esone1 introne1 esone2 introne2 esone3

esone1

esone1

introne1

esone2

esone2

introne2

esone3

esone3

SPLICING

eliminazione introni

unione esoni

GT GTAG AG

Alcuni modo di fare alternative splicing

Riconoscimento degli introni

Motivi conservati

Meccanismo dello splicing

- SnRNPs (Small nuclear ribonuclear proteins) binds critical sites on the pre-mRNA

- pronounced ‘SNURPs’

- these are complexes containing both protein and small RNAs

- the small RNAs are transcribed by RNA polymerase III

- they then associate with accessory proteins

- the complex then recognizes critical sites for splicing by base pairing

Particelle dello splicing

Particelle che intervengono nello splicing

U1 snRNP

Intron definition exon definition

Modello di exonic splicing enhancer mediato da proteine SR

Modello di exonic splicing silencer

Modelli di splicing silencing

Nell’esone si trovano motivi ESE e ESS sovrapposti, quindi c’è una competizione diretta tra i fattori che stimolano lo splicing (SR) e quelli che lo inibiscono (hnRNP). Il legame di uno o dell’altro elemento è mutuamente esclusivo. A questo punto i fattori importanti diventano la maggiore affinità di legame degli elementi regolativi e la concentrazione di questi.

Modelli di splicing silencing

Fattore inibitori per lo splicing si legano a elementi Intronic Splicing Silencer e per dimerizzazione formano un anello che esclude l’esone

Modelli di splicing silencing

Se non ci sono elementi inibitori l’esone viene incluso, se ci sono elementi inibitori e se questi si legano per primi, promuovono il legame di altri elementi inibitori (polimerizzazione) od ostacolano il legame di elementi rafforzativi

Nonsense mediated decay

Why Splicing?1. The intron-exon arrangement may facilitate the evolution of new proteins through recombination of exons.

2. Splicing increases the coding potential of the genome through alternative splicing.60% of transcripts in human are spliced in different ways.

Cell-type spcific splicing of fibronectin pre-mRNA

attggaaaccgaaacccgttggtcacctctgcaatagccctccctccctcacttctacaattttgtgacagtggtcttgttttctgcattctctgcttcacgtgcttgttttgttggagcgcgtttgcatgctgctttaaattctgaaatattaaaaaaatttcgaagtttttcagcacatgggatgggagttttgaatttcaattttttaaaaacatttttctgtgattagtgccgtcgtggcacggctgttagccgcctatccggtttattcgatactttGTGAGTTTTTTGTAACTTTATGGTCGTCGAAATGGGAAAACTTGGCCACCAATATAAGTTTGGAAAACAATTTCCTAAAAATAAAATAATTGAACTTTTCCGATGAATAAAAAAATCGATCAGATATTCTGGAAAAAAAATCGATAAATTAATCGATTTTCTTGGAAAATACATCGAAAAATTGAGAAAAATAGAAAAATGAATGTTTTTCGATTACCGATTTATTGATTTTTCGTGAAAACTGAGTTCAGATAATTTTAAAAGCAATGTTTTTCATTTTTCAAATCAGAATCACTATAGTTTTGAAAAATCAATAATTAATTTATTGATTTTTCAATATAATTTTTTGGAAAAAATAGAAAAATCCCTTTCTAAAAGTTTTAAATTTCCAAGAAAAATTCATTTTCAAAATCACCAACGCGCTCTATAGAGTAGTCGATGAAAATCTCCGTTAAGGGTGCATGGGCAAAACGCGCTCGAACGACAATTGTTATTGTATGTTTGGTCTTGCAACGAAAAGTTTGAAAAATTGAAAAAAAGTTGTGTCTGATACATTTTTTTTTGGCATTTTCTGCTATTTTACACCAGAAAAAATTTAATAAACATAAAAAATCGAAATTTTTCAAGTTGGACAATTTTCAGtgagcatcttatccatcctagttctcagttcaggacttgtgcacattcgtttagagccagatattcgcaaagccttttcaccggatgattcagatgctggataGTAAGTGACTACTGACCTTGAAGCCTCCTTCCTCCACCAGTCAGAAATAACACGTTTTTTCGCAATGTTTTTCTTTTTCTAATTCGATTTCCCTTTCTCCCTTTCTTATTGTGATTTGGTCAATGTTTGGTTGACTGGGAAGAAAATTGAATTTTTTTGGAATTCCACTTGAAGTTAAAAAACCCAAAATAAATATTTGATCAAAAATAAATAAGAAAAAAAAGAAAACTTTAAAGCAAATGAAAATTTCGTTCGTAACTATTTTGTTAATTTTTTTAAAACTCCTATTTTAAATATATGCTTTTTGCGGAAATTTCTATAAATTTTTTTACATTTTTCAGtgaaacccgtgtctggctggaatactacggactcgacatctatccggaacgagcattctgtatttttaccgccaagcgcgaaaattccagtattctccaggaaggcgcactggcagacGTAAGTTGATTCTCCGTCACGCCCACTTTTCTGGCGGGAATTTAAAAAATTTCAGatttatactgtggacaatcgactatcggcggcagttggctaccaagatggggatggacgaaaaaattgcgatccactctgcgacttgaacagcccctttcacttgttagcgGTAGGTGGTGGTCTAGGGTGTCATTTTTCGATTTTTTCAATTATTCGATGTTTTTAGTGAAAATCGAAAAATCTAAAAATTGAAAATCGAAAAATGAAAGAAACATTGTTTTTTGGGGACCAAACATCTTAATGAATTTAACAACAGGGAAAACTGAACAGAAACCTGGACGGTCTTATCCCATTTATCTATATTCTTAAAATGAATGATGGAGAAAAAAGTTAAAATAAAAACATTATCAGCTTTTTGTAAGTTTTTCTCAAAAATTGTTCGATTTTTCGATTTTCTAAAAAGTCGAAAAACCGAAACCCTTGGTGGTGGTGGTGGTGGACTAGAAAACTCTTCAACGACCACATGGCAATTTTCAGaatttgacgcggagaaacaatggtaccacaagtgtattcacctatccggatatgccatatagcggactggatattttcctgggacttcacttgagtaatgcggattttggtaagattttttttgaaatgttaaatgaaaagttgaaaaatagtttttatgatttagccactttccagttaaaatttcatttttttaactataaaaagttctggaaaaatg

aatttctAGgccgccgatcctaaaAGTgcaccatttcgcAGaAGTacGTacAGTttcccatctatccctAGTgGTcttGTtttctgcattctctgcttcacGTgcttGTtttGTtggAGcgcGTttgcatgctgctttaaattctgaaatattaaaaaaatttcgaAGTttttcAGcacatgggatgggAGTtttgaatttcaattttttaaaaacatttttctGTgattAGTgccGTcGTggcacggctGTtAGccgcctatccgGTttattcgatactttGTGAGTTTTTTGTAACTTTATGGTCGTCGAAATGGGAAAACTTGGCCACCAATATAAGTTTGGAAAACAATTTCCTAAAAATAAAATAATTGAACTTTTCCGATGAATAAAAAAATCGATCAGATATTCTGGAAAAAAAATCGATAAATTAATCGATTTTCTTGGAAAATACATCGAAAAATTGAGAAAAATAGAAAAATGAATGTTTTTCGATTACCGATTTATTGATTTTTCGTGAAAACTGAGTTCAGATAATTTTAAAAGCAATGTTTTTCATTTTTCAAATCAGAATCACTATAGTTTTGAAAAATCAATAATTAATTTATTGATTTTTCAATATAATTTTTTGGAAAAAATAGAAAAATCCCTTTCTAAAAGTTTTAAATTTCCAAGAAAAATTCATTTTCAAAATCACCAACGCGCTCTATAGAGTAGTCGATGAAAATCTCCGTTAAGGGTGCATGGGCAAAACGCGCTCGAACGACAATTGTTATTGTATGTTTGGTCTTGCAACGAAAAGTTTGAAAAATTGAAAAAAAGTTGTGTCTGATACATTTTTTTTTGGCATTTTCTGCTATTTTACACCAGAAAAAATTTAATAAACATAAAAAATCGAAATTTTTCAAGTTGGACAATTTTCAGtgAGcatcttatccatcctAGTtctcAGTtcAGgacttGTgcacattcGTttAGAGccAGatattcgcaaAGccttttcaccggatgattcAGatgctggatAGTAAGTGACTACTGACCTTGAAGCCTCCTTCCTCCACCAGTCAGAAATAACACGTTTTTTCGCAATGTTTTTCTTTTTCTAATTCGATTTCCCTTTCTCCCTTTCTTATTGTGATTTGGTCAATGTTTGGTTGACTGGGAAGAAAATTGAATTTTTTTGGAATTCCACTTGAAGTTAAAAAACCCAAAATAAATATTTGATCAAAAATAAATAAGAAAAAAAAGAAAACTTTAAAGCAAATGAAAATTTCGTTCGTAACTATTTTGTTAATTTTTTTAAAACTCCTATTTTAAATATATGCTTTTTGCGGAAATTTCTATAAATTTTTTTACATTTTTCAGTgaaacccGTGTctggctggaatactacggactcgacatctatccggaacgAGcattctGTatttttaccgccaAGcgcgaaaattccAGTattctccAGgaAGgcgcactggcAGacGTAAGTTGATTCTCCGTCACGCCCACTTTTCTGGCGGGAATTTAAAAAATTTCAGatttatactGTggacaatcgactatcggcggcAGTtggctaccaAGatggggatggacgaaaaaattgcgatccactctgcgacttgaacAGcccctttcacttGTtAGcgGTAGGTGGTGGTCTAGGGTGTCATTTTTCGATTTTTTCAATTATTCGATGTTTTTAGTGAAAATCGAAAAATCTAAAAATTGAAAATCGAAAAATGAAAGAAACATTGTTTTTTGGGGACCAAACATCTTAATGAATTTAACAACAGGGAAAACTGAACAGAAACCTGGACGGTCTTATCCCATTTATCTATATTCTTAAAATGAATGATGGAGAAAAAAGTTAAAATAAAAACATTATCAGCTTTTTGTAAGTTTTTCTCAAAAATTGTTCGATTTTTCGATTTTCTAAAAAGTCGAAAAACCGAAACCCTTGGTGGTGGTGGTGGTGGACTAGAAAACTCTTCAACGACCACATGGCAATTTTCAGaatttgacgcggAGaaacaatgGTaccacaAGTGTattcacctatccggatatgccatatAGcggactggatattttcctgggacttcacttgAGTaatgcggattttgGTaAGattttttttgaaatGTtaaatgaaaAGTtgaaaaatAGTttttatgatttAGccactttccAGTtaaaatttcatttttttaactataaaaAGTtctggaaaaatG

Distribuzione dimensioni introni C.elegans

0,00

0,01

0,02

0,03

0,04

0,05

0,06

0,07

0,08

0,09

202326293235384144475053565962656871747780838689929598101

104

107

110

113

116

119

122

125

128

131

134

137

140

143

146

149

152

155

158

161

164

167

170

dimensioni

freq

uenz

e

Sequenze in testa negli introni di C.elegans

gtaagtt

gtaattt

gtacgtt

gtaggtt

gtatgtt

gtattttgtcagtt

gtgagtt

gtgggtt

gttagtt

gtgagaa

gttcgttgttggtt

gtttgtt

gtgtgttgtgcgtt

0,00

0,02

0,04

0,06

0,08

0,10

gtaaaaa

gtaagac

gtacaag

gtacgat

gtagaca

gtaggcc

gtatacg

gtatgct

gtcaaga

gtcaggc

gtccagg

gtccggt

gtcgata

gtcggtc

gtctatg

gtctgtt

gtgacaa

gtgatac

gtgccag

gtgctat

gtggcca

gtggtcc

gtgtccg

gtgttct

gttacga

gttatgc

gttccgg

gttctgt

gttgcta

gttgttc

gtttctg

gtttttt

basi

freq

uenz

e

Sequenze in coda negli introni di C.elegans

tttccag

ttttcag

tcttcagtattcag

gtttcagctttcag

atttcag

agttcagacttcagaattcag

0,00

0,05

0,10

0,15

0,20

0,25

aaaaaag

aagaaag

acaaaag

acgaaag

agaaaag

aggaaag

ataaaag

atgaaag

caaaaag

cagaaag

ccaaaag

ccgaaag

cgaaaag

cggaaag

ctaaaag

ctgaaag

gaaaaag

gagaaag

gcaaaag

gcgaaag

ggaaaag

gggaaag

gtaaaag

gtgaaag

taaaaag

tagaaag

tcaaaag

tcgaaag

tgaaaag

tggaaag

ttaaaag

ttgaaag

basi

freq

uenz

e

Terne che precedono gli introni in C.elegans

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

aaa

taa

gca

cga

ata

tta

gac

ccc

agc

tgc

gtc

cag

acg

tcg

ggg

ctg

aat

tat

gct

cgt

att

ttt

basi

freq

uenz

e