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The Journal of Cell Biology Aug 1998Retinal pigment epithelial (RPE) cells apically polarize proteins that are basolateral in other epithelia. This reversal may be generated by the association of RPE with...
Retinal pigment epithelial (RPE) cells apically polarize proteins that are basolateral in other epithelia. This reversal may be generated by the association of RPE with photoreceptors and the interphotoreceptor matrix, postnatal expansion of the RPE apical surface, and/or changes in RPE sorting machinery. We compared two proteins exhibiting reversed, apical polarities in RPE cells, neural cell adhesion molecule (N-CAM; 140-kD isoform) and extracellular matrix metalloproteinase inducer (EMMPRIN), with the cognate apical marker, p75-neurotrophin receptor (p75-NTR). N-CAM and p75-NTR were apically localized from birth to adulthood, contrasting with a basolateral to apical switch of EMMPRIN in developing postnatal rat RPE. Morphometric analysis demonstrated that this switch cannot be attributed to expansion of the apical surface of maturing RPE because the basolateral membrane expanded proportionally, maintaining a 3:1 apical/basolateral ratio. Kinetic analysis of polarized surface delivery in MDCK and RPE-J cells showed that EMMPRIN has a basolateral signal in its cytoplasmic tail recognized by both cell lines. In contrast, the basolateral signal of N-CAM is recognized by MDCK cells but not RPE-J cells. Deletion of N-CAM's basolateral signal did not prevent its apical localization in vivo. The data demonstrate that the apical polarity of EMMPRIN and N-CAM in mature RPE results from suppressed decoding of specific basolateral signals resulting in randomized delivery to the cell surface.
Topics: Animals; Antigens, CD; Antigens, Neoplasm; Basigin; Biological Transport; Cell Line; Cell Line, Transformed; Cell Polarity; Dogs; Female; Gene Transfer Techniques; Humans; Male; Membrane Glycoproteins; Neural Cell Adhesion Molecules; Pigment Epithelium of Eye; Protein Sorting Signals; Rats; Receptor, Nerve Growth Factor; Receptors, Nerve Growth Factor
PubMed: 9700159
DOI: 10.1083/jcb.142.3.697 -
The Journal of Cell Biology Jun 2000Nedd4 is a ubiquitin protein ligase (E3) containing a C2 domain, three or four WW domains, and a ubiquitin ligase HECT domain. We have shown previously that the C2...
Nedd4 is a ubiquitin protein ligase (E3) containing a C2 domain, three or four WW domains, and a ubiquitin ligase HECT domain. We have shown previously that the C2 domain of Nedd4 is responsible for its Ca(2+)-dependent targeting to the plasma membrane, particularly the apical region of epithelial MDCK cells. To investigate this apical preference, we searched for Nedd4-C2 domain-interacting proteins that might be involved in targeting Nedd4 to the apical surface. Using immobilized Nedd4-C2 domain to trap interacting proteins from MDCK cell lysate, we isolated, in the presence of Ca(2+), a approximately 35-40-kD protein that we identified as annexin XIII using mass spectrometry. Annexin XIII has two known isoforms, a and b, that are apically localized, although XIIIa is also found in the basolateral compartment. In vitro binding and coprecipitation experiments showed that the Nedd4-C2 domain interacts with both annexin XIIIa and b in the presence of Ca(2+), and the interaction is direct and optimal at 1 microM Ca(2+). Immunofluorescence and immunogold electron microscopy revealed colocalization of Nedd4 and annexin XIIIb in apical carriers and at the apical plasma membrane. Moreover, we show that Nedd4 associates with raft lipid microdomains in a Ca(2+)-dependent manner, as determined by detergent extraction and floatation assays. These results suggest that the apical membrane localization of Nedd4 is mediated by an association of its C2 domain with the apically targeted annexin XIIIb.
Topics: Amino Acid Sequence; Animals; Annexins; Binding Sites; Calcium; Calcium-Binding Proteins; Cell Membrane; Cells, Cultured; Endosomal Sorting Complexes Required for Transport; Ligases; Molecular Sequence Data; Nedd4 Ubiquitin Protein Ligases; Organelles; Protein Structure, Tertiary; Ubiquitin-Protein Ligases
PubMed: 10871286
DOI: 10.1083/jcb.149.7.1473 -
The Journal of Contemporary Dental... May 2020To evaluate effect of apical root canal perforation size on push-out bond strength of glass fiber dowels cemented to sound or perforated root canals using two different...
AIM
To evaluate effect of apical root canal perforation size on push-out bond strength of glass fiber dowels cemented to sound or perforated root canals using two different adhesive systems.
MATERIALS AND METHODS
A total of 120 human-extracted intact upper central incisors were selected. Teeth were sectioned 3 mm coronal to cement enamel junction, and the remaining root received endodontic root canal therapy. The roots were divided into two experimental groups according to the root condition: either sound ( = 40) or apically perforated ( = 80). Dowel spaces were prepared for all specimens to a depth of 10 mm. Roots were restored with glass fiber dowels. The experimental group was further subdivided into four subgroups ( = 20) according to the adhesive system used and apical perforation size: group I, perforated root 2 mm apically, dowel cemented using total-etch adhesive cement; group II, perforated root 2 mm apically, dowel cemented using self-etch adhesive cement; group III, perforated root 4 mm apically, dowel cemented using total-etch adhesive cement; and group IV, perforated root 4 mm apically, dowel cemented using self-etch adhesive cement. The control group, sound root, was divided into two subgroups: group I, sound root, dowel cemented using total-etch adhesive cement, and group II, sound root, dowel cemented using self-etch or total-etch adhesive cement. Each root was then cut horizontally, and root segments were prepared to be tested. The bond strength between dowel and dentin was measured with universal testing machine using a push-out test. The two-way analysis of variance (ANOVA) was used to analyze the data and Tukey's test ( = 0.05).
RESULTS
Root canal perforation and the type of adhesive system used resulted in significant differences in push-out bond strength ( < 0.05). Regardless of root canal perforation size, glass fiber dowels in normal root canals had significantly higher mean bond strength values (9.2 ± 1.4 MPa) compared with perforated root canals (6.1 ± 1.4 MPa). Also, self-etch protocol had significantly higher mean bond strength values (9.1 ± 1.3 MPa) compared with total-etch protocol (6.2 ± 2.1 MPa).
CONCLUSION
The apical root perforation size caused a direct effect on the bond strength of the glass fiber dowels cemented to dentin by reducing the bond strength values to the root dentin regardless of the adhesive system used.
CLINICAL SIGNIFICANCE
Prior to perforation repair, dentist or endodontist should evaluate the perforation size to predict the treatment outcome.
Topics: Dental Bonding; Dental Pulp Cavity; Dentin; Glass; Humans; Materials Testing; Post and Core Technique; Resin Cements; Root Canal Therapy
PubMed: 32690833
DOI: No ID Found -
Developmental Cell Nov 2016Contractile actomyosin networks are central to cell shape change, rearrangements, and migration during animal tissue morphogenesis. In this issue of Developmental Cell,...
Contractile actomyosin networks are central to cell shape change, rearrangements, and migration during animal tissue morphogenesis. In this issue of Developmental Cell, Coravos and Martin (2016) report that the actin network is radially polarized in apically constricting cells, suggesting a constriction model similar to the contraction mechanism in muscle sarcomeres.
Topics: Actins; Actomyosin; Animals; Cell Polarity; Constriction; Morphogenesis
PubMed: 27825436
DOI: 10.1016/j.devcel.2016.10.017 -
Frontiers in Cell and Developmental... 2021The inner/apical surface of the embryonic brain wall is important as a major site for cell production by neural progenitor cells (NPCs). We compared the mechanical...
The inner/apical surface of the embryonic brain wall is important as a major site for cell production by neural progenitor cells (NPCs). We compared the mechanical properties of the apical surfaces of two neighboring but morphologically distinct cerebral wall regions in mice from embryonic day (E) E12-E14. Through indentation measurement using atomic force microscopy (AFM), we first found that Young's modulus was higher at a concave-shaped apical surface of the pallium than at a convex-shaped apical surface of the ganglionic eminence (GE). Further AFM analysis suggested that contribution of actomyosin as revealed with apical surface softening by blebbistatin and stiffness of dissociated NPCs were both comparable between pallium and GE, not accounting for the differential apical surface stiffness. We then found that the density of apices of NPCs was greater, with denser F-actin meshwork, in the apically stiffer pallium than in GE. A similar correlation was found between the decreasing density between E12 and E14 of NPC apices and the declining apical surface stiffness in the same period in both the pallium and the GE. Thus, one plausible explanation for the observed difference (pallium > GE) in apical surface stiffness may be differential densification of NPC apices. In laser ablation onto the apical surface, the convex-shaped GE apical surface showed quicker recoils of edges than the pallial apical surface did, with a milder inhibition of recoiling by blebbistatin than in pallium. This greater pre-stress in GE may provide an indication of how the initially apically concave wall then becomes an apically convex "eminence."
PubMed: 34368153
DOI: 10.3389/fcell.2021.702068 -
Oral Surgery, Oral Medicine, Oral... Jun 1995One hundred forty extracted permanent human teeth were prepared for examination with a scanning electron microscope to determine the number of foramina, their distances...
One hundred forty extracted permanent human teeth were prepared for examination with a scanning electron microscope to determine the number of foramina, their distances from the apices, and their locations. In most of the specimens, the root canals deviated to one side and ended short of the apices. Some specimens showed interradicular openings; others had configurations on the top of the apices that were similar to the crest on a helmet.
Topics: Adult; Aged; Dental Pulp Cavity; Humans; Microscopy, Electron, Scanning; Middle Aged; Tooth Root
PubMed: 7621038
DOI: 10.1016/s1079-2104(05)80315-4 -
Journal of Conservative Dentistry : JCD 2017This study was intended to evaluate the amount of apically extruded debris following root canal preparation with three different instrumentation systems.
AIM
This study was intended to evaluate the amount of apically extruded debris following root canal preparation with three different instrumentation systems.
MATERIALS AND METHODS
Sixty mandibular incisor teeth were selected and randomly divided into three groups ( = 20/group) according to the instrumentation system used: the ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), the Twisted File Adaptive (TFA; SybronEndo, Orange, CA, USA), and the WaveOne Gold (WOG; Dentsply Maillefer, Ballaigues, Switzerland). All apically extruded debris was collected and dried in preweighed glass vials. The mean weight of the apically extruded debris was obtained using a microbalance. The time for root canal preparation was also recorded. The data were analyzed using a one-way analysis of variance.
RESULTS
The mean weights of apically extruded debris were 0.00035 ± 0.00014 g (PTN); 0.00023 ± 0.0001 g (TFA); and 0.00019 ± 0.0001 g (WOG) ( < 0.01). The mean preparation time value was 301,13 ± 62.14 s (PTN); 234.27 ± 34.88 s (TFA); and 239.8 ± 58.6 s (WOG) ( < 0.05).
CONCLUSIONS
The PTN system extruded more debris than the TFA and WOG systems. The TFA and WOG systems were faster than the PTN system.
PubMed: 29386779
DOI: 10.4103/JCD.JCD_407_16 -
Restorative Dentistry & Endodontics May 2021The aim of this study was to evaluate the shaping ability of the TruShape and Reciproc Blue systems and the apical extrusion of debris after root canal instrumentation....
OBJECTIVES
The aim of this study was to evaluate the shaping ability of the TruShape and Reciproc Blue systems and the apical extrusion of debris after root canal instrumentation. The ProTaper Universal system was used as a reference for comparison.
MATERIALS AND METHODS
Thirty-three mandibular premolars with a single canal were scanned using micro-computed tomography and were matched into 3 groups ( = 11) according to the instrumentation system: TruShape, Reciproc Blue and ProTaper Universal. The teeth were accessed and mounted in an apparatus with agarose gel, which simulated apical resistance provided by the periapical tissue and enabled the collection of apically extruded debris. During root canal preparation, 2.5% sodium hypochlorite was used as an irrigant. The samples were scanned again after instrumentation. The percentage of unprepared area, removed dentin, and volume of apically extruded debris were analyzed. The data were analyzed using 1-way analysis of variance and the Tukey test for multiple comparisons at a 5% significance level.
RESULTS
No significant differences in the percentage of unprepared area were observed among the systems ( > 0.05). ProTaper Universal presented a higher percentage of dentin removal than the TruShape and Reciproc Blue systems ( < 0.05). The systems produced similar volumes of apically extruded debris ( > 0.05).
CONCLUSIONS
All systems caused apically extruded debris, without any significant differences among them. TruShape, Reciproc Blue, and ProTaper Universal presented similar percentages of unprepared area after root canal instrumentation; however, ProTaper Universal was associated with higher dentin removal than the other systems.
PubMed: 34123752
DOI: 10.5395/rde.2021.46.e16 -
Basal and apical regulation of VEGF-A and placenta growth factor in the RPE/choroid and primary RPE.Molecular Vision 2015Members of the vascular endothelial growth factor (VEGF) family are strongly involved in pathological processes in the retina, such as age-related macular degeneration...
PURPOSE
Members of the vascular endothelial growth factor (VEGF) family are strongly involved in pathological processes in the retina, such as age-related macular degeneration and diabetic retinopathy. Cells of the retinal pigment epithelium (RPE) constitutively secrete VEGF-A, and the secretion of placental growth factor (PlGF) has also been described. RPE cells are strongly polarized cells with different secretome at the apical and basal side. In this study, we evaluated the basal and apical regulation of VEGF-A and PlGF secretion in RPE/choroid explants and primary RPE cells.
METHODS
RPE/choroid tissue explants were prepared from porcine eyes and cultivated in modified Ussing chambers, separating apical (RPE) and basal (choroid) supernatant. Primary RPE cells were also prepared from porcine eyes and cultivated on Transwell plates. Explants and cells were treated with inhibitors for VEGFR-2 (SU1498), p38 (SB203580), and the transcription factors nuclear factor-kappa B (NF-κB) and SP-1 (mithramycin), respectively. VEGF-A and PlGF content was evaluated with enzyme-linked immunosorbent assay (ELISA). In addition, western blots were performed.
RESULTS
In the RPE/choroid, VEGF-A can initially be found on the apical and basal sides with significantly more pronounced secretion on the basal side. VEGF-A secretion is differentially regulated on the apical and basal sides, with the inhibition of SP-1 and NF-κB showing strong effects apically and basally after 24 h and 48 h, the inhibition of p38 displaying its effect mainly on the basal side with some effect apically after 48 h, and the inhibition of VEGFR-2 reducing the secretion of VEGF only on the apical side at 24 h and 48 h. In the RPE cell culture, similar effects were found, with inhibition of NF-κB or SP-1 displaying a strong decrease in VEGF-A on both sides, and p38 inhibition displaying only an inhibitory effect on the basal side. In contrast, an apical effect of VEGFR-2 inhibition was not found. However, the western blot experiments exhibited a significant decrease in the VEGF-A protein under SU1498 treatment. In the RPE/choroid organ cultures, PlGF was initially found mainly on the basal site with only minute amounts of PlGF found apically. NF-κB and SP-1 were strongly involved in PlGF regulation apically and basally, while VEGFR2 and to a lesser degree p38 displayed some regulation at the basal site. In the primary RPE cell culture, PlGF was not found on the apical or basal side.
CONCLUSIONS
VEGF-A and PlGF were constitutively secreted and regulated by the RPE/choroid complex, with PlGF secreted mainly by the choroid. Although the transcription factors NF-κB and SP-1 were involved in apical and basal regulation of both growth factors, VEGFR-2 displayed a strong polarity, with regulation of apical VEGF-A and basal PlGF secretion.
Topics: Animals; Cells, Cultured; Choroid; NF-kappa B; Organ Culture Techniques; Placenta Growth Factor; Pregnancy Proteins; Retinal Pigment Epithelium; Sp1 Transcription Factor; Sus scrofa; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; p38 Mitogen-Activated Protein Kinases
PubMed: 26167115
DOI: No ID Found -
Journal of Endodontics Mar 1998The purpose of this study was to investigate the quantity of apical debris produced in vitro using two hand and two rotary instrumentation techniques. Sixty minimally... (Comparative Study)
Comparative Study
The purpose of this study was to investigate the quantity of apical debris produced in vitro using two hand and two rotary instrumentation techniques. Sixty minimally curved, mature human mandibular premolars with single canals were divided into 4 groups of 15 teeth each and prepared using step-back instrumentation with K-files, balanced force with Flex-R files, Lightspeed nickel-titanium instruments, or .04 taper ProFile Series 29 rotary nickel-titanium files. Debris extruded through the apical foramen during instrumentation was collected on preweighed filters. The mean weight of extruded debris for each group was statistically analyzed using a Kruskal Wallis one-way analysis of variance and a Mann-Whitney U rank sum tested. Although all instrumentation techniques produced apically extruded debris, step-back instrumentation produced significantly more debris than the other methods (p < 0.0001). There was no difference between balanced force hand instrumentation and the two rotary nickel-titanium instrumentation methods (p > 0.05). Hand or engine-driven instrumentation that uses rotation seems to reduce significantly the amount of debris extruded apically when compared with a push-pull (filing) technique. Decreased apical extrusion of debris has strong implications for a decreased incidence of postoperative inflammation and pain.
Topics: Bicuspid; Dental Alloys; Dental Leakage; Humans; In Vitro Techniques; Mandible; Nickel; Root Canal Preparation; Titanium; Tooth Apex
PubMed: 9558583
DOI: 10.1016/S0099-2399(98)80179-9