Caspases are evolutionary conserved proteases traditionally known as participating in apoptosis and inflammation but recently discovered also in association with other processes such as proliferation or differentiation. This investigation focuses on caspase-12, ranked among inflammatory caspases but displaying other, not yet defined functions. A screening analysis pointed to statistically significant (P < 0.001) increase in expression of caspase-12 in a decisive period of mandibular bone formation when the original mesenchymal condensation turns into vascularized bone tissue. Immunofluorescence analysis confirmed the presence of caspase-12 protein in osteoblasts. Therefore, the osteoblastic cell line MC3T3-E1 was challenged to investigate any impact of caspase-12 on the osteogenic pathways. Pharmacological inhibition of caspase-12 in MC3T3-E1 cells caused a statistically significant decrease in expression of some major osteogenic genes, including those for alkaline phosphatase, osteocalcin and Phex. This downregulation was further confirmed by an alkaline phosphatase activity assay and by a siRNA inhibition approach. Altogether, this study demonstrates caspase-12 expression and points to its unknown physiological engagement in bone cells during the course of craniofacial development.

• Klíčová slova
• alkaline phosphatase, bone, caspase-12, differentiation, osteoblast,
• Publikační typ
• časopisecké články MeSH

Tuftelin was originally discovered and mostly studied in the tooth, but later found also in other organs. Despite its wide distribution among tissues, tuftelin's function has so far been specified only in the formation of enamel crystals. Nevertheless, in many cases, tuftelin was suggested to be associated with cellular adaptation to hypoxia and recently even with cell differentiation. Therefore, we aimed to investigate tuftelin expression along with hypoxia-inducible factors (HIFs) during the early development of the mandibular/alveolar (m/a) bone, when osteoblasts started to differentiate in vivo and to compare their expression levels in undifferentiated versus differentiated osteoblastic cells in vitro. Immunohistochemistry demonstrated the presence of tuftelin already in osteoblastic precursors which were also HIF1-positive, but HIF2-negative. Nevertheless, HIF2 protein appeared when osteoblasts differentiated, one day later. This is in agreement with observations made with MC3T3-E1 cells, where there was no significant difference in tuftelin and Hif1 expression in undifferentiated vs. differentiated cells, although Hif2 increased upon differentiation induction. In differentiated osteoblasts of the m/a bone, all three proteins accumulated, first, prenatally, in the cytoplasm and later, particularly at postnatal stages, they displayed also peri/nuclear localization. Such a dynamic time-space pattern of tuftelin expression has recently been reported in neurons, which, as the m/a bone, differentiate under less hypoxic conditions as indicated also by a prevalent cytoplasmic expression of HIF1 in osteoblasts. However, unlike what was shown in cultured neurons, tuftelin does not seem to participate in final osteoblastic differentiation and its functions, thus, appears to be tissue specific.

• Klíčová slova
• Bone, HIF1, HIF2, Intramembranous, Ossification, Tuftelin,
• MeSH
• buňky 3T3 MeSH
• faktor 1 indukovatelný hypoxií analýza   genetika   MeSH
• imunohistochemie MeSH
• kultivované buňky MeSH
• myši MeSH
• osteogeneze genetika   MeSH
• proteiny zubní skloviny analýza   genetika   MeSH
• transkripční faktory analýza   genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• faktor 1 indukovatelný hypoxií MeSH
• HIF-2 protein, mouse MeSH Prohlížeč
• proteiny zubní skloviny MeSH
• transkripční faktory MeSH
• tuftelin MeSH Prohlížeč

The mandible is a tooth-bearing structure involving one of the most prominent bones of the facial region. Mesenchymal cell condensation is the first morphological sign of osteogenesis, and several studies have focused on this stage also in the mandible. Little information is available about the early post-condensation period, during which avascular soft condensation turns into vascularized bone, and all three major bone cell types, osteoblasts, osteocytes, and osteoclasts, differentiate. In the mouse first lower molar region, the post-condensation period corresponds to the prenatal days 13-15. If during this critical period, when osteogenesis reaches the point of major bone cell differentiation, vascularization already has to play a critical role, one should be able to show molecular changes which support both types of cellular events. The aim of the present report was to follow in organ context the expression of major osteogenic and angiogenic markers and identify those that are up- or downregulated during this period. To this end, PCR Array was applied covering molecules involved in osteoblastic cell proliferation, commitment or differentiation, extracellular matrix (ECM) deposition, mineralisation, osteocyte maturation, angiogenesis, osteoclastic differentiation, and initial bone remodeling. From 161 analyzed osteogenic and angiogenic factors, the expression of 37 was altered when comparing the condensation stage with the bone stage. The results presented here provide a molecular survey of the early post-condensation stage of mandibular/alveolar bone development which has not yet been investigated in vivo.

• Klíčová slova
• PCR Array, angiogenesis, intramembranous ossification, mandibular bone, osteogenesis,
• Publikační typ
• časopisecké články MeSH

Development of mammalian teeth and surrounding tissues includes time-space changes in the extracellular matrix composition and organization. This requires complex control mechanisms to regulate its synthesis and remodeling. Fibril-associated collagens with interrupted triple helices (FACITs) and a group of small leucine-rich proteoglycans (SLRPs) are involved in the regulation of collagen fibrillogenesis. Recently, collagen type XII and collagen type XIV, members of the FACITs family, were found in the peridental mesenchyme contributing to alveolar bone formation. This study was designed to follow temporospatial expression of collagen types XIIa and XIVa in mouse first molar and adjacent tissues from embryonic day 13, when the alveolar bone becomes morphologically apparent around the molar tooth bud, until postnatal day 22, as the posteruption stage. The patterns of decorin, biglycan, and fibromodulin, all members of the SLRPs family and interacting with collagens XIIa and XIVa, were investigated simultaneously. The situation in the tooth was related to what happens in the alveolar bone, and both were compared to the periodontal ligament. The investigation provided a complex localization of the five antigens in soft tissues, the dental pulp, and periodontal ligaments; in the mineralized tissues, predentin/dentin and alveolar bone; and junction between soft and hard tissues. The results illustrated developmentally regulated and tissue-specific changes in the balance of the two FACITs and three SLRPs.

• Klíčová slova
• FACITs, SLRPs, alveolar bone, collagen, odontogenesis,
• Publikační typ
• časopisecké články MeSH