Ernesto Guccione obtained his Master's degree in Medical Biotechnology in 2000 from Bologna University and his PhD in 2004 from the International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy. He did his postdoctoral work at the European Institute of Oncology (Milan, Italy) where he studied the role of chromatin in defining c-Myc target site recognition. He also identified PRMT6, a member of the Protein Arginine MethylTransferase family, as an important enzyme in controlling transcriptional repression. During his postdoctoral training, he spent four months as an EMBO fellow in the laboratory of J.LaBaer at Harvard Institute of Proteomics. He joined IMCB in 2008 as an Assistant Professor.

Any cell in an organism derives from the same starting genetic material. Functional distinction between cell types is acquired through sequential epigenetic modifications that shape chromatin and in turn affect transcription and cellular state. DNA methylation and Post-translational modifications (PTMs) of histones convey epigenetic information that extends the coding potential of nucleic acids, a phenomenon that has been commonly referred to as “histone code”.

Histone modification map

These PTMs are regulated and in turn influence the role of key transcription factors such as Myc. The interplay between these transcription factors, chromatin modifying enzymes and chromatin structure is of central importance in normal cell homeostasis and cancer. The long-term objective of the lab is 1) to investigate the role of Arginine and Lysines Methyltransferases (PRMTs and HMTs), two families of transcriptional co-activators/repressors that target histones, in shaping of epigenetic landscapes and cellular identity and 2) to assess the role of PRMTs and HMTs in epigenetic deregulation linked to cancer. Lately, we are focusing our interests on five PRMTs: PRMT4-7 and 9. These are responsible for the methylation of two specific arginines on histone H3 (Arg2) and H4 (Arg3). We demonstrated that these histone marks co-exist on chromatin, and that they have a potential role in transcriptional repression. Their presence at promoters is counter-correlated with c-Myc binding and gene activation (Guccione et al., 2006). We also have evidence that the methylation of H3Arg2 is responsible for the exclusion from chromatin of an activation mark (methylation at Lysine 4 on histone H3 (Guccione et al., 2007), and is linked to the methylation of lysine 27 on histone H3 (Guccione et al., 2006) and Unpublished work). This latter is catalyzed by the polycomb-group of proteins, which coordinate the transcription of developmentally-regulated genes and are involved in cancer progression. To further study the link between Arginine and Lysine methylation we will:

1) Develop reagents, including antibodies against the relevant PRMTs/HMTs, for biochemical and quantitative Chromatin ImmunoPrecipitation (qChIP) analysis, create inducible shRNA vectors to knockdown the endogenous proteins and stable cell lines overexpressing TAP-tagged versions of the enzymes.

2) Set up a routine analysis of ES differentiation to Neuronal Stem Cells and Neurons, to study the epigenetic determinants of cell identity.

3) Assess the expression of PRMT4-9 during differentiation and their binding to chromatin on a genome-wide basis. The analysis will be paralleled by genome-wide analysis of arginine methylation and will elucidate the spatial and functional crosstalk between methylation of different histone Lysines and Arginines, in ES and differentiated cells. Figure 2 summarizes possible interactions between histone modifiers that will be addressed during our studies.

Figure 2.


Legend: Activating/Euchromatic (top panel) and Repressive/Heterochromatic (bottom panel) histone modifications are indicated on the corresponding aminoacid on Histone H3 tails. The enzymes that catalyze the methylation reactions are indicated next to them. The arrows (?) indicate possible interactions between histone modifying enzymes that will be addressed in the lab.

4) Monitor the effects of PRMT knockdown on histone modifications at target loci, gene transcription, and stem cell differentiation.

5) Use biochemical methods to assess the impact of arginine methylation on the “histone code” and to identify multiprotein complexes containing PRMT activity.

6) Study the role of PRMTs and Arginine methylation in cancer, first in cell lines and cancer tissues, and in the longer term exploiting the Eµ-Myc system. As c-Myc is one of the key transcription factors controlling cell cycle progression, differentiation, stem cells maintenance, and cancer formation, all the aspects discussed above will also be studied in the context of c-Myc biology. My studies will clarify the roles and the interplay of PRMT 4-7, PRMT 9, HMTs complexes (MLL and PRC) and Myc. Unraveling the order of events that leads to transcriptional activation or repression as well as the specific identity of target genes will allow us to better understand complex events such as differentiation and cancer progression. Our studies will also help to direct the use of ‘epigenetic drugs’ towards controlled reprogramming of adult cells into stem cells, or towards the cure of specific tumours .