Joshua Luo
Joshua Luo
Class of 2023
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Project: Single-molecule investigation of the interaction between MeCP2 and chromatin
Project: Single-molecule investigation of the interaction between MeCP2 and chromatin
Mentors: Dr. Shixin Liu and Gabriella Chua, Rockefeller University
Mentors: Dr. Shixin Liu and Gabriella Chua, Rockefeller University
2nd place in Cellular and Molecular Biology, Terra NYC STEM Fair ‘22
Semifinalist, Regeneron Science Talent Search ‘23
Semifinalist, New York-Metro Junior Science and Humanities Symposium ‘23
2nd place in Cellular and Molecular Biology, Terra NYC STEM Fair ‘23
While DNA encodes all genetic information, DNA can be subject to epigenetic modifications including methylation, which is the addition of a methyl group to a DNA base. Methylation sites are often occupied by methyl-binding proteins such as methyl-CpG-binding protein 2 (MeCP2). It’s important to study MeCP2 because mutations in MeCP2 cause Rett syndrome (RTT), a fatal neurological disorder. As a methyl binding protein, MeCP2 prefers to bind to methylated DNA over unmethylated DNA.
However, methods used by previous studies often lack the ability to track individual MeCP2 proteins along complex binding substrates, meaning that MeCP2 cannot be tracked along chromatin. If MeCP2 can be observed on chromatin, its activity will more closely resemble its behavior in the human body, potentially revealing the mechanisms of MeCP2 behind RTT and aiding in the development of potential RTT treatment strategies.
By combining optical tweezers with fluorescence microscopy to observe MeCP2 on the single-molecule level, I found that MeCP2 preferentially bound to nucleosomes over its canonical binding site, methylated DNA. When MeCP2 was increased to 5x concentration, it was able to bind to methylated DNA once it had saturated all nucleosome binding sites. Additionally, I implicated the importance of the MeCP2 c-terminus in MeCP2-nucleosome binding; specifically, that the 210 - 270 amino acid range of MeCP2 was highly responsible for nucleosome affinity.
Taken together, these results suggest the importance of nucleosomes in MeCP2 function. MeCP2 seems to navigate through nucleosomes in order to reach methylated DNA, with nucleosomes acting as “sinks,” regulating the amount of available MeCP2 for nucleosome binding. These findings generate unexpected, powerful, and previously unknown evidence that the bulk of MeCP2 binding and recruiting activity is directed toward nucleosomes, providing a new and compelling angle for disease intervention.
[online] Joshua Luo Senior Poster Final.pdfQ & A with Joshua
Q & A with Joshua
Most difficult part of your research project?
Learning each step of every single method involved in my research (site-directed mutagenesis, protein purification, optical tweezers, fluorescent microscopy). I messed up in all of these methods many many times in my attempts to master them, and by the end of my research project, was able to conduct each method relatively independently.
Most satisfying part of your research project?
Finally finishing collecting all of my data after two summers, as I was most definitely satisfied with the amount of work I had been able to complete in the lab. It’s truly a great feeling to look back and see how far one’s ASR journey has gone.
Coolest part of your research project?
Being allowed to operate cutting-edge technology independently. For example, I was allowed to operate optical tweezers on my own, which isn’t something a lot of people can say. In the process of using them, it was amazing to see how all these tiny pieces came together to view the behavior of minuscule molecules.
Proudest accomplishment in ASR?
Finishing my research paper. I had spent many hours trying to perfect it, and I’m really happy with how I stitched all the tiny pieces of my research into one coherent paper.
What were some of your fears and worries when you applied to ASR, and what would you say to younger students who have them?
One of my biggest worries was finding what to study, as I hadn't extensively thought about it before ASR. However, this was quickly addressed with the help of Mr. Yashin. When he had me conduct tons of background reading on various areas of interest, I quickly found an affinity for epigenetics.
What’s a misconception that people have about ASR or ASR students?
That all ASR students are extremely smart and gifted. I don’t think intellect is the main thing that matters for ASR. Rather, I believe that you’ll reap the benefits of the time and effort you put into your ASR work. At the end of the day, it’s the effort you put into your work that matters.
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