A synthetic, chemically modified ribozyme eliminates amelogenin, the major translation product in developing mouse enamel in vivo.

Lyngstadaas, Ståle Petter; Risnes, Steinar; Sproat, Brian S.; Thrane, P. S.; Prydz, Hans

doi:10.1002/j.1460-2075.1995.tb00207.x

Cited by 130 publications

(71 citation statements)

References 30 publications

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“…2A, lanes 1-5) or p70 (Fig. 2B, lanes [1][2][3][4][5], whereas Msx2FL by itself was a potent transcriptional repressor. On the other hand, C/EBP␣ was capable of overcoming the repressive effect of Msx2FL on the reporter construct p2207 (Fig.…”

Section: C/ebp␣ and Msx2 Antagonized Each Other In Regulating Mousementioning

confidence: 99%

“…Several mutations in the human Xchromosomal amelogenin gene have been identified from patients with the inherited enamel defect X-linked Amelogenesis imperfecta (1)(2)(3). Disruption of amelogenin synthesis during tooth development with either antisense oligonucleotides or ribozymes results in disorganized enamel (4,5). Amelogenin expression is ameloblast specific and developmentally regulated at the temporal and spatial level (6 -13).…”

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confidence: 99%

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Functional Antagonism between Msx2 and CCAAT/Enhancer-binding Protein α in Regulating the Mouse Amelogenin Gene Expression Is Mediated by Protein-Protein Interaction

Zhou

Lei

Snead

2000

Journal of Biological Chemistry

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Ameloblast-specific amelogenin gene expression is spatiotemporally regulated during tooth development. In a previous study, the CCAAT/enhancer-binding protein ␣ (C/EBP␣) was identified as a transcriptional activator of the mouse amelogenin gene in a cell typespecific manner. Here, Msx2 is shown to repress the promoter activity of amelogenin-promoter reporter constructs independent of its intrinsic DNA binding activity. In transient cotransfection assays, Msx2 and C/EBP␣ antagonize each other in regulating the expression of the mouse amelogenin gene. Electrophoresis mobility shift assays demonstrate that Msx2 interferes with the binding of C/EBP␣ to its cognate site in the mouse amelogenin minimal promoter, although Msx2 itself does not bind to the same promoter fragment. Proteinprotein interaction between Msx2 and C/EBP␣ is identified with co-immunoprecipitation analyses. Functional antagonism between Msx2 and C/EBP␣ is also observed on the stably transfected 2.2-kilobase mouse amelogenin promoter in ameloblast-like LS8 cells. Furthermore, the carboxyl-terminal residues 183-267 of Msx2 are required for protein-protein interaction, whereas the amino-terminal residues 2-97 of Msx2 play a less critical role. Among three family members tested (C/EBP␣, -␤, and -␥), Msx2 preferentially interacts with C/EBP␣. Taken together, these data indicate that protein-protein interaction rather than competition for overlapping binding sites results in the functional antagonism between Msx2 and C/EBP␣ in regulating the mouse amelogenin gene expression.

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Section: C/ebp␣ and Msx2 Antagonized Each Other In Regulating Mousementioning

confidence: 99%

mentioning

confidence: 99%

Functional Antagonism between Msx2 and CCAAT/Enhancer-binding Protein α in Regulating the Mouse Amelogenin Gene Expression Is Mediated by Protein-Protein Interaction

Zhou

Lei

Snead

2000

Journal of Biological Chemistry

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“…Amelogenin is unique in that it self-assembles into nanospheres, supra-molecular structures observed in vitro [6][7][8] and in vivo [7,9] which are believed to be critical to the function of the protein. Several in vivo studies using antisense mice [10], knock out mice [11], transgenic mice [12], and hammerhead ribozymes [13] have investigated the role of amelogenin in regulating enamel nucleation and growth. These studies have shown reduced mineralization in the absence of amelogenin or when amelogenin mutants did not form nanospheres.…”

Section: Introductionmentioning

confidence: 99%

The nucleation and growth of calcium phosphate by amelogenin

Tarasevich

Howard

Larson

et al. 2007

Journal of Crystal Growth

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The nucleation processes involved in calcium phosphate formation in tooth enamel are not well understood but are believed to involve proteins in the extracellular matrix. The ability of one enamel protein, amelogenin, to promote the nucleation and growth of calcium phosphate was studied in an in vitro system involving metastable supersaturated solutions. It was found that recombinant amelogenin (rM179 and rp(H)M180) promoted the nucleation of calcium phosphate compared to solutions without protein. The amount of calcium phosphate increased with increasing supersaturation of the solutions and increasing protein concentrations up to 6.5 μg/mL. At higher protein concentrations, the amount of calcium phosphate decreased. The kinetics of nucleation was studied in situ and in real time using a quartz crystal microbalance (QCM) and showed that the protein reduced the induction time for nucleation compared to solutions without protein. This work shows a nucleation role for amelogenin in vitro which may be promoted by the association of amelogenin into nanosphere templates, exposing charged functionality at the surface.

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“…Extensive modification of the hammerhead ribozyme motif can give dramatic enhancement of the ribozyme half-life in biological fluids (8,13). Modifications of this type have been demonstrated to give efficacy in cell culture (7) and in vivo (13,14).We have previously described dose-dependent inhibition of smooth muscle cell proliferation by select ribozymes targeting c-myb. Little inhibition was observed with catalytically inactive control RNA molecules.…”

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Optimizing the Cell Efficacy of Synthetic Ribozymes

Jarvis¹,

Wincott²,

Alby³

et al. 1996

Journal of Biological Chemistry

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Expression of the proto-oncogene c-myb is necessary for proliferation of vascular smooth muscle cells. We have developed synthetic hammerhead ribozymes that recognize and cleave c-myb RNA, thereby inhibiting cell proliferation. Herein, we describe a method for the selection of hammerhead ribozyme cleavage sites and optimization of chemical modifications that maximize cell efficacy. In vitro assays were used to determine the relative accessibility of the ribozyme target sites for binding and cleavage. Several ribozymes thus identified showed efficacy in inhibiting smooth muscle cell proliferation relative to catalytically inactive controls. A combination of modifications including several phosphorothioate linkages at the 5-end of the ribozyme and an extensively modified catalytic core resulted in substantially increased cell efficacy. A variety of different 2-modifications at positions U4 and U7 that confer nuclease resistance gave comparable levels of cell efficacy. The lengths of the ribozyme binding arms were varied; optimal cell efficacy was observed with relatively short sequences (13-15 total nucleotides). These synthetic ribozymes have potential as therapeutics for hyperproliferative disorders such as restenosis and cancer. The chemical motifs that give optimal ribozyme activity in smooth muscle cell assays may be applicable to other cell types and other molecular targets.Since the discovery that certain naturally occurring RNA motifs were capable of catalytically cleaving other RNA molecules in a sequence-specific manner, extensive studies have defined the sequence and structural characteristics that control the in vitro specificity and kinetics of these RNA enzymes or ribozymes (1-4). Ribozymes have a broad range of potential in vivo applications. These include the use of ribozymes as research tools for probing molecular mechanisms, the use of ribozymes to genetically engineer crops, and the use of ribozymes as therapeutics for human or animal diseases. Each of these applications requires that a ribozyme function efficiently within the intracellular environment. The sequence and structural features that promote optimal intracellular activity of ribozymes are currently under study.Several factors are likely to contribute to the intracellular efficacy of a ribozyme. A ribozyme must colocalize with its molecular target in the appropriate cellular compartment and must be present at sufficiently high concentration to promote hybridization. In addition, its catalytic cleavage rate must be fast enough, and its half-life must be long enough to allow cleavage of a substantial fraction of the target mRNA population. Finally, the cleavage site in the target mRNA must be accessible to ribozyme binding. When the ribozyme is made synthetically, a variety of modifications can be introduced to increase its half-life within the cell, to change its target sequence binding affinity, and possibly also to alter its intracellular trafficking properties. In this study, we have used chemically synthesized hammerhead ribozymes t...

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A synthetic, chemically modified ribozyme eliminates amelogenin, the major translation product in developing mouse enamel in vivo.

Cited by 130 publications

References 30 publications

Functional Antagonism between Msx2 and CCAAT/Enhancer-binding Protein α in Regulating the Mouse Amelogenin Gene Expression Is Mediated by Protein-Protein Interaction

Functional Antagonism between Msx2 and CCAAT/Enhancer-binding Protein α in Regulating the Mouse Amelogenin Gene Expression Is Mediated by Protein-Protein Interaction

The nucleation and growth of calcium phosphate by amelogenin

Optimizing the Cell Efficacy of Synthetic Ribozymes

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