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Yr 2 - IBMS > Proteopathic Diseases and Amelogenesis Imperfecta > Flashcards

Proteopathic Diseases and Amelogenesis Imperfecta Flashcards

1
Q

Define Proteopathy

A

a class of diseases where proteins become structurally abnormal and disrupt the functions of cells, tissues and organs of the body

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2
Q

What happens if the Proteins Mutate and Misfold?

A
  • become toxic and lose normal function
  • accumulate in the cell
  • damage the tissues
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3
Q

How does Amelogenesis Happen?

A
  • mutation on the amelogenin gene = Y64H
  • leads to dysfunctional protein
  • aggregation of the protein
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4
Q

What are the Secretory Cells of the Enamel?

A

ameloblasts

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5
Q

How are Ameloblasts formed? 2 Paths

A
  • gene transcribed onto mRNA
    TWO PATHS:

1) attach onto free ribosome in the cytoplasm
- protein constructed and used with the cells

2) attach onto fixed ribosome on the RER
- protein folds into 3D shape
- modified and package into vesicles
- transport to golgi apparatus
- enzymes modify protein and glycoprotein
- released into the extraceullar environment

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6
Q

What are Multiple Vesicles Called?

A

Cistamae

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7
Q

What are the 3 Different Types of Vesicles?

A

Lysosome - digestive enzymes
Secretory - empty products outside cell by exocytosis
Membrane - add new lipids and proteins to plasma membrane

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8
Q

What are the Two Different Pathways which Proteins Translocate to the Endoplasmic Reticulum

A

Co-translational translocation
Post-translational translocation

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9
Q

Describe Co-translational translocation

A
  • during translation
  • ribosome attaches onto the ER
  • protein is inserted into the ER membrane
  • protein gets translated
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10
Q

Describe Post-translational translocation

A
  • after translation
  • signal sequence
  • protein is released from the ribosome
  • protein is inserted and translocated into the rough endoplasmic reticulum
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11
Q

What does a Polypeptide Chain Develop into?

A

3D structure
- either alpha helices or beta pleated sheets

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12
Q

3 Descriptions of the Folding of Protiens

A

randomised
occurs in an aqueous solution
depends on the side chains

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13
Q

What is an Important Protein which Reduces the Error of Misfolding?

A

chaperone = BiP

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14
Q

2 Ways in Which Disrupted Protein Folding can Occur.

A

Mutation
Faulty Phosphorylated Modification

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15
Q

How can a Misfolded Protein lead to Disease? (5)

A
  • accumulates
  • forms inclusion bodies, fibres
  • ER stress
  • tissue dysfunction
  • disease
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16
Q

What happens when you get ER Stress?

A

= unfolded protein response

  • cell activates complementary adaptive mechanisms
  • eliminates damaged cells by apoptosis
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17
Q

Why don’t we Constantly get ER Stress?

A

UPR - unfolded protein response
- identifies the faulty proteins

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18
Q

What is the Mechanism of UPR?

A

to produce transcription regulatory proteins such as BIP
- receive signal to be induced from transmembrane sensors

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19
Q

How does BIP Help Fold Proteins Correctly?

A
  • regulate transmembrane sensors in the ER membrane and on the cytoplasmic side
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20
Q

Give 3 Transmembrane Sensors, which BIP regulates

A

IRE1, PERK and ATF6

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21
Q

How does BIP Regulate IRE1

A
  • two protein kinases phosphorylate due to misfolded protein
  • induces ribonuclease domain
    = splice a specific mRNA
  • activates specific transcription regulatory proteins
22
Q

How does BIP Regulate PERK

A
  • two protein kinases phosphorylate due to misfolded protein
  • activates translation initiation factors
  • forms specific transcription factors - increase genes for folding
23
Q

What is the Role of Translation Initiation Factors in PERK?

A
  • reduce synthetic rate of protein translocation
  • less ER stress
24
Q

How does BIP Regulate ATF6?

A
  • ATF6 moves to golgi apparatus
  • proteolytic cleavage of the cytosolic domain
  • activates genes specific to UPR
  • reduce ER stress
25
Q

3 Things Which can Happen After UPR.

A

ERAD - protein degradation
CHOP - apoptosis
genes activate to increase protein folding capacity

26
Q

What is the Prevalence of AI?

A

1/700-1400

27
Q

Define Genesis Imperfecta, where does it originate

A

a group of developmental conditions in the genome.

28
Q

Clinical Phenotypes of AI

A
  • hypoplastic enamel - thin or absent
  • hypomaturation - name is normal thickness but white surface - mistaken for fluorosis
  • hypermineralized
29
Q

When do you know you have AI?

A

when teeth are erupted

30
Q

Symptoms and Treatment of AI.

A
  • sensitivity
  • discolouration
  • prone to disintegration
  • can only be managed
31
Q

Describe the 5 Stages of Enamel Formation

A

Presecretory

Secretory - 30% mineral
- initial mineral and matrix
- complete when full thickness of tissue is layed
- ameloblasts = tall, columnar, densely packed, 7mm height

Transition
- at or during amelogenin secretion

Early Maturation - 40% mineral

Maturation - 90% mineral
- final matrix removal
- final mineral content acquired
- ameloblasts = shorted to half and nucleus at centre
- final mineralisation is considered complete post-eruption

32
Q

What do we use to Study AI?

A

mice showing enamel defects

33
Q

How do we study AI? What is the Project.

A

Mutagenesis Project
- induce the mutation in male rodent using chemical ‘N-Ethyl-N-Nitrosourea’ (ENU)
- cross bred with healthy mice
- search for abnormalities

34
Q

What is the Allele for the Phenotype known as?

A

wild-type

35
Q

Define Monophyodont

A

having one set of teeth - lab mice

36
Q

Describe the Enamel of Mice.

A

single crystal of hydroxyapatite
- rods within are rhombohedral, 25-50nm
- 10^4 Bundle into larger nanorods

inner enamel - nanorods are arranged in intersecting sections

outer enamel - nanorods are parallel
= makes the edge of enamel detachable and sharp
= resistant to acid wear

37
Q

In Mice’s genes, where is the Amelogenin allele?

A

on the X chromosome
women = XX
men = XY

38
Q

What is the Amelogenin Mutation?

A

Y64H

39
Q

In Humans Genes, where is the Amelogenin allele?

A

on X and Y
women = XX
men = XY

40
Q

Which gene produces Amelogenin?

A

Amex

41
Q

Define Homozygous.

A

having two identical alleles of the gene

42
Q

Define Heterozygous.

A

having two different alleles of a gene

43
Q

How does Enamel Differ in Beavers?

A

more iron, more strength

44
Q

How do Mutations Affect the Stages of Enamel?

A

Secretory and Maturation
- more secondary ameloblasts

Transition and Maturation
- ameloblast contact with enamel matrix is occasionally lost = blister like structure

45
Q

What is the Effect of Mutation on the Enamel?

A
  • tomes process is absent
    = disorganised vascular pattern
  • loss of normal ER and golgi structures
  • nuclei of ameloblasts become distorted
46
Q

How can you Measure if Mutant Amelogenins are being Secreted?

A

Western Blotting Analysis

47
Q

Describe Western Blotting Analysis

A
  • detect a specific protein
  • using gel electrophoresis to separate
48
Q

When Mutant Amelogenin Accumulates in the ER, does it cause ER Stress and Activation of UPR?

A
  • evidence needs to be found
  • perform in-situ-hybridization and quantitive real time PCR
49
Q

Does ER stress Lead to AI?

A

Yes

50
Q

What can be used to Manage ER Stress when it leads to AI?

A

4-phenylbuturate - used for urea cycle disorders
- shows improvement in incisors and recovery of enamel

Yr 2 - IBMS (21 decks)

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