Melanocyte Basic Science Flashcards

1
Q

Where can melanoma and pigmented lesions be detected?

A

Skin hair, the uveal tract of eye (choroid, iris, ciliary body), leptomeninges, and inner ear (striae vascularis of cochlea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In what disease does leptomeningeal melanoma become an important risk?

A

Giant congenital nevus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What produces the KIT ligand?

A

Dermamyotome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What melanomas are c-KIT mutations associated with?

A

Acral, photodamaged, and mucosal melanoma; mastocytosis (HIGH YIELD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main transcription factor involved in melanogensis?

A

MITF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What activiates MITF?

A

KIT ligand, WNT, MSH, ET3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the downstream effects of MITF

A

Melanocyte survival (CDKN2A, CDK2, BCL-2), melanogenesis, melanocyte differentiation, melanocyte proliferation, melanocyte survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Are melanocytes connected via desmosomes to keratinocytes?

A

NO they are “free floating”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the ratio of melanocytes to keratinocytes in the epidermal melanin unit?

A

1 melanocyte in contact with 36 keratinocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is different about the pigment in the epithelium of the retina?

A

Melanocytes don’t act in the same way as other tissues, don’t give melanin in the same way

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What organelle type are melanosomes?

A

Specialized types of lysosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 4 stages of melanosomes?

A

I: spherical, no melanin
II-III: oval + melaning and high tyrosinase activty
IV: oval, heavy melanin depositis, minimal tyrosinase activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 2 types of melanin?

A

Pheomelanin or eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What pigment colors are associated w/ the 2 types of melanin and why?

A
  1. Pheomelanin: yellow to red pigment (mutant MC1R and non-functional)
  2. Eumelanin: brown to black pigment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What acts on MC1R?

A

MSH and ACTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the order of binding for MC1R

A

Msh-alpha, acth>msh beta

17
Q

What is the difference in melanosomes between light skin vs darker skin?

A

Melanosome types (size and transfer). Darker skin has larger melanosomes and individual organelles are transferred vs membrane-bound clusters in lighter skin types

18
Q

Chronic sun exposure results in what changes in melanin?

A

increased melanosome size, augment anterograde transport of melansomes via kinesin activity

19
Q

What protein regulates the survival and migration of melanoblasts and melanocytes during embryogenesis?

A

c-kit

20
Q

What is the mutation involved in piebaldism?

A

Heterozygous germline KIT inactivating mutation

21
Q

What enzymes is melanin production dependent on?

A

Cu-dependent enzyme, tryosinase