Lecture 5 Flashcards
What are the four most common features of the nuclear morphology of cancer cells?
- Nucelar shape and magrin irregularities
- Changes to chromatin compaction/texture
- Altered Nuclei
- Variations ins size within a population (polymorphism)
What are the two main types of chromatin?
Heterochromatin- Highly compacted and generally inactive, found around the egde of the nucleus. Replicated in late S phase
Euchromatin - Less compacted and conatins active genes. Replicated in early S phase
How are chromatin loops formed?
scaffolding/matrix attachment regions (S/MARS)
Create 100kb loops
What makes up the nuclear matrix?
Filamentous and granular network of proteins and RNA
What further level os the nuclear matrix has been hypothesised?
The tissue matrix
The matrix connects cells possibly allowing communication
Molecular machines for what processes assemble on the nuclear matrix?
Transcription, splicing and DNA replication at the bases on chromatin loops
What protein is important for ensuring the correct spatial arrangement of genes in the nuclear matrix during transcription?
SATB1
Where will DNA replication occur?
At one of the immobolised sites on the nuclear matrix, spooling DNA through the machinery
Where are chromosomes found in the interphase nucleus?
As chromatid - but each would be chromatid has its own segregated area. But some do mingle for functional reasons
Outline 3C chromatin conformation capture
- Cross link chromatin with associated proteins
- Digest away any chromatin not crosslinked
- Ligate together ends of chromatin
- Analyse the pieces
What is Hi-C?
Uses sequenced product of 3C and whole genome map to map location of associated protein and chromatin in normal nucleus
What is 4C?
Look at interactions from Hi-C over time
How can mingling between the chromatid cause translocation?
Double strand breaks that occur in areas of mingling may be repaired by fusing chromatid from two different chromosomes together
Outline an example translocation seen due to chromatid mingling
BRC-ABL fusion
BCR gene from chromosome 22 and ABL gene from chromosome 9
Creates a tyrosine kinase which is hyper activated - causing cell growth and proliferation. Seen in chronic myeloid leukemia
What are balanced translocation associted with?
Leukemias and lymphomas - which can be cured by chemotherapy