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Telomere shortening and associated diseases
- shortened telomeres due to exhaustive replicative capacity inflammatory cytokines and growth factors cause activation of nearby cells --> interferes with normal tissue function
- Result in shortened telomeres
- responsible for:
- 1. Dyskeratosis congenita
- 2. Idiopathic Pulmonary Fibrosis
- 3. Cancers
- Inherited X-linked disease, rare disease (1 in 1mil), death at 16 median age
- Causes of death are bone marrow failure, pulmonary disease and cancer
- Dyskerin: involved in making ribosomes and pre-mRNA splicing, along with other protein formation. Patients with mutation in dyskerin or other associated proteins may have reduced TERC levels. Mutation in TERT also in DKC
- These mutations in TERT or TERC genes result in shorter telomere lengths.
Idiopathic Pulmonary Fibrosis
- fatal lung disease
- Diagnosis age 50, lifespan of 2-4 years after diagnosis
- TERT and TERC mutations (ie, nucleotide deletions to make frameshifts and truncated proteins) associated w/IPF
- these mutations cause shorter telomere lengths of circulating WHITE BLOOD CELLS
- each round of cell division results in DECREASED telomeres
- stem cells proliferate and telomerase shortening occurs, but the premature exhaustion of these stem cells leads to pulmonary fibrosis or other diseases (DKC), bone marrow failure
- Mutations in Cell cycle checkbone genes (ie p53) growth of cells continues and telomeres continue to shorten until they cannot protect chromosome ends.
- This can lead to cancer
- results in loss of telomeric DNA and apoptosis
- telomere dysfunction 1st promotes chromosomal instability that drives early carcinogenesis