Sequential expression of an amelin gene in mesenchymal and epithelial cells during odontogenesis in rats

Fong, Cheng Dan; Černý, Rudolf; Hammarström, Lars; Slaby, Ivan

doi:10.1111/j.1600-0722.1998.tb02193.x

Cited by 78 publications

(84 citation statements)

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“…Therefore, it is either not secreted or it is made and released in amounts too small to be detected immunocytochemically. At this early developmental stage, it has also been reported, using amelin probes, that preodontoblasts transiently express both mRNA and protein signal for ameloblastin (Fong et al 1998). As for preameloblasts, the lack of labeling in these other cells may be related to the immunodetectability threshold.…”

Section: Figure 16mentioning

confidence: 99%

“…IR, interrod enamel; R, rod enamel; RGS, rod growth site. pression of matrix proteins by epithelial and ectomesenchymal cells as they differentiate, may be part of the reciprocal epithelio-mesenchymal signaling during tooth morphogenesis (D'Souza et al 1997;Ritchie et al 1997;Fong et al 1998). In the maturation stage, message for amelogenin is found only during the early part of the stage, but that for ameloblastin persists throughout maturation.…”

Section: Figure 16mentioning

confidence: 99%

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Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Nanci

Zalzal

Lavoie

et al. 1998

J Histochem Cytochem.

128

155

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SUMMARYMineralized tissues are unique in using proteins to attract and organize calcium and phosphate ions into a structured mineral phase. A precise knowledge of the expression and extracellular distribution of matrix proteins is therefore very important in understanding their function. The purpose of this investigation was to obtain comparative information on the expression, intracellular and extracellular distribution, and dynamics of proteins representative of the two main classes of enamel matrix proteins. Amelogenins were visualized using an antibody and an mRNA probe prepared against the major alternatively spliced isoform in rodents, and nonamelogenins by antibodies and mRNA probes specific to one enamel protein referred to by three names: ameloblastin, amelin, and sheathlin. Qualitative and quantitative immunocytochemistry, in combination with immunoblotting and in situ hybridization, indicated a correlation between mRNA signal and sites of protein secretion for amelogenin, but not for ameloblastin, during the early presecretory and midto late maturation stages, during which mRNA signals were detected but no proteins appeared to be secreted. Extracellular amelogenin immunoreactivity was generally weak near secretory surfaces, increasing over a distance of about 1.25 m to reach a level slightly above an amount expected if the protein were being deposited evenly across the enamel layer. Immunolabeling for ameloblastin showed an inverse pattern, with relatively more gold particles near secretory surfaces and much fewer deeper into the enamel layer. Administration of brefeldin A and cycloheximide to stop protein secretion revealed that the immunoblotting pattern of amelogenin was relatively stable, whereas ameloblastin broke down rapidly into lower molecular weight fragments. The distance from the cell surface at which immunolabeling for amelogenin stabilized generally corresponded to the point at which that for ameloblastin started to show a net reduction. These data suggest a correlation between the distribution of amelogenin and ameloblastin and that intact ameloblastin has a transient role in promoting/stabilizing crystal elongation. A meloblasts , like all hard tissue-forming cells, release an intricate set of extracellular matrix proteins optimized for promoting the development of a closely associated mineral phase (reviewed in Deutsch et al.

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Section: Figure 16mentioning

confidence: 99%

Section: Figure 16mentioning

confidence: 99%

Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Nanci

Zalzal

Lavoie

et al. 1998

J Histochem Cytochem.

128

155

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“…The following probes were used: Bmp2, Bmp4 and Bmp7 (Åberg et al, 1997); PDGFRα (Boström et al, 1996); amelin (Cerny et al, 1996;Fong et al, 1998);Shh, Ptc2, Gli1, Gli2, Gli3, Dentin Sialoprotein (DSP), Dentin Matrix Protein 1 (DMP1) and Msx2 (Dassule et al, 2000); cyclin D1 (Long et al, 2001); Dlx3 and Dlx7 (Zhao et al, 2000); Ptc1 (Gritli-Linde et al, 2001). A 1 kb Bmp5 pro-region fragment was also used to generate an anstisense RNA probe.…”

Section: In Situ Hybridizationmentioning

confidence: 99%

Shh signaling within the dental epithelium is necessary for cell proliferation, growth and polarization

et al. 2002

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Sonic hedgehog (Shh), a member of the mammalian Hedgehog (Hh) family, plays a key role during embryogenesis and organogenesis. Tooth development, odontogenesis, is governed by sequential and reciprocal epithelial-mesenchymal interactions. Genetic removal of Shh activity from the dental epithelium, the sole source of Shh during tooth development, alters tooth growth and cytological organization within both the dental epithelium and mesenchyme of the tooth. In this model it is not clear which aspects of the phenotype are the result of the direct action of Shh on a target tissue and which are indirect effects due to deficiencies in reciprocal signalings between the epithelial and mesenchymal components. To distinguish between these two alternatives and extend our understanding of Shh's actions in odontogenesis, we have used the Cre-loxP system to remove Smoothened (Smo) activity in the dental epithelium. Smo, a seven-pass membrane protein is essential for the transduction of all Hh signals. Hence, removal of Smo activity from the dental epithelium should block Shh signaling within dental epithelial derivatives while preserving normal mesenchymal signaling. Here we show that Shh-dependent interactions occur within the dental epithelium itself. The dental mesenchyme develops normally up until birth. In contrast, dental epithelial derivatives show altered proliferation, growth, differentiation and polarization. Our approach uncovers roles for Shh in controlling epithelial cell size, organelle development and polarization. Furthermore, we provide evidence that Shh signaling between ameloblasts and the overlying stratum intermedium may involve subcellular localization of Patched 2 and Gli1 mRNAs, both of which are targets of Shh signaling in these cells.

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“…(9)(10)(11) Recent genetic and transgenic studies suggest that AMBN mutations cause non-syndromic human amelogenesis imperfecta (AI) and loss of prismatic enamel structure, (12) supporting earlier mouse transgenic studies in which an AMBN-enriched enamel matrix was occupied by short and randomly oriented apatite crystals instead of the long and parallel crystals necessary for the alignment into enamel prisms. (7) Soon after its initial discovery as an enamel matrix molecule, AMBN was also detected in pulp, (13) bone, (14) Hertwig's epithelial root sheath, (15,16) periodontal ligament, (17) and calvarial development. (18,19) Underlining its pleiotropic nature, the AMBN molecule contains a fibronectin interaction site, heparin-binding domains, CD63-interaction domains, and calcium binding sites in both human and mouse AMBN.…”

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confidence: 99%

Ameloblastin, an Extracellular Matrix Protein, Affects Long Bone Growth and Mineralization

Fukumoto

Yamada

et al. 2016

Journal of Bone and Mineral Research

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Matrix molecules such as the enamel-related calcium-binding phosphoprotein ameloblastin (AMBN) are expressed in multiple tissues, including teeth, bones, and cartilage. Here we have asked whether AMBN is of functional importance for timely long bone development and, if so, how it exerts its function related to osteogenesis. Adolescent AMBN-deficient mice (AMBN D5-6 ) suffered from a 33% to 38% reduction in femur length and an 8.4% shorter trunk spinal column when compared with WT controls, whereas there was no difference between adult animals. On a cellular level, AMBN truncation resulted in a shortened growth plate and a 41% to 49% reduction in the number of proliferating tibia chondrocytes and osteoblasts. Bone marrow stromal cells (BMSCs) isolated from AMBN mutant mice displayed defects in proliferation and differentiation potential as well as cytoskeleton organization. Osteogenesis-related growth factors, such as insulin-like growth factor 1 (IGF1) and BMP7, were also significantly (46% to 73%) reduced in AMBN-deficient BMSCs. Addition of exogenous AMBN restored cytoskeleton structures in AMBN mutant BMSCs and resulted in a dramatic 400% to 600% increase in BMP2, BMP7, and Col1A expression. Block of RhoA diminished the effect of AMBN on osteogenic growth factor and matrix protein gene expression. Addition of exogenous BMP7 and IGF1 rescued the proliferation and differentiation potential of AMBN-deficient BMSCs. Confirming the effects of AMBN on long bone growth, back-crossing of mutant mice with full-length AMBN overexpressors resulted in a complete rescue of AMBN D5-6 bone defects. Together, these data indicate that AMBN affects extracellular matrix production and cell adhesion properties in the long bone growth plate, resulting in altered cytoskeletal dynamics, increased osteogenesis-related gene expression, as well as osteoblast and chondrocyte proliferation. We propose that AMBN facilitates rapid long bone growth and an important growth spurt during the skeletogenesis of adolescent tooth-bearing vertebrates.

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Sequential expression of an amelin gene in mesenchymal and epithelial cells during odontogenesis in rats

Cited by 78 publications

References 0 publications

Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Shh signaling within the dental epithelium is necessary for cell proliferation, growth and polarization

Ameloblastin, an Extracellular Matrix Protein, Affects Long Bone Growth and Mineralization

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