Intermediate Filaments

Question 1

IF general structure

Answer 1

8 tetramers in 1 ropelike filament, many lateral contacts, subunit assembly doesn’t require ATP or GTP

Question 2

IF Organisation

Answer 2

Nuc to Cell membrane across cytoplasm linking cells together and to ECM. No polarity so no motor function.

Question 3

IF location and role

Answer 3

Role: tensile strength, stretch resistence
Anchoring junctions (desmo and hemides)
Cytoplasmic: Keratins (epi) Vimentin and Vim related (CT, M cells, neuroglia) Neurofilaments
Nuclear: Nuc lamina

Question 4

Describe Keratin IFs

Answer 4

If defective allows disconnect of epi layer from basal lamina

Question 5

Desmin: M IF

Answer 5

Mechanical stress, protective network around each myofibril at Z-disk

Question 6

GFAP

Answer 6

Astrocyte Mechanical strength

Question 7

Lamins

Answer 7

Inner surface of nuc envelope for struc stability of nucleus protecting DNA, anchor for chroms, TFs, nuclear pores

Question 8

Neurofilaments

Answer 8

Axons, NF crosslinking long axon.
NF: tensile str
MT: transport

Question 9

Role of IFs in Detection of Cancer Origin

Answer 9

Tumor cells lose normal appearance but can tell origin by IF expression. Fluorescent antibodies used to determine origin = epi, mesenchymal, neuronal tissue
Metastasis detection

Question 10

Describe Bullosa simplex

Answer 10

Rupture of Keratin IFs connected to Basal Lamina. AD, Keratin 5/14, blisters on BM, fragile skin - minor friction/trauma = blisters

Question 11

Describe Hyperkeratosis

Answer 11

Mut in keratin 1/10, supra basilar differentiation of keratinocytes
Defect weakens structural stability of keratinocytes leading to easy blisters
Chronic wounds = hyperproliferation = thick skin

Question 12

Describe Plantopalmer Keratoderma

Answer 12

K9 defect = only in thick skin