143 terms

CSB331 - Term Test 1 - True or False

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In epithelial tissues, the actin cytoskeleton is connected to the ECM through integrins
True
The first cell type present in the early embryo is epithelial
True
CPE treatment decreases transepithelial electric impedance (resistance) in MDCK cells.
True
CPE causes collapse of the blastocyst blastocoel cavity
True
The Par complex can bind to claudins through PDZ domain interactions
True
The Par complex localizes to the apicolateral cell junctions in both vertebrates and invertebrates
True
PI3-K and PTEN activities contribute to epithelial cell polarity
True
Adherens junction formation requires participation of the actin cytoskeleton
True
E-cadherin mediates blastocyst compaction
True
Classical cadherins interact only in a homotypical manner
True
Correct localization of occludins by immunohistochemistry doesn't imply tight junction function
True
Paracellular leak decreases exponentially with every additional sealing strand
True
RhoA activity can modify tight junction function to temporarily increase paracellular leakiness
True
Desmosomal junctions can't be formed in the absence of Ca2+
True
Desmosomal interactions are critical for epithelial tissue strength
True
Nectin interactions are higher affinity than classical cadherin interactions
True
Nectin and afadin interact through a PDZ-domain interaction
True
The nectin-afadin system interacts with Par proteins and helps to establish cell polarity
True
Laminin provides a polarization signal to epithelial cells
True
Laminin binds to integrins through its C-terminal large globular (LG) domain
True
Proper laminin assembly in the basal lamina requires participation of the actin cytoskeleton
True
SH2 domains and PTB (phosphotyrosine-binding) domains both bind to phosphotyrosine
True
PDZ domains bind to specific sequences of ~4 amino acids in C-terminal tails of certain transmembrane proteins
True
Integrin specificity for extracellular ligands is conferred by both the α and β chains
True
Formins inhibit actin capping
True
α-actinin cross-links actin arrays in stress fibers
True
Decreasing capping protein activity contributes to formation of filopodia
True
Increased formin nucleation contributes to formation of filopodia
True
β1-integrin can interact with a variety of α-integrin chains
True
Inside-out integrin activation is particularly important for blood cells
True
Integrins are heterodimeric bidirectional force transducers that bind to a variety of extracellular matrix ligands
True
The outer cells differentiate into extraembryonic tissue and deposit a basal lamina
True
Proper basal lamina deposition is dependent on nectin-afadin activities
True
The basal lamina polarizes the inner epiblast cells
True
Cdc42 activates N-WASP
True
RhoA activates formins
True
RhoA activates ROCK
True
Claudins have a C-terminal PDZ-binding tail
True
Cells can express more than one type of claudin and this is often necessary for their proper function
True
Microtubules are physically connected between cells through cell-cell junctions in epithelial tissues
False
In mesenchymal tissue, cell cytoskeletons are the main bearers of mechanical stress
False
Epithelial cells are polarized so that the apical side faces the basal lamin
False
CPE binds to classical cadherins causes their internalization and degradation
False
CPE disrupts mesenchymal cell attachments
False
CPE is responsible for Ca2+ loss in familial hypomagnesia with hypercalcuria and nephrocalcinosis (FHHNC)
False
Cell polarity can't be accomplished in the absence of basal collagen IV deposition
False
The Par complex associates with desmosomal cadherins
False
Trans-interactions between classical cadherins are primarily mediated by the EC-5 domains
False
Adherens junctions can become Ca2+-independent over time
False
Occludins contribute to formation of pores for negatively charged ions
False
If the charges on critical residues in the EL-2 of claudins are balanced they will most likely contribute to an ion-selective pore.
False
Desmosomal cadherins are targeted by CPE
False
In keratinocytes, desmosomal cadherins are important for initial cell contact and binding selectivity
False
Desmosomal cadherin C-terminal tails interact with Par complex proteins
False
The nectin-afadin system interacts with desmosomal cadherins to facilitate assembly
False
Homotypic nectin interactions are responsible for cell sorting behaviour
False
Laminin is important for giving tensile strength to the basal lamina
False
Knockdown of of laminin 5 (α3β3γ2) prevents polarization of embryoid body cells
False
SH3 domains bind to membrane phosphoinositides like PI(3,4,5)P3
False
The intracellular tails of cadherins link covalently to the actin cytoskeleton
False
Formins bind to the sides of pre-existing actin filaments when activated by WASP
False
Capping and severing are rate-limiting steps in lamellipodial actin protrusions
False
RhoA inhibits MLCK (myosin light chain kinase)
False
In outside-in activation, ligand binding stimulates conformational changes that cause the α and β integrin endodomains to bind strongly together
False
The endodomains of the majority of integrin subtypes are indirectly linked to intermediate filaments
False
Embryoid bodies are derived from blastocyst trophectoderm cells
False
Epiblast cells in contact with the basal lamina undergo apoptosis during cavitation
False
Rho family GTPases are activated by GAPs (GTPase Activating Factors)
False
Microinjection of active RhoA into cells produces microspikes (filopodia)
False
Claudins engage in homotypic interactions only
False
Claudins are linked to intermediate filaments through zona occludens (ZO) proteins
False
Claudins are indispensable for imparting resistance to mechanical stress
False
Addition of CPE to the MDCK cell culture results in a total absence of tight-junctions after 8 hours
False
Binding of CPE to claudin-4 is functionally compensated by the presence of claudin-1
False
Hydrolysis of PI 4,5-biphosphate by phospholipase C-β releases diacylglycerol, which diffuses in the cytosol where it binds to protein kinase C
False
PI 4,5-biphosphate is only generated by PI kinase
False
PI 4,5-biphosphate is only found in plasma membranes
False
Calcium ions are required for the dimerization of classical cadherin monomers
False
Disulfide-bridges stabilize homophilic binding between cadherin on adjacent cells
False
At about the 2-cell stage, mouse embryos begin to express E-cadherin
False
The endodomain of desmosomal cadherins bind directly to intermediate filaments
False
Desmosomal cadherins anchor hemidesmosomes to basal laminae
False
β1 integrins bind only collagens
False
Talin unfolding is mediated by the the endodomain of integrin α-chains
False
Integrin-activation on leukocytes is triggered by the binding macrophage-derived chemokines to integrins
False
Binding of α1β2 integrins to I-CAM triggers leukocytes intravasation
False
Sialic acids residues aren't associated with glycolipids
False
Highly sialated forms of N-CAM can promote cell-cell interactions
False
The short form of afadin has no PDZ domain
False
Cis-homodimer to trans-homodimer formation by nectin is calcium-dependent
False
Nectins form both homophilic and heterophilic associations
False
Following bacteria infection, the ectodomain of mucin-1 is cleaved
False
GSK3β blocks binding of PI3K to the endodomain of mucin-1
False
Hydroxylation of proline residues promotes HIF-1α ubiquitination
False
HIF-1α is translocated to the nucleus under normoxia
False
Serum-derived FN is secreted as a monomer
False
Type I and type II fibronectin repeats have no β-strands
False
The Arp2/3 complex stabilizes microfilaments
False
Hydrolysis of ATP by gelsolin enhances actin filament severing
False
Binding of the Arp2/3 complex to FAK inhibits binding of talin to β1 integrins
False
Activation of epidermal growth factor receptor signaling leads to the dissociation of c-Src from FAK
False
FAK activation promotes vinculin association with the FERM domain of FAK
False
Fibrin clots are enriched in cellular fibronectin
False
Granulation tissue isn't vascularized
False
Maximal wound contracture occurs 2 days after injury
False
Electrical resistance is restored 24 hours after CPE is removed from the culture media
True
CPE has no impact on the distribution of claudin-1
True
Claudin turnover at tight junctions occurs within 8 hours
True
PI 4,5-bisphosphate and PI3,4,5-biphosphate are recognized by different PH domains
True
Phosphoinositides are minor components of plasma membranes
True
Cadherin repeats have immunoglobulin-like folds
True
The EC1 domain of classical cadherin promotes homophilic interactions
True
The ectodomain of desmosomal cadherins is structurally similar to classical cadherins
True
Functional specificity is mediated by the endodomain
True
In autoimmune responses against desmoglein-1, the dominant epitope is found within the EC1 module
True
Binding of RGD peptides is an example of "outside-in activation"
True
Laminin integrin epitopes are distinct from collagen integrin epitopes
True
Activated integrins form weak bonds with ECM molecules
True
Rolling of leukocytes is triggered by binding of activated E-selectins to leukocyte sialyl-Lewis sites of infection
True
Extravasation is blocked by antibodies to tight-junction components
True
The transmigration of leukocytes across the endothelial cell basal laminae isn't dependent on matrix remodeling metalloproteinases
True
Integrins can be activated by addition of sialic acid residues
True
Cells with low amounts of sialic acid residues on N-CAM receptors adhere to each other
True
Sialic acid residues bind to some toxins
True
Inhibition of Par3 has no impact on the nectin-afadin complex
True
Nectins play a role in the formation of neural synapses
True
Mucin-1 anchors secreted mucins to epithelial cells
True
Overexpression of mucin-1 promotes cell migration
True
Low levels of mucin-1 promote leukocyte-endothelial cell interactions
True
Inhibition of HIF-1α leads to delayed wound closure scratch assays
True
HIF-1α expression by keratinocytes can only be activated following infiltration of blood vessel to the wound site
True
In scratch wound assays, LN-332 expression is induced by HIF-1α
True
Binding of FN dimers to integrins induces a reorganization of the actin cytoskeleton that promotes actin contractions
True
FN polymers are rendered detergent insoluble by transgluaminase-mediated cross-links
True
FN polymers serve as provisional matrices for the assembly of collagen fibrils
True
α-actinin binds to microfilaments as anti-parallel dimers
True
Fimbrin increases the mechanical strength of filopodia
True
PIP2 promotes the release of capping protein from the barbed-end of microfilaments
True
FAK autophosphorylation increases the number of SH2 binding sites on FAK
True
Under high tension, binding of FN to integrins is synergized by an interaction between the FN-III9 and FN-III10 modules
True
EDA-FN promotes the differentiation of dermal fibroblasts into myofibroblasts
True
Basal laminae and interstitial extracellular matrix remodeling occurs following inflammation
True
SH2, SH3 and PDZ domains all have anti-parallel β-sheets flanked by α-helices
True