cell adhesion

Question 1

What is the primary role of cellular adhesion in multicellular organisms?

Answer 1

Cellular adhesion allows cells to attach to each other and the ECM, forming tissues and maintaining structural integrity

Question 2

Provide examples of stable and transient cellular adhesions

Answer 2

Stable: Muscle-tendon connections, skin epithelial cells.
Transient: Leukocyte-endothelial interactions, cell-ECM binding during migration.

Question 3

What are the main types of cell junctions?

Answer 3

Adherens junctions, desmosomes, tight junctions, gap junctions, and cell-matrix adhesions

Question 4

What is the function of tight junctions?

Answer 4

They seal gaps between epithelial cells to regulate impermeability or selective permeability.

Question 5

name the tight junctions

Answer 5

Claudin and occluding

Question 6

How do gap junctions facilitate intercellular communication?

Answer 6

By allowing passage of small molecules and ions, enabling signal transduction

Question 7

What type of adhesion do cadherins mediate?

Answer 7

calcium dependent homophilic adhesion

Question 8

How are cadherins linked to the cytoskeleton?

Answer 8

through canteinins that attach to vinculin

Question 9

Why are cadherin-mediated adhesions strong despite low individual affinity?

Answer 9

multiple cadherins interactions combine

Question 10

What is a key feature of the immunoglobulin superfamily of adhesion molecules?

Answer 10

They mediate Ca²⁺-independent adhesion and can be homophilic or heterophilic.

Question 11

What role do immunoglobulin family molecules play in immune responses?

Answer 11

They are critical for antigen recognition, such as T-cell receptors binding antigens.

Question 12

What do selectins bind to?

Answer 12

Carbohydrates on glycoproteins (e.g., mucins)

Question 13

How do selectins assist in immune responses?

Answer 13

They enable transient adhesion of leukocytes to endothelial cells, facilitating leukocyte rolling and migration.

Question 14

What is the primary function of integrins?

Answer 14

mediate cell-ECM adhesion and signal transduction

Question 15

Describe the outside-in activation pathways of integrins

Answer 15

Ligand binding induces conformational change, exposing cytoskeletal binding sites.

Question 16

Describe the inside-out activation pathways of integrins

Answer 16

Intracellular signals activate integrins, increasing ligand affinity.

Question 17

What specialized integrin is involved in hemidesmosome attachment?

Answer 17

a6B4 links epithelial cells to laminin in the basement membrane

Question 18

What is the role of desmosomes?

Answer 18

They link intermediate filaments between adjacent cells , providing mechanical strength to tissues like the skin and heart.

Question 19

name the anchoring proteins involved in desmosomes

Answer 19

desmoplankin
plankofilin
plankoglobin

Question 20

name the cadherin family adhesion proteins used in desmosome adhesion

Answer 20

desmoglein
desmocollin

Question 21

What is the difference between focal adhesions and podosomes?

Answer 21

Focal adhesions are found in many cell types, while podosomes are restricted to specialized hematopoietic cells.

Question 22

How are selectins regulated during inflammation?

Answer 22

Inflammatory mediators (e.g., TNFα, thrombin) upregulate E-selectin and P-selectin to promote leukocyte adhesion and platelet aggregation.

Question 23

What diseases are linked to defects in adhesion molecules?

Answer 23

Cadherin dysregulation in cancer metastasis, and integrin mutations in skin and muscle disorders.

Question 24

How do integrins contribute to cell migration?

Answer 24

focal adhesions are dynamic and allow for cell migration

Question 25

What roles do adhesion molecules play in neutrophil recruitment?

Answer 25

Selectins enable rolling adhesion, while integrins mediate tight binding and migration into tissues.

Question 26

what are sydnecans

Answer 26

proteoglycans that bind proteins to ECM