Biology subjects

Lorincz, M.

Publications and source records attributed to Lorincz, M..

4 recordsLinked to original sources

bioRxiv2025

Methylome profiling of SetDB1 deficient ESCs reveals diverse epigenetic cross-talk during pluripotency

SetDB1 is best known as a chromatin modifier catalyzing H3K9me3. However, recent studies show that SetDB1 can promote H3K27me3-deposition and CTCF-binding, and potentially recruit de novo DNA methyltransferases. Given the tight connection with these processes, we hypothesized that DNA methylation (DNAme) may integrate these combined features of SetDB1. Thereto, we conducted time-course whole-genome bisulfite sequencing following Setdb1 knockout (KO) in mouse embryonic stem cells (ESCs). In serum-cultured ESCs, nearly half of SetDB1 binding sites are DNA methylated, coinciding with H3K9me3, mainly silencing retrotransposons and imprinting control regions. Both H3K9me3 and DNAme are lost upon Setdb1 KO, but while TET2 rapidly removes DNAme at many of these sites, some retrotransposons are shielded from TET2 and lose DNAme slowly via passive dilution. SetDB1-mediated regulation via H3K27me3, CTCF, SMAD3, and histone acetylation are uncoupled from the DNAme-H3K9me3 axis. Hypomethylated naive ESCs show massive reactivation of retrotransposons upon Setdb1 KO, providing functional evidence that DNAme adds a protective layer against such activity. Altogether, our findings reveal how DNAme coordinates the multifaceted regulatory roles of SetDB1. HighlightsO_LIIn serum ESCs, SetDB1-dependent deposition of H3K9me3 and DNAme are tightly coupled, primarily silencing repeats and imprinted control regions; C_LIO_LILoss of SetDB1 causes demethylation of a large range of repeat types, the pace of which is dependent on TET pre-loading; C_LIO_LIThe regulatory modes of SetDB1 mediated by H3K27me3, CTCF, TGF-{beta} signalling and histone acetylation are uncoupled from the SetDB1 DNAme-H3K9me3 axis and/or from each other; C_LIO_LILoss of SetDB1-dependent DNAme in hypomethylated 2i ESCs reveals that DNAme serves as a buffering layer to repress SetDB1-mediated H3K9me3 targets. C_LI

molecular biology↗

bioRxiv2022

Higher-order thalamic nuclei facilitate the generalization and maintenance of spike-and-wave discharges in absence seizures

Spike-and-wave discharges (SWDs), generated by the cortico-thalamo-cortical (CTC) network, are pathological, large amplitude oscillations and the hallmark of absence seizures (ASs). SWDs begin in a cortical initiation network in both humans and animal models, including the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), where it is located in the primary somatosensory cortex (S1). The behavioral manifestation of an AS occurs when SWDs spread from the cortical initiation site to the whole brain, however, the mechanisms behind this rapid propagation remain unclear. Here we investigated these processes beyond the principal CTC network, in higher-order (HO) thalamic nuclei (lateral posterior (LP) and posterior (PO) nuclei) since their diffuse connectivity and known facilitation of intracortical communications make these nuclei key candidates to support SWD generation and maintenance. In freely moving GAERS, multi-site LFP in LP, PO and multiple cortical regions revealed a novel feature of SWDs: during SWDs there are short periods (named SWD-breaks) when cortical regions far from S1, such the primary visual cortex (V1), become transiently unsynchronized from the ongoing EEG rhythm. Inactivation of HO nuclei with local muscimol injections or optogenetic perturbation of HO nuclei activity increased the occurrence of SWD-breaks and the former intervention also increased the SWD propagation-time from S1. The neural underpinnings of these findings were explored further by silicon probe recordings from single units of PO which uncovered two previously unknown groups of excitatory neurons based on their burst firing dynamics at SWD onset. Moreover, a switch from tonic to burst firing at SWD onset was shown to be an important feature since it was much less prominent for non-generalized events, i.e. SWDs that remained local to S1. Additionally, one group of neurons showed a reverse of this switch during SWD-breaks, demonstrating the importance of this firing pattern throughout the SWD. In summary, these results support the view that multiple HO thalamic nuclei are utilized at SWD onset and contribute to cortical synchrony throughout the paroxysmal discharge.

neuroscience↗

bioRxiv2019

The majority of histone acetylation is a consequence of transcription

Histone acetylation is a ubiquitous hallmark of transcriptional activity, but whether the link is of a causal or consequential nature is still a matter of debate. In this study we resolve this question. Using both immunoblot analysis and chromatin immunoprecipitation-sequencing (ChIP-seq) in S. cerevisiae, we show that the majority of histone acetylation is dependent on transcription. Loss of histone H4 acetylation upon transcription inhibition is partially explained by depletion of histone acetyltransferases (HATs) from gene bodies, implicating transcription in HAT targeting. Despite this, HAT occupancy alone poorly predicts histone acetylation, suggesting that HAT activity is regulated at a step post-recruitment. Collectively, these data show that the majority of histone acetylation is a consequence of RNAPII promoting both the recruitment and activity of histone acetyltransferases.

molecular biology↗

bioRxiv2019

Epigenetic regulation of unique genes and repetitive elements by the KRAB zinc finger protein ZFP57

BackgroundKRAB-zinc finger proteins (KZFPs) represent one of the largest families of DNA binding proteins in vertebrate genomes and appear to have evolved to silence transposable elements (TEs) including endogenous retroviruses through sequence-specific targeting of repressive chromatin states. ZFP57 is required to maintain the post-fertilization DNA methylation memory of parental-origin at genomic imprints along with ZFP445 which is specific for imprints. However, ZFP57 has multiple methylated genomic targets. Here we conduct RNA-seq and ChIP-seq analyses in normal and ZFP57 mutant mouse ES cells to understand the relative importance of ZFP57 at unique and repetitive regions of the genome.\n\nResultsOver 80% of ZFP57 targets are TEs, however, ZFP57 is not essential for their repression. The remaining targets lie within unique imprinted and non-imprinted sequences. Though loss of ZFP57 influences imprinted genes as expected, the majority of unique gene targets lose H3K9me3 with little effect on DNA methylation and very few exhibiting alterations in expression. Comparison with DNA methyltransferase-deleted ES cells (TKO) identifies remarkably similar losses of H3K9me3 and changes in expression, defining regions where H3K9me3 is secondary to DNA methylation. We show that ZFP57 is the principal methylation-sensitive KZFP recruiting KAP1 and H3K9me3 in ES cells. Finally, like imprints, other unique targets of ZFP57 are enriched for germline-derived DNA methylation including oocyte-specific methylation that is resistant to post-fertilisation epigenetic reprogramming.\n\nConclusionOur analyses suggest the evolution of a rare DNA methylation-sensitive KZFP that is not essential for repeat silencing, but whose primary function is to maintain DNA methylation and repressive histone marks at germline derived imprinting control regions.

developmental biology↗