|
|
Role of sequence context in DNA methylation
Polák, Jan ; Fischer, Lukáš (advisor) ; Širl, Marek (referee)
Cytosine methylation of DNA is a pivotal epigenetic mark, which contributes to the regulation of the gene expresion, silencing of transposable elements, and co-defines chromatine state. There are three cytosine contexts: CG, CHG and CHH (where H stands for C, A, or T). Arabidopsis thaliana (and plants in general) has an arsenal of molecular mechanisms capable of cytosine methylation in all of its contexts. That said, there are two tasks at hand: maintaining of pre-existing methylation and if need be, creating new methylated spots. The actual process of maintaining of the methylation depends on the cytosine context. Methylation of symmetrical contexts of CG and CHG can utilize the information about the methylation pattern from the second DNA strand. The aymmetrical context of CHH, and also CHG need to look for this information elsewhere: in the methylation of the lysine 9 of H3 histone. This creates a self-reinforcing loop and a crosstalk between two epigenetic mechanisms. Maintaince of methylation of CHH is also navigated by small RNA complementary to the locus in question. This mechanism of enzyme navigating by RNA is also used in establishing a new methylated site for all of the contexts. CG methylation is most prevalent in both heterochromatine and euchromatine. It also has a special functions...
|
|
|
The role of methylation of histone 3 on lysine 4 (H3K4) during mouse spermatogenesis
Blumenstein, Jan ; Trachtulec, Zdeněk (advisor) ; Král, Jiří (referee)
Epige eti ké odifika e hro ati u hrají z ač ou roli v regula i přístup osti DNA. odifika í je etyla e histo ů. V H a lysi u ěhe sper atoge eze yši do á í a to zej é a ve Běhe eioti ké profáze I do hází k hro ozo ů, a k eioti ké reko i a i. Tyto pro esy jsou kriti ký ode tvor y pohlav í h u ěk a jeji h selhá í vede k eioti ké zástavě a tí páde k poruše tvor y haploid í h u ěk. Histo ová etyltra sferáza PRDM9 hraje klíčovou roli v eioti ké reko i a e, e oť je zodpověd á za urče í progra ova ý h dvouřetěz ový h zlo ů v íste h zva ý h hotspoty. Ni é ě ge je důležitý i ve spe ia i, a to řed i tví fe o é u hy rid í sterility. Další i protei y, které se podílí a etyla i histo u H a lysi u ěhe sper atoge eze, jsou MLL KMT D , MLL KMT E a yší h varlate h ovše az ačují, že regula i této odifika e hro ati u podílí ví e ge ů. Avšak ejsou z á é ko krét í fu k e, které ají tyto z ývají í ge y ěhe vývoje sa čí h pohlav í h u ěk. Další zkou á í tě hto ge ů ohou ýt užiteč á pro o jas ě í částeč é e o úpl é eplod os Klíčová slova: eioti ká reko i a e, dvouřetěz ové zlo y, hy rid í sterilita, sper atoge eze, etyla e histo ů
|
guest ::
