets per panicle, number of primary branch per panicle, and 100-grain weight. Furthermore, the result of subcellular localization analysis indicated that the OsAGO17 protein was localized to both the nucleus and the cytoplasm. Conclusion: These results represent the first report of the biological function for OsAGO17 in rice and indicate that OsAGO17 may possibly play crucial regulatory roles in rice pollen development. It helps us to better understand the mechanism of pollen development in rice.

Altered PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression in ejaculated spermatozoa of men with impaired sperm characteristics / 亚洲男科学杂志(英文版)

In about half the cases of involuntary childlessness, a male infertility factor is involved. The PIWI-LIKE genes, a subclade of the Argonaute protein family, are involved in RNA silencing and transposon control in the germline. Knockout of murine Piwi-like 1 and 2 homologs results in complete infertility in males. The aim of this study was to analyze whether the mRNA expression of human PIWI-LIKE 1-4 genes is altered in ejaculated spermatozoa of men with impaired sperm characteristics. Ninety male participants were included in the study, among which 47 were with normozoospermia, 36 with impaired semen characteristics according to the World Health Organization (WHO) manual, 5th edition, and 7 with azoospermia serving as negative control for the PIWI-LIKE 1-4 mRNA expression in somatic cells in the ejaculate. PIWI-LIKE 1-4 mRNA expression in the ejaculated spermatozoa of the participants was measured by quantitative real-time PCR. In nonazoospermic men, PIWI-LIKE 1-4 mRNA was measurable in ejaculated spermatozoa in different proportions. PIWI-LIKE 1 (100.0%) and PIWI-LIKE 2 (49.4%) were more frequently expressed than PIWI-LIKE 3 (9.6%) and PIWI-LIKE 4 (15.7%). Furthermore, a decreased PIWI-LIKE 2 mRNA expression showed a significant correlation with a decreased sperm count (P = 0.022) and an increased PIWI-LIKE 1 mRNA expression with a decreased progressive motility (P = 0.048). PIWI-LIKE 1 and PIWI-LIKE 2 mRNA expression exhibited a significant association with impaired sperm characteristics and may be a useful candidate for the evaluation of the impact of PIWI-LIKE 1-4 mRNA expression on male infertility.

Cancer stem-like cell-derived exosomes promotes the proliferation and invasion of human umbilical cord blood-derived mesenchymal stem cells / 南方医科大学学报

OBJECTIVE@#To investigate the effect of Piwil2-induced cancer stem-like cell (Piwil2-iCSC)-derived exosomes on the proliferation,migration and invasion of human umbilical cord blood-derived mesenchymal stem cells (hucMSCs).@*METHODS@#Piwil2-iCSC-derived exosomes were isolated by ultracentrifugation and identified using transmission electron microscopy,nanoparticle tracking analysis and Western blotting.Exosome uptake assay was used to identify the pathway that Piwil2-iCSCderived exosomes utilized.HucMSCs were divided into control group,PBS intervention group and exosome intervention group,and CCK-8 assay,wound healing assay,Transwell assay,Western blotting and cell karyotype analysis were used to observe the proliferation,migration,invasion,expression levels of MMP2 and MMP9 proteins,and chromosome structure of hucMSCs.@*RESULTS@#The diameter of Piwil2-iCSC-derived exosomes ranged from 50 nm to 100 nm,and most of them were oval or spherical capsules rich in CD9,CD63 and Piwil2 proteins.Exosomal uptake assay showed that the exosomes executed theirs functions after entering the cells.Compared with the control cells and PBS-treated cells,hucMSCs treated with the exosomes showed significantly increased number of proliferating cells (<0.05) with accelerated healing rate (<0.05 at 24 h;<0.01 at 48 h),increased invasive cells (<0.01),enhanced protein expressions of MMP2(<0.05 PBS group;<0.01 control group) and MMP9(<0.05),but their karyotype still remained 46XY without any abnormalities.@*CONCLUSIONS@#Piwil2-iCSC-derived exosomes can promote the proliferation,migration and invasion but does not cause cancer-like heterogeneity changes in hucMSCs.

Histological features of tumor-bearing tissues formed by human fibroblasts after reprograming by Piwil2 / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To observe the histological features of tumor-bearing tissues formed by human fibroblasts after reprograming by spermatogonial stem cell self-renewal key regulating gene Piwil2 (Piwil2-iCSC).</p><p><b>METHODS</b>Piwil2-iCSC tumor spheroids-like colonies were selected for tumor formation assay in four nude mice. Pathological features of Piwil2-iCSC tumors were observed by histology. Stem cell markers and common triploblastic markers were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) assay and immunohistochemistry. Germ cell tumor markers were detected by immunohistochemical examination.</p><p><b>RESULTS</b>Two weeks after inoculation, subcutaneous tumors were formed in all the four nude mice with a tumor formation rate of 100%. In the Piwil2-iCSC tumor tissues, Piwil2-GFP(+) cells showed high-density nuclear expression and were widely observed in DAPI-stained sections. Numerous mitotic figure of the neoplastic cells were seen (>10 cells/field of vision under high magnification) in HE-stained sections. Enlarged abnormal cell nuclei were observed. RT-PCR assay showed that Piwil2-iCSC tumors still expressed Piwil2 and some self-renewal and pluripotent markers of stem cells and some markers of triploblastic differentiation. Immunohistochemical staining showed that the tumors expressed stem cell markers, triploblastic markers and germ cell tumor markers AFP and HCG.</p><p><b>CONCLUSIONS</b>Piwil2-iCSC tumors are probably undifferentiated embryonic small cell carcinoma, most likely to be immature teratoma, mixed with yolk sac tumor and choriocarcinoma components. It can be used as a useful model for the research of origin or genesis mechanism of cancer stem cells and the treatment of relevant tumors.</p>

Cloning and sequence analysis of AGO1 gene in Panax ginseng / 中国中药杂志

Argonaute 1 (AGO1) is a core component of the RNA-induced silencing complex (RISC) which plays a crucial role in small RNA-mediated gene silencing. AGO1 gene has been characterized in various plants, such as Arabidopsis and rice. However, there is no information about AGO1 in the medicinal plant species, Panax ginseng. Using the rapid amplification of cDNA ends technology (RACE), we cloned full-length PgAGO1 cDNA from Panax ginseng. It is 3 776 bp in length, including 204 bp of 5' UTR, 254 bp of 3' UTR, and 3 318 bp of ORF encoding 1106 amino acids. The molecular weight (MW) and theroretical isoelectric point (pI) of the deduced PgAGO1 protein is 122.22 kDa and 9.71, respectively. PgAGO1 shares 91.72% similarity with Arabidopsis AtAGO1 and contains three consered domains, including DUF1785, PAZ and Piwi, suggesting it is an authentic AGO. PgAGO1 was expressed in all of the tissues analyzed with the highest level in flowers and the lowest level in roots. The results provide useful information for further elucidating the function of AGO1 in Panax ginseng.

Expression of Piwil2 and its relationship with tumor invasion and metastasis in papillary thyroid carcinoma / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To study the expressions of Piwil2 protein and mRNA in papillary thyroid carcinoma (PTC) and the relationship between Piwil2 and the invasion and metastasis of PTC.</p><p><b>METHODS</b>Immunohistochemistry and in situ hybridization were used to detect the expression of Piwil2 protein and mRNA in 60 cases of PTC with the matched adjacent non-cancerous epithelium (NCE).</p><p><b>RESULTS</b>The positive rates of Piwil2 protein expression in PTC and NCE were 88.3% (53/60) and 10.0% (6/60) respectively, with significant difference (χ² = 73.654, P < 0.01). The positive rates of Piwil2 mRNA expression in PTC and NCE were 85.0% (51/60) and 6.7% (4/60) respectively, also with significant difference (χ(2) = 74.148, P < 0.01). Up-regulated expressions of Piwil2 protein and mRNA were related to the invasion and metastasis of PTC (P < 0.05).</p><p><b>CONCLUSIONS</b>Piwil2 may play a role in the invasion and metastasis of PTC.</p>

HIWI expression profile in cancer cells and its prognostic value for patients with colorectal cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>HIWI is a member of PIWI gene family and its expression is found in various tumors, indicating that it may play a pivotal role in tumor development. This study was designated to examine HIWI protein expression profile in several cancer cell lines and its prognostic value for patients with colorectal cancer.</p><p><b>METHODS</b>Totally 270 patients who underwent surgical resection of primary colorectal cancer between January 1999 and December 2002 with a median follow-up time of 33 months were registered in the study. Formalin-fixed and paraffin-embedded specimens from these patients and 236 matched adjacent non-cancerous normal colorectal tissues were collected. Anti-HIWI monoclonal antibodies were generated and used for evaluating HIWI protein expression. χ(2) tests were conducted to determine the association between HIWI expression and the other variables. Survival curves were estimated using the Kaplan-Meier method and compared by the log-rank test. Multivariate analysis was performed by using the Cox regression model.</p><p><b>RESULTS</b>By generating antibodies specific for HIWI, we examined HIWI protein expression in several cancer cell lines and demonstrated positive expression of HIWI in 69 out of 270 (25.6%) colorectal cancer tissues; 15 of 236 (6.4%) matched adjacent non-cancerous tissues were also positive for HIWI. Patients with positive HIWI expression in adjacent non-cancerous tissue had statistically lower overall survival (OS) and disease free survival (DFS) compared with negative patients (OS: 10.4% vs. 55.5%, P = 0.009; DFS: 10.4% vs. 55.1%, P = 0.015). For early stage group (stages I and II), patients with positive HIWI expression had significantly lower OS and DFS (OS: 57.4% vs. 79.5%, P = 0.014; DFS: 56.7% vs. 80.5%, P = 0.010). In lymph node negative group, patients with positive HIWI expression had statistically lower OS and DFS (OS: 53.0% vs. 73.5%, P = 0.037; DFS: 52.2% vs. 74.6%, P = 0.025). Multivariate analysis revealed that HIWI over-expression was a significant prognostic factor for OS (95%CI: 1.132 - 2.479, P = 0.010).</p><p><b>CONCLUSION</b>HIWI could be a potential prognostic biomarker for the patients with colorectal cancer, especially for those at early stages or without lymph node metastasis.</p>

Modeling and analysis of Schistosoma Argonaute protein molecular spatial conformation

<p><b>OBJECTIVE</b>To analyze the amino acid sequence composition, secondary structure, the spatial conformation of its domain and other characteristics of Argonaute protein.</p><p><b>METHODS</b>Bioinformatics tools and the internet server were used. Firstly, the amino acid sequence composition features of the Argonaute protein were analyzed, and the phylogenetic tree was constructed. Secondly, Argonaute protein's distribution of secondary structure and its physicochemical properties were predicted. Lastly, the protein functional expression form of the domain group was established through the Phyre-based analysis on the spatial conformation of Argonaute protein domains.</p><p><b>RESULTS</b>593 amino acids were encoded by Argonaute protein, the phylogenetic tree was constructed, and Argonaute protein's distribution of secondary structure and its physicochemical properties were obtained through analysis. In addition, the functional expression form which comprised the N-terminal PAZ domain and C-terminal Piwi domain for the Argonaute protein was obtained with Phyre.</p><p><b>CONCLUSIONS</b>The information relationship between the structure and function of the Argonaute protein can be initially established with bioinformatics tools and the internet server, and this provides the theoretical basis for further clarifying the function of Schistosoma Argonaute protein.</p>