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Arthur Veis

Publications and source records attributed to Arthur Veis.

At least 19 recordsLinked to original sources
PubMed2006

Molecular recognition in the assembly of collagens: terminal noncollagenous domains are key recognition modules in the formation of triple helical protomers.

The alpha-chains of the collagen superfamily are encoded with information that specifies self-assembly into fibrils, microfibrils, and networks that have diverse functions in the extracellular matrix. A key self-organizing step, common to all collagen types, is trimerization that selects, binds, and registers cognate alpha-chains for assembly of triple helical protomers that subsequently oligomerize into specific suprastructures. In this article, we review recent findings on the mechanism of chain selection and infer that terminal noncollagenous domains function as recognition modules in trimerization and are therefore key determinants of specificity in the assembly of suprastructures. This mechanism is also illustrated with computer-generated animations.

Biopolymers↗
PubMed2006

The composition and structure of bovine peritubular dentin: mapping by time of flight secondary ion mass spectroscopy.

The dentin layer of the tooth is a complex mineralized tissue traversed by a closely packed system of tubules. Each tubule is surrounded by highly mineralized tissue referred to as peritubular dentin (PTD). The remaining mineralized collagen network between the tubules is the intertubular dentin (ITD). A TOF-SIMS analysis of the PTD constituents has been used to compare the PTD to the ITD. The PTD differs from the ITD not only in the degree of mineralization but also in the amount and nature of the mineral elements and amino acids. The organic matrix of the PTD consists of a unique collagen free assembly of proteins rich in glutamic acid, where the ITD organic matrix is collagen-rich and Asp-rich. The apparent concentration of organic fragment ions observed in the PTD in the TOF-SIMS negative ion mode was much higher than expected. The PTD was found to be rich in Ca2+, Na+, Mg2+, and K+. The amount of Mg2+ and K+ in the PTD was significantly reduced after deproteination, while Ca2+ and Na+ were still accumulated in the PTD. This implies that Mg2+ and K+ are mainly associated with the organic matrix rather than with the mineral of the PTD.

Animals↗
PubMed2006

Composition of calcifications in children with juvenile dermatomyositis: association with chronic cutaneous inflammation.

OBJECTIVE: Calcific deposits develop in 20-40% of children with juvenile dermatomyositis (juvenile DM), contributing to disease morbidity and mortality. This study was undertaken to define the structure and composition of these deposits and to characterize their association with chronic inflammation. METHODS: We examined calcific deposits from 5 children with juvenile DM (2 boys and 3 girls). The crystal structure and mineral content of the deposits was analyzed by x-ray diffraction, Fourier transform infrared spectroscopy, and imaging. The protein content of the deposits, following solubilization, was assayed by Western blotting. RESULTS: All 5 children had both a young age at disease onset (mean +/- SD 3.3 +/- 1.9 years) and, despite therapy, persistent cutaneous inflammation (mean +/- SD duration 81.3 +/- 58.7 months). The bone proteins, osteopontin, osteonectin, and bone sialoprotein, were identified in the protein extracts; the only mineral detected was hydroxyapatite, but the tissue was distinct from bone, with an extremely high mineral content and an irregular distribution of mineral. CONCLUSION: These results indicate that chronic cutaneous inflammation may contribute to the formation of hydroxyapatite-containing pathologic calcifications in children with juvenile DM.

Adolescent↗
PubMed2006

Expression and potential role of dentin phosphophoryn (DPP) in mouse embryonic tissues involved in epithelial-mesenchymal interactions and branching morphogenesis.

Dentin sialophosphoprotein (DSPP) is synthesized in both mesenchyme and epithelium at varying stages of tooth development. At the tooth cap stage, corresponding to embryonic day (E) 13.5 of mouse embryonic life, the phosphophoryn (DPP) portion of DSPP was immunohistochemically localized to the enamel organ with intense staining of oral ectoderm but no expression in dental follicle mesenchyme. Surprisingly, DPP was also expressed in ureteric bud branches of embryonic metanephric kidney and alveolar epithelial buds of developing lung. Reverse transcriptase-polymerase chain reaction analysis verified the presence of DSPP mRNA with identical sequences in the tooth, lung, and kidney. The DSPP(-/-) mouse with ablated DPP expression in the teeth, also exhibited aberrant organogenesis in kidney and lung. In the kidney, malformed metanephric S-shaped bodies and increased mesenchymal apoptosis were observed. Inclusion of anti-DPP antibodies in organ culture of metanephroi, harvested from E13.5 wild-type mice, likewise resulted in altered ureteric bud morphogenesis, suggesting a role for DPP in epithelial-mesenchymal interactions in meristic tissues during embryonic development.

Animals↗
PubMed2006

The impact of bioactive molecules to stimulate tooth repair and regeneration as part of restorative dentistry.

After implantation in the exposed pulp, some molecules of the den-tin extracellular matrix induce the formation of a reparative dentinal bridge in the coronal pulp. In some cases, total occlusion of the root canal also is observed. This is the case for bone sialoprotein, bone morphogenetic protein-7, Dentonin (a fragment from matrix extracellular phosphoglycoprotein), and two small amelogenin gene splice products (A+4 and A-4). Cells implicated in the reparative process are recruited, proliferate, and differentiate into osteoblast-like and odontoblast-like cells. The same results may be obtained by direct implantation of odontoblast progenitor cell into the pulp.

Animals↗
PubMed2006

Identification of temporal and spatial expression patterns of amelogenin isoforms during mouse molar development.

Amelogenin synthesis is initiated in a restricted time frame during odontogenesis. Polypeptides translated from several alternatively spliced isoforms of amelogenin mRNA have been identified in ameloblasts and odontoblasts. Recent studies suggest that the isoforms deleting exons 6a, 6b, and 6c produce polypeptides that might exert regulatory functions governing the late stages of ameloblast and odontoblast differentiation. Herein, the spatial and temporal expression of mouse amelogenin mRNA isoforms M194, M180, M73, and M59 have been determined around the perinatal development period using splice form-specific probes. Expression levels and distribution patterns varied with developmental stage and cell location. Amelogenin mRNA expression was most prominent within the enamel organ at boundaries between cell layers, beginning at the newborn stage (PN0.5). Odontoblasts supported the expression of M73 and M59 mRNA from developmental stages PN0.5 to PN1.5 (1 d of age). In contrast, ameloblasts expressed predominantly the M180 mRNA isoform with full exon 6 but devoid of exon 4. In the enamel organ, the stratum intermediun cells supported expression of the full-length isoform, M194, including the full exon 6 and exon 4 sequences, and strikingly, expression of M180 message was inhibited. In conclusion, ameloblasts, odontoblasts, and stratum intermedium cells demonstrate selective alternative splicing patterns of the amelogenin pre-mRNA transcript.

Aging↗
PubMed2006

Early in vivo and in vitro effects of amelogenin gene splice products on pulp cells.

Recombinant amelogenin gene splice products A+4 and A-4, implanted in the pulp, induce the recruitment, proliferation, and differentiation of reparative cells. Our aim was to investigate the precocious events occurring in the pulp 1 d and 3 d after implantation of agarose beads alone or loaded with A+4 or A-4. Proliferation and cell recruitment towards an odonto/osteogenic phenotype were visualized by detection of the proliferation cell nuclear antigen (PCNA) and RP59. After implantation of beads alone or loaded with A+4, at day 3, pulp cells were moderately immunopositive for osteopontin (OP), whereas labeling was strongly positive upon treatment with A-4. Dentin sialoprotein (DSP) labeling was not detectable. Parallel in vitro studies were carried out on odontoblastic and mesenchymal progenitor cells in order to evaluate the effect of the amelogenin peptides on the expression of a series of marker genes involved in the odontoblastic/osteogenic/chondrogenic differentiation pathways. Altogether, our results suggest that the 'signaling' effects of the amelogenin peptides A+4 and A-4 may differ according to the type of target cells, their stage of differentiation, the time of treatment, and the type of amelogenin peptide (A+4 or A-4).

Amelogenin↗
PubMed2005

Structure and assembly of the heterotrimeric and homotrimeric C-propeptides of type I collagen: significance of the alpha2(I) chain.

Assembly of the type I procollagen molecule begins with interactions among the C-pro alpha1(I) and C-pro alpha2(I) domains. The C-propeptide domains themselves have subdomains of distinct structures. The important questions are where chain association begins and the basis of the chain selectivity which leads to the preferential formation of the [C-pro alpha1(I)]2[C-pro alpha2(I)] heterotrimer. These questions are addressed by energy minimization modeling of the individual C-propeptide structures, study of their docking interactions, and comparison of the heterotrimeric and homotrimeric C-pro structures and stability. The comparisons show the remarkable impact of the C-pro alpha2 chain on the structure of the assembled trimeric C-propeptide. In the modeling, the three chains were anchored and registered by a short C-terminal collagen triple-helical segment followed by the C-telopeptides in their docked conformation, and then the remaining C-propeptide chains were allowed to interact and dock. Surprisingly, propeptide trimerization did not proceed through the previously proposed N-terminal "oligomerization domain" of the C-propeptide [McAlinden et al. (2003) J. Biol. Chem. 278, 42200] but rather in the most C-terminal domains of type I procollagen chains. Molecular dynamics showed heterotrimer assembly to begin with dimer formation between globular G2alpha2 and the G2alpha1(2) domains followed by trimerization at the G1 domains. Assembly initiation in the putative oligomerization coiled-coil domain is not possible because of the Pro residues at positions 3, 7, and 11 at the N-terminus of the alpha2 C-propeptide chain. To confirm the computations and proposed assembly pathway, the G2alpha1 and G2alpha2 domains were prepared recombinantly as the maltose binding protein constructs, and their interactions were studied by dynamic light scattering and gel filtration chromatography. Under the conditions examined MBP remained as monomer, MBP-G2alpha1 and MBP-G2alpha2 alone formed dimers, but a 2:1 mixture of MBP-G2alpha1 and MBP-G2alpha2 favored trimer formation. Thus, the C-terminal globular domains (G2) of the type I collagen C-propeptides play a crucial role in the initiation of intermolecular assembly and heterotrimer selectivity.

Amino Acid Sequence↗
PubMed2005

Characterization of a mouse amelogenin [A-4]/M59 cell surface receptor.

Amelogenin proteins comprise up to 90% of the organic matrix of developing enamel in the vertebrate tooth. Alternative splicing of mouse amelogenin pre-mRNA leads to the production of more than 14 protein isoforms, the functions of which are not totally understood. The smaller splice products, [A + 4] or M73 and [A - 4] or M59, have been shown to act differently as signaling molecules affecting odontogenic and other cell types. The mechanisms of these signaling processes, beginning with receptor identification, are not well understood. Utilizing radiolabeled [A - 4], we show here that 3H[A - 4] binds in a saturable fashion to the cell surface of C2C12 mouse fetal myoblasts at 4 degrees C, and not only binds at the surface but is internalized at 37 degrees C. "Far Western" immunohistochemistry performed on sections of E18 mouse incisors and molars with biotin-labeled [A - 4] as the primary ligand demonstrates [A - 4]-biotin binding to polarizing ameloblasts and odontoblasts, cells of the dental follicle, and along the stratum intermedium. Using [A - 4] affinity column chromatography and [A - 4]-biotin label transfer reaction, we have identified a 95 kDa C2C12 cell surface protein which bound [A - 4]. Utilizing Tandem MS (MS/MS) sequencing, we report the novel finding of the 95 kDa murine transmembrane protein, LAMP-1, originally identified as a lysosomal membrane protein that is also found at the cell surface, as an [A - 4] cell binding protein.

Alternative Splicing↗
PubMed2005

Phosphorylation of phosphophoryn is crucial for its function as a mediator of biomineralization.

Phosphoproteins of the organic matrix of bone and dentin have been implicated as regulators of the nucleation and growth of the inorganic Ca-P crystals of vertebrate bones and teeth. One such protein identified in the dentin matrix is phosphophoryn (PP). It is highly acidic in nature because of a high content of aspartic acid and phosphate groups on serines. The 244-residue carboxyl-terminal domain of rat PP, predominantly containing the aspartic acid-serine repeats, has been cloned, and the corresponding protein has been expressed recombinantly in Escherichia coli. This portion of PP, named DMP2 (dentin matrix protein 2), is not phosphorylated by the bacteria and thus provided a means to study the function of the phosphate groups, the major post-translational modification of native PP. The recombinant DMP2 (rDMP2) possessed much lower calcium binding capacity than native PP. Small angle x-ray scattering experiments demonstrated that PP folds to a compact globular structure upon calcium binding, whereas rDMP2 maintained an unfolded structure. In vitro nucleation experiments showed that PP could nucleate plate-like apatite crystals in pseudophysiological buffer, whereas rDMP2 failed to mediate the transformation of amorphous calcium phosphate to apatite crystals under the same experimental conditions. Collagen binding experiments demonstrated that PP favors the formation of collagen aggregates, whereas in the presence of rDMP2 thin fibrils are formed. Overall these results suggested that the phosphate moieties in phosphophoryn are important for its function as a mediator of dentin biomineralization.

Amino Acid Sequence↗
PubMed2004

Heterotrimeric type I collagen C-telopeptide conformation as docked to its helix receptor.

The amino (N-telo) and carboxyl (C-telo) telopeptides of type I collagen play crucial roles, in vivo and in vitro, in the assembly of collagen fibrils, regulating the axial alignment of the molecules within a fibril, azimuthal orientations of neighboring molecules, and cross-link formation. High-resolution structures of the telopeptides are not available from X-ray diffraction studies, but computational methods permitted prediction of the N-telo structure within a fibril. Here, using a suite of molecular modeling software, the more complex heterotrimeric C-telo of human type I collagen has been built from the correct sequences and energy minimized and the energy minimum confirmed by molecular dynamics. The receptor triple helix was modeled on the basis of the Protein Data Bank coordinates of a collagen-like sequence. Docking of the heterotrimeric C-telopeptide to its receptor showed that hydrophobic interactions involving the short alpha2 C-telopeptide are crucial determinants of its azimuthal orientation within the docked structure. A docked C-telo can interact with only one neighboring helix. The two alpha1(I) C-telo chains in the alpha1(Alpha)-alpha2-alpha1(B) chain stagger do not have identical docked conformations, and one of the alpha1(I) C-telo chains appears to be favored for formation of a cross-link between its K(16C) and a helix K87. Prior studies showed that a docked N-telopeptide can interact with two adjacent collagen monomers, forming a tightly packed region. A recent X-ray analysis showed the N- and C-telo regions pack differently, with the C-telo region being less densely packed than N-telo regions. This difference between N- and C-telopeptide docked structures demonstrates how unique and specific packing can occur in the fibril at each boundary of the type I collagen gap region.

Amino Acid Sequence↗
PubMed2004

Two related low molecular mass polypeptide isoforms of amelogenin have distinct activities in mouse tooth germ differentiation in vitro.

UNLABELLED: Embryonic mouse tooth germs were cultured in vitro in the presence of two related amelogenin isoforms to determine their effects on tooth development. Our results show that these individual proteins have specific but quite different effects on epithelial-derived ameloblasts versus mesenchymal-derived odontoblasts. INTRODUCTION: Amelogenins, the main protein components of enamel matrix, have been shown to have signaling activity. Amelogenin isoforms differing only by the presence or exclusion of exon 4, designated [A+4] (composed of exons 2, 3, 4, 5, 6d, and 7) and [A-4] (composed of exons 2, 3, 5, 6d, and 7), showed similar, but different, effects both in vitro and in vivo on postnatal teeth. MATERIALS AND METHODS: Lower first molar tooth germs of E15/16 CD1 mice were microdissected and cultured in vitro in a semisolid media containing either 20% FBS, 2% FBS, or 2% FBS with either 1.5 nM [A+4], [A-4], or both for 6 days. Tooth germs were analyzed by H&E staining and immunohistochemistry for collagen I, dentin matrix protein 2, and DAPI nuclear staining. RESULTS: Teeth cultured in media containing 20% FBS showed normal development with polarized ameloblasts, and odontoblasts producing dentin matrix, and DMP2 expression in odontoblasts and pre-ameloblasts. Culture in 2% FBS media resulted in no ameloblast polarization and modest odontoblast differentiation with scant dentin matrix. Tooth germs cultured with [A+4] in 2% FBS media had well-polarized odontoblasts with robust dentin production and concomitant ameloblast polarization. DMP2 expression was equal to or greater than seen in the 20% FBS culture condition. In cultures with [A-4] in 2% FBS media, odontoblast polarization and dentin production was reduced compared with [A+4]. However, the pre-ameloblast layer was disorganized, with no ameloblast polarization occurring along the dentin surface. DMP2 expression was reduced in the odontoblasts compared with the 20% FBS and [A+4] conditions and was almost completely abrogated in the pre-ameloblasts. CONCLUSION: These data show different signaling activities of these closely related amelogenin isoforms on tooth development. Here we make the novel observation that [A-4] has an inhibitory effect on ameloblast development, whereas [A+4] strongly stimulates odontoblast development. We show for the first time that specific amelogenin isoforms have effects on embryonic tooth development in vitro and also hypothesize that DMP2 may play a role in the terminal differentiation of both ameloblasts and odontoblasts.

Amelogenin↗
PubMed2004

Type I collagen N-telopeptides adopt an ordered structure when docked to their helix receptor during fibrillogenesis.

The in vitro rate and specificity of fibrillogenesis in type I collagen depends on the integrity of the amino (N)-telopeptide domain. In vivo an intact N-telopeptide domain is also required for normal fibril assembly. Although Chou-Fasman predictions and NMR studies suggested that a type I beta-turn could be induced in alpha1(I) N-telopeptide chains, computer modeling did not identify ordered structures. Nevertheless, X-ray analysis and electron tomography studies have shown that the N-telopeptide is in one of the most highly ordered fibril domains. This study was undertaken to determine if the docking of the N-telopeptide to its helix receptor domain could induce the telopeptides to take up a specific conformation. With use of molecular modeling suite of programs, a (Gly-Pro-Pro)(n) triple-helical structure was built on the basis of high-resolution X-ray crystallographic coordinates and then replaced with the actual bovine collagen residues 924-938, the triple-helical alpha1(I)-N-telopeptide-receptor sequences. Energy minimization produced a modified triple-helical conformation. The bovine alpha1(I) N-telopeptide sequence was similarly minimized and docked to this receptor. The docking induced an ordered conformation with a stabilizing hydrogen bond in the N-telopeptide and, importantly, a reciprocal reordering of the triple-helical conformation in the binding domain. This docked structure placed Lys residues in both telopeptide and helix in the correct locations for cross-link formation. The modeling has been extended to the three-chain N-telopeptide domain and finally to the construction of the Hulmes-Miller quasi-hexagonal packing structure. Each N-telopeptide domain can form linkages with two adjacent, aligned helix receptor domains. The telopeptides and the order of staggering of the three chains in the helix play crucial roles in the packing and intrafibrillar cross-linking patterns and the relative azimuthal orientations of adjacent molecules in the fibril. The models confirm the high order in the N-telopeptide 4D overlap zone.

Amino Acid Sequence↗
PubMed2003

Evidence for the proteolytic processing of dentin matrix protein 1. Identification and characterization of processed fragments and cleavage sites.

Full-length cDNA coding for dentin matrix protein 1 (DMP1) has been cloned and sequenced, but the corresponding complete protein has not been isolated. In searching for naturally occurring DMP1, we recently discovered that the extracellular matrix of bone contains fragments originating from DMP1. Shortened forms of DMP1, termed 37K and 57K fragments, were treated with alkaline phosphatase and then digested with trypsin. The resultant peptides were purified by a two-dimensional method: size exclusion followed by reversed-phase high performance liquid chromatography. Purified peptides were sequenced by Edman degradation and mass spectrometry, and the sequences compared with the DMP1 sequence predicted from cDNA. Extensive sequencing of tryptic peptides revealed that the 37K fragments originated from the NH2-terminal region, and the 57K fragments were from the COOH-terminal part of DMP1. Phosphate analysis indicated that the 37K fragments contained 12 phosphates, and the 57K fragments had 41. From 37K fragments, two peptides lacked a COOH-terminal lysine or arginine; instead they ended at Phe173 and Ser180 and were thus COOH termini of 37K fragments. Two peptides were from the NH2 termini of 57K fragments, starting at Asp218 and Asp222. These findings indicated that DMP1 is proteolytically cleaved at four bonds, Phe173-Asp174, Ser180-Asp181, Ser217-Asp218, and Gln221-Asp222, forming eight fragments. The uniformity of cleavages at the NH2-terminal peptide bonds of aspartyl residues suggests that a single proteinase is involved. Based on its reported specificity, we hypothesize that these scissions are catalyzed by PHEX protein. We envision that the proteolytic processing of DMP1 plays a crucial role during osteogenesis and dentinogenesis.

Alkaline Phosphatase↗
PubMed2003

Nucleation of apatite crystals in vitro by self-assembled dentin matrix protein 1.

Bones and teeth are biocomposites that require controlled mineral deposition during their self-assembly to form tissues with unique mechanical properties. Acidic extracellular matrix proteins play a pivotal role during biomineral formation. However, the mechanisms of protein-mediated mineral initiation are far from understood. Here we report that dentin matrix protein 1 (DMP1), an acidic protein, can nucleate the formation of hydroxyapatite in vitro in a multistep process that begins by DMP1 binding calcium ions and initiating mineral deposition. The nucleated amorphous calcium phosphate precipitates ripen and nanocrystals form. Subsequently, these expand and coalesce into microscale crystals elongated in the c-axis direction. Characterization of the functional domains in DMP1 demonstrated that intermolecular assembly of acidic clusters into a beta-sheet template was essential for the observed mineral nucleation. Protein-mediated initiation of nanocrystals, as discussed here, might provide a new methodology for constructing nanoscale composites by self-assembly of polypeptides with tailor-made peptide sequences.

Biomimetic Materials↗