Gene Expression and Localization of Amelogenin in the Rat Incisor

1996 ◽  
Vol 10 (2) ◽  
pp. 201-207 ◽  
Author(s):  
T. Inage ◽  
H. Shimokawa ◽  
K. Wakao ◽  
S. Sasaki
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Maturation Stage ◽  
Enamel Matrix ◽  
Rat Incisor ◽  
Early Maturation ◽  
Incisal Edge ◽  
Enamel Epithelium ◽  
Developing Rat

Gene expression and localization of amelogenin were studied in the developing rat incisor by the methods of in situ hybridization and immunohistochemistry. ISH revealed the first expression of amelogenin mRNA in the inner enamel epithelium of the cervical loop. The signals were clearly observed in pre-ameloblasts in the region bordering on predentin formation and became more intense toward the cells on the initial enamel matrix secretion. The maximal signals were found in the cytoplasm of secretory ameloblasts. From the terminal secretion zone, the signals then became gradually weaker toward the incisal edge but were still evident in the cytoplasm of shortening, transitional ameloblasts and those at the early maturation stage. No signals were found in the cells of the stratum intermedium and stellate reticulum throughout amelogenesis. Immunohistochemistry by means of an antibody against amelogenin C-telopeptide consisting of 12 amino acids revealed immunoreaction in the secretory ameloblasts reacting to the ISH. When a polyclonal antibody against amelogenin was used, immunoreaction was found in the distal ends of ruffle-ended ameloblasts (RA) in the maturation zone. Those results indicated that amelogenin is synthesized by ameloblastic cells from the inner enamel epithelium to the early maturation stage and is then resorbed by the RA.

Studies on the Changes in Developing Enamel Caused By Ingestion of High Levels of Fluoride in the Rat

1987 ◽  
Vol 1 (2) ◽  
pp. 176-180 ◽  
Author(s):  
P.K. Denbesten ◽  
M.A. Crenshaw
Keyword(s):  
Enamel Organ ◽  
Maturation Stage ◽  
Careful Study ◽  
Enamel Matrix ◽  
Rat Incisor ◽  
Early Maturation ◽  
Enamel Proteins ◽  
And Control ◽  
Water Fluoride

Exposure to chronic high levels of fluoride results in the formation of fluorosed enamel. Although enamel may be more susceptible to fluorotic effects at certain stages of development, fluoride at sufficiently high levels may affect enamel at all stages of formation. Careful study of the changes in enamel caused by chronic fluoride ingestion is needed to understand more fully the mechanisms involved in the formation of fluorotic enamel. This paper discusses the various studies we have completed to define the changes, in developing enamel of the rat incisor, caused by long-term ingestion of fluoride in drinking water. Fluoride has been found to inhibit secretion of enamel proteins. Changes in the maturation stage of enamel formation include the retention of amelogenin proteins during early maturation. The various mechanisms which have been investigated in the formation of fluorosed enamel include a direct effect of fluoride on the enamel organ, and specific interactions of fluoride with the extracellular enamel matrix. Although the same amount of protease appears to be secreted in fluorosed and control enamel, a delay in the digestion of amelogenin protein occurs. This suggests that fluoride may directly or indirectly inhibit the protease present in fluorosed enamel to slow the proteolysis of amelogenins.

Correlation of Apical and Lateral Membrane Modulations of Maturation Ameloblasts

1985 ◽  
Vol 64 (8) ◽  
pp. 1055-1061 ◽  
Author(s):  
Z. Skobe ◽  
F. LaFrazia ◽  
K. Prostak
Keyword(s):  
Apical Membrane ◽  
Apical Cell ◽  
Matrix Proteins ◽  
Maturation Stage ◽  
Enamel Matrix ◽  
Enamel Matrix Proteins ◽  
Rat Incisor ◽  
Lateral Membrane ◽  
Apical Junctions ◽  
Scanning Electron

Maturation ameloblasts of rat incisor teeth have smooth-ended and ruffle-ended apical membrane configurations. It has also been reported that maturation ameloblasts have several lateral membrane configurations. The purpose of this study was to determine the correlation between the modulations of lateral and apical cell membranes of murine incisor ameloblasts in the maturation stage of amelogenesis. Maxillary and mandibular incisors were dissected, demineralized, embedded in paraffin, sectioned and then de-paraffinized, and the enamel organs were prepared for scanning electron microscopy. Additional mouse and rat incisor enamel organs were fixed and teased apart during dehydration, then observed in the SEM. The lengths of smooth- and ruffle-ended ameloblast segments were measured, and the site, length, and frequency of each lateral membrane configuration were determined within each segment. The lateral membrane configuration with folds forming from 12 to 14 channels around the periphery of the cells was most predominant in both smooth- and ruffle-ended cells. Cells surrounded by from six to eight channels were the only other lateral membrane configuration observed in ruffle-ended ameloblasts. Smooth-ended ameloblasts had lateral membrane configurations with either dense or sparse microvillous projections in addition to both types of channel cells. The observation that channelled extracellular spaces are always associated with ruffle-ended cells suggests that channels somehow function in conjunction with the ruffled apical membrane in resorption and removal of enamel matrix proteins. The smooth-ended ameloblasts lack tight apical junctions, and their microvillous lateral membranes permit the passage of plasma fluids around cells to the maturing enamel surface. Analysis of our data indicates that specific lateral membrane configurations are related to the type of apical membrane present.

scholarly journals Cytochemical and biochemical characterization of glycoproteins in forming and maturing enamel of the rat incisor.

1989 ◽  
Vol 37 (11) ◽  
pp. 1619-1633 ◽  
Author(s):  
A Nanci ◽  
J P Ahluwalia ◽  
S Zalzal ◽  
C E Smith
Keyword(s):  
Secretory Granules ◽  
Helix Pomatia ◽  
Extracellular Proteins ◽  
Maturation Stage ◽  
Variable Degree ◽  
Rat Incisor ◽  
Double Labeling ◽  
Early Maturation ◽  
Enamel Proteins ◽  
Lowicryl K4m

Biochemical and histochemical studies have shown the presence of various carbohydrates in enamel. Using lectin-gold cytochemistry, we have examined the distribution of glycoconjugates containing N-acetyl-D-galactosamine (GalNAc) and/or N-acetyl-glucosamine (GlcNAc)/N-acetyl-neuraminic acid (NeuNAc) residues in rat incisor ameloblasts and in forming and maturing enamel embedded in Lowicryl K4M, LR Gold, and LR White resins. The enamel proteins that contain these carbohydrate moieties were further characterized by lectin blotting. All three resins allowed, albeit to a variable degree, detection of the binding sites for Helix pomatia agglutinin (HPA) and wheat germ agglutinin (WGA) GalNAc, and GlcNAc/NeuNAc, respectively. In general, Lowicryl K4M permitted more intense reactions with both lectins. Lectin binding was observed over the rough endoplasmic reticulum (weak labeling with WGA), the Golgi apparatus, lysosomes, secretory granules, and the enamel matrix. These compartments were shown by double labeling with WGA and anti-amelogenin antibody, and by previous immunocytochemical studies, to contain enamel proteins. Furthermore, WGA binding was more concentrated at the growth sites of enamel. Lectin blotting showed that several proteins in the amelogenin group were glycosylated and contained the sugars GalNAc and GlcNAc/NeuNAc. Fewer proteins were stained by HPA than by WGA, and the staining pattern suggested that the extracellular proteins recognized by these two lectins are processed differently. The HPA-reactive proteins were lost by or during the early maturation stage, whereas many of the WGA-reactive proteins persisted into the mid maturation stage. The heterogeneous staining of certain protein bands observed with WGA suggests that they contain more than one component. Two distinct glycoproteins containing GlcNAc/NeuNAc also appeared during the maturation stage. These results are consistent with the notion that ameloblasts produce an extracellular matrix composed mainly of glycosylated amelogenins which are differently processed throughout amelogenesis.

Ultrastructure of granular materials in rat incisor enamel organ at early maturation stage

1984 ◽  
Vol 29 (2) ◽  
pp. 157-159 ◽  
Author(s):  
K. Yamamoto ◽  
S. Matsuo ◽  
T. Nishimoto ◽  
S. Wakisaka ◽  
H. Ichikawa ◽  
...  
Keyword(s):  
Granular Materials ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Rat Incisor ◽  
Early Maturation

scholarly journals Expression of Alternatively Spliced RNA Transcripts of Amelogenin Gene Exons 8 and 9 and Its End Products in the Rat Incisor

2002 ◽  
Vol 50 (9) ◽  
pp. 1229-1236 ◽  
Author(s):  
Otto Baba ◽  
Nobuyuki Takahashi ◽  
Tatsuo Terashima ◽  
Wu Li ◽  
Pamela K. DenBesten ◽  
...  
Keyword(s):  
Enamel Matrix ◽  
Temporal Expression ◽  
Rat Incisor ◽  
Amelogenin Gene ◽  
Rna Transcripts ◽  
Alternatively Spliced ◽  
Exon 9 ◽  
Enamel Proteins ◽  
Tooth Germs

In addition to seven known exons of the amelogenin gene, recent studies have identified two exons downstream of amelogenin exon 7 in genomic DNA of mouse and rat. Here the spatial and temporal expression of mRNAs and of the translated proteins derived from alternative splicing of the amelogenin gene ending with exon 8 and exon 9 were examined by in situ hybridization (ISH) and immunohistochemistry (IHC). RNA signals for exons 8 and 9 were expressed in the ameloblast layer extending from early presecretory to postsecretory transitional stages of amelogenesis. IHC of amelogenin proteins that include sequences encoded by these exons demonstrated identical localization of these proteins in the ameloblast layer corresponding to RNA signals identified by ISH. There was intense immunostaining of the enamel matrix secreted by these cells. Western blotting analysis of rat enamel proteins revealed three distinct protein bands with sequences encoded by the new exons. These data confirmed the existence of the transcripts of alternatively spliced mRNAs coding for exons 8 and 9 of the amelogenin gene in rat tooth germs and suggest that the translated proteins contribute to the heterogeneity of amelogenins and have some significant roles in enamel formation and mineralization.

scholarly journals Proteinases in Developing Dental Enamel

1999 ◽  
Vol 10 (4) ◽  
pp. 425-441 ◽  
Author(s):  
J.D. Bartlett ◽  
J.P. Simmer
Keyword(s):  
Proteinase Inhibitors ◽  
Dental Enamel ◽  
Serine Proteinase ◽  
Organic Matrix ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Enamel Matrix ◽  
Enamel Matrix Proteins ◽  
Early Maturation

For almost three decades, proteinases have been known to reside within developing dental enamel. However, identification and characterization of these proteinases have been slow and difficult, because they are present in very small quantities and they are difficult to purify directly from the mineralizing enamel. Enamel matrix proteins such as amelogenin, ameloblastin, and enamelin are cleaved by proteinases soon after they are secreted, and their cleavage products accumulate in the deeper, more mature enamel layers, while the full-length proteins are observed only at the surface. These results suggest that proteinases are necessary for "activating" enamel proteins so the parent proteins and their cleavage products may perform different functions. A novel matrix metalloproteinase named enamelysin (MMP-20) was recently cloned from tooth tissues and was later shown to localize primarily within the most recently formed enamel. Furthermore, recombinant porcine enamelysin was demonstrated to cleave recombinant porcine amelogenin at virtually all of the sites that have previously been described in vivo. Therefore, enamelysin is at least one enzyme that may be important during early enamel development. As enamel development progresses to the later stages, a profound decrease in the enamel protein content is observed. Proteinases have traditionally been assumed to degrade the organic matrix prior to its removal from the enamel. Recently, a novel serine proteinase named enamel matrix serine proteinase-1 (EMSP1) was cloned from enamel organ epithelia. EMSP1 localizes primarily to the early maturation stage enamel and may, therefore, be involved in the degradation of proteins prior to their removal from the maturing enamel. Other, as yet unidentified, proteinases and proteinase inhibitors are almost certainly present within the forming enamel and await discovery.

Molecular and Microscopic Analysis of Altered Gene Expression in Transgenic and Gene Targeted Mice

1996 ◽  
Vol 54 ◽  
pp. 12-13
Author(s):  
W. K. Jones ◽  
J. Robbins
Keyword(s):  
Gene Expression ◽  
Pulmonary Veins ◽  
Microscopic Analysis ◽  
Mouse Tissue ◽  
Adult Heart ◽  
Heavy Chains ◽  
Altered Gene Expression ◽  
Altered Gene ◽  
Pulmonary Myocardium

Two myosin heavy chains (MyHC) are expressed in the mammalian heart and are differentially regulated during development. In the mouse, the α-MyHC is expressed constitutively in the atrium. At birth, the β-MyHC is downregulated and replaced by the α-MyHC, which is the sole cardiac MyHC isoform in the adult heart. We have employed transgenic and gene-targeting methodologies to study the regulation of cardiac MyHC gene expression and the functional and developmental consequences of altered α-MyHC expression in the mouse.We previously characterized an α-MyHC promoter capable of driving tissue-specific and developmentally correct expression of a CAT (chloramphenicol acetyltransferase) marker in the mouse. Tissue surveys detected a small amount of CAT activity in the lung (Fig. 1a). The results of in situ hybridization analyses indicated that the pattern of CAT transcript in the adult heart (Fig. 1b, top panel) is the same as that of α-MyHC (Fig. 1b, lower panel). The α-MyHC gene is expressed in a layer of cardiac muscle (pulmonary myocardium) associated with the pulmonary veins (Fig. 1c). These studies extend our understanding of α-MyHC expression and delimit a third cardiac compartment.

Long term dietary intake of aromatic amino acids are associated with leptin gene expression in adipose tissues of non-diabetic adults

2018 ◽  
Author(s):  
Golaleh Asghari ◽  
Emad Yuzbashian ◽  
Maryam Zarkesh ◽  
Parvin Mirmiran ◽  
Mehdi Hedayati ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Dietary Intake ◽  
Aromatic Amino Acids ◽  
Adipose Tissues

scholarly journals PSIV-6 Effect of a Phytogenic Water Additive on Growth Performance, Blood Metabolites and Gene Expression of Amino Acids Transporters in Nursery Pigs Fed with Low Protein Diets

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 281-282
Author(s):  
Cedrick N Shili ◽  
Mohammad Habibi ◽  
Julia Sutton ◽  
Jessie Barnes ◽  
Jacob Burchkonda ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Growth Performance ◽  
Mrna Abundance ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Blood Calcium ◽  
Low Protein ◽  
Protein Diets ◽  
Standard Protein

Abstract Moderately low protein (MLP) diets can help decrease nutrient excretion from the swine production. However, MLP diets negatively impact growth performance. We hypothesized that supplementing MLP diets with phytogenics may reduce the negative effects of these diets on growth. The objective of this study was to investigate the effect of a phytogenic water additive (PWA; Herbanimal®) on growth performance, blood metabolite and gene expression of amino acids transporters in pigs fed with MLP diets. Forty-eight weaned barrows were allotted to six dietary treatments (n = 8) for 4 weeks: >CON-NS: standard protein diet-no PWA; CON-LS: standard protein diet-low PWA dose (4 ml/L); CON-HS: standard protein diet-high PWA dose (8 ml/L); LP-NS: low protein diet-no PWA; LP-LS: low protein diet-low PWA dose (4 ml/L); LP-HS: low protein diet- high PWA dose (8 ml/L). Feed intake and body weight were recorded daily and weekly, respectively. At week 4, blood and tissue samples were collected and analyzed for metabolites using a chemistry analyzer and amino acid transporters using qPCR, respectively. The data were analyzed by univariate GLM (SPSS®) and the means were separated using paired Student’s t-test corrected by Benjamini-Hochberg. Pigs fed CON-HS improved the average daily gain and serum calcium and phosphorus concentrations compared to CON-NS. Pigs fed LP-LS had higher serum phosphorus and blood urea nitrogen compared to the pigs fed with LP-NS. The mRNA abundance of SLC7A11 in the jejunum was lower in CON-LS and CON-HS compared to CON-NS. Additionally, mRNA abundance of SLC6A19 in the jejunum of pigs fed with LP-LS was higher compared to LP-NS and lower in CON-HS relative to pigs fed with CON-LS. In conclusion, PWA improved the growth performance of pigs fed standard protein diets but not low protein diets. Further, the PWA improved the concentrations of blood calcium and phosphorous in pigs fed MLP diets. Funding: Agrivida and Animal Health and Production and Animal Products: Improved Nutritional Performance, Growth, and Lactation of Animals from the USDA-NIFA.

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