Lect 8 Tissue Architecture

Question 1

Cytoskeletal Filaments

What are the 3 types of filaments?

Answer 1

Intermediate Filaments

Microtubules

Microfilaments

Question 2

Intermediate Filaments

What enables cells to withstand mechanical stress?

Where are they located in cells?

Where are they anchored?

What underlies and strengthens the nuclear envelope?

Answer 2

• Tensile strength (rope like properties)
• Cytoplasm of most animal cells
• Plasma membrane at cell-cell junctions
• Mesh-like structure called nuclear lamina

Question 3

Microtubules

What are they? Why are they important?

What functions does it have in the cell?

Components?

Answer 3

Long and stiff hollow tubes important for organization in all euk cells

Transportation of vesicles, organelles; Form mitotic spindle for chromosome segregation; Part of cilia and flagella

a- & B-tubulins with a plus (+ extend away from centrosome) end and minus (- attach to centrosome) end

Question 4

Microfilaments

What are they composed of?

What are they essential for?

Answer 4

• Actin filaments (F-actin) with structural polarity (+ & - ends)
• Cell movement (Locomotion, phagocytosis, cell division, contraction)

Question 5

Extracellular Matrix and Basal Lamina

ECM Proteins?

Answer 5

• Proteoglycans (cell-cell interactions), Collagens, Laminin & Fibronectin (Basement membrane)

Question 6

Collagen

Main structural protein in ECM/CT and basal laminae is what?

Two main types?

What is the structural formation of collagen?

Answer 6

• Collagen
• Sheet forming (Type IV - Basement membrane) & Fibrillar Collagens (Type I, II, III)
• Trimeric Collagenous Helix

Question 7

Scurvy

Loss of what cofactors?

What enzymes become inhibited?

What are the clinical sx? Why does this occur?

Answer 7

Fe and ascorbate

Prolyl Hydroxylase/Lysyl Hydroxylase

Wounds re-open due to loss of collagen synthesis

Question 8

Ehlers-Danlos Syndrome

Caused by what?

Which Collagens are affected?

Answer 8

Mutation in collagen (AD) or collagen synthesis (AR)

Collagen I, III, V (skin, bones, blood vessels, organs)

Question 9

Cell Connections and Junctions

What are cell junctions?

What are focal contacts?

What do these have roles in?

What are the four types? (CAOS)

Answer 9

Link cells to neighboring cells

Link cells to ECM or Basil Lamina

Migration, Immune system function, Wound healing, Tissue architrecture, Intracellular signaling pathways

Anchoring Junctions; Occluding Junctions; Channel-Forming Junctions; Signal Relaying Junctions

Question 10

Adherin

Adhesion type?

Principal CAMs or Adhesion Receptors?

Attachments?

Role?

Answer 10

Cell-Cell

Cadherins

Catenin binds to Actin

Role in metastasis

Question 11

Desmosomes

Adhesion type?

Attachments?

Role?

Answer 11

Cell-Cell

Bond to intermediate filaments

Role in strength

Question 12

Gap Junctions

Adhesion type?

Principal CAMs or Adhesion Receptors?

Answer 12

Cell-Cell

Connexins

Question 13

Hemidesmosomes

Adhesion type?

Principal CAMs or Adhesion Receptors?

Attachments?

Answer 13

Cell to ECM

Integrin

Attaches to intermediate filaments

Question 14

Focal Adhesion

Adhesion type?

Principal CAMs or Adhesion Receptors?

Attachments?

Role?

Answer 14

Cell to ECM

Integrins

Attaches to Actin filaments

Resisting shear stress

Question 15

Tight Junctions

Adhesion type?

Principal CAMs or Adhesion Receptors?

Attachments?

Role?

Answer 15

Cell-Cell

Occludin & Claudins

Attaches to Actin filaments

Maintains concentration gradient

Question 16

Cell Adhesion Molecules (CAMs)

What are the three major domains and functions?

What are the 4 major families?

Answer 16

• Extracellular
  
  • Binding to adjacent cell/matrix proteins
• Transmembrane
  
  • Links CAM to membrane
• Cytoplasmic
  
  • Bind to cytoskeleton via linker proteins
• Cadherins; Ig Superfamily; Integrins; Selectins

Question 17

Cadherin Superfamily

_ dependent adhesion molecule

Important in formation of what?

Types of Cadherins?

Answer 17

Ca²⁺ dependent adhesion molecule

Junctions between cells (desmosomes and adherens junctions)

E-cadherin (epithelial), N-cadherin (neural), VE-cadherin (vascular-endothelial), LI-cadherin (liver-intestine)

Question 18

EMT & Cadherin Switching

Cadherins serve as biomarkers for what?

What is EMT? What is it used for?

Answer 18

• Invasive, metastatic tumors
• Epithelia to Mesenchymal Transition
  
  • Decreased E-cadherin and increased N-cadherin –> increased invasiveness of tumor cells and metastatic potential

Question 19

Ig Superfamily CAMs

What are they?

What types of interactions?

Answer 19

Calcium-independent transmembrane glycoproteins

Immune cell interactions

Question 20

Selectins

What are they and what do they bind to?

Important roles in what?

Increased presentation during what?

WBC surface marks include what?

Low-affinity of selectins to ligands allows for what?

Answer 20

Calcium dependent glycoproteins that bind to extracellular carbohydrates

Host defense mechanism

Local inflammatory response

CHO which act as ligands for selectins

Leukocyte “rolling” durin leukocyte adhesion cascade

Question 21

Integrins

Couple the _ to the _. Examples?

What can they activate?

Answer 21

• Couple the ECM to cell cytoskeleton
  
  • Fibronectin, Collage, Laminin, Vitronectin
• Signaling Pathways