We have shown that Rop1At, a pollen-specific Rop GTPase that is a member of the Rho family of small GTP binding proteins, acts as a key molecular switch controlling tip growth in Arabidopsis pollen tubes. Pollen-specific expression of constitutively active rop1at mutants induced isotropic growth of pollen tubes. Overexpression of wild-type Arabidopsis Rop1At led to ectopic accumulation of Rop1At in the plasma membrane at the tip and caused depolarization of pollen tube growth, which was less severe than that induced by the constitutively active rop1at. These results indicate that both Rop1At signaling and polar localization are critical for controlling the site of tip growth. Dominant negative rop1at mutants or antisense rop1at RNA inhibited tube growth at 0.5 mM extracellular Ca 2 ϩ , but growth inhibition was reversed by higher extracellular Ca 2 ϩ . Injection of anti-Rop antibodies disrupted the tip-focused intracellular Ca 2 ϩ gradient known to be crucial for tip growth. These studies provide strong evidence for a Rop GTPase-dependent tip growth pathway that couples the control of growth sites with the rate of tip growth through the regulation of tip-localized extracellular Ca 2 ϩ influxes and formation of the tip-high intracellular Ca 2 ϩ gradient in pollen tubes.

Interleukin 22 (IL-22), which acts as either a pro-inflammatory or anti-inflammatory cytokine in various disease models, is markedly upregulated in chronic liver diseases, including hepatitis B and C. In this report, we demonstrate a strong correlation between IL-22 expression in the liver with active, inflammatory human liver disease. To clarify the role of IL-22 upregulation in the pathogenesis of liver diseases, liver specific IL-22 transgenic (IL-22TG) mice, under the control of albumin promoter, were developed. Despite elevated IL-22 serum levels ranging from 4000 to 7000 pg/ml, IL-22TG mice developed normally without obvious adverse phenotypes or evidence of chronic inflammation except slightly thicker epidermis and minor inflammation in the skin compared with wild-type mice. Most interestingly, IL-22TG mice were completely resistant to Concanavalin A-induced T cell hepatitis with minimal effect on liver inflammation and had accelerated liver regeneration after partial hepatectomy. Although they did not spontaneously develop liver tumors, IL-22TG mice were more susceptible to diethylnitrosamine-induced liver cancer. Microarray analyses revealed that a variety of anti-oxidant, mitogenic, acute phase genes were upregulated in the livers from IL-22TG mice compared with those from wild-type mice. These findings indicate that localized production of IL-22 in the liver promotes hepatocyte survival and proliferation but primes the liver to be more susceptible to tumor development without significantly affecting liver inflammation.

G proteins are universal molecular switches in eukaryotic signal transduction. The Arabidopsis genome sequence reveals no RAS small GTPase and only one or a few heterotrimeric G proteins, two predominant classes of signaling G proteins found in animals. In contrast, Arabidopsis possesses a unique family of 11 Rop GTPases that belong to the Rho family of small GTPases. Previous studies indicate that Rop controls actin-dependent pollen tube growth and H 2 O 2 -dependent defense responses. In this study, we tested the hypothesis that the Rop GTPase acts as a versatile molecular switch in signaling to multiple developmental processes in Arabidopsis. Immunolocalization using a general antibody against the Rop family proteins revealed a ubiquitous distribution of Rop proteins in all vegetative and reproductive tissues and cells in Arabidopsis. The cauliflower mosaic virus 35S promoter-directed expression of constitutively active GTP-bound rop2 (CA-rop2) and dominant negative GDP-bound rop2 (DN-rop2) mutant genes impacted many aspects of plant growth and development, including embryo development, seed dormancy, seedling development, lateral root initiation, morphogenesis of lateral organs in the shoot, shoot apical dominance and growth, phyllotaxis, and lateral organ orientation. The rop2 transgenic plants also displayed altered responses to the exogenous application of several hormones, such as abscisic acid-mediated seed dormancy, auxin-dependent lateral shoot initiation, and brassinolide-mediated hypocotyl elongation. CA-rop2 and DN-rop2 expression had opposite effects on most of the affected processes, supporting a direct signaling role for Rop in regulating these processes. Based on these observations and previous results, we propose that Rop2 and other members of the Rop family participate in multiple distinct signaling pathways that control plant growth, development, and responses to the environment.

The present study investigated the relationship between the expression of miR-146a and miR-146b with the occurrence and prognosis of papillary thyroid carcinoma. Experiments in vitro were also used to explore the effect of the knocked down expression of the miRNAs on growth and migration of papillary thyroid carcinoma cells. A total of 73 patients with papillary thyroid carcinoma admitted to Yidu Central Hospital of Weifang from September 2013 to September 2015 were enrolled in the study. Carcinoma samples were obtained from each patient, and adjacent tissues were used as control samples to determine expression levels of miR-146a and miR146b by semi-quantitative RT-PCR. An analysis was conducted to find possible correlations between the miRNAs expression levels and clinicopathological features in the patients followed up for one year after diagnosis. Additionally, to examine the function of miR-146a and miR-146b on TPC-1 cells, the expression of miRNAs was knocked down using specific siRNAs. MTT and Transwell assays were used to evaluate cell proliferation and migration, respectively, in the miRNA cell lines. Finally, western blot analysis was used to analyze the expression of IRAK1 in PTC cancer cells. Our results showed that the expression levels of miR-146a and miR-146b in carcinoma tissues were significantly higher than the levels in cancer-free tissues (P<0.01). The relative expression levels of miR-146a and miR-146b in cancerous tissues could be associated with the pathological type and presence or absence of lymph node metastasis (P<0.05). Compared with the siRNA-control cell, MTT and Transwell assays showed that the cell growth and migration of TPC-1 cells were decreased in miR-146a and miR-146b low expression cells (P<0.01). Western blot analysis showed that the expression of IRAK1 in papillary thyroid carcinoma was higher than in adjacent tissue (P<0.01). Based on our findings, the expression of miR-146a and miR-146b correlates with the occurrence and prognosis of papillary thyroid carcinoma, and the expression levels of miR-146a and miR-146b seem to affect the cell proliferation and migration and regulate the expression of IRAK1 protein in cancer cells. Further studies are needed to validate our results to provide new targets for prevention and treatment of papillary thyroid carcinoma.

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