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Lo splicing dell’RNA definizione importanza predizione. Ing Francesco Piva Gruppo di biologia computazionale e molecolare Dipartimento di Biochimica, Biologia e Genetica Università Politecnica delle Marche Edificio Scienze 3, Brecce Bianche, Ancona f.piva@univpm.it.
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Lo splicing dell’RNA • definizione • importanza • predizione Ing Francesco Piva Gruppo di biologia computazionale e molecolare Dipartimento di Biochimica, Biologia e Genetica Università Politecnica delle Marche Edificio Scienze 3, Brecce Bianche, Ancona f.piva@univpm.it
These are synonymous words, are we sure ? GCAGTACGA GCAGTACGC GCAGTACGG GCAGTACGT GCAGTAAGA GCAGTAAGG GCAGTCCGA GCAGTCCGC GCAGTCCGG GCAGTCCGT GCAGTCAGA GCAGTCAGG GCAGTGCGA GCAGTGCGC GCAGTGCGG GCAGTGCGT GCAGTGAGA GCAGTGAGG GCAGTTCGA GCAGTTCGC GCAGTTCGG GCAGTTCGT GCAGTTAGA GCAGTTAGG GCCGTACGA GCCGTACGC GCCGTACGG GCCGTACGT GCCGTAAGA GCCGTAAGG GCCGTCCGA GCCGTCCGC GCCGTCCGG GCCGTCCGT GCCGTCAGA GCCGTCAGG GCCGTGCGA GCCGTGCGC GCCGTGCGG GCCGTGCGT GCCGTGAGA GCCGTGAGG GCCGTTCGA GCCGTTCGC GCCGTTCGG GCCGTTCGT GCCGTTAGA GCCGTTAGG GCGGTACGA GCGGTACGC GCGGTACGG GCGGTACGT GCGGTAAGA GCGGTAAGG GCGGTCCGA GCGGTCCGC GCGGTCCGG GCGGTCCGT GCGGTCAGA GCGGTCAGG GCGGTGCGA GCGGTGCGC GCGGTGCGG GCGGTGCGT GCGGTGAGA GCGGTGAGG GCGGTTCGA GCGGTTCGC GCGGTTCGG GCGGTTCGT GCGGTTAGA GCGGTTAGG GCTGTACGA GCTGTACGC GCTGTACGG GCTGTACGT GCTGTAAGA GCTGTAAGG GCTGTCCGA GCTGTCCGC GCTGTCCGG GCTGTCCGT GCTGTCAGA GCTGTCAGG GCTGTGCGA GCTGTGCGC GCTGTGCGG GCTGTGCGT GCTGTGAGA GCTGTGAGG GCTGTTCGA GCTGTTCGC GCTGTTCGG GCTGTTCGT GCTGTTAGA GCTGTTAGG . . . Ala Val Arg . . . GCA C G T GTA C G T CGA C G T AGA G 4 * 4 * 6 = 96 Three AAs specified by 96 synonymous words
Genomic DNA ATGTAAACGTATATCGTGACAGTGGTCTGTTAGTATTCCTTTAGTCATGGTTT ATGTAAACTGGTCTGTTATCATGGTTT mRNA
attggaaaccgaaacccgttggtcacctctgcaatagccctccctccctcacttctacaattttgtgacagtggtcttgttttctgcattctctgcttcacgtgcttgttttgttggagcgcgtttgcatgctgctttaaattctgaaatattaaaaaaatttcgaagtttttcagcacatgggatgggagttttgaatttcaattttttaaaaacatttttctgtgattagtgccgtcgtggcacggctgttagccgcctatccggtttattcgatactttGTGAGTTTTTTGTAACTTTATGGTCGTCGAAATGGGAAAACTTGGCCACCAATATAAGTTTGGAAAACAATTTCCTAAAAATAAAATAATTGAACTTTTCCGATGAATAAAAAAATCGATCAGATATTCTGGAAAAAAAATCGATAAATTAATCGATTTTCTTGGAAAATACATCGAAAAATTGAGAAAAATAGAAAAATGAATGTTTTTCGATTACCGATTTATTGATTTTTCGTGAAAACTGAGTTCAGATAATTTTAAAAGCAATGTTTTTCATTTTTCAAATCAGAATCACTATAGTTTTGAAAAATCAATAATTAATTTATTGATTTTTCAATATAATTTTTTGGAAAAAATAGAAAAATCCCTTTCTAAAAGTTTTAAATTTCCAAGAAAAATTCATTTTCAAAATCACCAACGCGCTCTATAGAGTAGTCGATGAAAATCTCCGTTAAGGGTGCATGGGCAAAACGCGCTCGAACGACAATTGTTATTGTATGTTTGGTCTTGCAACGAAAAGTTTGAAAAATTGAAAAAAAGTTGTGTCTGATACATTTTTTTTTGGCATTTTCTGCTATTTTACACCAGAAAAAATTTAATAAACATAAAAAATCGAAATTTTTCAAGTTGGACAATTTTCAGtgagcatcttatccatcctagttctcagttcaggacttgtgcacattcgtttagagccagatattcgcaaagccttttcaccggatgattcagatgctggataGTAAGTGACTACTGACCTTGAAGCCTCCTTCCTCCACCAGTCAGAAATAACACGTTTTTTCGCAATGTTTTTCTTTTTCTAATTCGATTTCCCTTTCTCCCTTTCTTATTGTGATTTGGTCAATGTTTGGTTGACTGGGAAGAAAATTGAATTTTTTTGGAATTCCACTTGAAGTTAAAAAACCCAAAATAAATATTTGATCAAAAATAAATAAGAAAAAAAAGAAAACTTTAAAGCAAATGAAAATTTCGTTCGTAACTATTTTGTTAATTTTTTTAAAACTCCTATTTTAAATATATGCTTTTTGCGGAAATTTCTATAAATTTTTTTACATTTTTCAGtgaaacccgtgtctggctggaatactacggactcgacatctatccggaacgagcattctgtatttttaccgccaagcgcgaaaattccagtattctccaggaaggcgcactggcagacGTAAGTTGATTCTCCGTCACGCCCACTTTTCTGGCGGGAATTTAAAAAATTTCAGatttatactgtggacaatcgactatcggcggcagttggctaccaagatggggatggacgaaaaaattgcgatccactctgcgacttgaacagcccctttcacttgttagcgGTAGGTGGTGGTCTAGGGTGTCATTTTTCGATTTTTTCAATTATTCGATGTTTTTAGTGAAAATCGAAAAATCTAAAAATTGAAAATCGAAAAATGAAAGAAACATTGTTTTTTGGGGACCAAACATCTTAATGAATTTAACAACAGGGAAAACTGAACAGAAACCTGGACGGTCTTATCCCATTTATCTATATTCTTAAAATGAATGATGGAGAAAAAAGTTAAAATAAAAACATTATCAGCTTTTTGTAAGTTTTTCTCAAAAATTGTTCGATTTTTCGATTTTCTAAAAAGTCGAAAAACCGAAACCCTTGGTGGTGGTGGTGGTGGACTAGAAAACTCTTCAACGACCACATGGCAATTTTCAGaatttgacgcggagaaacaatggtaccacaagtgtattcacctatccggatatgccatatagcggactggatattttcctgggacttcacttgagtaatgcggattttggtaagattttttttgaaatgttaaatgaaaagttgaaaaatagtttttatgatttagccactttccagttaaaatttcatttttttaactataaaaagttctggaaaaatgattggaaaccgaaacccgttggtcacctctgcaatagccctccctccctcacttctacaattttgtgacagtggtcttgttttctgcattctctgcttcacgtgcttgttttgttggagcgcgtttgcatgctgctttaaattctgaaatattaaaaaaatttcgaagtttttcagcacatgggatgggagttttgaatttcaattttttaaaaacatttttctgtgattagtgccgtcgtggcacggctgttagccgcctatccggtttattcgatactttGTGAGTTTTTTGTAACTTTATGGTCGTCGAAATGGGAAAACTTGGCCACCAATATAAGTTTGGAAAACAATTTCCTAAAAATAAAATAATTGAACTTTTCCGATGAATAAAAAAATCGATCAGATATTCTGGAAAAAAAATCGATAAATTAATCGATTTTCTTGGAAAATACATCGAAAAATTGAGAAAAATAGAAAAATGAATGTTTTTCGATTACCGATTTATTGATTTTTCGTGAAAACTGAGTTCAGATAATTTTAAAAGCAATGTTTTTCATTTTTCAAATCAGAATCACTATAGTTTTGAAAAATCAATAATTAATTTATTGATTTTTCAATATAATTTTTTGGAAAAAATAGAAAAATCCCTTTCTAAAAGTTTTAAATTTCCAAGAAAAATTCATTTTCAAAATCACCAACGCGCTCTATAGAGTAGTCGATGAAAATCTCCGTTAAGGGTGCATGGGCAAAACGCGCTCGAACGACAATTGTTATTGTATGTTTGGTCTTGCAACGAAAAGTTTGAAAAATTGAAAAAAAGTTGTGTCTGATACATTTTTTTTTGGCATTTTCTGCTATTTTACACCAGAAAAAATTTAATAAACATAAAAAATCGAAATTTTTCAAGTTGGACAATTTTCAGtgagcatcttatccatcctagttctcagttcaggacttgtgcacattcgtttagagccagatattcgcaaagccttttcaccggatgattcagatgctggataGTAAGTGACTACTGACCTTGAAGCCTCCTTCCTCCACCAGTCAGAAATAACACGTTTTTTCGCAATGTTTTTCTTTTTCTAATTCGATTTCCCTTTCTCCCTTTCTTATTGTGATTTGGTCAATGTTTGGTTGACTGGGAAGAAAATTGAATTTTTTTGGAATTCCACTTGAAGTTAAAAAACCCAAAATAAATATTTGATCAAAAATAAATAAGAAAAAAAAGAAAACTTTAAAGCAAATGAAAATTTCGTTCGTAACTATTTTGTTAATTTTTTTAAAACTCCTATTTTAAATATATGCTTTTTGCGGAAATTTCTATAAATTTTTTTACATTTTTCAGtgaaacccgtgtctggctggaatactacggactcgacatctatccggaacgagcattctgtatttttaccgccaagcgcgaaaattccagtattctccaggaaggcgcactggcagacGTAAGTTGATTCTCCGTCACGCCCACTTTTCTGGCGGGAATTTAAAAAATTTCAGatttatactgtggacaatcgactatcggcggcagttggctaccaagatggggatggacgaaaaaattgcgatccactctgcgacttgaacagcccctttcacttgttagcgGTAGGTGGTGGTCTAGGGTGTCATTTTTCGATTTTTTCAATTATTCGATGTTTTTAGTGAAAATCGAAAAATCTAAAAATTGAAAATCGAAAAATGAAAGAAACATTGTTTTTTGGGGACCAAACATCTTAATGAATTTAACAACAGGGAAAACTGAACAGAAACCTGGACGGTCTTATCCCATTTATCTATATTCTTAAAATGAATGATGGAGAAAAAAGTTAAAATAAAAACATTATCAGCTTTTTGTAAGTTTTTCTCAAAAATTGTTCGATTTTTCGATTTTCTAAAAAGTCGAAAAACCGAAACCCTTGGTGGTGGTGGTGGTGGACTAGAAAACTCTTCAACGACCACATGGCAATTTTCAGaatttgacgcggagaaacaatggtaccacaagtgtattcacctatccggatatgccatatagcggactggatattttcctgggacttcacttgagtaatgcggattttggtaagattttttttgaaatgttaaatgaaaagttgaaaaatagtttttatgatttagccactttccagttaaaatttcatttttttaactataaaaagttctggaaaaatg
Struttura tipica dei geni umani esoni introni
esone1 introne1 esone2 introne2 esone3 GT AG GT AG SPLICING eliminazione introni introne1 introne2 esone2 esone3 esone1 unione esoni esone1 esone2 esone3
Lo splicing avviene in tutto il trascritto, anche nelle zone non codificanti
R = G, A Y = T, C
Meccanismo di splicing estere alcool O + ORI R C HO RII = O + ORII R C HO RI due legami fosfoesterici
U2AF si lega al tratto pirimidinico a valle del sito di ramificazione Arg-Ser arly snRNP U2 si lega al sito di ramificazione (richiesta idrolisi ATP) U2AF U2AF il 3’ss è tagliato e gli esoni vengono saldati insieme, il cappio verrà deramificato si legano insieme le prot SR connettono U2Af con snRNP U1 U2AF U2AF snRNP U5 si lega al 5’ss, snRNP U6 si lega a snRNP U2 snRNP U1 è rilasciato, snRNP U5 si sposta dall’esone all’introne, snRNP U6 si lega al 5’ss snRNP U4 è rilasciato (richiesta idrolisi ATP), snRNP U6 e U2 catalizzano la transesterificazione, snRNP U5 si lega al 3’ss, il 5’ ss è tagliato e si forma il cappio
snRNP U1 Sm protein
RBD: RNA binding domain G16 C5
snRNP U2 si appaiano con snRNA U6 Sm protein si appaia al sito di ramificazione
U17 U5
5 2 3 1 Muscolo cardiaco 5 3 1 Muscolo uterino 1 3 4 5 Lo splicing è tessuto specifico 2 4
Alcuni genomi virali subiscono splicing all’interno della cellula ospite
AIM: mRNA structure pre mRNA sequence SPLICING PREDICTION TOOL
Segnali per il riconoscimento degli introni Motivi conservati
I segnali dei siti di splicing sono ben conservati tra le specie probabilmente la comparsa del meccanismo di splicing è molto antica
One point mutation at a time BRCA1 exon 18 100% 18 19 17 20% 19 17 18 80% 17 19 Binding of DAZAP1 and hnRNPA1/A2 to an Exonic Splicing Silencer in a Natural BRCA1 Exon 18 Mutant Goina E, Skoko N, Pagani F. Mol Cell Biol 2008; 28: 3850–3860
Two point mutations at a time BRCA1 exon 18 Decreased efficiency Complete exon 18 skipping Binding of DAZAP1 and hnRNPA1/A2 to an Exonic Splicing Silencer in a Natural BRCA1 Exon 18 Mutant Goina E, Skoko N, Pagani F. Mol Cell Biol 2008; 28: 3850–3860
WT5’-ACAGTTGTTGGCGGTTG-3’ TACCACCC TTATT GGTTC AA CCGC G G T pathological 100 90 Effect of variations in CFTR exon 9 80 pathological 70 % exon 9 inclusion 60 pathological 50 40 30 20 10 0 A G T G A G T C T C G C A C A C A C C T T C A G T T C T 144A WT 145C 146A 147G 148T 149T 150G 151T 153G 154G 155C 156G 157G ex9 + ex9 - • Pagani, F., Buratti, E., Stuani, C., and Baralle, F. E. (2003) J Biol Chem • Pagani, F., Stuani, C., Zuccato, E., Kornblihtt, A. R., and Baralle, F. E. (2003) J Biol Chem
The genetic code is degenerate, but it is not all rodustness GCTGTACGA GCTGTACGC GCTGTACGG GCTGTACGT GCTGTAAGA GCTGTAAGG GCTGTCCGA GCTGTCCGC GCTGTCCGG GCTGTCCGT GCTGTCAGA GCTGTCAGG GCTGTGCGA GCTGTGCGC GCTGTGCGG GCTGTGCGT GCTGTGAGA GCTGTGAGG GCTGTTCGA GCTGTTCGC GCTGTTCGG GCTGTTCGT GCTGTTAGA GCTGTTAGG GCGGTACGA GCGGTACGC GCGGTACGG GCGGTACGT GCGGTAAGA GCGGTAAGG GCGGTCCGA GCGGTCCGC GCGGTCCGG GCGGTCCGT GCGGTCAGA GCGGTCAGG GCGGTGCGA GCGGTGCGC GCGGTGCGG GCGGTGCGT GCGGTGAGA GCGGTGAGG GCGGTTCGA GCGGTTCGC GCGGTTCGG GCGGTTCGT GCGGTTAGA GCGGTTAGG GCAGTACGA GCAGTACGC GCAGTACGG GCAGTACGT GCAGTAAGA GCAGTAAGG GCAGTCCGA GCAGTCCGC GCAGTCCGG GCAGTCCGT GCAGTCAGA GCAGTCAGG GCAGTGCGA GCAGTGCGC GCAGTGCGG GCAGTGCGT GCAGTGAGA GCAGTGAGG GCAGTTCGA GCAGTTCGC GCAGTTCGG GCAGTTCGT GCAGTTAGA GCAGTTAGG GCCGTACGA GCCGTACGC GCCGTACGG GCCGTACGT GCCGTAAGA GCCGTAAGG GCCGTCCGA GCCGTCCGC GCCGTCCGG GCCGTCCGT GCCGTCAGA GCCGTCAGG GCCGTGCGA GCCGTGCGC GCCGTGCGG GCCGTGCGT GCCGTGAGA GCCGTGAGG GCCGTTCGA GCCGTTCGC GCCGTTCGG GCCGTTCGT GCCGTTAGA GCCGTTAGG . . . Ala Val Arg . . . GCA C G T GTA C G T CGA C G T AGA G 4 * 4 * 6 = 96 Three AAs specified by 96 synonymous words
cryptic exon exon31 NF1 gene ttttatagTGAGAATA A>G WT MUT La mutazione attiva un esone criptico (in rosso) Raponi M, Upadhyaya M, Baralle D. Functional splicing assay shows a pathogenic intronic mutation in neurofibromatosis type 1 (NF1) due to intronic sequence exonization. Hum Mutat. 2006; 27(3):294-295.
cryptic exon exon31 NF1 gene CAGgtattg TAGataata Disruption of 5’ss restores normal splicing CAAgtattg TAGgtggga CAAgtaagc TAGgtaata CAAgtaagg La seq 2 ha un sito di splicing in 5’ più debole della seq 1. La seq 3 non ha il sito. Raponi M, Upadhyaya M, Baralle D. Functional splicing assay shows a pathogenic intronic mutation in neurofibromatosis type 1 (NF1) due to intronic sequence exonization. Hum Mutat. 2006;27(3):294-295.
ATM gene structure 20 21 WT: GGCCAGGTAAGTGATA 20 21 mutations DEL: GGCCAG____GTGATA MUT: GGCCAGGTCTGTGATA M WT del mut results 21 20 A new type of mutation causes a splicing defect in ATM Pagani F, Buratti E, Stuani C, Bendix R, Dörk T, Baralle FE Nature Genetics 2002, 30: 426-429 20 21
Many elements regulate the splicing process exonic splicing enhancer ESE exonic splicing silencer ESS intronic splicing enhancer ISE intronic splicing silencer ISS
A compact formalism, but… score matrix
Compression and reconstruction of motifs AGG AGT CGT AGG CGT Experimental assessed binding sites zip AGG AGT CGG CGT A G consensus sequence G unzip C T
elements promoting exons elements promoting introns
ESE, ISS: esone ESS, ISE: introne
PROTEINS REGULATING SPLICING STORED IN SPLICEAID 9G8, CUG-BP1, DAZAP1, ETR-3, Fox-1, Fox-2, FMRP, hnRNP A0, hnRNP A1, hnRNP A2/B1, hnRNP C, hnRNP C1, hnRNP C2, hnRNP D, hnRNP D0, hnRNP DL, hnRNP E1, hnRNP E2, hnRNP F, hnRNP G, hnRNP H1, hnRNP H2, hnRNP I (PTB), hnRNP J, hnRNP K, hnRNP L, hnRNP LL, hnRNP M, hnRNP P (TLS), hnRNP Q, hnRNP U, HTra2alpha, HTra2beta1, HuB, HuD, HuR, KSRP, MBNL1, Nova-1, Nova-2, nPTB, PSF, RBM4, RBM25, Sam68, SAP155, SC35, SF1, SF2/ASF, SLM-1, SLM-2, SRp20, SRp30c, SRp38, SRp40, SRp54, SRp55, SRp75, TDP43, TIA-1, TIAL1, YB-1, ZRANB2 …
Some comparisons among literature data (SpliceAid) and prediction tools