Role of the transcription factor Stat3 in inflammation and neoplastic transformation (Poli)

Signal Transducers and Activators of Transcription (STAT) factors have been identified as important players in the signalling through many cytokine and growth factor receptors. The family member STAT3 is the main mediator of gp130 cytokines functions, but its activation is triggered by many other cytokines or growth factors and indeed, in contrast with other STAT factors, STAT3 inactivation leads to early embryonic lethality. STAT3 exists in two isoforms, the full length STAT3alpha and the truncated STAT3beta. STAT3 is considered an oncogene. It is constitutively activated in a variety of tumours, where its activity is required for survival and/or proliferation, and an engineered mutant form of STAT3, STAT3C, which can dimerise independently from tyrosine phosphorylation, is able to transform fibroblasts and epithelial cells. We have generated conditional Stat3 mutant mice, and mice in which the Stat3alpha or beta isoforms have been specifically ablated. More recently, we have generated mice expressing exclusively the STAT3C form by a knock-in approach. We are making use of these mouse models to investigate the core mechanisms involved in STAT3 activities as an oncogene, at the cross-road between inflammation, immune response,tumor and stem cell niche and tumor transformation, analyzing its interactions with other oncogenes/oncosuppressor genes and trying to identify specific pro-oncogenic target genes.

Moreover, we have recently demonstrated that STAT3 constitutive activity in the liver triggers a feedback activating loop with IL6 and the IL6 receptor, leading to the activation of acute phase response genes and to the overproduction of complement factors. This in turn triggers the onset of auto-immune myocarditis. We have now started exploring the feasibility of treating myocarditis by menas of liver-specific STAT3 or C3 inactivation.

Analysis of the cross-talk between intracellular membranes and cytoskeleton (Di Cunto)

The group is interested in the molecular pathways that control the cross-talk between intracellular membranes and cytoskeleton, in biological processes as different as neuronal differentiation and cytokinesis. On the second side, we are developing new bioinformatic approaches may help experimental biologists in establishing the functions of mammalian genes and also their role in human diseases.

Analysis of gene regulation at the transcriptional and post-transcriptional level (Provero)

We are developing computational approaches to study the evolution and variation of regulatory sequences. We recently investigated the human-specific aspects of gene regulation by comparing the affinity of human regulatory regions for transcription factors [Molineris et al 2011], and by studying human-specific regulatory regions [Marnetto et al 2014]. In [Molineris, Schiavone et al. 2013] we investigated the role of genetic variation in shaping the human transcriptome by identifying variants that affect transcription factor binding. Regarding post-transcriptional regulation, our lab is interested in competing endogenous RNAs [Ala, Karreth et al 2013] and in the role of alternative polyadenylation [Lembo et al 2012]. We are developing a method to identify cellular contexts allowing cross-regulation of mRNAs through the ceRNA mechanism, and we are systematically investigating the effect of genetic variants on alternative polyadenylation.

• Homologous recombination in ES cells

• gene targeting

• mouse models of inflammation, neurodegeneration, auto-immunity and cancer
• in vivo imaging
• confocal microscopy, fluorescent microscopy
• echocardiography

• Real time PCR and RT-PCR
• Bioinformatics coexpression analysis
• Bioniformatic analysys of gene expression patterns and mechanisms of gene expression regulation

• Northern blot - slot blot

• DNA binding assays

• promoter analysis
• ChIP and ChIP-sequencing assays

• DNA-, RNA- and protein-protein interactions

1. Alonzi T., Maritano D., Gorgoni B., Rizzuto G., Libert C., Poli V. Essential role of STAT3 in the control of the acute phase response as revealed by inducible gene inactivation in the liver. (2001) Mol Cell Biol. 21, 1621-1632.

2. Costa-Pereira, A.P.,Tininini, S., Strobl, B. Alonzi, T., Schlaak, J.F., Is’harc, H., Gesualdo, I. Newman, S.J., Kerr, I.M. and Poli, V. An Interferon--like response through IL-6 in the absence of STAT3. (2002) Proc. Natl. Acad. Sci. USA 99, 8043-8047

3. Camera, P., Da Silva, J. S., Griffiths, G., Giuffrida, M. G., Ferrara, L., Schubert, V., Imarisio, S., Silengo, L., Dotti, C. G. & Di Cunto, F. Citron-N is a neuronal Rho-associated protein involved in Golgi organization through actin cytoskeleton regulation. (2003) Nature Cell Biology 5, 1071-1078

4. Maritano, D., Sugrue, M.L., Tininini, S., Dewilde, S., Strobl, B., Fu, XP, Murray-Tait, V., Chiarle, R. and Poli. V. The STAT3 isoforms,  and , play unique and specific roles. (2004) Nat. Immunol. 5, 401-409.

5. Pellegrino, M., Provero, P., Silengo, L. & Di Cunto, F. CLOE: Identification of putative functional relationships among genes by comparison of expression profiles between two species. (2004) BMC Bioinformatics 5, 179

6. Molineris I, Schiavone D, Rosa F, Matullo G, Poli V* and Provero P. Identification of functional cis-regulatory polymorphisms in the human genome. (2013) Human Mutation 34, 735-742. doi: 10.1002/humu.22299. *co-corresponding author

7. Camporeale A, Marino F, Papageorgiou A, Carai P, Fornero S, Fletcher S, Page BDG, Gunning P, Forni M, Chiarle R, Morello M, Jensen O, Levi R, Heymans S, Poli V. STAT3 activity is necessary and sufficient for the development of immune-mediated myocarditis in mice and promotes progression to dilated cardiomyopathy. (2013) EMBO Mol. Medicine 5: 572–590, DOI: 10.1002/emmm.201201876.

8. Demaria M, Camporeale A, Poli V STAT3 and metabolism: How many ways to use a single molecule? (2014) Int J Cancer, 135, 9, 1997-2003. doi: 10.1002/ijc.28767. PMID: 24500994.

9. Marino F, Orecchia V, Regis G, Musteanu M, Tassone B, Jon C, Forni M, Calautti E, Chiarle R, Eferl R, Poli V. STAT3β controls inflammatory responses and early tumor onset in skin and colon experimental cancer models. (2014) Am J Cancer Res., 4, :484-94. eCollection 2014. PMID: 25232490

10. Berto GE, Iobbi C, Camera P, Scarpa E, Iampietro C, Bianchi F, Gai M, Sgrò F, Cristofani F, Gärtner A, Dotti CG, Di Cunto F. The DCR protein TTC3 affects differentiation and Golgi compactness in neurons through specific actin-regulating pathways. PLoS One. 2014 Apr 2;9(4):e93721. doi: 10.1371/journal.pone.0093721. eCollection 2014. PMID:24695496

11. Molineris I, Ala U, Provero P, Di Cunto F. Drug repositioning for orphan genetic diseases through Conserved Anticoexpressed Gene Clusters (CAGCs). BMC Bioinformatics. 2013 Oct 2;14:288. doi: 10.1186/1471-2105-14-288. PMID:24088245.

12. Bosio Y, Berto G, Camera P, Bianchi F, Ambrogio C, Claus P, Di Cunto F. PPP4R2 regulates neuronal cell differentiation and survival, functionally cooperating with SMN. Eur J Cell Biol. 2012 Aug;91(8):662-74. doi: 10.1016/j.ejcb.2012.03.002. Epub 2012 May 3. PMID:22559936

13. Ala U, Karreth FA, Bosia C, et al. Integrated transcriptional and competitive endogenous RNA networks are cross-regulated in permissive molecular environments. Proc Natl Acad Sci U S A. 2013;110(18):7154-9. doi:10.1073/pnas.1222509110.

14. Lembo A, Di Cunto F, Provero P. Shortening of 3′UTRs Correlates with Poor Prognosis in Breast and Lung Cancer. Li J, ed. PLoS One. 2012;7(2):e31129. doi:10.1371/journal.pone.0031129.

15. Marnetto D, Molineris I, Grassi E, Provero P. Genome-wide Identification and Characterization of Fixed Human-Specific Regulatory Regions. Am J Hum Genet. 2014;95(1):39-48. doi:10.1016/j.ajhg.2014.05.011.

16. Molineris I, Grassi E, Ala U, Di Cunto F, Provero P. Evolution of promoter affinity for transcription factors in the human lineage. Mol Biol Evol. 2011;28(8):2173-2183. doi:10.1093/molbev/msr027.