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Michael Grunstein

Publications and source records attributed to Michael Grunstein.

At least 19 recordsLinked to original sources
PubMed2006

Histone H2B deacetylation at lysine 11 is required for yeast apoptosis induced by phosphorylation of H2B at serine 10.

Chromatin alterations, induced by covalent histone modifications, mediate a wide range of DNA-templated processes, including apoptosis. Apoptotic chromatin condensation has been causally linked to the phosphorylation of histone H2B (serine 14 in human; serine 10 in yeast, H2BS10ph) in human and yeast cells. Here, we extend these studies by demonstrating a unidirectional, crosstalk pathway between H2BS10 phosphorylation and lysine 11 acetylation (H2BK11ac) in yeast. We demonstrate that the H2BK11 acetyl mark, which exists in growing yeast, is removed upon H(2)O(2) treatment but before H2BS10ph occurs, in a unidirectional fashion. H2B K11Q mutants are resistant to cell death elicited by H(2)O(2), while H2B K11R mutants that mimic deacetylation promote cell death. Our results suggest that Hos3 HDAC deacetylates H2BK11ac, which in turn mediates H2BS10ph by Ste20 kinase. Together, these studies underscore a concerted series of enzyme reactions governing histone modifications that promote a switch from cell proliferation to cell death.

Acetylation↗
PubMed2006

Genome-wide patterns of histone modifications in yeast.

Post-translational histone modifications and histone variants generate complexity in chromatin to enable the many functions of the chromosome. Recent studies have mapped histone modifications across the Saccharomyces cerevisiae genome. These experiments describe how combinations of modified and unmodified states relate to each other and particularly to chromosomal landmarks that include heterochromatin, subtelomeric chromatin, centromeres, origins of replication, promoters and coding regions. Such patterns might be important for the regulation of heterochromatin-mediated silencing, chromosome segregation, DNA replication and gene expression.

Chromosomes, Fungal↗
PubMed2006

Acetylation of H2AZ Lys 14 is associated with genome-wide gene activity in yeast.

Histone variants and their post-translational modifications help regulate chromosomal functions. Htz1 is an evolutionarily conserved H2A variant found at several promoters in the yeast Saccharomyces cerevisiae. In this study, we undertook a genome-wide analysis of Htz1 and its modifications in yeast. Using mass spectrometric analysis, we determined that Htz1 is acetylated at Lys 3, Lys 8, Lys 10, and Lys 14 within its N-terminal tail, with K14 being the most abundant acetylated site. ChIP and microarray analysis were then used to compare the location of Htz1-K14 acetylation to that of Htz1 genome-wide. The data presented here demonstrate that while Htz1 is associated preferentially with the promoters of repressed genes, K14 acetylation is enriched at the promoters of active genes, and requires two known histone acetyltransferases, Gcn5 and Esa1. In support of our genome-wide analysis, we found that the acetylatable lysines of Htz1 are required for its full deposition during nucleosome reassembly upon repression of PHO5. Since the majority of Htz1 acetylation is seen at active promoters, where nucleosomes are known to be disassembled, our data argue for a dynamic process in which reassembly of Htz1 is regulated by its acetylation at promoters during transcription.

Acetylation↗
PubMed2005

Cotranscriptional set2 methylation of histone H3 lysine 36 recruits a repressive Rpd3 complex.

The yeast histone deacetylase Rpd3 can be recruited to promoters to repress transcription initiation. Biochemical, genetic, and gene-expression analyses show that Rpd3 exists in two distinct complexes. The smaller complex, Rpd3C(S), shares Sin3 and Ume1 with Rpd3C(L) but contains the unique subunits Rco1 and Eaf3. Rpd3C(S) mutants exhibit phenotypes remarkably similar to those of Set2, a histone methyltransferase associated with elongating RNA polymerase II. Chromatin immunoprecipitation and biochemical experiments indicate that the chromodomain of Eaf3 recruits Rpd3C(S) to nucleosomes methylated by Set2 on histone H3 lysine 36, leading to deacetylation of transcribed regions. This pathway apparently acts to negatively regulate transcription because deleting the genes for Set2 or Rpd3C(S) bypasses the requirement for the positive elongation factor Bur1/Bur2.

Acetylation↗
PubMed2005

Genomewide analysis of nucleosome density histone acetylation and HDAC function in fission yeast.

We have conducted a genomewide investigation into the enzymatic specificity, expression profiles, and binding locations of four histone deacetylases (HDACs), representing the three different phylogenetic classes in fission yeast (Schizosaccharomyces pombe). By directly comparing nucleosome density, histone acetylation patterns and HDAC binding in both intergenic and coding regions with gene expression profiles, we found that Sir2 (class III) and Hos2 (class I) have a role in preventing histone loss; Clr6 (class I) is the principal enzyme in promoter-localized repression. Hos2 has an unexpected role in promoting high expression of growth-related genes by deacetylating H4K16Ac in their open reading frames. Clr3 (class II) acts cooperatively with Sir2 throughout the genome, including the silent regions: rDNA, centromeres, mat2/3 and telomeres. The most significant acetylation sites are H3K14Ac for Clr3 and H3K9Ac for Sir2 at their genomic targets. Clr3 also affects subtelomeric regions which contain clustered stress- and meiosis-induced genes. Thus, this combined genomic approach has uncovered different roles for fission yeast HDACs at the silent regions in repression and activation of gene expression.

Acetylation↗
PubMed2005

Histone H2B ubiquitylation controls processive methylation but not monomethylation by Dot1 and Set1.

Methylation is a relatively stable histone modification, yet regulation of the transition between mono-, di-, and trimethylation of lysine (K) residues may control dynamic processes such as transcription and DNA repair. Identifying factors that regulate the ability of methyltransferases to perform successive rounds of methylation on the same lysine residue is important for understanding the functions of histone methylation. Previous reports have indicated that ubiquitylation of histone H2B K123 is required for methylation of lysines 4 and 79 of histone H3 by the methyltransferases Set1 and Dot1, respectively. In contrast, by using chromatin immunoprecipitation and mass spectrometry, we find that ubiquitylation of H2B-K123 is dispensable for monomethylation of H3-K4 and H3-K79 but is required for the transition from monomethylation to subsequent methylation states. Dot1 binding to chromatin occurs normally in the absence of H2B-K123 ubiquitylation, suggesting that ubiquitylation does not regulate enzyme recruitment but does regulate the processive activity of the histone methyltransferase.

Chromatin Immunoprecipitation↗
PubMed2005

Global histone modification patterns predict risk of prostate cancer recurrence.

Aberrations in post-translational modifications of histones have been shown to occur in cancer cells but only at individual promoters; they have not been related to clinical outcome. Other than being targeted to promoters, modifications of histones, such as acetylation and methylation of lysine and arginine residues, also occur over large regions of chromatin including coding regions and non-promoter sequences, which are referred to as global histone modifications. Here we show that changes in global levels of individual histone modifications are also associated with cancer and that these changes are predictive of clinical outcome. Through immunohistochemical staining of primary prostatectomy tissue samples, we determined the percentage of cells that stained for the histone acetylation and dimethylation of five residues in histones H3 and H4. Grouping of samples with similar patterns of modifications identified two disease subtypes with distinct risks of tumour recurrence in patients with low-grade prostate cancer. These histone modification patterns were predictors of outcome independently of tumour stage, preoperative prostate-specific antigen levels, and capsule invasion. Thus, widespread changes in specific histone modifications indicate previously undescribed molecular heterogeneity in prostate cancer and might underlie the broad range of clinical behaviour in cancer patients.

Acetylation↗
PubMed2005

Acetylation in histone H3 globular domain regulates gene expression in yeast.

In Saccharomyces cerevisiae, known histone acetylation sites regulating gene activity are located in the N-terminal tails protruding from the nucleosome core. We report lysine 56 in histone H3 as a novel acetylation site that is located in the globular domain, where it extends toward the DNA major groove at the entry-exit points of the DNA superhelix as it wraps around the nucleosome. We show that K56 acetylation is enriched preferentially at certain active genes, such as those coding for histones. SPT10, a putative acetyltransferase, is required for cell cycle-specific K56 acetylation at histone genes. This allows recruitment of the nucleosome remodeling factor Snf5 and subsequent transcription. These findings indicate that histone H3 K56 acetylation at the entry-exit gate enables recruitment of the SWI/SNF nucleosome remodeling complex and so regulates gene activity.

Acetylation↗
PubMed2004

Mapping global histone acetylation patterns to gene expression.

Histone acetyltransferases and deacetylases with specificities for different sites of acetylation affect common chromatin regions. This could generate unique patterns of acetylation that may specify downstream biological processes. To search for existence of these patterns and their relationship to gene activity, we analyzed the genome-wide acetylation profiles for eleven lysines in the four core histones of Saccharomyces cerevisiae. We find that both hyper- and hypoacetylation of individual lysines are associated with transcription, generating distinct patterns of acetylation that define groups of biologically related genes. The genes within these groups are significantly coexpressed, mediate similar physiological processes, share unique cis-regulatory DNA motifs, and are enriched for binding of specific transcription factors. Our data also indicate that the in vivo binding of the transcription factor Bdf1 is associated with acetylation on most lysines but relative deacetylation on H4 lysine 16. Thus, certain acetylation patterns may be used as surfaces for specific protein-histone interactions, providing one mechanism for coordinate regulation of chromatin processes that are biologically related.

Acetylation↗
PubMed2003

Genomewide histone acetylation microarrays.

Histone acetylation and methylation are important regulators of gene activity. Chromatin immunoprecipitation (ChIP or ChrIP) has made it possible to examine not only the state of histone acetylation at a gene but also that of histone methylation and may soon be extended to other histone modifications such as phosphorylation and ubiquitination. In principle such studies are possible as long as an antibody is available to the particular histone modification. Once a target gene is identified it is instructive to see the effect of mutating putative enzymes responsible for the modification to determine how a particular enzyme is responsible for altering chromatin of that gene. Although specific target genes have been studied that contain such modifications recent technical advances have made it possible to study histone modifications genomewide. This not only allows for alternate views of particular paradigms to be investigated, but also uncovers chromosomal patterns of histone modification that would be missed in analyzing individual genes. We describe here an approach to rapidly study histone modifications genomewide by combining chromatin immunoprecipitation and DNA microarrays.

Acetylation↗
PubMed2003

In vivo protein-protein and protein-DNA crosslinking for genomewide binding microarray.

Chromatin immunoprecipitation (ChrIP or ChIP) has commonly been used to map protein-DNA interaction sites at specific genomic loci through use of formaldehyde-induced crosslinking. However, formaldehyde alone has proved inadequate for crosslinking of certain proteins such as the yeast histone deacetylase Rpd3. We report here a modified crosslinking procedure that includes a protein-protein crosslinking agent in addition to formaldehyde. Using this double crosslinking method, we have successfully mapped Rpd3 binding sites in vivo. We also describe the use of ChrIP in combination with DNA microarrays (ChrIP-array) to determine the pattern of Rpd3 binding genomewide. This approach couples the versatility of ChrIP with that of microarrays to identify binding patterns that would otherwise be hidden in a gene-by-gene survey.

Base Sequence↗
PubMed2003

Histone acetylation and deacetylation in yeast.

Histone acetylation and deacetylation in the yeast Saccharomyces cerevisiae occur by targeting acetyltransferase and deacetylase enzymes to gene promoters and, in an untargeted and global manner, by affecting most nucleosomes. Recently, new roles for histone acetylation have been uncovered, not only in transcription but also in DNA replication, repair and heterochromatin formation. Interestingly, specific acetylatable lysines can function as binding sites for regulatory factors. Moreover, histone deacetylation is not only repressive but can be required for gene activity.

Acetyltransferases↗
PubMed2003

Identification of a functional domain within the essential core of histone H3 that is required for telomeric and HM silencing in Saccharomyces cerevisiae.

Fourteen novel single-amino-acid substitution mutations in histone H3 that disrupt telomeric silencing in Saccharomyces cerevisiae were identified, 10 of which are clustered within the alpha1 helix and L1 loop of the essential histone fold. Several of these mutations cause derepression of silent mating locus HML, and an additional subset cause partial loss of basal repression at the GAL1 promoter. Our results identify a new domain within the essential core of histone H3 that is required for heterochromatin-mediated silencing.

Gene Silencing↗
PubMed2002

Requirement of Hos2 histone deacetylase for gene activity in yeast.

Histone deacetylases, typified by class I Rpd3 in the yeast Saccharomyces cerevisiae, have historically been associated with gene repression. We now demonstrate that Hos2, another member of the class I family, binds to the coding regions of genes primarily during gene activation, when it specifically deacetylates the lysines in H3 and H4 histone tails. Moreover, Hos2 is preferentially associated with genes of high activity genome-wide. We also show that Hos2 and an associated factor, Set3, are necessary for efficient transcription. Therefore, our data indicate that, in contrast to other class I histone deacetylases, Hos2 is directly required for gene activation.

Acetylation↗
PubMed2002

Sir2p and Sas2p opposingly regulate acetylation of yeast histone H4 lysine16 and spreading of heterochromatin.

The Sir3 protein helps form telomeric heterochromatin by interacting with hypoacetylated histone H4 lysine 16 (H4-Lys16). The molecular nature of the heterochromatin boundary is still unknown. Here we show that the MYST-like acetyltransferase Sas2p is required for the acetylation (Ac) of H4-Lys16 in euchromatin. In a sas2Delta strain or a phenocopy Lys16Arg mutant, Sir3p spreads from roughly 3 kb to roughly 15 kb, causing hypoacetylation and repression of adjacent chromatin. We also found that disruption of Sir3p binding in a deacetylase-deficient Sir 2Delta strain can be suppressed by sas2Delta. These data indicate that opposing effects of Sir2p and Sas2p on acetylation of H4-Lys16 maintain the boundary at telomeric heterochromatin.

Acetylation↗
PubMed2002

Genome-wide binding map of the histone deacetylase Rpd3 in yeast.

We describe the genome-wide distribution of the histone deacetylase and repressor Rpd3 and its associated proteins Ume1 and Ume6 in Saccharomyces cerevisiae. Using a new cross-linking protocol, we found that Rpd3 binds upstream of many individual genes and upstream of members of gene classes with similar functions in anabolic processes. In addition, Rpd3 is preferentially associated with promoters that direct high transcriptional activity. We also found that Rpd3 was absent from large sub-telomeric domains. We show by co-immunoprecipitation and by the high similarity of their binding maps that Ume1 interacts with Rpd3. In contrast, despite the known role of Ume6 in Rpd3 recruitment, only a limited number of the genes targeted by Rpd3 are also enriched for (or targeted by) Ume6. This suggests that Rpd3 is brought to many promoters by alternative recruiters, some of which may bind the putative cis-regulatory DNA elements that we have identified in sets of Rpd3 target genes. Finally, we show that comparing the genome-wide pattern of Rpd3 binding with gene expression and histone acetylation in the rpd3 Delta mutant strain reveals new sites of Rpd3 function.

Acetylation↗
PubMed2002

Rap1-Sir4 binding independent of other Sir, yKu, or histone interactions initiates the assembly of telomeric heterochromatin in yeast.

In Saccharomyces cerevisiae, heterochromatin-like regions are found near telomeres and at the silent mating-type loci, where they can repress genes in an epigenetic manner. Several proteins are involved in telomeric heterochromatin structure including Rap1, Sir2, Sir3, Sir4, yKu70 (Hdf1), yKu80 (Hdf2), and the N termini of histones H3 and H4. By recognizing cis-acting DNA-binding sites, Rap1 is believed to recruit Sir and other silencing proteins and determine where heterochromatin forms. The integrity of heterochromatin also requires the binding of Sir proteins to histones that may form a scaffold for Sir protein interactions with chromatin. In this study we describe how the heterochromatin complex may form initially and how it differs from the complex that spreads along the chromosome. We found that close to the telomere end, Sir4 can bind Rap1 independently of Sir2, Sir3, yKu70/yKu80, and the intact H4 N terminus. In contrast, Sir4 binding requires all of the silencing factors further along telomeric heterochromatin. These data indicate that Sir4 binding to Rap1 initiates the sequential association of Sir and other proteins, allowing the subsequent spreading of the heterochromatin proteins along the chromosome.

Antigens, Nuclear↗