Project description:Dissemination of prostate cancer (PCa) cells to the bone marrow is an early event in the disease process. In some patients, following initial treatment, disseminated tumor cells (DTC) proliferate to form active metastases after a prolonged period of undetectable disease known as tumor dormancy. Identifying mechanisms of PCa dormancy and reactivation remain a challenge due to the lack of in vitro models. Here, we characterized in vitro PCa dormancy-reactivation by inducing three apparently dormant patient-derived xenograft (PDX) lines to proliferate through tumor cell contact with each other and with bone marrow stroma. Proliferating PCa cells demonstrated tumor cell-cell contact and integrin clustering on immunofluorescence. Global gene expression analyses on proliferating cells cultured on bone marrow stroma revealed a downregulation of TGFB2 in all of the three proliferating PCa PDX lines when compared to their non-proliferating counterparts. Furthermore, constitutive activation of myosin light chain kinase (MLCK), a downstream effector of integrin-beta1 and TGF-beta2, in non-proliferating cells resumed cell proliferation. This cell proliferation was associated with an upregulation of CDK6 and a downregulation of E2F4. Taken together, our data provide evidence to support cellular adhesion and downregulation of TGFB2 as a potential mechanism by which PCa cells escape from dormancy. Targeting TGF-beta 2-associated mechanism could provide novel opportunities to prevent lethal PCa metastasis. Custom Agilent-016162 44K whole human genome expression oligonucleotide microarrays were used to profile dormant and proliferating cells isolated from three separate LuCaP xenograft lines grown in co-culture with bone marrow stromal cells isolated from a patient with PCa bone metastases. RNA from 10 cells was amplified prior to hybridization against a common reference pool of prostate tumor cell lines.
Project description:Mycobacterium tuberculosis is the causative agent of tuberculosis, a disease that affects one-third of the world’s population. The sole extant vaccine for tuberculosis is the live attenuated Mycobacterium bovis bacille Calmette-Guerin (BCG). We examined 13 representative BCG strains from around the world to ascertain their ability to express DosR-regulated dormancy antigens. These are known to be recognized by T-cells of M. tuberculosis infected individuals, especially those harboring latent infections. Differences in expression of these antigens could be valuable for use as diagnostic markers to distinguish BCG vaccination from latent tuberculosis. We determined that all BCG strains were defective for induction of two dormancy genes, narK2 (Rv1737c) and narX (Rv1736c). NarK2 is known to be necessary for nitrate respiration during anaerobic dormancy. Analysis of the narK2/X promoter region revealed a base substitution mutation in all tested BCG strains and M. bovis in comparison to the M. tuberculosis sequence. We also show that nitrate reduction by BCG strains during dormancy was greatly reduced compared to M. tuberculosis and varied between tested strains. Several dormancy regulon transcriptional differences were also identified among the strains, as well as variation in their growth and survival. These findings demonstrate defects in DosR regulon expression during dormancy and phenotypic variation between commonly used BCG vaccine strains. 12 different BCG strains were examined as well as M. tuberculosis H37Rv and M. bovis. Two arrays per strain were analyzed, one with the addition of nitric oxide and the other utilizing hypoxia treatment, both conditions shown to induce expression of the dormancy regulon. The reference sample for each array was log phase M. tuberculosis H37Rv.
Project description:Temperate perennial plants have to adapt their growth in order to survive over winter conditions and protect their tissues by entering into dormancy. The dormancy phenomenon is a complex process regulated by many factors, externals (photoperiod and temperature) or internals through the transport towards the buds. In order to better understand the molecular mechanisms involved in the regulation of dormancy, we conducted a transcriptomic analysis of flower buds from the late flowering sweet cherry cultivar 'Fertard' during dormancy, from October 2017 to March 2018.
Project description:Dissemination of prostate cancer (PCa) cells to the bone marrow is an early event in the disease process. In some patients, following initial treatment, disseminated tumor cells (DTC) proliferate to form active metastases after a prolonged period of undetectable disease known as tumor dormancy. Identifying mechanisms of PCa dormancy and reactivation remain a challenge due to the lack of in vitro models. Here, we characterized in vitro PCa dormancy-reactivation by inducing three apparently dormant patient-derived xenograft (PDX) lines to proliferate through tumor cell contact with each other and with bone marrow stroma. Proliferating PCa cells demonstrated tumor cell-cell contact and integrin clustering on immunofluorescence. Global gene expression analyses on proliferating cells cultured on bone marrow stroma revealed a downregulation of TGFB2 in all of the three proliferating PCa PDX lines when compared to their non-proliferating counterparts. Furthermore, constitutive activation of myosin light chain kinase (MLCK), a downstream effector of integrin-beta1 and TGF-beta2, in non-proliferating cells resumed cell proliferation. This cell proliferation was associated with an upregulation of CDK6 and a downregulation of E2F4. Taken together, our data provide evidence to support cellular adhesion and downregulation of TGFB2 as a potential mechanism by which PCa cells escape from dormancy. Targeting TGF-beta 2-associated mechanism could provide novel opportunities to prevent lethal PCa metastasis.
Project description:Seeds are highly resilient to the external environment, which allow plants to persist in unpredictable and unfavorable conditions. Some plant species have adopted a bet-hedging strategy to germinate a variable fraction of seeds in any given condition, and this could be explained by population-based threshold models. Here, in the model plant Arabidopsis (Arabidopsis thaliana) we induced secondary dormancy to address the transcriptional heterogeneity among seeds that leads to binary germination/non-germination outcomes. We developed a single seed RNA-seq strategy that allowed us to observe a reduction in seed transcriptional heterogeneity as seeds enter stress conditions, followed by an increase during recovery. We identified groups of genes whose expression showed a specific pattern through a time course and used these groups to position the individual seeds along the transcriptional gradient of germination competence. In agreement, transcriptomes of dormancy-deficient seeds (mutant of DELAY OF GERMINATION 1 gene) showed a shift towards higher values of the germination competence index. Interestingly, a significant fraction of genes with variable expression encoded translation-related factors. In summary, interrogating hundreds of single seed transcriptomes during secondary dormancy-inducing treatment revealed variability among the transcriptomes that could result from the distribution of population-based sensitivity thresholds. Our results also showed that single seed RNA-seq is the method of choice for analyzing seed bet-hedging-related phenomena.