CCN3 and calcium signaling

The CCN family of genes consists presently of six members in human (CCN1-6) also known as Cyr61 (Cystein rich 61), CTGF (Connective Tissue Growth Factor), NOV (Nephroblastoma Overexpressed gene), WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins). Results obtained over the past decade have indicated that CCN proteins are matricellular proteins, which are involved in the regulation of various cellular functions, such as proliferation, differentiation, survival, adhesion and migration. The CCN proteins have recently emerged as regulatory factors involved in both internal and external cell signaling. CCN3 was reported to physically interact with fibulin-1C, integrins, Notch and S100A4. Considering that, the conformation and biological activity of these proteins are dependent upon calcium binding, we hypothesized that CCN3 might be involved in signaling pathways mediated by calcium ions. In this article, we review the data showing that CCN3 regulates the levels of intracellular calcium and discuss potential models that may account for the biological effects of CCN3

Stimulating a Canadian narrative for climate

ABSTRACT: This perspective documents current thinking around climate actions in Canada by synthesizing scholarly proposals made by Sustainable Canada Dialogues (SCD), an informal network of scholars from all 10 provinces, and by reviewing responses from civil society representatives to the scholars' proposals. Motivated by Canada's recent history of repeatedly missing its emissions reduction targets and failing to produce a coherent plan to address climate change, SCD mobilized more than 60 scholars to identify possible pathways towards a low-carbon economy and sustainable society and invited civil society to comment on the proposed solutions. This perspective illustrates a range of Canadian ideas coming from many sectors of society and a wealth of existing inspiring initiatives. Solutions discussed include climate change governance, low-carbon transition, energy production, and consumption. This process of knowledge synthesis/creation is novel and important because it provides a working model for making connections across academic fields as well as between academia and civil society. The process produces a holistic set of insights and recommendations for climate change actions and a unique model of engagement. The different voices reported here enrich the scope of possible solutions, showing that Canada is brimming with ideas, possibilities, and the will to act

Chapitre 7. L’analyse de la vulnérabilité sociale et territoriale

Le double défi du XXIe siècle lancé à l’humanité pourrait bien être celui de son développement urbain dans un contexte de changements climatiques (CC). La croissance urbaine effrénée, maintenant commune au monde entier, pose drastiquement le problème des ressources, des inégalités sociales et de notre rapport à l’environnement. Les CC auront pour effet d’exacerber ces pressions. Les zones inondables qui se situent en milieu urbanisé sont ainsi des territoires vulnérables, tant du point de vue..

Hypoxia-induced down-regulation of CYP1A1/1A2 and up-regulation of CYP3A6 involves serum mediators

1. Acute moderate hypoxia modifies the catalytic activity and expression of certain isoenzymes of hepatic cytochrome P450 (P450). The aim of this study was to document whether hypoxia affects hepatic P450 directly or through the release of serum mediators. 2. Rabbits were subjected to a FiO(2) of 8% for 48 h, sacrificed, and serum and hepatocytes were isolated; hepatocytes from control and rabbits with hypoxia were incubated with serum from control and hypoxic rabbits for 4 and 24 h, and total P450 content, CYP1A1, 1A2 and 3A6 activities and expressions were assessed. Sera were fractionated by size exclusion chromatography and fractions tested for their ability to modify activity and amount of P450, and serum mediators were identified through neutralization experiments. 3. Total serum and fractions with proteins of 15–23 and 65–94 kDa of M(r) reduced P450 content and expression of CYP1A1, 1A2 and 3A6, as well as CYP1A1, 1A2 and 3A6 mRNA. Total serum and the fraction with 32–44 kDa proteins increased CYP3A6 activity and protein and mRNA. The serum mediators implicated in the decrease in activity and expression of CYP1A1, 1A2 and 3A6 were interferon-γ (IFN-γ), interleukin-1β (IL-1β) and IL-2. Erythropoietin (Epo) was partly responsible for the increase in P450 content and CYP3A6 expression. 4. In conclusion, acute moderate hypoxia diminishes the activity and expression of CYP1A1, 1A2 and CYP1A1, 1A2 mRNA, and increases CYP3A6 protein, activity and CYP3A6 mRNA. Several mechanisms contribute to these changes in P450, among them the release of cytokines acting as serum mediators

Matricellular Protein CCN3 (NOV) Regulates Actin Cytoskeleton Reorganization*

CCN3 (NOV), a putative ligand for integrin receptors, is tightly associated with the extracellular matrix and mediates diverse cellular functions, including cell adhesion and proliferation. CCN3 has been shown to negatively regulate growth although it promotes migration in a cell type-specific manner. In this study, overexpression of CCN3 reduces growth and increases intercellular adhesion of breast cancer cells. Interestingly, CCN3 overexpression also led to the formation of multiple pseudopodia that are enriched in actin, CCN3, and vinculin. Breast cancer cells preincubated with exogenous CCN3 protein also induced the same phenotype, indicating that secreted CCN3 is sufficient to induce changes in cell morphology. Surprisingly, extracellular CCN3 is internalized to the early endosomes but not to the membrane protrusions, suggesting pseudopodia-enriched CCN3 may derive from a different source. The presence of an intracellular variant of CCN3 will be consistent with our finding that the cytoplasmic tail of the gap junction protein connexin43 (Cx43) associates with CCN3. Cx43 is a channel protein permitting intercellular communication to occur. However, neither the channel properties nor the protein levels of Cx43 are affected by the CCN3 protein. In contrast, CCN3 proteins are down-regulated in the absence of Cx43. Finally, we showed that overexpression of CCN3 increases the activity of the small GTPase Rac1, thereby revealing a pathway that links Cx43 directly to actin reorganization

La ville résiliente

Lieux majeurs de toutes les accumulations matérielles, sociales et économiques, les villes sont au cœur de la question des changements climatiques. Leur avenir dépendra de notre capacité à inventer des espaces urbains habitables, justes et résilients. Les auteurs font ici le pari d'une action collective capable de transformer les menaces en force constructrice, de maîtriser la vulnérabilité des espaces urbanisés tout en renforçant leur résilience. Pour ce faire, il faut comprendre les formes et les structures de la ville contemporaine, afin d'orienter les politiques et la planification territoriale. Ce livre offre un recueil des connaissances les plus récentes sur l'adaptation des villes aux changements climatiques et rassemble les réflexions de professeurs-chercheurs et de professionnels non seulement du Québec mais aussi de France, de Suisse, des États-Unis et du Brésil. Les auteurs y analysent avec acuité certaines des controverses les plus pressantes sur le climat, sujet épineux et source de grandes préoccupations dans la population.À nos proches

Domain-specific CCN3 antibodies as unique tools for structural and functional studies

CCN3 is a member of the CCN family of cell growth and differentiation regulators that play key roles during embryonic development, and are associated with severe human pathologies. The level of CCN genes’ expression is of prognostic value in several types of tumors. In the present manuscript, we report the isolation and characterization of a new set of antibodies targeted against each individual module of the human CCN3 protein. The need for module-specific antibodies stemmed from recent reports indicating that the expression of truncated CCN variant proteins was associated with development of cancers. Each of the four CCN3 modules were expressed as GST fusion proteins and used for rabbits immunization. Polyclonal IgGs purified by two rounds of affinity–chromatography specifically detected both the individual CCN3 domains and the full length CCN3 protein expressed in mammalian cell lines and tissues, as well as recombinant full length and truncated CCN3 proteins. The purified module-specific antibodies were successfully used for Western blotting, immunoprecipitation, immunofluorescence and immunocytochemistry. These antibodies permitted the detection of CCN3 proteins under native and denaturing conditions, and confirmed the sublocalisation of CCN3 proteins in the extracellular compartment, at the cell membrane, in the cytoplasm and in the nucleus of positive cells. Immunocytochemistry and Western blotting studies performed with the module-specific antibodies identified truncated CCN3 proteins in kidney tumor samples. The detection of these rearranged variants provides clues for their involvement in tumorigenesis. Therefore, these antibodies constitute unique tools for the identification of truncated CCN3 proteins in human tissues and may be of great interest in molecular medicine

Kallikrein-related peptidase 12 hydrolyzes matricellular proteins of the CCN family and modifies interactions of CCN1 and CCN5 with growth factors

Kallikrein-related peptidases (KLKs) are an emerging group of secreted serine proteases involved in several physiological and pathological processes. We used a degradomic approach to identify potential substrates of KLK12. MDA-MB-231 cells were treated either with KLK12 or vehicle control, and the proteome of the overlying medium was analyzed by mass spectrometry. CCN1 (cyr61, ctgf, nov) was among the proteins released by the KLK12-treated cells, suggesting that KLK12 might be responsible for the shedding of this protein from the cell surface. Fragmentation of CCN1 by KLK12 was further confirmed in vitro, and the main cleavage site was localized in the hinge region between the first and second half of the recombinant protein. KLK12 can target all six members of the CCN family at different proteolytic sites. Limited proteolysis of CCNs (cyr61, ctgf, nov) was also observed in the presence of other members of the KLK family, such as KLK1, KLK5, and KLK14, whereas KLK6, KLK11, and KLK13 were unable to fragment CCNs. Because KLK12 seems to have a role in angiogenesis, we investigated the relations between KLK12, CCNs, and several factors known to be involved in angiogenesis. Solid phase binding assays showed that fragmentation of CCN1 or CCN5 by KLK12 prevents VEGF(165) binding, whereas it also triggers the release of intact VEGF and BMP2 from the CCN complexes. The KLK12-mediated release of TGF-β1 and FGF-2, either as intact or truncated forms, was found to be concentration-dependent. These findings suggest that KLK12 may indirectly regulate the bioavailability and activity of several growth factors through processing of their CCN binding partners