scholarly journals Characterization of functional domains of the tenascin-R (restrictin) polypeptide: cell attachment site, binding with F11, and enhancement of F11-mediated neurite outgrowth by tenascin-R.

1995 ◽  
Vol 130 (2) ◽  
pp. 473-484 ◽  
Author(s):  
U Nörenberg ◽  
M Hubert ◽  
T Brümmendorf ◽  
A Tárnok ◽  
F G Rathjen
Keyword(s):  
Neurite Outgrowth ◽  
Cell Attachment ◽  
Attachment Site ◽  
Direct Interaction ◽  
Bacterial Cells ◽  
Fibronectin Type Iii ◽  
Attachment Region ◽  
A Cell ◽  
Function Relationship

The extracellular matrix glycoprotein tenascin-R (TN-R) is a multidomain protein implicated in neural cell adhesion. To analyze the structure-function relationship of the different domains of TN-R, several recombinant TN-R fragments were expressed in bacterial cells. Two distinct binding regions were localized on the TN-R polypeptide: a region binding the axon-associated immunoglobulin (Ig)-like F11 protein and a cell attachment site. The binding region of the glycosylphosphatidylinositol (GPI)-anchored F11 was allocated to the second and third fibronectin type III (FNIII)-like domain within TN-R. By using a mutant polypeptide of F11 containing only Ig-like domains, a direct interaction between the Ig-like domains of F11 and FNIII-like domains 2-3 of TN-R was demonstrated. The interaction of TN-R with F11 in in vitro cultures enhanced F11-mediated neurite outgrowth, suggesting that the combined action of F11 and TN-R might be of regulatory influence on axon extension. A cell attachment region was identified in the FNIII-like domain eight of TN-R by domain-specific antibodies and fusion constructs. This site is distinct from the F11 binding site within TN-R.

Glycoproteins on the surface of smooth muscle cells involved in their interaction with type V collagen

1985 ◽  
Vol 63 (11) ◽  
pp. 1176-1182 ◽  
Author(s):  
James R. A. Leushner ◽  
M. Daria Haust
Keyword(s):  
Protein Synthesis ◽  
Cyanogen Bromide ◽  
Attachment Site ◽  
Membrane Glycoproteins ◽  
Type V Collagen ◽  
Attachment Region ◽  
A Cell ◽  
Type V ◽  
In Vitro Interaction

Type V collagen is a major component of the pericellular coat of smooth cells (SMC). The purpose of the present study was to assess biochemically the nature of an in vitro interaction between bovine aortic SMC and type V collagen from the same source. This interaction was originally shown to be mediated by a cell-surface glycoconjugate. Data obtained in the present study suggests that the binding system consists of integral membrane glycoproteins which act alone or in combination with a surface glycolipid in type V attachment. The nature of this system was indicated by the finding of 80 000 and 50 000 components in the plasma membrane fractions which were specifically retained by type V collagen – Sepharose columns and incorporated both methionine and mannose label. Moreover, inhibition of protein synthesis lowered SMC attachment by 25%. The mannose label associated with these components was probably in the form of a simple oligosaccharide at the attachment site since it bound to concanavalinA (ConA) and was sensitive to endoglycosidase H. Iodinated ConA labelling indicated elevated levels of these components were associated with SMC – type V collagen interaction. The attachment region on the type V molecule was localized within the cyanogen bromide peptide 6 of the α2 (V) chain.

scholarly journals L-form bacteria, cell walls and the origins of life

Open Biology ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 120143 ◽  
Author(s):  
Jeff Errington
Keyword(s):  
Cell Wall ◽  
Cell Envelope ◽  
Evolutionary Development ◽  
Last Common Ancestor ◽  
Bacterial Cells ◽  
A Cell ◽  
Evolutionary Radiations ◽  
Key Steps ◽  
Bacterial Domain

The peptidoglycan wall is a defining feature of bacterial cells and was probably already present in their last common ancestor. L-forms are bacterial variants that lack a cell wall and divide by a variety of processes involving membrane blebbing, tubulation, vesiculation and fission. Their unusual mode of proliferation provides a model for primitive cells and is reminiscent of recently developed in vitro vesicle reproduction processes. Invention of the cell wall may have underpinned the explosion of bacterial life on the Earth. Later innovations in cell envelope structure, particularly the emergence of the outer membrane of Gram-negative bacteria, possibly in an early endospore former, seem to have spurned further major evolutionary radiations. Comparative studies of bacterial cell envelope structure may help to resolve the early key steps in evolutionary development of the bacterial domain of life.

scholarly journals Structural basis of peptidoglycan endopeptidase regulation

2020 ◽  
Vol 117 (21) ◽  
pp. 11692-11702 ◽  
Author(s):  
Jung-Ho Shin ◽  
Alan G. Sulpizio ◽  
Aaron Kelley ◽  
Laura Alvarez ◽  
Shannon G. Murphy ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Basis ◽  
Bacterial Cells ◽  
Cell Wall Degradation ◽  
Open Conformation ◽  
Poor Understanding ◽  
A Cell ◽  
Inhibitory Domain

Most bacteria surround themselves with a cell wall, a strong meshwork consisting primarily of the polymerized aminosugar peptidoglycan (PG). PG is essential for structural maintenance of bacterial cells, and thus for viability. PG is also constantly synthesized and turned over; the latter process is mediated by PG cleavage enzymes, for example, the endopeptidases (EPs). EPs themselves are essential for growth but also promote lethal cell wall degradation after exposure to antibiotics that inhibit PG synthases (e.g., β-lactams). Thus, EPs are attractive targets for novel antibiotics and their adjuvants. However, we have a poor understanding of how these enzymes are regulated in vivo, depriving us of novel pathways for the development of such antibiotics. Here, we have solved crystal structures of the LysM/M23 family peptidase ShyA, the primary EP of the cholera pathogenVibrio cholerae. Our data suggest that ShyA assumes two drastically different conformations: a more open form that allows for substrate binding and a closed form, which we predicted to be catalytically inactive. Mutations expected to promote the open conformation caused enhanced activity in vitro and in vivo, and these results were recapitulated in EPs from the divergent pathogensNeisseria gonorrheaeandEscherichia coli. Our results suggest that LysM/M23 EPs are regulated via release of the inhibitory Domain 1 from the M23 active site, likely through conformational rearrangement in vivo.

scholarly journals Actin polymerization downstream of integrins: signaling pathways and mechanotransduction

2020 ◽  
Vol 477 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Stéphane Romero ◽  
Christophe Le Clainche ◽  
Alexis M. Gautreau
Keyword(s):  
Actin Cytoskeleton ◽  
Signaling Pathways ◽  
Actin Polymerization ◽  
Cell Attachment ◽  
Direct Interaction ◽  
Directed Migration ◽  
A Cell ◽  
Migration Of Cells ◽  
Intense Research ◽  
Surrounding Extracellular Matrix

A cell constantly adapts to its environment. Cell decisions to survive, to proliferate or to migrate are dictated not only by soluble growth factors, but also through the direct interaction of the cell with the surrounding extracellular matrix (ECM). Integrins and their connections to the actin cytoskeleton are crucial for monitoring cell attachment and the physical properties of the substratum. Cell adhesion dynamics are modulated in complex ways by the polymerization of branched and linear actin arrays, which in turn reinforce ECM-cytoskeleton connection. This review describes the major actin regulators, Ena/VASP proteins, formins and Arp2/3 complexes, in the context of signaling pathways downstream of integrins. We focus on the specific signaling pathways that transduce the rigidity of the substrate and which control durotaxis, i.e. directed migration of cells towards increased ECM rigidity. By doing so, we highlight several recent findings on mechanotransduction and put them into a broad integrative perspective that is the result of decades of intense research on the actin cytoskeleton and its regulation.

scholarly journals Dissection of Complex Molecular Interactions of Neurofascin with Axonin-1, F11, and Tenascin-R, Which Promote Attachment and Neurite Formation of Tectal Cells

1998 ◽  
Vol 142 (4) ◽  
pp. 1083-1093 ◽  
Author(s):  
Hansjürgen Volkmer ◽  
Ute Zacharias ◽  
Ursel Nörenberg ◽  
Fritz G. Rathjen
Keyword(s):  
Alternative Splicing ◽  
Neurite Outgrowth ◽  
Molecular Interactions ◽  
Cell Attachment ◽  
Binding Assays ◽  
Ig Superfamily ◽  
Competition Binding ◽  
Neurite Formation ◽  
Additional Protein

Neurofascin is a member of the L1 subgroup of the Ig superfamily that promotes axon outgrowth by interactions with neuronal NgCAM-related cell adhesion molecule (NrCAM). We used a combination of cellular binding assays and neurite outgrowth experiments to investigate mechanisms that might modulate the interactions of neurofascin. In addition to NrCAM, we here demonstrate that neurofascin also binds to the extracellular matrix glycoprotein tenascin-R (TN-R) and to the Ig superfamily members axonin-1 and F11. Isoforms of neurofascin that are generated by alternative splicing show different preferences in ligand binding. While interactions of neurofascin with F11 are only slightly modulated, binding to axonin-1 and TN-R is strongly regulated by alternatively spliced stretches located in the NH2-terminal half, and by the proline-alanine-threonine-rich segment. In vitro neurite outgrowth and cell attachment assays on a neurofascin-Fc substrate reveal a shift of cellular receptor usage from NrCAM to axonin-1, F11, and at least one additional protein in the presence of TN-R, presumably due to competition of the neurofascin– NrCAM interaction. Thereby, F11 binds to TN-R of the neurofascin/TN-R complex, but not to neurofascin, whereas axonin-1 is not able to bind directly to the neurofascin/TN-R complex as shown by competition binding assays. In conclusion, these investigations indicate that the molecular interactions of neurofascin are regulated at different levels, including alternative splicing and by the presence of interacting proteins.

scholarly journals Umbilical mesenchymal stem cell-derived exosomes facilitate spinal cord functional recovery through the miR-199a-3p/145-5p-mediated NGF/TrkA signaling pathway in rats

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yang Wang ◽  
Xunwei Lai ◽  
Depeng Wu ◽  
Bin Liu ◽  
Nanxiang Wang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neurite Outgrowth ◽  
Signaling Pathway ◽  
Direct Interaction ◽  
Lesion Size ◽  
Human Umbilical Cord ◽  
Cord Injury ◽  
Direct Target

Abstract Background Although exosomes, as byproducts of human umbilical cord mesenchymal stem cells (hUC-MSCs), have been demonstrated to be an effective therapy for traumatic spinal cord injury (SCI), their mechanism of action remains unclear. Methods We designed and performed this study to determine whether exosomes attenuate the lesion size of SCI by ameliorating neuronal injury induced by a secondary inflammatory storm and promoting neurite outgrowth. We determined the absolute levels of all exosomal miRNAs and investigated the potential mechanisms of action of miR-199a-3p/145-5p in inducing neurite outgrowth in vivo and in vitro. Results miR-199a-3p/145-5p, which are relatively highly expressed miRNAs in exosomes, promoted PC12 cell differentiation suppressed by lipopolysaccharide (LPS) in vitro through modulation of the NGF/TrkA pathway. We also demonstrated that Cblb was a direct target of miR-199a-3p and that Cbl was a direct target of miR-145-5p. Cblb and Cbl gene knockdown resulted in significantly decreased TrkA ubiquitination levels, subsequently activating the NGF/TrkA downstream pathways Akt and Erk. Conversely, overexpression of Cblb and Cbl was associated with significantly increased TrkA ubiquitination level, subsequently inactivating the NGF/TrkA downstream pathways Akt and Erk. Western blot and coimmunoprecipitation assays confirmed the direct interaction between TrkA and Cblb and TrkA and Cbl. In an in vivo experiment, exosomal miR-199a-3p/145-5p was found to upregulate TrkA expression at the lesion site and also promote locomotor function in SCI rats. Conclusions In summary, our study showed that exosomes transferring miR-199a-3p/145-5p into neurons in SCI rats affected TrkA ubiquitination and promoted the NGF/TrkA signaling pathway, indicating that hUC-MSC-derived exosomes may be a promising treatment strategy for SCI.

scholarly journals Functional analyses of thymic CD5+ B cells. Responsiveness to major histocompatibility complex class II-restricted T blasts but not to lipopolysaccharide or anti-IgM plus interleukin 4.

1990 ◽  
Vol 171 (1) ◽  
pp. 321-326 ◽  
Author(s):  
M Inaba ◽  
K Inaba ◽  
Y Adachi ◽  
K Nango ◽  
H Ogata ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Antibody Formation ◽  
Direct Interaction ◽  
Interleukin 4 ◽  
In Vitro Assays ◽  
B Cell Growth Factor ◽  
A Cell ◽  
Functional Analyses

The function of thymic B cells in several standard in vitro assays was investigated. Thymic B cells, 75% of which were CD5+, showed a poor responsiveness to the mitogens LPS or anti-mu plus IL-4. Both proliferation and antibody formation were much lower in thymic than splenic B cell cultures. However, CD5- B cells purified using a cell sorter responded well to B cell stimulants, whereas purified CD5+ thymic B cells did not, indicating that CD5+ thymic B cells were unresponsive to B cell growth factor or LPS. Thymic B cells could be activated polyclonally by direct interaction with alloreactive T blasts, as manifested by DNA synthesis and antibody formation. These findings indicate that CD5+ thymic B cells may not be stimulated via sIg and IL-4, but require instead direct interaction with T blasts.

scholarly journals The fourth immunoglobulin-like domain of NCAM contains a carbohydrate recognition domain for oligomannosidic glycans implicated in association with L1 and neurite outgrowth.

1993 ◽  
Vol 121 (6) ◽  
pp. 1409-1421 ◽  
Author(s):  
R Horstkorte ◽  
M Schachner ◽  
J P Magyar ◽  
T Vorherr ◽  
B Schmitz
Keyword(s):  
Cell Surface ◽  
Neurite Outgrowth ◽  
Adhesion Molecules ◽  
Consensus Sequence ◽  
Carbohydrate Recognition ◽  
Cell Biol ◽  
Carbohydrate Recognition Domains ◽  
Fibronectin Type Iii ◽  
Fibronectin Type

We have previously shown that the neural adhesion molecules L1 and NCAM interact with each other to form a complex which binds more avidly to L1 than L1 to L1 alone (Kadmon, G., A. Kowitz, P. Altevogt, and M. Schachner. 1990a. J. Cell Biol. 110:193-208). This cis-association between L1 and NCAM is carbohydrate-dependent (Kadmon, G., A. Kowitz, P. Altevogt, and M. Schachner. 1990b. J. Cell Biol. 110:209-218). In the present study, we report that L1 and NCAM bind to each other via oligomannosidic carbohydrates expressed by L1, but not by NCAM, as shown in several experiments: (a) complex formation between L1 and NCAM is inhibited by a mAb to oligomannosidic carbohydrates and by the oligosaccharides themselves; (b) NCAM binds to oligomannosidic carbohydrates; (c) within the L1/NCAM complex, the oligomannosidic carbohydrates are hidden from accessibility to a mAb against oligomannosidic carbohydrates; (d) the recombinant protein fragment of NCAM containing the immunoglobulin-like domains and not the fragment containing the fibronectin type III homologous repeats binds to oligomannosidic glycans. Furthermore, the fourth immunoglobulin-like domain of NCAM shows sequence homology with carbohydrate recognition domains of animal C-type lectins and, surprisingly, also with plant lectins. A peptide comprising part of the C-type lectin consensus sequence in the fourth immunoglobulin-like domain of NCAM interferes with the association between L1 and NCAM. The functional importance of oligomannosidic glycans at the cell surface was shown for neurite outgrowth in vitro. When neurons from early postnatal mouse cerebellum were maintained on laminin or poly-L-lysine, neurite outgrowth was inhibited by oligomannosidic glycans, by glycopeptides, glycoproteins, or neoglycolipids containing oligomannosidic glycans, but not by nonrelated oligosaccharides or oligosaccharide derivates. Neurite outgrowth was also inhibited by the peptide comprising part of the C-type lectin consensus sequence in the fourth immunoglobulin-like domain of NCAM. The combined results suggest that carbohydrate-mediated cis-associations between adhesion molecules at the cell surface modulate their functional properties.

In Vitro Cytotoxic Evaluation of Processed Natural Coral in Human Osteoblasts

2011 ◽  
Vol 30 (4) ◽  
pp. 443-451 ◽  
Author(s):  
Nor Shamsuria Omar ◽  
Thirumulu Ponnuraj Kannan ◽  
Abdul Rashid Ismail ◽  
Siti Fadilah Abdullah ◽  
Abdul Rani Samsudin ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Attachment ◽  
Neutral Red ◽  
Cytotoxic Effects ◽  
Human Osteoblasts ◽  
A Cell ◽  
Diphenyl Tetrazolium Bromide ◽  
Fcm Analysis ◽  
Natural Coral

This study aimed to evaluate the in vitro cytotoxic effects of locally produced processed natural coral (PNC) using human osteoblasts (HOS). Cytotoxicity was not observed when HOS cells were cultured with PNC, as assessed by (3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyl tetrazolium bromide; MTT) and Neutral Red (NR) assays at concentration up 200 mg/mL for up to 72 hours. Flow cytometry (FCM) analysis showed that PNC (200 mg/mL) did not decrease viability of HOS cells after 48 and 72 hours of treatment. In a cell attachment study, the HOS cells attached to the edge of the PNC disc, and later grew into the pores of the PNC disc. All results from these studies indicate that locally produced PNC material is noncytotoxic and favors the growth of HOS cells.

scholarly journals The Xer activation factor of TLCΦ expands the possibilities for Xer recombination

2021 ◽  
Author(s):  
Solange Miele ◽  
Justine Vergne ◽  
Christophe Possoz ◽  
Françoise Ochsenbein ◽  
François-Xavier Barre
Keyword(s):  
Attachment Site ◽  
Tyrosine Recombinases ◽  
Resolution System ◽  
Activation Factor ◽  
Bacterial Chromosomes ◽  
A Cell ◽  
Synaptic Complexes ◽  
Recombination Reactions

ABSTRACTMany mobile elements take advantage of the highly-conserved chromosome dimer resolution system of bacteria, Xer. They participate in the transmission of antibiotic resistance and pathogenicity determinants. In particular, the toxin-linked cryptic satellite phage (TLCΦ) plays an essential role in the continuous emergence of new toxigenic clones of the Vibrio cholerae strain at the origin of the ongoing 7th cholera pandemic. The Xer machinery is composed of two chromosomally-encoded tyrosine recombinases, XerC and XerD. They resolve chromosome dimers by adding a crossover between sister copies of a specific 28 base pair site of bacterial chromosomes, dif. The activity of XerD depends on a direct contact with a cell division protein, FtsK, which spatially and temporally constrains the process. TLCΦ encodes for a XerD-activation factor (XafT), which drives the integration of the phage into the dif site of the primary chromosome of V. cholerae independently of FtsK. However, XerD does not bind to the attachment site (attP) of TLCΦ, which raised questions on the integration process. Here, we compared the integration efficiency of thousands of synthetic mini-TLCΦ plasmids harbouring different attP sites and assessed their stability in vivo. In addition, we compared the efficiency with which XafT and the XerD activation domain of FtsK drive recombination reactions in vitro. Taken together, our results suggest that XafT promotes the formation of synaptic complexes between canonical Xer recombination sites and imperfect sites.

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