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Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s Programmes at the University.

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Presentation on theme: "Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s Programmes at the University."— Presentation transcript:

1 Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s Programmes at the University of Pécs and at the University of Debrecen Identification number: TÁMOP /1/A

2 AGING AND GENE EXPRESSION – ALTERATIONS OF THE GENOME DUE TO AGING Krisztián Kvell Molecular and Clinical Basics of Gerontology – Lecture 22 Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s Programmes at the University of Pécs and at the University of Debrecen Identification number: TÁMOP /1/A

3 TÁMOP /1/A TT A G G T G DNA RNA template Telomerase Nucleotides AAU CC C A Telomere sequence and telomerase function

4 TÁMOP /1/A Most favored clock, but cause or marker? Sequence: TTAGGG hexanucleotide > 1000x Polymerase leaves gap with every replication Oxidative stress accelerates telomere loss rate Telomeres as biological clocks

5 TÁMOP /1/A Telomeres form terminal loops for stability Role of TRF2 in telomere stability Issue of telomere length threshold Issue of telomere loss rate vs. stress rate Factors influencing telomere loss rate

6 TÁMOP /1/A Telomere is repetitive DNA sequence Embyonic stem cells Adult Telomere long Telomere short Active telomerase Telomerase inactive or absent AATCCC TTAGGG Changes in telomere length Chromosome Extending the length of a telomere New DNAShort end of DNA GGTT AAUCCCAAUC RNA template TCCCCATACCAA TTAGAGGG Telomerase DNA polymerase

7 TÁMOP /1/A Counteracting (oxidative) stress conditions Telomerase activity increases telomere length ALT: alternative telomere lengthening Slowing, reversing telomere shortening

8 TÁMOP /1/A Telomerase reactivation Further evolution Loss of telomere function Significance of telomere in cancer Telomere lenght Number of aberrations Genome instability Normal tissue HyperplasiaCarcinoma in situ Telomerecrisis Invasive cancer

9 TÁMOP /1/A Soluble factors / cell non- autonomous spreading Pineal clock, role of melatonin Circadian clock mechanisms DNA methylation, acetylation, de- acetylation Further clocks ticking

10 TÁMOP /1/A Werner-syndrome Cockayne syndrome Hutchinson-Guilford progeria Xeroderma pigmentosum Genomic instability in progeria types

11 TÁMOP /1/A Homozygous recessive (skin, cataract, diabetes mellitus osteoporosis) WRN protein (anti-recombinase, helicase, removes recombination and repair intermediates) Defective transcription (50%) Relation with p53 (attenuated apoptosis) Increased telomere loss rate Werner syndrome

12 TÁMOP /1/A Rare segmental progeria (dwarfism, photosensitivity, neurological degeneration etc.) Defect in transcription coupled repair (TCR) Defective 8-oxodG excision (50%) Subtypes: CS-A, CS-B Global genome repair (GGR) is proficient Cockayne syndrome

13 TÁMOP /1/A Lamin A mutation (nuclear envelope fragility) Primerily affects mesenchymal tissues HGPS cells have decreased stress resistence Rapid progeria, premature death Hutchinson-Guilford progeria syndrome

14 TÁMOP /1/A DNA REPAIR (limited synthesis: small fragments) DNA REPAIR (limited synthesis: small fragments) Cell cycle arrest (Apoptosis) Mutations Cancer and genetic diseases Cell cycle arrest (Apoptosis) Mutations Cancer and genetic diseases Replication errors X rays UV light Alkylating agents Spontaneous reactions Reactive oxygen species (ROS) I DNA damage: causes, results I

15 TÁMOP /1/A Oxidative DNA damage > 10,000 DNA lesions / cell / day A variety of DNA damage types (> 50 types) 5 distinctive groups -Oxidized purines -Oxidized pyrimidines -Abasic sites -Single-strand breaks -Double-strand breaks

16 TÁMOP /1/A Stochastic Regulated II DNA damage: causes, results II Mutations, epi-mutations Altered regulatory circuits Dampened GH/IGF axis Cellular responses (apoptosis, senescence) Improved survival Tissue atrophy, lost regeneration Exogenus Metabolism DNA damage Tissue/organ functional decline, degenerative or hyperplastic disease

17 TÁMOP /1/A Base excision repair (BER) is most important, subtypes: AP endonuclease or lyase repair Removal of oxidized purines (two types of lesions: 8-oxodG and formamido-pyrimidines) Removal of oxidized pyrimidines (strong block, strongly cytotoxic) Repair of abasic sites (most frequent) by AP endonucleases I Oxidative DNA damage repair types I

18 TÁMOP /1/A Repair of strand breaks (single- strand breaks occur 10x more frequently than doubles) Limited mitochondrial DNA repair (nuclear encoded proteins of OGG1, POLG) Nucleotide excision repair (NER) that is transcription-coupled repair of active genes II Oxidative DNA damage repair types II

19 TÁMOP /1/A Defect is lethal: APE1, FEN1, POLB, LIG1, LIG3, XRCC1 Defect is viable: OGG1, NTHL1, MYH, ADPRT Severity not tested: NEIL1, 2, 3, TDG, SMUG1, APE2 Genes related to oxidative DNA damage repair

20 TÁMOP /1/A Elevated cancer frequencies Werner syndrome (anti- recombinase) Cockayne syndrome (TCR) XPD and XPA (repair deficiency) Base excision repair (BER) defect is lethal Back-up repair pathways Oxidative DNA damage repair and aging

21 TÁMOP /1/A Depurination and depyrimidination Deamination Single-strand breaks Spontaneous methylation Glycation Cross-linking Non-oxidative DNA damage

22 TÁMOP /1/A Biosynthetic errors Transcriptional errors Translational errors Racemization and isomerization Deamidation (asparagine and glutamine) Reactive carbonyl groups (non- oxidative) Serine dephosphorylation Non-oxidative protein damage


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