Sun-nuclear structures Flashcards
What are the 3 major components of the nucleolus?
- Fibrillar centres
- Dense fibrillar components
- Granular components
What are nucleoli formed around?
Specific genetic loci called nucleolar organising regions (tandem repeats of rRNA genes)
How are rRNA genes transcribed?
As a single unit.
What brings RNA-modifying enzymes to the rRNAs?
Small nucleolar RNAs (snoRNAs)
Name 3 ribosomopathies
- Diamond-Blackfan Anemia
- Dyskeratosis congenita
- Teacher Collins Syndrome
What is c-Myc?
A proto-oncogene which is upregulated in a variety of leukaemias and solid tumours. Increases recruitment of Pol I leading to an increase in rRNA transcription and ribosome biogenesis.
Give 3 sub-nuclear structures with splicing related functions
Nuclear Speckles, Cajal Bodies and Gems
Give a sub-nuclear structure involved in transcriptional repression
PcG Bodies
Give a sub-nuclear structure involved in protein complex assembly
PML bodies
What does the spliceosome consist of?
U1, U2, U4, U5 and U6 small nuclear RNPs (snRNPs) and a large number of proteins
What are cajal bodies?
Contain proteins that participate in the biogenesis of mRNA. Maturation and assembly of the spliceosome sub complexes.
What are nuclear Gems?
Do not contain snRNPs but contain a SMN protein which functions in the biogenesis of snRNPs. Assist CBs.
What is spinal muscular atrophy?
Genetic defect in SMN1 which encodes a major Cb and gem protein. Cell death of neuronal cells and subsequent muscle wasting.
What are nuclear speckles?
Structures enriched in pre-mRNA splicing factors located in the nucleoplasm. Storage and modification compartment for pre-mRNA splicing factors, always close to active genes.
What is retinis pigmentosa?
A genetic eye condition in which the vision progresses from night blindness to tunnel vision to complete blindness. Linked to mutations in splicing factor PRP31.
