Influence of Spartan protein on DNA repair genes expression

Abstract

Popravak DNA oštećenja je nužan za održavanje stabilnosti genoma i visoke vjernosti replikacije genoma. Homologna rekombinacija, nehomologno sparivanje krajeva i popravak krivo sparenih baza su glavni mehanizmi popravka oštećenja DNA koji doprinose očuvanju genoma. Zbog stalne izloženosti ljudskog genoma štetnim tvarima iz okoliša i nusproduktima staničnog metabolizma, važno je pravilno djelovanje navedenih mehanizama. Ukoliko oštećenja ostanu nepopravljena mogu inducirati apoptozu, kromosomske aberacije, uzrokovati anomalije u razvoju, maligne bolesti i preuranjeno starenje (progeriju). Spartan je protein koji sudjeluje u održavanju stabilnosti genoma i pomoću metaloproteazne domene uklanja proteine kovalentno vezane za DNA, jednu od najčešćih tipova DNA lezija. Mutacije u genu SPRTN kod ljudi uzrokuju preuranjeno starenje i razvoj hepatocelularnog karcinoma u adolescentnoj dobi. Oštećenja u obliku kovalentno vezanih proteina na DNA se nakupljaju i u drugim vrstama stanica, ali specifično jetrene stanice razvijaju karcinom, što znači da ostale vrste stanica kompenziraju nedostatak proteina Spartan. U ovom radu istraživano je utječe li smanjenje količine ili poremećaj funkcije proteina Spartan na ekspresiju gena čiji proteini sudjeluju u različitim putevima popravka oštećenja DNA. Mjerenjem ekspresije gena lančanom reakcijom polimerazom u stvarnom vremenu uočili smo da postoji ovisnost ekspresije gena uključenih u popravak DNA o funkciji i ekspresiji gena SPRTN.DNA repair is crucial for maintaining genome stability and high fidelity replication. Homologous recombination, non-homologous end joining and mismatch repair are the main repair mechanisms of DNA damage that contribute to the maintenance of the genome. Due to constant exposure of human genome to harmful agents from the environment and byproducts of cell metabolism, the proper functioning of these mechanisms is important. If the damage remains unrepaired, it can induce apoptosis, chromosomal aberrations, developmental anomalies, malignancy and premature aging. Spartan is protein involved in maintaining the genome stability and with metalloprotease domain removes crosslinked proteins from DNA, one of the most common types of DNA lesions. Mutations in the SPRTN gene in humans cause premature aging and hepatocellular carcinoma. Crosslinked proteins also accumulate on DNA in other cell types, but specifically liver cells develop cancer, which suggests that other types of cells compensate for the lack of Spartan protein. This paper investigated effects of the amount reduction or function disorder of the Spartan protein on the expression of genes whose proteins participate in various repair pathways of DNA damage. Measuring the expression of genes with quantitative realtime polymerase chain reaction, we have observed that correlation between expression of genes involved in DNA repair and SPRTN exist