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1. Histone modifications & prospects
2. The nucleosome (1980s)
3. H4 isoforms resolved by electrophoresis
4. Antibodies can be raised by immunization
5. Antibodies provide exquisitely sensitive reagents
6. Modifications associated with functional effects
7. Polygene chromosomes stained with Hoechst
8. Female Xs show no selective labeling
9. Immunolabeling with anti-MLE and anti-H4acK16
10. Instar neuroblasts stained with Hoechst
11. Neuroblasts selectively labeled with antibodies
12. Modifications to individual amino acids
13. The nucleosome carries signaling information
14. Nucleosome surface markers and signaling
15. Decoding the Nucleosome
16. Histone modifying enzymes have been identified
17. Enzyme families that modify histone tails
18. Binding proteins influence chromatin structure
19. Residue-specific, histone modifications
20. H3K9 is methylated by SET-domain enzymes
21. Complex array of modifications on Histone tails
22. How the tails are coated with such an array
23. Modifications on the same amino acid differ
24. Arginines can be methylated in three different ways
25. Lysine modifications
26. Atomic structures of methylated lysines
27. H4 isoforms have different distributions
28. Rapid turn-over by modifying/de-modifying actions
29. H4 isoforms resolved by electrophoresis
30. Turnover influence by a variety of factors
31. Factors that influence histone tail acetylation
32. "cross-talk" between histone modifications
33. Histone marks may be removed or hidden
34. HP1 binds to H3 by (HMT) SUV39
35. Acetylation & phosphorylation block methylation
36. Modifications of H3 can block methylation
37. Histone modifications provide "epigenetic code" ?
38. Epigenetic/histone code hypothesis
39. Difference to nucleosome "signaling" hypothesis
40. Properties of an epigenetic code
41. Roles of chromatin modification
42. Distinguishing long and short term effects of H.M.
43. How should we look for an epigenetic code?
44. ChIP can be used to show modification distribution
45. ChIP assay
46. ChIP used to study transcriptional activity
47. ChIP shows effects of acetylation changes
48. ChIP can be combined with microarray analysis
49. The ChIP-chip procedure
50. Histone acetylation and H3K4 tri-methylation
51. Correlation of H3K4me3 & individual genes
52. Both marks are enriched at promoters in yeast
53. Summarization of results from the Young lab
54. H.M. plays crucial roles in transcription, but...
55. So where should we look?
56. Heterochromatin staining
57. Heterochromatic regions are marked by H.M.
58. H4K20me3 located at centromeres of autosomes
59. Euchromatic domains are also marked by H.M.
60. Antibodies show banding along chromosome arms
61. Epigenetic mapping is in its infancy
62. Epigenetic marking of large chromosome domains
63. Summary
64. Questions to address in the near future

Topics Covered

• Enzyme-catalyzed modification of the N-terminal tail domains of core histones provides an array of marks across the nucleosome surface and a source of epigenetic information
• this information influences protein-protein interactions during short-term regulation of ongoing transcription and is a means of maintaining or modifying patterns of gene expression from one cell generation to the next
• cellular memory
• histone modifications may constitute a heritable epigenetic code that acts in concert with the genetic code as a long-term regulator of gene expression

Links

Series:

• Epigenetics

Categories:

• Biochemistry
• Cell Biology
• Genetics & Epigenetics

Talk Citation

Publication History

• Published on October 1, 2007
• Reviewed on January 19, 2015

Financial Disclosures

• Prof. Bryan Turner has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.