Week 4 Basal and Lateral Domain of Epithelium Module

Question 1

how many types of epithelial junctions are there? where are they located?

Answer 1

5 total. 4 in lateral domain. 1 in basal domain

Question 2

what are the two general roles of epithelial junctions

Answer 2

cellular adhesion, cellular communication

Question 3

what are the 4 major families of cell adhesion molecules (CAMs)

Answer 3

cadherins, integrins, immunoglobulin super family, selectins

Question 4

which CAMs are responsible for epithelial cell jxns?

Answer 4

cadherins and integrins

Question 5

which CAMs play a role in inflammation?

Answer 5

IGSF and selectins

Question 6

what is the general structure of cadherins and integrins

Answer 6

transmembrane proteins with extracellular binding domains

Question 7

Cadherin: type seen in epithelial cell? Calcium? Interactions in the intracellular domain? role?cancer?

Answer 7

E- cadherin seen in epithelial cells Ca dependent extracelular domain (CA dependent ADHERINs) associated with catenins that link the adherin to the actin cytoskeleton important in cell-cell connections; cell recognition, tumor suppresssion cancer cells lose cadherin molecules and are able to metastasize

Question 8

Intergrins: strucutre? Calcium? role 3?

Answer 8

heterodimer: alpha and beta chains calcium independent cell-cell, cell-ECM binding, facilitates cell movement in ECM

Question 9

what are the four types of cell jxns found in the lateral domain of epithelial cells?

Answer 9

zonula occludens (tight jxn), zonula adherens (intermediate jxns), macula adherens (desmosomes), gap jxn

Question 10

what is the general location of zona occludens?

Answer 10

this is the most apical jxn

Question 11

what is the general location of zona adherens

Answer 11

just beneath the Zona occludens

Question 12

where are macula adherens found on the lateral domain of epithelial cells?

Answer 12

erratically. desmosomes are sometimes termed “spot welds”. below zona adherens (more towards basal surface)

Question 13

what is the role of gap junctions?

Answer 13

permit direct passage of signaling molecules from one cell to another

Question 14

what is the role of Zonula occludens?

Answer 14

tight jxns. forms a barrier that prevents paracellular transport (transport between cells). separates apical domain from the basal and lateral domain

Question 15

what are two proteins associated with zonula occludens?

Answer 15

occludin and claudin

Question 16

what is the function of zonula adherens?

Answer 16

intermediate junctions. anchor cells to each other through actin filaments within the cell attached to cadherin and catenins

Question 17

what is the funciton of macula adherens?

Answer 17

desmosomes: spot welds between epithelial cells that resist shear force.

Question 18

what proteins are associated with macula adherens? 4

Answer 18

desmoglein, desmocolin (cadherin), desmoplakin, plakoglobin

Question 19

given the fxn of macula adherins, where would we expect to see them in the most abundance?

Answer 19

stratified squamous epithelium (skin’s epidermis) where cells must resist a lot of friction

Question 20

gap junctions are made of ____ which form____

Answer 20

connexin which forms connexon

Question 21

what is the overall function of the basal domain

Answer 21

anchors epithelium to the Basement membrane

Question 22

what are the two regions of the basement membrane

Answer 22

basal lamina (more superficial; interfaces with connective tissue and epithelial cells) and reticular lamina (more deep)

Question 23

what is the clinical significance of the basal lamina

Answer 23

penetration of the basal lamina indiacates a tumor is undergoing malignant progression and is capable of metastasis

Question 24

what is the role of focal adhesions? 2

Answer 24

link network of cytoplasmic actin filaments to basal lamina proteins (attach cell to ECM), signal transduction from ECM to cell

Question 25

focal adhesions are made of ____ and bind to ___3__ in the basal lamina

Answer 25

integrins. fibronectin, collagen, laminin

Question 26

what is the role of hemidesmosomes?

Answer 26

anchor the basal plasma membrane to the basal lamina

Question 27

what are the 2 important structures you should associate with hemidesmosomes

Answer 27

BP230, basement membrane

Question 28

Pemphigus vulgaris: what type of jxn is affected? how? which domains are lost? where/what type of blister?

Answer 28

desmosomes are lost: cell attachement to each other are lost, but basal domain remains. body creates antibodies against desmogleins 1 and 3. flaccid blisters occur in the epidermis

Question 29

what is Nikolsky’s sign?

Answer 29

a test where a pencil eraser is twirled on the skin, if a blister develops it is a postive test for a blistering skin condition

Question 30

Bulous Pemphigoid: what type of jxn affected? how? which domains are lost? what type of blister?

Answer 30

body produces antibodies against BP230 and destroy hemidesmosomes. cells lose basal domain connection but keep lateral domain. tense blister

Question 31

Blisters: what are they, where do they form? what types?

Answer 31

Clear area filled with leukocytes and fibrin, form between intact epidermis and the dermis. Flaccid=easy to rupture, Tense=difficult to rupture

Question 32

what causes dystrophic epidermolysis bullosa? why is this a problem?

Answer 32

inherited defect in collagen VII. collagen VII plays a role in holding the BM to the underlying connective tissue. epidermis with attached BM comes off surface. Epidermis+BM shears right off (loss of dermal-epidermal jxn).

Question 33

does dystrophic epidermolysis bullosa impact anything other than skin? why?

Answer 33

yes. Collagen VII is important in stratified squamous epithelium which is also seen in the esophagus.

Question 34

Answer 34

Dystrophic Epidermolysis Bullosa

Question 35

Answer 35

Bullous Pemphigoid

Question 36

Answer 36

Pemphigus Vulgaris