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PubMed2002

[Effects of Notch and its ligands on the differentiation of 32D cell].

OBJECTIVE: To explore the mechanism of Notch signaling transduction system and its effects on hematopoietic system. METHODS: Notch ligands transfected CHO cells were added into Notch1 and Notch2 transfected CHO cells, which were transiently transfected with reporter gene TP1. PGL-100 was used as substrate to test the interaction between Notch and Notch ligands. CHO, Jagged2-CHO and Delta 4-CHO cells were seeded in the petri dish containing G-CSF, and then Notch 1-32D cells were added in it to observe the differentiation of Notch1-32D cell after incubation and staining. RESULTS: All of the five Notch ligands binding to Notch1 could induce TP1 activity, it increased significantly the Jagged2-CHO, Delta 4-CHO1-4 and Delta 4-CHO1-5 cells. For Notch2, the TP1 activity induced by the five ligands in these cells was much higher than that of CHO. At the presence of G-CSF, Notch1-32D could differentiate to mature granulocyte. Jagged2 could inhibit G-CSF induced Notch1-32D cell differentiation, but Delta 4 could not. CONCLUSION: Jagged2 and Delta 4 are the ligands of Notch1. Jagged2 can inhibit G-CSF induced Notch1-32D cell differentiation, but Delta 4 can not.

Animals↗
PubMed2003

Notch activity is required to maintain floorplate identity and to control neurogenesis in the chick hindbrain and spinal cord.

Notch signalling plays a major role in many invertebrate and vertebrate patterning systems. In this paper, we use high-titre, non-replicative pseudotype viruses to show that the two Notch ligands, Delta1 and Serrate1 (Jagged1), have differing activities in the developing chick spinal cord and hindbrain. In the walls of the neural tube, Serrate1 appears not to affect neurogenesis, in contrast to Delta1 which mediates lateral inhibition as elsewhere in the nervous system. In the floorplate we find that there is also a requirement for Notch, but with a different type of dependence on the two Notch ligands: cells with a floorplate character are lost when Notch activity is blocked with dominant-negative, truncated forms of either Delta1 or Serrate1. Our results are consistent with ligand-receptor specificity within the Notch signalling pathway, Serrate1 recognising selectively Notch2 (which is expressed in the floorplate), and Delta1 acting on both Notch2 and Notch1 (which is expressed in the walls of the neural tube).

Animals↗
PubMed2004

The Notch ligand, Delta-1, partially inhibits GM-CSF-induced differentiation and apoptosis along with reducing the cleavage of PARP in U937 cells.

Notch signaling plays an important role in the regulation of self-renewal and differentiation of hematopoietic cells. Human monoblastic U937 cells undergo differentiation into macrophage-like cells, growth suppression, and apoptosis following stimulation with GM-CSF. We examined the effects of Notch activation induced by Notch ligands on GM-CSF-induced differentiation and apoptosis in U937 cells. Furthermore, the molecular mechanism of the effects was investigated. A recombinant Notch ligand, Delta-1 protein did not affect the growth of U937 cells by itself. GM-CSF-induced growth suppression and apoptosis of U937 cells were partially rescued by incubation with Delta-1. Delta-1 also reduced the GM-CSF-induced differentiation. Incubation with Delta-1 did not affect the expression of GM-CSF receptor. GM-CSF stimulation induced the phosphorylation of ERK1/2 and STAT5 and the cleavage of caspase-8, which were not affected by Delta-1 incubation, either. GM-CSF stimulation induced the cleavage of PARP, which is the key molecule for differentiation and apoptosis. We found that incubation with Delta-1 significantly suppressed the GM-CSF-induced cleavage of PARP. Taken together, we found that Notch activation induced by Delta-1 partially inhibited GM-CSF-induced differentiation, growth suppression, and apoptosis, along with reducing the GM-CSF-induced cleavage of PARP. These findings suggest one of the mechanisms by which Notch activation inhibits differentiation and apoptosis.

Apoptosis↗
PubMed2004

Cellular analysis of growth suppression induced by the Notch ligands, Delta-1 and Jagged-1 in two myeloid leukemia cell lines.

It is known that Notch activation promotes the self-renewal of hematopoietic cells. However, we have previously found that the growth of a myeloid leukemia cell line, OCI/AML-6, was suppressed by Notch activation induced by stimulation with a recombinant Notch ligand, Delta-1 protein. We recently found that the growth of another leukemia cell line, THP-1, was also suppressed by the ligands Delta-1 and Jagged-1. In this study, we tried to clarify the cellular and molecular mechanism of the growth suppression induced by Notch activation. Flow cytometric analysis showed that Delta-1 stimulation increased the expression of differentiation markers such as CD11b and CD13 while it decreased the expression of CD117 (c-KIT), a marker for primitive cells in THP-1 cells. In OCI/AML-6 cells, Delta-1 stimulation decreased the expression of CD11b and CD14 and increased CD34 expression. Namely, Delta-1 showed the opposite effects on the differentiation markers of each cell line. Delta-1 stimulation did not increase the binding of annexin V, a marker for apoptotic cells in either cell line. Since the growth of myeloid cells is regulated by MAP kinase and JAK/STAT pathways, we investigated the effects of the ligand stimulation on these pathways. Delta-1 stimulation did not induce the phosphorylation of ERK1/2 and STAT3 proteins in either cell line. Pre-exposure to Delta-1 did not affect the phosphorylation of ERK1/2 and STAT3 induced by G-CSF in OCI/AML-6 cells, either. Namely, it is thought that these pathways are not involved in the growth suppression caused by Notch ligands. Our study revealed several findings on Notch function. However, the precise mechanism remains to be elucidated.

Annexin A5↗
PubMed2004

Axoglial interaction via the notch receptor in oligodendrocyte differentiation.

INTRODUCTION: Increasing evidence has revealed that the Notch signalling pathway is one of the pivotal systems that mediate oligodendrocyte development. The Notch receptor is a type I transmembrane molecule that represents a novel cellular signalling paradigm, namely, regulated intramembrane proteolysis (RIP). METHOD: The typical Notch ligands, such as Delta, Serrate/Jagged and Lag2 (DSL), promote the formation of oligodendocyte precursor cells (OPCs) and maintain them in an uncommitted stage, thus retarding oligodendrocyte appearance in the central nervous system (CNS). RESULTS: In contrast, our recent studies have revealed that F3/contactin, a GPI-linked neural adhesion molecule, interacts with Notch and speeds up the generation and maturation of oligodendrocytes. CONCLUSIONS: Considering the distinct, albeit somewhat overlapping expression patterns of F3 and DSL in the CNS, the Notch receptor appears to function ligand-dependently during oligodendrocyte development. This multipotentiality may well designate the Notch receptor as one of the therapeutic targets that one can manoeuvre to treat demyelinating diseases, such as multiple sclerosis, that is characterised by chronic myelin degeneration.

Animals↗
PubMed1990

The Notch gene, adhesion, and developmental fate in the Drosophila embryo.

The Notch locus in Drosophila encodes a transmembrane protein required for the determination of cell fate in ectodermal cells. When these cells are faced with a choice of two possible fates, Notch enables some of them to advance from the fate that represents a "default" state. The decision appears to involve both an interaction between cells and the presence of the Notch product on the surface of those advancing from the default state. The timing of gene action suggests that Notch plays a role in the stabilization of the choice of cell fate and that the Notch-mediated interaction occurs between presumptive epidermal cells. Several properties of the Notch product are characteristic of an adhesion molecule, and thus cell adhesion may play a role in the determination of cell fate.

Animals↗
PubMed1996

Isolation of a novel chick homolog of Serrate and its coexpression with C-Notch-1 in chick development.

Intercellular signaling mediated by the transmembrane proteins, Notch as receptor and its ligands, Delta and Serrate, plays essential roles in the developmental fate decision of many cell types in Drosophila. The Notch genes are highly conserved both in invertebrates and in vertebrates, suggesting that Notch pathway regulates cell fate decisions during vertebrates development. Notch, Delta and Serrate homologs in chicken have been cloned (Henrique et al., Nature 375: 787-790, 1995; Myat et al., Dev. Biol. 174: 233-247, 1996). We isolated a novel chick homolog of Drosophila Serrate, named C-Serrate-2, and examined its expression patterns during the early chick development using whole-mount in situ hybridization. C-Serrate-2 transcripts were detected in several tissues including the forebrain, the myotome and the apical ectodermal ridge (AER) of the limb bud of a 4-day-old chick embryo. In most of the regions where C-Serrate-2 was expressed, C-Notch-1 was also expressed. Our observations suggest that Serrate-2-Notch-1 signaling plays a role in a variety of morphogeneses during the chick development.

Amino Acid Sequence↗
PubMed2000

Notch-1 activation by familial Alzheimer's disease (FAD)-linked mutant forms of presenilin-1.

We prepared a cleavage site-directed antibody against Notch-1, that specifically recognized the cleaved Notch-1 intracellular domain (NICD). To assess Notch-1 processing and its nuclear localization in familial Alzheimer's disease (FAD)-linked presenilin-1 (PS-1) mutants, we overexpressed wild type, M146V, A246E, C410Y, or deltaE9 PS-1 mutant with a membrane-bound Notch-1 in a PS-1-deficient cell line. On Western blot and immunocytochemical analyses using the NICD specific antibody, M146V and A246E mutants showed the comparable levels of Notch-1 processing and nuclear localizing activities to wild type PS-1 whereas C410Y and deltaE9 mutants failed to show these activities. These results suggest that the loss or partial loss of PS-1 activities in Notch-1 proteolysis and its nuclear translocation may be irrelevant for the neuropathology of Alzheimer's disease.

3T3 Cells↗
PubMed1989

Appearance of a labial notch in maxillary incisors: a population survey.

A labiogingival notch appearing on the enamel of maxillary central incisors seems to be a potential factor for compromised gingival and dental health. The objective of the survey was to describe the phenomenon and its prevalence in a random Israeli population. One thousand eight hundred eighty children with fully erupted permanent incisors were clinically examined. The appearance of the labiogingival notch on the enamel surface of the maxillary central incisors was determined. Two depth categories of the phenomenon were distinguished by probing. The possible differences in the prevalence of the labial notch appearance, between the sexes as well as between the right and left sides, were statistically evaluated. The prevalence between the right and left sides, were statistically evaluated. The prevalence of the labial notch on at least one incisor in the population examined was 6.5% (5.1% unilaterally and 1.4% bilaterally). No significant difference between the sexes regarding the appearance of this phenomenon was found. The shallow notch was similarly distributed between the right and left sides in both sexes. However, the deeper malformations appeared significantly more on the left side in boys (P less than 0.05) and in girls (P less than 0.01). The gingivae tended to follow the enamel contour; however, only in few cases was gingival inflammation or incipient caries diagnosed. It was concluded that the labio-gingival notch is not a rare phenomenon, and it should be given special attention to prevent possible damage to the dental and gingival tissues.

Anthropology, Physical↗
PubMed2004

Notch signaling can regulate endoderm formation in zebrafish.

Early in vertebrate development, the processes of gastrulation lead to the formation of the three germ layers: ectoderm, mesoderm, and endoderm. The mechanisms leading to the segregation of the endoderm and mesoderm are not well understood. In mid-blastula stage zebrafish embryos, single marginal cells can give rise to both endoderm and mesoderm (reviewed by Warga and Stainier [2002] The guts of endoderm formation. In: Solnica-Krezel L, editor. Pattern formation in zebrafish. Berlin: Springer-Verlag. p 28-47). By the late blastula stage, however, single marginal cells generally give rise to either endoderm or mesoderm. To investigate this segregation of the blastoderm into cells with either endodermal or mesodermal fates, we analyzed the role of Notch signaling in this process. We show that deltaC, deltaD, and notch1 are expressed in the marginal domain of blastula stage embryos and that this expression is dependent on Nodal signaling. Activation of Notch signaling from an early stage leads to a reduction of endodermal cells, as assessed by sox17 and foxA2 expression. We further find that this reduction in endoderm formation by the activation of Notch signaling is preceded by a reduction in the expression of bonnie and clyde (bon) and faust/gata5, two genes necessary for endoderm formation (Reiter et al. [1999] Genes Dev 13:2983-2995; Reiter et al. [2001] Development 128:125-135; Kikuchi et al. [2001] Genes Dev 14:1279-1289). However, activation of Notch signaling in bon mutant embryos leads to a further reduction in endodermal cells, also arguing for a bon-independent role for Notch signaling in endoderm formation. Altogether, these results suggest that Notch signaling plays a role in the formation of the endoderm, possibly in its segregation from the mesoderm.

Animals↗
PubMed2006

Effect of valine on the efficiency and precision at S4 cleavage of the Notch-1 transmembrane domain.

Presenilin-dependent intramembranous proteolysis mediates the dual cleavage of the Notch-1 protein (S4 and S3) as well as the beta amyloid precursor protein (betaAPP) (gamma40 and epsilon-site). betaAPP has a valine residue just before the gamma40 (amyloid beta [Abeta] numbering) site and after the epsilon-site. Both gamma40 and epsilon have multiple cleavage sites, and the varieties of gamma40 cleavage are associated with Alzheimer's disease (AD). These lines of evidence suggest that valine plays a role in the intramembranous proteolysis. S4 cleavage in the middle of the Notch-1 transmembrane domain (TMD) corresponds to the gamma40 cleavage of betaAPP. The cleavage site is in the center of four sequential alanine residues between Ala1731 and Ala1732, neither of which has a valine residue. To investigate the effects of valine on presenilin-dependent intramembranous proteolysis, we replaced the transmembrane domain residue of Notch-1 with valine and analyzed the efficiency and precision at S4 and S3. We observed that all valine-mutated Notch-1 proteins have a dominant cleavage site (S4) between Ala1731 and Ala1732 with some variations of cleavage precision, suggesting that valine is not indispensable for determining the cleavage site of the Notch-1 transmembrane domain, but affects the efficiency and precision at S4 cleavage of the Notch-1 transmembrane domain.

Amino Acid Sequence↗
PubMed1995

An innovative dicrotic notch detection algorithm which combines rule-based logic with digital signal processing techniques.

Automated, real-time localization of the dicrotic notch, a component of the arterial pressure waveform, represents a deceptively complex problem in computerized biomedical signal processing. The high-frequency nature of the notch can make it difficult to distinguish from artifactual noise or from other high-frequency physiological components of the waveform. In addition, the contour of the notch varies with vascular status and with propagation through arterial beds, requiring any detection algorithm to recognize various possible notch conformations. Finally, location of the notch along the waveform may vary widely depending on other hemodynamic variables, further complicating detection algorithms. We have reviewed various published algorithms and have implemented a number of them to determine the strengths and shortcomings of each. We then developed a reliable and accurate hybrid algorithm which utilizes the strengths of the various algorithmic approaches reviewed; after analyzing the waveform, the algorithm selects the most appropriate method for accurate notch localization based on a series of waveform features. The application of rule-based logic represents a relatively unique approach to digital signal processing.

Algorithms↗
PubMed1988

Amino acid compositions of different protein fractions in developing grains of NP 113 barley and its high lysine Notch-2 mutant.

The percent distributions of protein fractions namely albumin + globulin, prolamine and glutelin were studied in developing grains of NP 113 barley and its high lysine mutant Notch-2. During development the percentage of albumin + globulin fraction decreased in NP 113, while those of prolamine and glutelin remained unchanged. The increase in prolamine was substantial from 24 to 31DAA. In Notch-2 the trend followed by albumin + globulin and prolamine was like that in NP 113, while the glutelin fraction showed an increase as compared to 10 DAA. The percent of albumin + globulin was slightly higher in Notch-2 as compared to NP 113. The absolute amount (mg/grain) of all the protein fractions increased during development in both NP 113 and its mutant Notch-2. During the grain development the prolamine content was substantially lower in the mutant than in the parent NP 113. The albumin + globulin content per endosperm was in general also higher in NP 113 than Notch-2. Amino acid analysis of the protein fractions did not reveal significant changes in lysine between NP 113 and Notch-2. Thus, the improvement in lysine in the mutant is primarily due to reduced synthesis of the prolamine fraction and not due to an increase in lysine in the mutant hordein fraction. Part of the improvement in lysine may also be due to increase in the percentage of albumin + globulin fractions which is lysine rich.

Amino Acids↗
PubMed1998

Relation between dicrotic notch and mean pulmonary artery pressure studied by using a Swan-Ganz catheter in critically ill patients.

OBJECTIVE: It has been recently shown that there is a match between dicrotic notch and mean pulmonary artery (PA) pressures in spontaneously breathing patients studied by means of high-fidelity pressure catheters. The aim of the study was to analyze the relation between mean PA pressure and PA pressure at the incisura by using a Swan-Ganz catheter in critically ill, mechanically ventilated patients. MEASUREMENTS AND RESULTS: Fluid-filled PA pressures were obtained over four ventilatory cycles in 32 consecutive, mechanically ventilated patients in the intensive care unit. We measured mean PA pressure and dicrotic notch pressure. We also calculated the widely used approximation of mean PA pressure (mean PAPapprox = diastolic + 1/3 pulse pressure). Cardiac output was measured in triplicate by using the thermodilution technique. Dicrotic notch was clearly identified in 30 of 32 patients. Mean PA pressure (32.1 +/- 10.2 mm Hg) and PA dicrotic notch pressure (31.8 +/- 10.4 mm Hg) were linearly related (r = 0.989, p < 0.001). Agreement between dicrotic notch and mean PA pressures was suggested (mean difference +/- SD = -0.3 +/- 1.5 mm Hg). Similar agreement was found between mean PAPapprox and mean PA pressure (mean difference +/- SD = -0.7 +/- 0.8 mm Hg; p = 0.20). CONCLUSION: By using a Swan-Ganz catheter we found that dicrotic notch pressure equalled mean PA pressure in the critically ill, mechanically ventilated patients studied. This indicated that right-sided ejection was completed at a PA pressure equal to mean PA pressure in these patients.

Aged↗
PubMed1997

Distal fibular notch: a frequent manifestation of the rheumatoid ankle.

OBJECTIVE: To describe the distal fibular notch, an infrequently described manifestation of rheumatoid arthritis, and to speculate on its etiology through gross dissection, histologic correlation and MR imaging. DESIGN AND PATIENTS: One hundred and twenty-one conventional ankle radiographs were obtained and reviewed in 76 patients with clinically diagnosed rheumatoid arthritis. Additional imaging of three ankles was obtained utilizing CT and MR imaging. In addition to evaluating erosive changes, note was made of the presence and location of a well-defined scalloped defect along the medial border of the distal fibula. Ankle specimen dissection and histoanatomic examination was performed in an attempt to determine the exact pathogenesis of this fibular notch. RESULTS: The distal fibular notch was identified in 52 of 121 ankles (43%). Seventy-five percent of notches were syndesmotic and extended down to the horizontal ankle joint level, while 25% of notches were syndesmotic with extension below the joint. The majority of ankles (79%) demonstrated coexistent marginal erosions and/or joint narrowing. Ankle specimen dissection revealed a single-celled synovial fold within the distal tibiofibular syndesmotic recess without underlying articular cartilage extension. CONCLUSION: The fibular notch within the distal tibiofibular syndesmosis is a frequent manifestation of rheumatoid arthritis and appears to result from synovial proliferation rather than from mechanical instability.

Adult↗
PubMed2006

A modeling study of notch noise responses of type III units in the gerbil dorsal cochlear nucleus.

A computational model of the neural circuitry of the gerbil dorsal cochlear nucleus (DCN), based on the MacGregor's neuromime model, was used to simulate type III unit (P-cell) responses to notch noise stimuli. The DCN patch model is based on a previous computational model of the cat DCN [Hancock, K. E., and H. F. Voigt. Ann. Biomed. Eng. 27:73-87, 1999]. According to the experimental study of Parsons et al. [Ann. Biomed. Eng. 29:887-896, 2001], the responses of gerbil DCN type III units to notch noise stimuli are similar to those of cat DCN type IV units, which are thought to be spectral notch detectors. This suggests that type III units in the gerbil DCN may serve as spectral notch detectors. In this modeling study, a simplified notch noise response plot-spike discharge rate vs. notch cutoff frequency plot-was used to compare model responses to the experimental results. Parameter estimation and sensitivity analysis of three connection parameters within the DCN patch have been studied and shows the model is robust, providing reasonable fits to the experimental data from 14 of 15 type III units examined [work supported by a grant from NIDCD, Boston University's Biomedical Engineering department and Hearing Research Center].

Animals↗
PubMed2006

A modeling study of notch noise responses of type III units in the gerbil dorsal cochlear nucleus.

A computational model of the neural circuitry of the gerbil dorsal cochlear nucleus (DCN), based on the MacGregor's neuromime model, was used to simulate type III unit (P-cell) responses to notch noise stimuli. The DCN patch model is based on a previous computational model of the cat DCN [Hancock, K. E., and H. F. Voigt. Ann. Biomed. Eng. 27:73-87, 1999]. According to the experimental study of Parsons et al. [Ann. Biomed. Eng. 29:887-896, 2001], the responses of gerbil DCN type III units to notch noise stimuli are similar to those of cat DCN type IV units, which are thought to be spectral notch detectors. This suggests that type III units in the gerbil DCN may serve as spectral notch detectors. In this modeling study, a simplified notch noise response plot--spike discharge rate vs. notch cutoff frequency plot--was used to compare model responses to the experimental results. Parameter estimation and sensitivity analysis of three connection parameters within the DCN patch have been studied and shows the model is robust, providing reasonable fits to the experimental data from 14 of 15 type III units examined.

Acoustic Stimulation↗
PubMed2006

Notching of the anterior femoral cortex during total knee arthroplasty characteristics that increase local stresses.

Notching of the anterior femoral cortex during primary total knee arthroplasty can occur when making an anterior femoral bone cut. To examine the increased stress caused by a notch, we used a validated 3-dimensional finite element model of the femur under gait loads. Three factors that affected the stress concentration were identified: First, larger notches associated with increased stress concentrations. Second, sharper notches led to increased local stresses. Third, the proximity of the notch to the prostheses affected the stress concentration. In summary, anterior femoral notches greater than 3 mm with sharp corners located directly at the proximal end of the prosthesis produced the highest stress concentrations and may lead to a significant risk of periprosthetic fracture.

Arthroplasty, Replacement, Knee↗