RESUMO
Flap endonuclease-1 (FEN1) belongs to the Rad2 family of structure-specific nucleases. It is required for several DNA metabolic pathways, including DNA replication and DNA damage repair. Here, we have identified a shade avoidance mutant, sav6, which reduces the mRNA splicing efficiency of SAV6. We have demonstrated that SAV6 is an FEN1 homologue that shows double-flap endonuclease and gap-dependent endonuclease activity, but lacks exonuclease activity. sav6 mutants are hypersensitive to DNA damage induced by ultraviolet (UV)-C radiation and reagents that induce double-stranded DNA breaks, but exhibit normal responses to chemicals that block DNA replication. Signalling components that respond to DNA damage are constitutively activated in sav6 mutants. These data indicate that SAV6 is required for DNA damage repair and the maintenance of genome integrity. Mutant sav6 plants also show reduced root apical meristem (RAM) size and defective quiescent centre (QC) development. The expression of SMR7, a cell cycle regulatory gene, and ERF115 and PSK5, regulators of QC division, is increased in sav6 mutants. Their constitutive induction is likely due to the elevated DNA damage responses in sav6 and may lead to defects in the development of the RAM and QC. Therefore, SAV6 assures proper root development through maintenance of genome integrity.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Endonucleases Flap/genética , Genoma de Planta/genética , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Endonucleases Flap/classificação , Endonucleases Flap/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Histocitoquímica , Hipocótilo/genética , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/metabolismo , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Dados de Sequência Molecular , Mutação , Hormônios Peptídicos/genética , Hormônios Peptídicos/metabolismo , Filogenia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Background: No previous studies have reported on the use of minimally invasive endoscopic therapy for colon cancer in older patients. Case presentation: An 80-year-old man was admitted to our hospital with haematochezia and diagnosed with advanced colon cancer in 2018. Traditional surgical care was rejected by his family. We successfully treated the patient with multiple minimally invasive endoscopic therapies, such as argon plasma coagulation, from 2018 to 2021. Conclusion: Invasive endoscopic therapy is a feasible way to treat colon cancer in older patients.