One of the most interesting areas in chromatin research is investigating chromatin function in stem cells such as
embryonic stem (ES) cells induced pluripotent stem
cells (iPS). These studies will have impact on the fields of chromatin biology, cancer, and regenerative medicine.
Some of the best tools for investigating chromatin function include functional genomics methods such as ChIP-chip (chromatin immunoprecipitation coupled with array analysis) or ChIP-Seq, immunostaining cells with antibodies against specific modified forms of histones, quantifying modified histones using acid extraction and either Western blot or mass spectrometric analysis.
Stem and tumor cells have unique chromatin structure, often reflecting a globally more active chromatin state that "normal" cells. In addition to possible roles of Myc in stem and tumor cells, I am also interested in the histone modifying enzymes themselves that regulate chromatin structure including histone acetyltransferases such as GCN5 (KAT2A) and histone methylases and demethylases (KMTs and KDMs).
Please visit our stem cell blog.
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| What is chromatin? Walther Flemming referred to chromatin as the darkly staining (from Greek 'Khroma' for "color") nuclear material. Chromatin is DNA "packaged" with histones and other proteins. Inactive heterochromatic foci stain darkly by EM (left).
I am interested in the influence of chromatin and gene expression on stem and tumor cell biology. One important observation from our research, as one can see in the animated model above, is that the loss of Myc appears to result in dramatic spreading of heterochromatic foci. The mechanisms underlying this global chromatin function of Myc remain to be defined, but our initial evidence would suggest a dual model in which Myc operates both directly through its own DNA binding and recruitment of histone modifying enzymes but also indirectly through regulating expression of the HAT GCN5.
- Paul Knoepfler
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In the movie above, N-Myc levels correlate with active chromatin and larger
nuclear size, while repressive chromatin increases in knockout nuclei
with progressively less N-Myc. N-Myc floxed cerebellar granule neural progenitors.
Paul S. Knoepfler, Ph.D.
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