The ever-increasing access to high-quality medical care has led to unprecedented changes in the demographic makeup of most advanced societies. Never in the history of humankind have individuals older than 65 constituted a larger percentage of global population, and the trend is predicted to persist. Dramatic changes in the prevalence of diseases have followed this demographic shift: aging is the main risk factor for many chronic conditions, some of which frequently appear simultaneously in the same individual. The incidence of neurodegenerative and cardiovascular disease, metabolic syndrome and cancer increase rapidly past age 50. We study how gene expression affects the biology of aging and aging-related diseases. Evidence from the past two decades show that the activity of genes can dramatically extend the lifespan of model organisms, unveiling an unanticipated level of plasticity in the trajectory of aging. This has led to the hope that aging can become a risk factor amenable to amelioration, thanks to research that focus on the process of aging itself, of which the single ailments can be seen as epiphenomena.
Aging is best understood at the level of whole organisms, yet none of the traditional laboratory animals are ideal for studies encompassing their entire lifespan. Yeasts or invertebrate models lack the anatomical structures that are most frequently affected by human aging-related disease, while mice or zebrafish live years - long enough to make lifespan experiments unmanageable. For these reasons, we have imported the short-lived African turquoise killifish (Nothobranchius furzeri) to the laboratory. At 3-4 months, the lifespan of turquoise killifish mirrors the ephemeral existence of its natural habitat, the seasonal lakes in South-East Africa, and is closer to D. melanogaster (3 months) than to zebrafish or mouse. Killifish shares with humans age-related phenomena such as loss of skeletal muscle mass, decreased fertility, neurological decline and high incidence of spontaneous cancers. The compressed lifespan of turquoise killifish offers the unique possibility to test multiple experimental treatments on rate of aging and lifespan in a manageable time frame. In the three years we would wait to observe the results of an experiment in an old mouse, we can study several generations of killifish, accelerating the speed at which we can explore the causes of aging-related disease with a reduction of time to new treatments.
- Aging of adult stem cells: Like humans and most vertebrates, killifish maintains the integrity of tissues thanks to the presence of pools of adult stem cells. Broadly speaking, adult stem cells can be responsible for the constant renewal of a tissue (e.g. hematopoietic stem cells) or remain quiescent unless damage requires tissue repair (e.g. muscle stem cells). In humans, aging is accompanied by stem cell exhaustion, resulting in declining function and loss of regenerative potential at the tissue and organ levels. The rapid aging of killifish offers a unique point of entry for the study of adult stem cell aging. We are particularly interested in the aging of the hematopoietic and muscle stem cells as examples of the two paradigms of adult stem cell behavior with clear implications for human health.
- Genomic instability in aging and cancer: Genomic instability is a hallmark of both cancer and aging. The accrual of mutations during aging results in the two seemingly antithetical outcomes of loss of regenerative capability (with defect in proliferation, e.g. bone marrow failure) and uncontrolled proliferation in cancer. Nothobranchius furzeri ages much faster and develops tumors much more readily than animals of similar size (hence with a similar number of cells, e.g. zebrafish) exposed to the same environment. This observation leads us to hypothesize that in Nothobranchius furzeri mechanisms of DNA damage repair are less efficient than in longer living teleost species. We are currently testing the DNA damage repair pathways in Nothobranchius furzeri and exploring the ability of factors involved in DNA damage response, stem cells exhaustion and cancer, such as Tet2 and SIRT6, to lengthen lifespan and healthspan.
- Giovanni Stefani, PI
- Marie-Laure Baudet, Armenise-Harvard laboratory of Axonal Neurobiology, CIBio, Trento, Italy
- Stefano Biressi, Dulbecco Telethon Laboratory of Stem Cells and Regenerative Biology, CIBio, Trento, Italy
- Stephanie Halene, Yale University School of Medicine, New Haven, CT, USA
- Deborah Toiber, Ben Gurion University of the Negev, Beer-Sheva, Israel
- Gabriella Viero, CNR Institute of Biophysics & Bruno Kessler Foundation, Trento, Italy
Yang Liang,* , Toma Tebaldi*, Kai Rejeski*, Giovanni Stefani* , Ashley Taylor, Jamie Maziarz, Yuanbin Song, Radovan Vasic, Edo Kapetanovic, Alessandro Quattrone, Stephanie Halene; Integrative analysis of RNA binding and splicing reveals complex loss and gain of function nature of SRSF2 mutations in myeloid malignancies. (* equal contribution) In preparation; expected publication: 2017
Xiaowei Chen, Dongjun Chung, Giovanni Stefani, Frank J. Slack, and Hongyu Zhao. Statistical issues in binding site identification through CLIP-seq. Statistics and Its Interface. 2015 Volume 8, 4; 419–436
Moyano M, Stefani G. piRNA involvement in genome stability and human cancer. J Hematol Oncol. 2015;8: 38.
Stefani G*, Chen X, Zhao H, Slack FJ*. A novel mechanism of LIN-28 regulation of let-7 microRNA expression revealed by in vivo HITS-CLIP in C. elegans. RNA. 2015;21: 985–996. (*= co-corresponding author)
Stefani G., Slack, F.; A ‘pivotal’ new rule for microRNA-mRNA interactions; Nature Structural & Molecular Biology. 2012, 19, 3, 265–266
Maller Schulman BR, Liang X, Stahlhut C, Del Conte C, Stefani G, Slack FJ. The let-7 microRNA target gene, Mlin41/Trim71 is required for mouse embryonic survival and neural tube closure. Cell Cycle. 2008 Dec 15;7(24):3935-42.
Stefani G., Slack, F.; Small non-coding RNAs in animal development. Nat Rev Mol Cell Biol. 2008 Mar 9; 3:219-30.
Stefani G.; Roles of microRNAs and their targets in cancer. Expert Opin Biol Ther. 2007 Dec 7; 12:1833-40.
Johnson, C. D.*, Esquela-Kerscher, A.*, Stefani, G.*, Byrom, M., Kelnar, K., Ovcharenko, D., Wilson, M., Wang, X., Shelton, J., Shingara, J., Chin, L., Brown, D., Slack, F. J. (* equal contribution). The let-7 MicroRNA Represses Cell Proliferation Pathways in Human Cells. Cancer Res 2007 Aug 15; 67: 7713-22
Stefani G., Slack, F.; MicroRNAs in search of a target. Cold Spring Harb Symp Quant Biol 2006 71: 129-34.
Jernej Ule*, Giovanni Stefani*, Aldo Mele, Matteo Ruggiu, Xuning Wang, Bahar Taneri, Terri Gaasterland, Benjamin J. Blencowe and Robert B. Darnell (* equal contribution). An RNA map predicting Nova-dependent splicing regulation. Nature 2006 Nov 30; 444: 580-6.
Darnell JC, Fraser CE, Mostovetsky O, Stefani G, Jones TA, Eddy SR, Darnell RB; Kissing complex RNAs mediate interaction between the Fragile-X mental retardation protein KH2 domain and brain polyribosomes, Genes Dev. 2005 Apr 15; 19: 903-18.
Dredge KB, Stefani G, Engelhard CC, Darnell RB; Nova autoregulation reveals dual functions in neuronal splicing. EMBO J. 2005, 24(8):1608-20.
Stefani G, Fraser CE, Darnell JC, Darnell RB; Fragile X mental retardation protein is associated with translating polyribosomes in neuronal cells. J Neurosci. 2004 Aug 18;24(33):7272-6.
(Featured in Editor's Choice, Science, Volume 305, Number 5690, Issue of 10 September 2004)
Talikka M, Stefani G, Brivanlou AH, Zimmerman K; Characterization of Xenopus Phox2a and Phox2b defines expression domains within the embryonic nervous system and early heart field. Gene Expr Patterns. 2004 Sep;4: 601-7
Polydorides AD, Okano HJ, Yang YY, Stefani G, Darnell RB; A brain-enriched polypyrimidine tract-binding protein antagonizes the ability of Nova to regulate neuron-specific alternative splicing. Proc Natl Acad Sci U S A. 2000 Jun 6; 97 : 6350-5
Jensen KB, Dredge BK, Stefani G, Zhong R, Buckanovich RJ, Okano HJ, Yang YY, Darnell RB; Nova-1 regulates neuron-specific alternative splicing and is essential for neuronal viability. Neuron. 2000 Feb; 25 : 359-71.
Kao HT, Porton B, Hilfiker S, Stefani G, Pieribone VA, DeSalle R, Greengard P; Molecular evolution of the synapsin gene family. J Exp Zool. 1999 Dec 15; 285 : 360-77.
G.Stefani, F. Onofri, F.Valtorta, P. Greengard, F. Benfenati; Rapid Modulation of Synapsin I binding to Synaptic Vesicles by Phosphorylation: a study using time resolved fluorescence resonance energy transfer. J Physiol. 1997 Nov 1; 504 : 501-15