Project description:Flowering of Arabidopsis thaliana is accelerated by several environmental cues, including exposure to long days. The photoperiod-dependent promotion of flowering involves the transcriptional induction of FLOWERING LOCUS T (FT) in the phloem of the leaf. FT encodes a mobile protein that is transported from the leaves to the shoot apical meristem, where it forms part of a regulatory complex that induces flowering. Whether FT also has biological functions in leaves of wild-type plants remains unclear. In order to address this issue, we first studied the leaf transcriptomic changes associated with its over expression in the companion cells of the phloem. To this end, transgenic A. thaliana plants that misexpress FT from the pGAS1 promoter in a ft-10 tsf-1 double mutant background were employed (pGAS1:FT ft-10 tsf-1). In these transgenic plants, the use of the pGAS1 promoter ensures that the FT transgene is expressed in phloem companion cells of the minor veins, recreating the spatial pattern of expression described for the native gene. In this studuy, the transcriptome of leaves of pGAS1:FT ft-10 tsf-1 transgenic plants was compared to that of ft-10 tsf-1 and Col-0 plants using Tiling Arrays.
Project description:Background: It has been shown previously that administration of Francisella tularensis (Ft) LVS lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response. Methods: To investigate further the molecular mechanisms that underlie Ft LVS LPS-mediated protection, we profiled global hepatic gene expression following Ft LVS LPS or saline pretreatment and subsequent Ft LVS challenge using Affymetrix arrays. Results: A large number of genes (> 3000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by LPS-pretreatment in the surviving mice. However, LPS alone had a subtle but significant effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of peroxisome proliferator activated receptors (PPARs) and their target genes in LPS-treated liver. Conclusions: We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (alpha and gamma).
Project description:Background: It has been shown previously that administration of Francisella tularensis (Ft) LVS lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response. Methods: To investigate further the molecular mechanisms that underlie Ft LVS LPS-mediated protection, we profiled global hepatic gene expression following Ft LVS LPS or saline pretreatment and subsequent Ft LVS challenge using Affymetrix arrays. Results: A large number of genes (> 3000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by LPS-pretreatment in the surviving mice. However, LPS alone had a subtle but significant effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of peroxisome proliferator activated receptors (PPARs) and their target genes in LPS-treated liver. Conclusions: We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (alpha and gamma). Experiment Overall Design: Two groups of 9 mice each were used for this experiment. 48 hours prior to Ft LVS challenge, mice were injected i.p. with either 100 ng of Ft LVS LPS or an equivalent volume of saline. On the day of challenge, 3 saline- and 3 Ft LVS LPS-pretreated animals were sacrificed (uninfected controls), while all remaining mice were challenged i.p. with ~4-5 X 105 Ft LVS. Ft LVS-challenged mice were sacrificed (in groups of 3) at 24 and 48 hours post-infection.
Project description:Despite its significance to reproduction, fertility, sexually transmitted infections and various pathologies, the fallopian tube (FT) is relatively understudied. Strong evidence points to the FT as the tissue-of-origin of high grade serous ovarian cancer (HGSOC), the most fatal gynaecological malignancy. HGSOC precursor lesions arise specifically in the distal FT (fimbria) which is reported to be enriched in stem-like cells. Investigation of the role of FT stem cells in health and disease has been hampered by a lack of characterization of FT stem cells and lack of models that recapitulate stem cell renewal and differentiation in vitro. Using optimized organoid culture conditions to address these limitations, we found that FT stem cell renewal is highly dependent on WNT/β-catenin signaling and engineered endogenous WNT/β-catenin signaling reporter organoids to biomark, isolate and characterize putative FT stem cells. Using functional approaches as well as bulk and single cell transcriptomic analyses, we show that an endogenous hormonally-regulated WNT7A-FZD5 signaling axis is critical for self-renewal of human FT stem cells, and that WNT/β-catenin pathway-activated cells form a distinct transcriptomic cluster of FT cells enriched in ECM remodelling and integrin signaling pathways. In addition, we find that the WNT7A-FZD5 signaling axis is dispensable for mouse oviduct regeneration. Overall, we provide a deep characterization of FT stem cells and their molecular requirements for self-renewal, paving the way for mechanistic work investigating the role of stem cells in FT health and disease.
Project description:Despite its significance to reproduction, fertility, sexually transmitted infections and various pathologies, the fallopian tube (FT) is relatively understudied. Strong evidence points to the FT as the tissue-of-origin of high grade serous ovarian cancer (HGSOC), the most fatal gynaecological malignancy. HGSOC precursor lesions arise specifically in the distal FT (fimbria) which is reported to be enriched in stem-like cells. Investigation of the role of FT stem cells in health and disease has been hampered by a lack of characterization of FT stem cells and lack of models that recapitulate stem cell renewal and differentiation in vitro. Using optimized organoid culture conditions to address these limitations, we found that FT stem cell renewal is highly dependent on WNT/β-catenin signaling and engineered endogenous WNT/β-catenin signaling reporter organoids to biomark, isolate and characterize putative FT stem cells. Using functional approaches as well as bulk and single cell transcriptomic analyses, we show that an endogenous hormonally-regulated WNT7A-FZD5 signaling axis is critical for self-renewal of human FT stem cells, and that WNT/β-catenin pathway-activated cells form a distinct transcriptomic cluster of FT cells enriched in ECM remodelling and integrin signaling pathways. In addition, we find that the WNT7A-FZD5 signaling axis is dispensable for mouse oviduct regeneration. Overall, we provide a deep characterization of FT stem cells and their molecular requirements for self-renewal, paving the way for mechanistic work investigating the role of stem cells in FT health and disease.
Project description:Receptor tyrosine kinase pathway signalings plays a central role in the growth and progression of glioblastoma, a highly aggressive group of brain tumors. We recently reported that miR-218 repression, an essentially uniform feature of human GBM, directly promotes RTK hyperactivation by increasing the expression of key positive signaling effectors, including EGFR, PLCr1, PIK3CA and ARAF. However, enhanced RTK signaling is known to activate compensatory inhibitory feedback mechanisms in both normal and cancer cells. We demonstrate here that miR-218 repression in GBM cells also increases the abundance of additional up stream and downstream signaling mediators, including PDGFRa, RSK2, and S6K1, which collectively funciton to alleviate inhibitory RTK feedback regulation. In turn, RTK signaling suppresses miR-218 expression via STAT3, which binds to the miR-218 locus, along with BCLAF1, to repress its expression. These data identify novel interacting feedback loops by which miR-218 repression promotes increased RTK signaling in high-grade gliomas.