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Christoforos Nikolaou Profile
Christoforos Nikolaou

@guilderstern

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Computational Biologist, Researcher at @BSRC_Fleming, author and amateur sports journalist. "What difference can you make, a single man in all this madness?"

Athens, Greece
Joined June 2009
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Christoforos Nikolaou
6 months
Really excited to see this work, in collaboration with Thomas Graf from @CRGenomica, finally out. This is the capstone of @aklonizakis PhD and if it doesn't change the way you think about enhancers forever, it will certainly challenge the view you may have had up to now. 🧵👇
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Christoforos Nikolaou
3 months
RT @Raws_LFC: Let’s take a look at what rival fans were saying about Wirtz BEFORE he chose Liverpool vs. What they are saying AFTER he chos….
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Join millions who have switched to Grok.
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Christoforos Nikolaou
4 months
RT @TheBenShepherd: I take it back. THIS is the best video so far.
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Christoforos Nikolaou
4 months
A working-class hero is something to be.
@TheAnfieldWrap
The Anfield Wrap
4 months
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@guilderstern
Christoforos Nikolaou
4 months
RT @ManUtd: Never forgotten.
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Christoforos Nikolaou
4 months
RT @oilysailor: timely reminder than Alan Shearer is one day younger than Paris Saint-Germain.
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@guilderstern
Christoforos Nikolaou
6 months
RT @aklonizakis: The last part of my PhD thesis is out! If you are interested in enhancer synergy and enhancer clusters have a look at the….
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@guilderstern
Christoforos Nikolaou
6 months
@threadreaderapp please unroll.
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@guilderstern
Christoforos Nikolaou
6 months
This work was driven at both computational and experimental levels by the brilliant @aklonizakis. A great collaboration between our lab at @BSRC_Fleming and the very special (also in my heart) @CRGenomica.
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@guilderstern
Christoforos Nikolaou
6 months
Our discovery that individual enhancers within PTCs may not only act synergistically but also antagonistically and in a differentiation-stage-specific manner, could represent as-yet-overlooked new principles of enhancer interactions.
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Christoforos Nikolaou
6 months
We don't believe these are singular cases but rather that they represent examples of complex enhancer "grammars" that can give rise to equally sophisticated gene expression programs.
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Christoforos Nikolaou
6 months
Thus, in both cases we were able to untangle intricate enhancer interactions that can be explained down at the molecular level.
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Christoforos Nikolaou
6 months
In the case of FOS, on the other hand, we were able to observe a clear binding site of the transcriptional repressor ETV6. Two tandem ETV6 sites had a strong contribution to the chromatin accessibility patterns at both early and late stages of transdifferentiation.
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Christoforos Nikolaou
6 months
For IRF8, we found binding sites for two positive regulators (PU.1 and CEBPA) being particularly important at the early stage of cell-fate transition.
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@guilderstern
Christoforos Nikolaou
6 months
In this way, we could go deeper in the particular enhancer elements that we had characterized and look at them through a "magnifying glass" in order to identify the DNA sequences that were likely responsible for the binding of transcriptional regulators.
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Christoforos Nikolaou
6 months
ChromBPNet ( not only identifies potential binding sites of transcriptional regulators but can also predict the degree to which their binding contributes to chromatin accessibility for the given conditions.
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github.com
Bias factorized, base-resolution deep learning models of chromatin accessibility (chromBPNet) - kundajelab/chrombpnet
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Christoforos Nikolaou
6 months
What could explain such behaviour? As a last step we deployed ChromBPNet, a deep learning model that can predict the specific contribution of DNA elements in regions of increased chromatin accessibility.
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@guilderstern
Christoforos Nikolaou
6 months
We now had two examples of radically different enhancer behaviour. A synergistic enhancer with elements functioning redundantly and probably compensatorily (IRF8) and -strikingly- an antagonistic one, with two elements functioning in opposite ways.
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@guilderstern
Christoforos Nikolaou
6 months
Modeling also supported the unequal contribution of the two distinct FOS enhancer elements but this time the contributions of the two elements were not only quantitatively but also qualitatively different. The upstream element having an antagonistic, repressive function.
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@guilderstern
Christoforos Nikolaou
6 months
In plain words, by removing an *enhancer* element we observed a significant and robust increase in the gene expression of the downstream gene.
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