Title: Transcriptional Control
1Transcriptional Control ?? Eukaryotes
2Gene Expression ?? Eukaryotic Cells
- Control ???
- Spatial Temporal regulation
- Transcriptional control ??? DNA
- Alternate splicing ??? RNA
- Cytoplasmic control ??? mRNA stability
- Induction ??? transcriptional activity ???
environment ??? biological factors
3Spatial Temporal Regulation
- Spatial regulation ????????????? genes
???????????????????????????????? ??????????
(tissue-specific expression) gene product
????????????????????????????????????????? - Temporal regulation ????????????? genes
???????????????? ??????????????????
????????????????
4- Transcriptional control ??? DNA RNA polymerase
promoter - Alternate splicing ??? RNA ????????? RNA
??????? (maturation ??? RNA) - Induction ??? transcriptional activity
????????, ???, hormones ???????? genes ???????
??????????????????????? (development)
5Cytoplasmic control ??? mRNA stability
- mRNA ??????????? ????????? transcription
????????????????? - polypeptides ???????????????? gene
??????????????????? - polypeptides ??????????????????????????????????
- ??????? (degradation) mRNA ???????????????????????
genes - mRNA stable ??? Poly-A tail ??? Estrogen
- mRNA ???????????? 3 untranslated sequence AUUUA
????????????
6Transcriptional in Eukaryotes
- Factors ????????
- 1. RNA Polymerases 2. Promoters 3.
Transcription Factors 4. Enhancers - 5. Upstream promoter elements
71. RNA Polymerase
- RNA polymerase ?? Eukaryotic cell ?? 3 types ???
- RNA Pol I ????????????? rRNA precursor (18S
28S 5.8S) - RNA Pol II ????????????? mRNA precursor
- RNA Pol III ????????????? tRAN precursor ???
- 5S rRNA precursor
- RNA polymerase ???? 3 ??????? eukaryote ?????
- s factor
- structure ???????
- ?? promoter ???????
82. Promoter
- Promoter ?????? RNA Polymerase ????????? ???????
??? - Element(s) ???????? ???????????? DNA
?????????????????? RNA polymerase ?????
(recognition site) ????????????????? promoter
???????? control ??????? - ??????? RNA polymerase ??????????? promoter ?????
93. Transcription Factors
- Transcription factor ???? TF ??????????????? RNA
Polymerase ???????????? ???? - TATA-binding protein (TBP)
- TFIIA --gt TFIIH
- ???????? DNA ???
- DNA binding domain ???
- Transcription activation domain
104. Enhancers and Silencers
- ??????????? DNA ??????? stimulate transcription
??? promoter ????????????????? promoter - ??????????????????????????????? DNA (fixed
spatial relationship)????? control genes
????????????????????????? DNA
11Enhancer Silencer
125. Upstream promoter elements
- ???? binding site ?????? transcription factors
??? RNA polymerase II - ?????????????? promoter
13Control ??? RNA Polymerase I?????? rRNA (18 S,
28 S ??? 5.8 S)
- Promoter ???????????? (control element) ???????
2 blocks ??? - 1) Core element (Core)
- position ??????? - 45 ??? 20 ?????? RNA
Polymerase - 2) Upstream control element (UCE)
- position ??????? -156 ??? -107
- ???????? transcription ?????????????
- ???? 2 blocks ?????????? consensus sequence
14RNA Pol I Promoter
- Human rRNA promoter
- RNA Polymerase I ?????? -45 (downstream) ??? 20
(upstream) - TIF-I ?????? -67 (downstream) ??? -14 (upstream)
- ??????? RNA Pol I - TIF-I complex ????? promoter
- sequence ??? -67 ??? 20
15Control ??? RNA Polymerase II
- Promoter ?? control element 2 ??? ??????? genes
- 1. TATA box ???? Hogness box ??? -25
- ?? consensus sequence ??? TATAAAA
- ??????? upstream promoter element 21 bp
- (???? 3 repeats) ??????? -40 ??? -103
- 2. CAAT box
- consensus sequence (GC)CCAATCT ??? -75
16Control Elements ??? RNA Polymerase II Promoter
17- Initiation complex ??? RNA polymerase II
- ??????? TBP ??? TFII A --gt H
18- Enhancer ??? RNA pol II
- Stimulate transcription ??? promoter?????
consensus sequences - ???? tissue-specific ???? mouse immunoglobulin
enhancer ????????? immunoglobulin genes ???????
immune system ??????????????? mouse connective
tissue cell
Enhancer
Closed promoter
19Enhancer
- Enhancer ???? RNA polymerase ???? promoter
??????? transcription
Opened Promoter
20Control ??? RNA Polymerase III
- Promoter ???? Internal promoter
- 5S rRNA gene promoter
- ?? control element upstream ?????????? 55 ???
80 -
- tRNA gene promoter
- ?? 2 blocks ?????? A block ??????? 8 ??? 30
??? - B block ??????? 51 ??? 72
21Posttranscriptional Control ???? RNA Processing
22Posttranscriptional Control in Eukaryote
- RNA ??? ?????????????? nucleus ???????? Primary
transcript - ??????????????????????????????????????
- Primary transcript ???? precursor ??? mRNA
???????? Heterogeneous nuclear RNA (hnRNA)
23Heterogeneous nuclear RNA (hnRNA)
24mRNA Processing
- hnRNA ????????? modified ????????? 3 ???????
??? - 1. Capping
- 2. Tailing
- 3. Intron Splicing
251. Capping
- ???????????????? 5 ??????? Cap ????????
7-methylguanosine - ????????????????? nuclease
- ??? ribosome ?? mRNA ??? ???
- ???????? mRNA ?????? nucleus ?? cytoplasm
- Guanine triphosphonucleotide
- (GTP) ?????? nucleotide ???? 5
- Guanine (G) ??????? CH3(methyl) ??????? N7
??????????
26Capping Methylation
27 Capping Reaction
282. Tailing
- ?????????????? Adenine ??????????????????? 3
end (trailer) ??? hnRNA ???????? Polyadenylation
- ??? poly-A polymerase
- ????? stability ??? transportation RNA ??????
nucleus
29Tailing ??? mRNA
303. Intron splicing
- Primary transcript ??? mRNA, tRNA ??? rRNA
???????????????????????????? ??????? mature RNA
?????????? cytoplasm ??? - ???????? ???? noncoding sequence ???????? Intron
??????????? coding sequences ???????????? Exon
31(No Transcript)
32 33Intron ???????? 4 ?????
- 1. Group I intron intron ?? 5 UA ??? 3
G - nuclear rRNA precursor ??? mitochondrail rRNA
- 2. Group II intron intron ?? 5 G ??? 3
A-Nn-G - mitochondrial mRNA precursor
- 3. Nuclear mRNA intron intron ?? 5 G ??? 3
UACUAAC box (TACTAAC box ?? DNA) - mRNA precursor ?? nucleus ??? eukaryotes
- 4. tRNA intron ??????????????
34Mechanism ??? Splicing
- 1. Self splicing ??? Autocatalytic property of
intron ??? - 1.1 ??????? Guanine-containing nucleotide
- (GMP, GDP, GTP) ???? group I introns
- 1.1 ?????????? Guanine-containing nucleotide
- ???? group II introns
35- 2. Spliceosome ??????? snRNA ??????????????
????? proteins ?????????????? ??????????? small
nuclear ribonucleoproteins (snRNPs) ???? Snurps
???? Spliceosomes ???? mRNA precursor - 3. tRNA precursor splicing ??? Splicing
endonuclease ??? Splicing ligase
36Self-splicing ??? Group I intron??????? Guanine
37Self-splicing ??? Group II intron??????????
Guanine
38Spliceosome??????? Snurps ??? snRNA ?? enzyme
activity (Ribozyme)
39Alternative Splicing ??? mRNAs
- ?????? Introns ???? ??? Exons ???????????? mRNA
precursor - ????????? Splicing site ??? 5 ??? 3 ?? intron
????????????? ????? gene 1 gene ????????? mRNA
??????????? Family ??? mRNAs - ??????? 1 gene ?????? code ??? protein
??????????????????????? ???????????? Protein
Isoforms - ???? Immunoglibulin genes code ??? antibody
????????
40Alternate Splicing
41tRNA Splicing
- Splicing endonuclease ??????????? 2 ???????
intron - Splicing ligase ?????????? 2 exons ???????????
42Reverse Transcription
43Reverse transcription
- ?????????? DNA ?????? RNA ?????????? ???
- ??? RNA-dependent DNA polymerase ????
- Reverse transcriptase (RT)
- DNA ?????????????? Complementary DNA (cDNA)
- RNA tumor virus ????????????????????????? cDNA
???? - ?????????? (integrate) ???? DNA ??? host ???
- cDNA ??????????????????? mRNA ?????????????
- (in vitro)
44Reverse Transcription
45Mechanism ??? Reverse Transcription
46Central Dogma Update
V. 2
V. 1
V. 3
V. 4
(forbidden)