Croatia - Basement Membrane Flashcards
Autoimmune disease resulting from autoantibodies against BP230 or BP180?
bullous pemphigoid
T/F: Integrins are transmembrane proteins.
True - connect the extracellular matrix to the cytoskeleton of the cell
What are the anchoring filaments?
connect hemidesmosomes to anchoring fibrils throughout the lamina lucida
Where does collagen XVII attach?
hemidesmosome outer plaque [integrin beta-4, BPAG1-3]
non-collagenous terminus binds to integrin alpha-6
-laminin-5 (Lm3A32) in lamina densa
What is the most important laminin isoform present in the epidermal basement membrane
Laminin-5 (alpha-3/beta-3/gamma-2)
What plakins are found in the cornified envelope?
envoplakin, periplakin
What are intermediate filaments composed of?
keratin-5 and keratin-14
To what does Laminin-5 bind?
Integrin alpha-6/beta-4
Collagen VII
Collagen XVII
Keratin-14 is what type of keratin (type 1 or 2)?
Type 1 = small, acidic
Autoimmune disease resulting from autoantibodies against Collagen VII?
Epidermolysis Bullosa Acquisita
T/F: The lamina lucida is a fixation artefact and does not exist in vivo.
True
Collagen IV makes up what structure of the hemidesmosome?
lamina densa
Mutations in genes that encode for keratin filaments OR plectins can result in what clinical disease?
epidermolysis bullosa simplex
Autoimmune disease resulting from autoantibodies against BP230, BP180 (NC16A), Laminin-5?
Mucous membrane pemphigoid
Mutations in genes for Collagen IV cause what clinical disease(s)?
none recognized in animals
Autoimmune Subepidermal Blistering Disease with Renal Insufficiency (humans) – collagen IV located in glomerulus of kidneys
Genetic disease(s) resulting from dysfunction of Collagen VII?
- Dominant Dystrophic Epidermolysis Bullosa (humans)
- Recessive Dystrophic Epidermolysis Bullosa (humans, white alpine/Assaf sheep, Rotes Hohenvieh/Voderwald cattle, dogs, cats)
Mutations in genes that encode for Integrins or Laminins can result in what clinical disease?
Junctional Epidermolysis Bullosa
What are anchoring FIBRILS?
extend from lamina densa to dermal banded collagen fibers and to rare anchoring plaques, can loop back to the lamina densa
Mutations in the gene for integrin alpha-6/beta-4 can result in what clinical disease (reported in Charolais cattle)?
junctional epidermolysis bullosa
-lack the molecule to anchor the keratin filaments to the basement membrane (integrins)
Autoimmune disease resulting from autoantibodies against Laminin-5?
Acquired Junctional Epidermolysis Bullosa
What is the function of plakins?
they are cytolinkers – link cytoskeletal networks (intermediate filaments, actin, tubulin) to each other and to membrane-associated adhesion structures such as desmosomes and hemidesmosomes
What are the two keratins usually present in the stratum basale keratinocytes?
keratin-5 and keratin-14
What plakins are found in the dermis?
desmoplakin I & II
What is the purpose of intermediate filaments?
maintain the integrity and structure of basal epidermal cells
Keratins always form heterodimers with what two types of keratin?
type 1 = small, acidic
type 2 = large, basic
Autoimmune condition(s) that targets Collagen VII?
*Epidermolysis Bullosa Acquisita
Type I Bullous Systemic Lupus Erythematosus (develop EBA as part of SLE) – reported in humans & 1 dog
What are focal contacts?
inter-hemidesmosomal adhesion structures that mostly functional during wound healing in which epidermal migration occurs
Mutations in Laminin-5 result in what clinical disease(s)?
Junctional Epidermolysis Bullosa – Generalized or Localized–humans, dogs, horses, cattle
_______ are a family of adhesion molecules that usually link the actin cytoskeleton to molecules of the extracellular matrix.
Integrins
What is the outer plaque of the hemidesmosome composed of?
integrin alpha-6/beta-4 + cytoplasmic domain (aminal terminus) of collagen XVII (BPAG2, BP180)
Collagen XVII is also known as what?
BPAG2, BP180
bullous pemphigoid antigen 2– but actually most important in disease
Mutations in the gene that encodes for BPAG1-e/BP230 (DST/BPAG1) can cause what clinical disease(s)?
Bullous Pemphigoid (rare variant) Mucous Membrane Pemphigoid (rare variant)
What are the major components of focal contacts?
on the keratinocyte membrane: -integrin alpha-2/beta-1 -integrin alpha-3/beta-1 -integrin alpha-5/beta-1 on the lamina densa: -laminin isoforms (3A32, 3A11) -collagen XXIII -nidogens -fibulins
What is the inner plaque of the hemidesmosome composed of?
plectin + BPAG1-e
Why is the basement membrane highlighted with PAS stain? (i.e. what molecule is being stained)
sugars in perlecan are being stained
Perlecans link Collagen IV & laminin-alpha chains
What are intermediate filaments?
connect the nuclear membrane to hemidesmosomes on keratinocyte membrane
What are the main epidermal basement membrane collagens?
collagen XVII, IV, and VII
What are the plakins found in the hemidesmosomes?
BPAG1e, epiplakin, plectin I & II
Keratin-5 is what type of keratin (type 1 or 2)?
Type 2 = large, basic
What are the anchoring filaments composed of?
intact and shed extracellular domain (carboxyl terminus) of collagen XVII (BPAG2, BP180)
Autoimmune disease(s) directed against Laminin-5?
Mucous Membrane (cicatricial) Pemphigoid Acquired Junctional Epidermolysis Bullosa
Mutations in KRT5 (gene encoding for keratin-5) can lead to what disease(s)?
Basal epidermolysis bullosa (EB) simplex variants
Autoantibodies against collagen XVII can result in what clinical diseases?
bullous pemphigoid (against NC16A segment) mucous membrane (cicatricial) pemphigoid (against NC16A segment, col15 segment, or carboxyl terminus of collagen XVII) Linear IgA bullous disease
Mutations in the gene that encodes for plectin (PLEC/PLEC1) can cause what clinical disease(s)?
- Epidermolysis Bullosa Simplex and Laminitis (horses)
- Epidermolysis Bullosa Simplex (EBS Plectin) - Eurasier dogs
What are anchoring FIBRILS composed of?
collagen VII
What is the lamina densa composed of?
- collagen IV
- laminin isoforms (laminin-5 [Lm332], -6 [LM311], -10 [Lm511])
- perlecan (heparan-sulfate proteoglycan)
- nidogens
- fibulins
- other components
Integrin alpha-6/beta-4 connects ______ ______ via hemidesmosomes to ______.
intermediate filaments; laminin-5
What are hemidesmosomes?
half-desmosomes situated on the internal aspect of the basal side of stratum basale keratinocytes
-divided into outer & inner plaques
Mutations in genes that encode for Collagen VII can result in what clinical disease?
Dystrophic Epidermolysis Bullosa
What is a collagen domain?
glycine-aminoacid1-aminoacid2 triad
What collagen type is the sole member of the anchoring fibril-forming subfamily?
Collagen VII – anchors hemidesmosomes to dermal collagens
How are keratins formed into intermediate filaments?
two keratins form heterodimers, then two dimers join into tetramers –> tetramers assemble into profilmanets –> protofibrils –> intermediate filaments
Humans and a single case report of a dog with paraneoplastic pemphigus are reported to have auto-antibodies against what molecule?
epiplakin (plakins)