Epithelium II

Question 1

What is the general blueprint for junctional complexes?

Answer 1

1) Cytoskeletal elements
2) Intracellular anchor proteins
3) Cell adhesion molecules

Question 2

What is the role of claudins?

Answer 2

Required for tight junction formation and function

Question 3

What molecules are required for tight junction formation and function?

Answer 3

Claudins

Question 4

Loss of claudin 9 leads to what condition?

Answer 4

Deafness

Question 5

Loss of claudin 5 leads to what condition?

Answer 5

Breach of blood-brain barrier

Question 6

What does Helicobacter pylori disrupt?

Answer 6

Occludins

Question 7

What are the ZO (zonula occludens) proteins?

Answer 7

Peripheral proteins located on the cytoplasmic side of the plasmalemma that anchor claudins and occludins to actin cytoskeleton

Question 8

What is the function of ZO proteins?

Answer 8

Anchor claudins and occludins to the actin cytoskeleton

Question 9

What are the functions of the zonula occludens (tight junctions)?

Answer 9

1) Selective movement
2) Prevent cell separation
3) Regulate epithelial proliferation
4) Establishing functional polarity

Question 10

What is contained in the zonula adherens (intermediate junctions)?

Answer 10

1) Intracellular anchor proteins (a- and B- catenins, actinin, vinculin) which attach to actin microfilaments
2) Transmembrane adhesion proteins or CAMs (e.g. e-cadherin)
3) Actin microfilaments of zonula adherens form terminal web

Question 11

What is contained in the macula adherens (desmosome)?

Answer 11

1) Intracellular anchor proteins - intermediate filaments attach at these sites
2) Transmembrane adhesion proteins (e.g. cadherins like desmoglein, desmocollin)

Question 12

In pemphigus vulgaris, patients develop antibodies against what protein?

Answer 12

Desmoglein 3 of desmosomes

Question 13

What are the symptoms of pemphigus vulgaris?

Answer 13

Blistering of the skin

Question 14

What is contained in focal adhesions?

Answer 14

1) Intracellular anchor proteins - actin filaments attach to these sites
2) Transmembrane adhesion proteins (integrins) anchor cell to proteins of ECM

Question 15

What is the function of focal adhesions?

Answer 15

Anchors cell to proteins of ECM

Question 16

What is the function of the hemidesmosome?

Answer 16

Anchors basal plasma membrane to underlying basal lamina

Question 17

What is contained in the hemidesmosome?

Answer 17

1) Intracellular anchor proteins - intermediate filaments attach at these sites
2) Transmembrane adhesion proteins (integrin and collagen) interact with ECM of basal lamina

Question 18

In Bullous pemphigoid, autoantibodies develop against what protein?

Answer 18

Type XVII collagen

Question 19

What is a nexus?

Answer 19

Gap junction

Question 20

What is a connexon?

Answer 20

Hollow cylindrical structure formed by six transmembrane proteins called connexins

Question 21

What types of connections are present in a nexus?

Answer 21

Electrical and chemical

Question 22

Where are nexuses (gap junctions) especially numerous?

Answer 22

1) Cardiac muscle
2) Smooth muscle
3) Hepatocytes

Question 23

What is an in situ carcinoma?

Answer 23

A cancer type that has not penetrated through the basal lamina

Question 24

What is the term for a cancer that has not penetrated the basal lamina?

Answer 24

In situ carcinoma

Question 25

What is an invasive carcinoma?

Answer 25

A cancer type that has penetrated through the basal lamina

Question 26

What is the term for a cancer that has penetrated the basal lamina?

Answer 26

Invasive carcinoma

Question 27

Which junctional complex is responsible for the establishment of polarity in the epithelium?

Answer 27

Tight junctions