Metilacija DNA pri slovenskih moških, žrtvah samomora z obešanjem

doktorska disertacija

Katarina Kouter (Avtor), Alja Videtič (Mentor), Tomaž Zupanc (Komentor)

Povzetek

Samomorilno vedenje je poligensko, večfaktorsko vedenje, ki prizadane ljudi širom sveta. Na samomorilno vedenje vplivajo številni biološki in zunanji dejavniki, ki jih lahko povežemo z epigenetiko. Mehanizmi in dejavniki samomorilnega vedenja kljub širokemu naboru novih dognanj niso v celoti poznani. Na podlagi molekularno-bioloških študij pa lahko sklepamo, da obstaja tudi pomembna biološka komponenta samomorilnega vedenja. Ena izmed njih je metilacija DNA in spremenjena stopnja le-te. Da bi preverili, ali obstajajo razlike v stopnji metilacije, smo tvorili dve skupini, ki smu ju primerjali med seboj. Prva je zajemala moške, ki so umrli zaradi samomora z obešanjem; druga skupina pa je predstavljala kontrolno skupino (zajemala je moške, ki so umrli zaradi nenadne srčne smrti). Z uporabo tehnologije sekvenciranja naslednje generacije (NGS) smo v prvem delu preiskovali stopnjo metilacije DNA širom celotnega genoma na manjšem naboru preiskovancev (v možganskih regijah hipokampus in Brodmannovo področje (BA) 9). V drugem delu smo na celotni skupini preiskovancev preverili stopnjo metilacije tarčnih zaporedij DNA izbranih kandidatnih genov (možganske regije amigdala, BA46, hipokampus in insula ter kri). Rezultate, pridobljene z NGS smo želeli potrditi z dodatno metodo. Kandidatne gene, pri katerih smo opazili spremenjeno stopnjo metilacije med obema preiskovanima skupinama, smo dodatno preučili z analizo njihovega izražanja s qPCR tako za prvi kot tudi za drugi del doktorske naloge. Pokazali smo številne razlike v stopnji metilacije med žrtvami samomora in kontrolno skupino. V prvem delu smo z analizo metilacije DNA širom genoma pri obeh preiskovanih možganskih regijah našli večje število diferenčno metiliranih citozinov z razliko v odstotku metilacije med obema skupinama preiskovancev večjo od 25 % in q-vrednostjo pod 0,01. V analizi genske ontologije so bili obogateni izrazi, povezani s strukturno integriteto celice in z uravnavanjem živčnega sistema. V analizi izražanja genov smo v BA9 pri žrtvah samomora opazili povišano izražanje dveh genov (ZNF714 in NRIP3). V drugem delu, analizi metilacije tarčnih zaporedij DNA, smo prav tako opazili razlike v stopnji metilacije med preiskovanima skupinama. Razlike smo opazili v vseh sekvenciranih kandidatnih genih, pri čemer pa so bile nekatere razlike v odstotku metilacije nizke (nižje od enega odstotka). Spremenjeno izražanje genov smo opazili v hipokampusu (ZNF714, NR3C1, SLC6A4 in HTR1A) in krvi (NRIP3). Rezultati naših analiz dajejo nov uvid v spremenjeno stanje metilacije pri samomorilnem vedenju in nakazujejo možnost spremenjene plastičnosti možganov. Pridobili smo nove kandidatne gene ter pokazali povezavo s samomorilnim vedenjem pri že obstoječih kandidatnih genih. Rezultati tako podpirajo vlogo biološke komponente ozadja samomorilnega vedenja in prispevajo k osvetljevanju problematike na visoko samomorilno ogroženi slovenski populaciji.

Ključne besede

samomori;samomorilno vedenje;Slovenija;molekularna genetika;epigenetika;samomorilci;možgani;genom;sekvenciranje naslednje generacije;genetika, biokemična;psihiatrija;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2019
Tipologija:	2.08 - Doktorska disertacija
Organizacija:	UL MF - Medicinska fakulteta
Založnik:	[K. Kouter]
UDK:	577.21:616.89-008.441.44(043.3)
COBISS:	303464960
Št. ogledov:	1103
Št. prenosov:	336
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	DNA methylation in Slovenian male suicide victims by hanging
Sekundarni povzetek:	Suicidal behaviour is a polygenic and multifactorial disorder affecting people all around the world. It is influenced by multiple factors, which can be tied together by epigenetics. Although comprehensive amount of knowledge on suicidal behaviour has been gathered, complete mechanism and factors leading to suicidal behaviour are yet to be determined. However, based on molecular studies, we can conclude that there is an important biological component to suicidal behaviour, and DNA methylation could play an important role. For the purpose of this work we formed two study groups. First included 25 male suicide victims, who died by hanging. The second group was a control group, including 28 males who died from sudden cardiac arrest. Using advances of the next-generation sequencing technology (NGS), we first analysed genome-wide DNA methylation on a smaller subset. DNA methylation was examined in hippocampus and in a cortical region, Brodmann area (BA) 9. Next, we interrogated DNA methylation of selected candidate genes in additional brain regions (beside hippocampus also amygdala, insula and BA46) and blood using the complete set of subjects. We wanted to confirm the results obtained using NGS with an additional method. Candidate genes for which we observed an altered rate of methylation between the two study groups were further examined by analysing their expression by qPCR for both the first and second part of the doctoral thesis. In our study we determined multiple differences in DNA methylation state between suicide victims and the control group. Genome-wide DNA methylation revealed increased hypomethylation in suicide victims for both brain regions. We found a large number of differentially methylated cytosines with the difference of the percentage of methylation between the two groups greater than 25 % and with the q-value below 0.01. Gene ontology analysis showed enrichment for genes associated with cell structural integrity and nervous system regulation. In BA9 expression of two genes was elevated in suicide victims (ZNF714 and NRIP3). In the second part of our work, we performed DNA methylation analysis for candidate genes, and we detected differences in DNA methylation for all studied brain regions and blood. Although we observed differences within all candidate genes, some differences in DNA methylation were low (less than one percent between studied groups). Gene expression between suicide victims and control group differed statistically in the hippocampus (ZNF714, NR3C1, SLC6A4, and HTR1A) and blood (NRIP3). The results of our analyses provide new insights into the methylation-altered state in suicidal behaviour and suggest the possibility of changes in brain plasticity. We identified new potential candidate genes and strengthen the association with suicidal behaviour in already known candidate genes. The results therefore support the role of the biological component in suicidal behaviour and contribute to its understanding in a highly suicidal Slovenian population.
Sekundarne ključne besede:	Samomorilnost;Disertacije;Genetika;Metilacija DNA;DNA methylation;Suicidal ideation;Genetics;Suicide;Epigenetics;Genes, candidate;Gene expression;Genetic predisposition;Male;DNA metilacija;Samomor;Epigenetika;Kandidatni gen;Gensko izražanje;Genetska predispozicija;Moški;Slovenia;Slovenija;
Vrsta dela (COBISS):	Doktorska disertacija
Študijski program:	0
Konec prepovedi (OpenAIRE):	1970-01-01
Komentar na gradivo:	Univ. v Ljubljani, Medicinska fak.
Strani:	IX, 117 str.
ID:	11311738