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C Colnot

Publications and source records attributed to C Colnot.

10 recordsLinked to original sources
PubMed2006

Analyzing the cellular contribution of bone marrow to fracture healing using bone marrow transplantation in mice.

The bone marrow is believed to play important roles during fracture healing such as providing progenitor cells for inflammation, matrix remodeling, and cartilage and bone formation. Given the complex nature of bone repair, it remains difficult to distinguish the contributions of various cell types. Here we describe a mouse model based on bone marrow transplantation and genetic labeling to track cells originating from bone marrow during fracture healing. Following lethal irradiation and engraftment of bone marrow expressing the LacZ transgene constitutively, wild type mice underwent tibial fracture. Donor bone marrow-derived cells, which originated from the hematopoietic compartment, did not participate in the chondrogenic and osteogenic lineages during fracture healing. Instead, the donor bone marrow contributed to inflammatory and bone resorbing cells. This model can be exploited in the future to investigate the role of inflammation and matrix remodeling during bone repair, independent from osteogenesis and chondrogenesis.

Animals↗
PubMed2001

Uncoupling of chondrocyte death and vascular invasion in mouse galectin 3 null mutant bones.

Galectin 3 is a beta-galactoside binding protein which localizes to the cytoplasm of proliferative, mature, and hypertrophic chondrocytes in the growth plate cartilage of developing long bones. To elucidate the function of galectin 3 during bone development, we examined the epiphyseal femurs and tibias of fetal mice carrying a null mutation for the galectin 3 gene. Detailed histological and ultrastructural studies identified abnormalities in the cells of the proliferative, mature, and hypertrophic zones and in the extracellular matrix of the hypertrophic zone, as well as a reduction in the total number of hypertrophic chondrocytes. The expression patterns of several chondrocyte and bone cell markers were analyzed and revealed a subtle modification of Ihh expression in the galectin 3 mutant growth plate. A striking difference was observed at the chondrovascular junction where many empty lacunae are present. In addition, large numbers of condensed chondrocytes exhibiting characteristic signs of cell death were found in the late hypertrophic zone, indicating that the rate of chondrocyte death is increased in the mutants. These results suggest a role for galectin 3 as a regulator of chondrocyte survival. In addition, this unique phenotype shows that the elimination of chondrocytes and vascular invasion can be uncoupled and indicates that galectin 3 may play a role in the coordination between chondrocyte death and metaphyseal vascularization.

Animals↗
PubMed1999

HIP/PAP gene, encoding a C-type lectin overexpressed in primary liver cancer, is expressed in nervous system as well as in intestine and pancreas of the postimplantation mouse embryo.

We originally isolated the HIP/PAP gene in a differential screen of a human hepatocellular carcinoma cDNA library. This gene is expressed at high levels in 25% of primary liver cancers but not in nontumorous liver. HIP/PAP belongs to the family of C-type lectins and acts as an adhesion molecule for hepatocytes. In normal adult human tissues, HIP/PAP expression is found in pancreas (exocrine and endocrine cells) and small intestine (Paneth and neuroendocrine cells). In order to gain insight into the possible role of HIP/PAP in vivo, we have investigated the pattern of HIP/PAP expression in the developing postimplantation mouse embryo by in situ hybridization. Detailed analysis of developing mouse embryos revealed that HIP/PAP gene exhibits a restricted expression pattern during development. Thus, HIP/PAP transcripts are first observed within the nervous system from day 14.5 onwards in trigeminal ganglia, dorsal root ganglia, and spinal cord where it appears to be an early specific marker of a subpopulation of motor neurons. At laster stages, HIP/PAP transcripts were detected in intestine and pancreas at day 16.5 but not in embryonic liver. This highly restricted expression pattern suggests that HIP/PAP might participate in neuronal as well as intestinal and pancreatic cell development.

Animals↗
PubMed1999

Expression of galectin-7 during epithelial development coincides with the onset of stratification.

Galectin-7 is a 14 KDa member of the galectin family that we have cloned from human, rat and mouse. Our previous studies have shown that in the adult, galectin-7 is expressed in all cell layers of epidermis and of other stratified epithelia such asthe cornea and the lining of the oesophagus. This suggested that galectin-7 expression might be induced at a particular stage in the embryonic development of stratified epithelia. In the present study we have investigated this hypothesis by in situ hybridization of galectin-7 mRNA in mouse embryos. Starting from E13.5, weak expression of galectin-7 was detected in bilayered ectoderm, and stronger expression was found in areas of embryonic epidermis where stratification was more advanced. Galectin-7 expression was maintained in all living layers after epidermal development was completed. Galectin-7 was also strongly and specifically expressed in stratified regions of ectodermally-derived non-epidermal epithelia such as the lining of the buccal cavity, the oesophagus and the ano-rectal region. In contrast, no expression of galectin-7 was found in epithelia derived from endoderm, such as lining of the intestine, kidney and lung. Our results demonstrate that galectin-7 is expressed in all stratified epithelia examined so far, and that the onset of its expression coincides with the first visible signs of stratification. These results establish galectin-7 as the first region-independent marker of epithelial stratification.

Animals↗
PubMed1999

Cellular and subcellular distribution of galectin-3 in the epiphyseal cartilage and bone of fetal and neonatal mice.

Galectin-3 is a 30 kDa beta-galactoside binding protein that belongs to the galectin family of animal lectins. By immunocytochemistry we show the presence of galectin-3 protein in the differentiated chondrocytes of the epiphyseal plate cartilage of long bones of both fetal and neonatal mice. The highest concentrations of galectin-3 are found in the cytoplasm of mature and early hypertrophic chondrocytes. Very little protein is detected in the late hypertrophic chondrocytes undergoing terminal maturation and cell death. Galectin-3 has also been found in osteoblasts and osteocytes of the woven bone of the metaphysis and the cortical bone of the diaphysis, as well as in osteoclasts and mononuclear cells within bone marrow cavities. Galectin-3 is never detected extracellularly, the protein seems restricted to the cytoplasm of chondrocytes and bone cells, although it is occasionally detected in the nuclei of dense non-hypertrophic chondrocytes in the zone of calcification and in young osteoblasts. The results indicate that galectin-3 is a marker of both chondrogenic and osteogenic cell lineages. They also suggest that galectin-3 could be involved in the process of endochondral bone formation, possibly as a regulator of chondrocyte survival.

Animals↗
PubMed1998

Galectin-4 and galectin-6 are two closely related lectins expressed in mouse gastrointestinal tract.

Galectins are a family of carbohydrate-binding proteins that share a conserved sequence and affinity for beta-galactosides. Some, such as galectin-1, are isolated as dimers and have a single carbohydrate recognition domain (CRD) in each monomer, whereas others, such as galectin-4, are isolated as monomers and have two CRDs in a single polypeptide chain. In the course of studying mouse colon mRNA for galectin-4, we detected a related mRNA that encodes a new galectin that also has two CRDs in a single peptide chain. The new galectin, galectin-6, lacks a 24-amino acid stretch in the link region between the two CRDs that is present in galectin-4. Otherwise, these two galectins have 83% amino acid identity. Expression of both galectin-4 and galectin-6 is confined to the epithelial cells of the embryonic and adult gastrointestinal tract. Galectin-4 is expressed at about equal levels in colon and small intestine but much less in stomach, whereas galectin-6 is expressed at about equal levels throughout the gastrointestinal tract.

Animals↗
PubMed1998

Embryonic implantation in galectin 1/galectin 3 double mutant mice.

Galectin 1 and galectin 3 are first expressed in the trophectoderm cells of the implanting embryo and have been implicated in the process of implantation. However, we had previously shown that the lack of galectin 1 in galectin 1 null mutant mice is compatible with implantation. In this study, we describe the generation of galectin 3 null mutant mice and show that they are viable and have no overt abnormalities. The importance of galectin 1 and galectin 3 in implantation was assessed by obtaining double mutant mice [gal1 -/-; gal3 -/-]. We find that implantation can still occur in the absence of both galectin 1 and galectin 3. However, we show that galectin 5, a third member of this gene family, is also present in the blastocyst at the time of implantation.

Animals↗
PubMed1998

Maintenance of granulocyte numbers during acute peritonitis is defective in galectin-3-null mutant mice.

Galectin-3, also known as the macrophage marker Mac-2, is a member of a family of structurally related animal lectins that exhibit specificity for beta-galactosides. In order to investigate the role of galectin-3 in acute inflammation, we have compared the number of leucocytes present in the peritoneal cavity of wild type and galectin-3 null mutant mice after intraperitoneal (i.p.) injection of thioglycolate broth. At day 1 after injection, we found no difference in the recruitment of mononuclear phagocytes and granulocytes to the peritoneal cavity. However, 4 days after thioglycolate injection, galectin-3 mutant mice exhibited a significantly reduced number of recoverable granulocytes compared to wild-type animals. As mutant granulocytes did not exhibit an accelerated rate of apoptosis and their uptake by macrophages appeared to be unaffected by the mutation, the phenotype described here suggests that galectin-3 participates in an additional level of control during the resolution of acute inflammation.

Acute Disease↗
PubMed1995

Galectin-3 is expressed in the notochord, developing bones, and skin of the postimplantation mouse embryo.

The galectins are a family of low molecular weight, calcium-independent mammalian carbohydrate binding proteins that exhibit specificity for beta-galactoside derivatives. We have examined the expression pattern of galectin-3 in the developing mouse embryo by in situ hybridisation and immunohistochemistry. In the embryo proper, galectin-3 message and protein are first detected in notochord, starting from 8.5 days post coitum (dpc), and persist until this structure disappears. Galectin-3 is later found in cartilage primordia and in developing skin from 13.5 dpc. This very restricted and dynamic pattern suggests that galectin-3 may participate in the establishment and/or maintenance of notochord as well as the formation of cartilage and differentiation of skin. Finally, we find that galectin-3, which is identical to the macrophage marker Mac-2, is also expressed in embryonic macrophages.

Animals↗