No description available.

Ischemic stroke related brain damage causes loss of multiple cell types, including neural and vascular cells. The extent of post-stroke neurogenesis and angiogenesis predicts the level of functional regeneration/recovery after stroke. In this regard, my thesis was focused on defining the molecular process that modulates post-stroke functional recovery by co-ordinating post-stroke neurovascular remodeling. Since stroke-related brain damage releases enriched local microenvironmental cues, I examined the role of a signaling-induced epigenetic pathway, an atypical protein kinase C (aPKC)-mediated phosphorylation of CREB Binding Protein (CBP), in regulating post-stroke neurovascular remodeling and functional recovery. This pathway has previously been shown to be activated by metformin, an adenosine monophosphate kinase (AMPK) activator, to promote the differentiation of neural precursors in the developing and adult brain. Here, I first developed a murine focal cortical ischemic stroke model with persistent motor function deficits by combined intra-cortical injections of endothelin-1 (ET-1) and L-NAME into the sensorimotor cortex. Second, I applied the ET-1/L-Name-induced focal cortical stroke model in a knock-in mouse CBPS436A where the aPKC-CBP pathway is deficient, and showed that the aPKC-CBP pathway is involved in post-stroke functional recovery by coordinating neurovascular remodeling. Specifically, CBPS436A-KI mice displayed reduced motor recovery, correlated with reduced vascular remodeling and impaired post-stroke angiogenesis. Intriguingly, I also observed that CBPS436A-KI mice showed a reduction in the population of stroke-induced newborn pericytes but an increase in the population of perivascularly-derived neural precursors, implying that the aPKC-CBP pathway may be involved in the process that reprograms pericytes into neural precursors. Together, this study elucidates the novel role of the aPKC-CBP pathway in modulating neurovascular remodeling and functional recovery following focal ischemic cortical stroke.

No description available.

The function of chitin binding protein (CBP) and two isoforms of cathepsin B (cathB1, cathB2) were tested by using RNA interference in the tick I. ricinus. Two different methods have been used to deliver dsRNA for RNAi in ticks {--} injection and capillary feeding. The synthesized dsRNA was used to find out the impact of RNAi in the tick tissues, which were tested by RT-PCR and Western blot. The expression of CBP was successfully silenced by RNAi in the salivary glands. The silencing of cathB1 and cathB2 in the gut was less effective, but still limited tick`s ability to feed.

No description available.

Background: Conventional chemotherapeutics target bulk tumour cells and generally leave cancer stem cell (CSC) populations unaffected. Recent literature characterized the presence and the role of CSC in several types of solid tumors, including colorectal cancer. Colorectal CSCs (CCSCs) display enhanced WNT/β-catenin pathway activity, sustaining self-renewal and tumor-initiating capacity. Thus, CCSCs are crucial for tumour recurrence and metastasis. As one of the main contributors to sustained self-renewal activity in CCSCs, enhanced formation of β-catenin/CBP complex is fostering transactivation of canonical WNT target genes such as c-myc. However, maintenance of healthy intestinal stem cells also dependents on the canonical WNT pathway. Thus, selective targeting CCSCs while sparring normal intestinal cells is still a significant challenge. Interestingly, Sam68 is a key mediator of the interaction between β-catenin and CBP. It has been reported as a “druggable” target to selectively disrupt β-catenin/CBP in CSCs. Indeed, CWP232228 successfully targets CSCs in AML by facilitating Sam68/CBP complex formation, and consequently lowering the abundance of β-catenin/CBP complexes. CWP232228 was clinically tested on multiple human cancers. Unfortunately, such clinical trials were halted due to unknown causes, and limited information was released on clinical safety and benefits. Consequently, developing more potent pharmacological modulators of Sam68/CBP complex formation is still highly relevant to eradicate CCSCs. Here we describe the discovery and characterization of a new CWP analog, known as YB-0158, which displays enhanced potency and neoplastic selectivity against CCSC. Methods and Results: Following the confirmation that ICG/CWP class of compounds bind to Sam68 in CSCs, I used in silico docking methods to screen for CWP analogs having high predicted affinity for Sam68 Cterminal proline-rich domain. Using high content imaging techniques, I confirmed our top candidate (YB-0158) as more potent vs. CWP parent molecule to compromise cell growth, to induce loss of pluripotency, and to increase Sam68 nuclear localization in a surrogate model of human CSCs. YB-0158 also displayed enhanced selective toxicity in colorectal cancer models vs. normal intestinal epithelium progenitor cells. Moreover, I confirmed that YB-0158 exert negative impact on cancer cell growth by inducing apoptosis and reducing proliferation. Lentiviral-based knockdowns explicitly displayed decrease in drug effectivity in the absence of Sam68, reinforcing the essential role of Sam68 mediating ICG-001/CWP response in CSCs. I demonstrated that Sam68 expression is enriched in tumor-initiating cell fractions derived from primary colorectal tumor tissues vs. bulk heterogeneous tumor organoids. Therefore, YB-0158 showed striking efficacy at supressing tumor-initiation activity in a patient-based serial organoid formation assay. Finally, YB-0158 eradicated CSCs activity in vivo as demonstrated by a syngeneic mouse-to-mouse serial transplantation assay. Conclusion: Overall, YB-0158 is a novel analog of CWP232228 with superior potency to target CCSCs activity through facilitation of Sam68 nuclear localization, thus reducing the interaction frequency between CBP and β-catenin.

No description available.

African swine fever virus (ASFV) is a large double-stranded DNA virus which causes a lethal haemorrhagic fever in domestic pigs. This virus primarily infects cells from the monocyte/macrophage lineage and its ability to manipulate the function of these cells is key to the pathogenesis of this disease. ASFV encodes several proteins involved in immune evasion. One of these proteins, A238L, has been shown to inhibit host macrophage gene transcription. This protein has been shown to interact with several cellular proteins involved in signal transduction: a serine/threonine protein phosphatase, calcinerurin (CaN), the transcription factor NF-кB, and most recently the transcriptional co-activator CREB binding protein (CBP/P300). However its exact mechanism of action is not fully understood. Previous work has been limited to the investigation of individual signaling pathways and/or the expression of individual host genes. The aim of this study was to investigate the global effect of A238L on host macrophage gene transcription and also to carry out further investigation into the mechanism by which this protein functions. To determine the global effect of A238L on host macrophage gene transcription differential gene expression between porcine cells expressing A238L and control cells was examined using a porcine oligonucleotide microarray. These results demonstrated that A238L was a potent inhibitor of host macrophage gene expression. Functional characterisation of the annotated genes showed that a large proportion of A238L down-regulated genes are typically induced in response to cell stress. Significantly, genes regulated by the I kappa B kinase (IKK), mitogen-activated protein kinase (MAPK) and janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathways were all shown to be down regulated by A238L. Genes associated with the MAPK pathways were particularly enriched. The transcription of A238L-regulated genes is controlled by numerous different transcription factors, including NF-кB. All of the transcription factors identified interact with the transcription co-activator CBP/P300. This provides a common link between these factors, and indicates that A238L may target CBP/P300 to inhibit gene transcription. This observation supports recent work demonstrating that A238L interacts with and inhibits CBP/P300 function. To explore the potential mechanisms involved in the nuclear localisation of A238L, ASFV-infected Vero cells, expressing A238L under the control of its own promoter, were examined under a range of conditions using confocal microscopy. The results demonstrated that A238L was actively imported into the nucleus and exported by a CRM 1 mediated pathway, although a pool of A238L protein remained in the cytoplasm. Sequence analysis of A238L identified the presence of two putative nuclear localisation signals (NLS-1 and NLS-2). NLS-2 was located within A238L’s CaN docking motif. Mutation of these motifs indicated that both NLS-1 and NLS-2 are active and exhibit functional redundancy. Mutation of the CaN docking motif alone, in the presence of intact NLS-2, resulted in a dramatic increase in the nuclear localisation of A238L. These results are consistent with a model in which A238L functions within both the nucleus and the cytoplasm and suggest that binding of CaN to A238L masks NLS-2, contributing to the cytoplasmic retention of A238L.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

>Magister Scientiae - MSc / Bioethanol is currently the most widely used biofuel and can be used as a direct replacement for current fossil fuel based transportation fuels. Consolidated bioprocessing (CBP), in which bioethanol is produced in a single reactor by a single microorganism, is a cost-effective way of producing bioethanol in a second generation process using lignocellulosic biomass as feedstock. The yeast Saccharomyces cerevisiae possesses industrially desirable traits for ethanol production and is able to produce heterologous cellulases, which are required for CBP. However, S. cerevisiae produces low titres of cellulases and one suspected reason for this is the stress caused by the heterologous proteins that induce the unfolded protein response (UPR). The UPR is a stress response pathway that will either lead to increased folding capacity within the ER or to degradation of these proteins and possibly apoptosis of the cell. It is thus beneficial to be able to determine when and to what extent the UPR is active during CBP organism development. Current methods of measuring the UPR include RNA and reverse transcriptase qPCR (r.t.qPCR) measurements, which can be cumbersome and expensive. The purpose of this study was to develop a vector based biosensor that will detect and quantify UPR activation. The vector consisted of either the T.r.xyn2 or eGFP reporter genes under the control of the S. cerevisiae HAC1p or KAR2p promoters. HAC1 and KAR2 are important regulators of UPR as their activation allows the UPR to achieve its function. The eGFP reporter under the transcriptional control of KAR2p was shown to be the superior combination due to the improved dynamic range when the UPR was induced in transformed S. cerevisiae strains by the stress inducer, tunicamycin. This UPR biosensor also proved to be more sensitive when measuring UPR induction in cellulase producing strains, depicting significant differences, compared to previous r.t.qPCR based tests which were unable to detect these differences. We thus developed a UPR biosensor that has greater sensitivity for changes in UPR induction compared to RNA based methods and the first KAR2p based UPR biosensor plasmid that allowed for more accurate detection and measurement of the UPR in cellulase secreting S. cerevisiae strains. The ability to quantify UPR induction will assist in identifying candidate cellulase genes that do not greatly induce the UPR, making them ideal to use in developing CBP yeasts.