Cell Junctions & Adhesion

Question 1

Anchoring cell junctions also known as ___________ __________ (ZA) involves this type of protein, ____________. They bind _______ filaments

Answer 1

Belt Desmosomes
Cadherins
Actin

Question 2

This occluding junction also known as _________ ________ (ZO) involves these 2 types of proteins ________ and ________. They bind to ____filaments.

Answer 2

Tight Junction
Occludins and claudins
Actin

Question 3

Polyuria

Answer 3

Mutations in Claudins 16 and 19 within Tight junctions.
Increased paracellular transport btw tubule cells lead to
High levels of Magnesium and Calcium left in the urine; low levels in the serum (in other words, it’s being excreted at a HIGH rate)
Symptoms: high urine output, high risk for kidney stones

Question 4

This anchoring junction ________ ________ (MA) is at the bottom of the Junctional complex and involves these 2 proteins ________ and _________. They bind to ___________ filaments.

Answer 4

Spot desmosomes,
Desmoplakins and desmogleins; super-cadherins
Intermediate

Question 5

Pemphigus

Answer 5

Blister appears within epidermis layers
Defected spot desmosomes
Etiology: Antibodies destroy desmoglein 1 in (MA), epidermis layers

Question 6

This type of floor anchor __________ uses plaques and involves ___________ filaments and this type of adhesion protein __________.

Answer 6

Hemidesmisomes
Intermediate
Alpha-6-Beta-4

Question 7

Pemphigoid

Answer 7

Defect of hemidesmisomes (basal side)
Blister between epidermis and dermis layers
Etiology: mast cell protease degrade plaque of hemidesmisome

Question 8

This type of floor anchor _______ ______ uses integrins to interact with other proteins and binds __________ filaments.

Answer 8

Focal adhesions
Actin
*It is known for growth and migration of epithelial cells and looks like dark clusters on the basal side.

Question 9

Gap Junctions
(Subunits, function, location, specific mutations)

Answer 9

Clusters of 6 Connexins
Enables quick communication between cells
Especially in cardiac muscle cells of the heart
Connexin 26 mutation - defective cochlea, deafness
Connexin 32 mutation - defective myelin, PNS neuropathies

Question 10

Describe Cadherins Proteins.

Answer 10

These proteins hold epithelial cells together in a sheet arrangement (present in ZA and MA). They are Ca2+ dependent and connected to catenins. Also able to form a cis-homophilic dimers too.

Question 11

Where are these Connexins expressed and what comes about from a mutation in each?
(26 and 32)

Answer 11

26 - expressed in cochlea; mutation leads to deafness

32 - expressed in peripheral myelin; mutation leads to neuropathies of the PNS

Question 12

What are the steps in Leukocyte Extravasation?

Answer 12

1. Rolling Leukocyte SLOWS down by interacting with selectins.
2. Integrins of the WBC are activated when bound to receptors on endothelial cells.
3. Transendothelial migration migrate in btw epithelial cells or barrage right through them using proteases!
4. Slide through using F-actin dynamics initiated by WASP and Arp2/3 complex proteins. Extravasation Complete!
   “Rolling R-I-T-S Crackers!”