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z:Cell 300 > Lecture 13: Polarized cells > Flashcards

Lecture 13: Polarized cells Flashcards

1
Q

epithelial tissue (def.)

A

One of the major tissues types in human body—covers all surfaces…inside and out as well as forming glands (mammary) and organs (liver, lung)

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2
Q

epithelial tissue functions

A

Protection
* Absorption,
* Secretion
* Sensory reception

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3
Q

apical surface of epithelial tissue faces ___

A

outside world

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4
Q

basolateral surface of epithelial tissue faces ___

A

ajacent cells and underlying CT and blood vessels

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5
Q

loss of cell polarity in epithelial tissue lead to ___

A

metastatic phenotype!

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6
Q

Carcinoma (def.)

A

type of cancer that develops from epithelial cells

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7
Q

adenocarcinoma (def.)

A

cancer that forms in the glandular tissue

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8
Q

cancer doesn’t form in ___

A

cells that don’t divide (ex. neuron)

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9
Q

apical and basolateral membrane of epithelial tissue are _____ because ____

A

compositionally distinct because they are separated by tight junctions (creating membrane polarity)

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10
Q

tight junctions do what?

A

restricts movement of macromolecules between cells
allow for directional movement of nutrients

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11
Q

Establishment and maintenance of cell polarity in epithelial tissue involves ____

A

sorting at the TGN to apical/basolateral side

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12
Q

studying epithelial cells requires ____ to identify Apical and Basolateral sorting signals

A

compartmentalized culture system

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13
Q

compartmentalized culture system (descri.)

A

has monolayer of MDCK cells (highly polarized)
apical medium and basal medium
sits porous filter

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14
Q

MDCK cells stands for ____

A

Madin-Darby Canine Kidney epithelial cells

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15
Q

limitations of MDCK cells

A

less dog reagents available

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16
Q

GH is a ___

A

non glycosylated secretory protein (usually)

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17
Q

adding glycosylation sites to GH does what?

A

increase secretion to apical side

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18
Q

blocking glycosylation of GH12 (glycos.) with tunicamycin results in what?

A

non-polarized secretion

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19
Q

apical sorting signals

A

-N or O-linked carbohydrate in ectodomain (membrane protein)
-transmembrane GPI domain (membrane protein)

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20
Q

ectodomain (def.)

A

part of membrane protein that faces extracellular space

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21
Q

mechanism of apical sorting

A

partitioning in glycosphingolipid-cholesterol (lipid rafts) rafts in TGN with TGN-localized lectin as receptors

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22
Q

Apical sorting is a ____ process in TGN which suggest that it uses ___

A

-saturable
-receptors to recruit cargo

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23
Q

Lectins are defined as ____

A

proteins that bind to carbohydrates

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24
Q

Lectin in TGN bind to ____ and partition into ____ for apical sorting

A

oligosaccharides
lipid rafts

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25
Q

other pathway for apical sorting

A

biosynthetic (direct) route- directly from protein production -NSF-independent , SNARES, tethering factors

26
Q

PM is rich in ___ (from TGN)

A

lipid rafts

27
Q

RNAi knockdown of Galectin-3 causes ____

A

apically targeted membrane proteins to be found on basolateral side, suggesting that it is an apical sorting receptor

28
Q

Cation dependent M6P receptor (goes to
_______)

A

basolateral surface/endosomes

29
Q

lysing cells with gentle non-ionic detergent retains ____

A

antibody-protein interactions

30
Q

antibody-protein can be recovered with ___ + detected (radioactive proteins) with ____

A

protein A sepharose
SDS page + autoradiography

31
Q

Basolateral sorting like apical soring is ____

A

saturable (uses receptors)

32
Q

Basolateral sorting signals are found in ____

A

cytoplasmic regions of membrane proteins (need to be exposed to cytoplasm)

33
Q

basolateral sorting motifs are ___ which are similar to ___

A

tyrosine and di-leucine-based motifs
endocytic/lysosomal targeting motifs

34
Q

other route for basolateral sorting

A

biosynthetic (direct) route- directly from protein production -NSF-independent , SNARES, tethering factors

35
Q

AP-1 adaptor protein + basolateral sorting

A

contain µ1B rather than µ1A which is part of “regular” AP1 complex
sorted to basolateral side

36
Q

argeting to apical and basolateral domains requires ____Rabs, SNARES and tethering factors

A

different

37
Q

sorting signal hierarchy

A

Basolateral signals dominant»>Apical sorting occurs in the absence of basolateral sorting signals

38
Q

Caveolae (general def.)

A

invaginations of apical plasma membrane (distinct morphology)

39
Q

Caveolae abundant on ____ and ___ cells

A

-endothelium and smooth muscle

40
Q

Caveolae absent in ___

A

lymphocytes, RBCs

41
Q

Caveolae coating description

A

striated

42
Q

Caveolae are a type of ____ containing the protein ____

A

lipid raft
caveolin

43
Q

lipid rafts are present at ___ and ___

A

PM and TGN

44
Q

lipid raft properties

A

-rich in cholesterol and sphingolipids
-rich in GPI anchored proteins
-thicker regions

45
Q

not all ___ are caveolae but all caveolae are _____

A

lipid rafts

46
Q

_____ can determine lipid raft association

A

Membrane anchoring domains

47
Q

influenza virus and caveolae

A

HA and NA proteins of flu virus concentrate in lipid rafts to bud off, important for virus entry too

48
Q

Caveolin is a ____ that localizes at ___

A
  • 21 kD phosphoprotein
    caveolae
49
Q

forms of caveolin

A

Cav-1,2 - form heterodimers
Cav-3 (present only in muscle cells)

50
Q

expression of which caveolin promotes caveolae formation

A

Cav-1
Cav-3

51
Q

disruption of cholesterol in membranes by this drug prevent caveolae formation?

A

filipin (flattened structures)

52
Q

without ____ in membrane, caveolae can’t form

A

cholesterol

53
Q

how caveolin forms caveolae

A

-caveolin forms hair pin in membrane (N/C termin. in cytoplasm)
-binds cholesterol & sphingolipids
-oligomerizes with 14-16 subunits
-palmitoylated near C-termin.

54
Q

caveolae can form ____ structures

A

interconnected

55
Q

knout out caveolin-1 gene in mice results

A

-no caveolae in vascular endothelial cells
-leaner, resistant to high fat
-more fatty acids in blood serum (enlarged heart)
-insulin resistance
-hypersensitivity to cancer

56
Q

insulin resistance and caveolin-1

A

mutation in caveolin-binding domain of insulin receptor
caveolin stabilizes insulin receptor

57
Q

caveolin and cancer

A

-caveolin-1 might be tumour suppressor
-dominant-negative mutation in gene in some breast cancer

58
Q

are caveolae dynamic + involved in endocytosis?

A

yes

59
Q

caveolae and endocytosis

A

-GTP hydrolysis required
-colocalize with intersectin (scaffolding) and dynamin (fission) at their necks

60
Q

where does intersection and dynamin localize in caveolae

A

-necks of caveolae

61
Q

Labelled _____can be used to follow caveolae-dependent transport

A

CTxB (Cholera toxin b-chain subunit )

62
Q

_____ is required for budding of caveolae from PM

A

dynamin (interconnected structure still forms without dynamin)

z:Cell 300 (17 decks)

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