Bio

Honors & Awards


  • Damon Runyon Fellow, Damon Runyon Cancer Research Foundation (2013-2016)

Professional Education


  • Bachelor of Science, University Of The Negev (2006)
  • Master of Science, Weizmann Institute Of Science (2008)
  • Doctor of Philosophy, Weizmann Institute Of Science (2012)

Stanford Advisors


Research & Scholarship

Current Research and Scholarly Interests


The overarching goal of the Brunet lab is to understand the genetic mechanisms of aging and longevity. Aging is a highly plastic process regulated by a combination of genetic and environmental factors.

I am interested in the basic molecular components that characterize “young” and “aged” cellular states. Aging is associated with an increased onset of cancer, and I seeks to define the set of factors that can rejuvenate an aged cell, without the risk of malignant transformation. Ultimately, we might be able to design strategies to directly convert “old” cells from a patient into “young” ones, eventually developing more effective cancer therapies and prevention methods.

Publications

Journal Articles


  • Pharyngeal mesoderm regulatory network controls cardiac and head muscle morphogenesis PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Harel, I., Maezawa, Y., Avraham, R., Rinon, A., Ma, H., Cross, J. W., Leviatan, N., Hegesh, J., Roy, A., Jacob-Hirsch, J., Rechavi, G., Carvajal, J., Tole, S., Kioussi, C., Quaggin, S., Tzahor, E. 2012; 109 (46): 18839-18844

    Abstract

    The search for developmental mechanisms driving vertebrate organogenesis has paved the way toward a deeper understanding of birth defects. During embryogenesis, parts of the heart and craniofacial muscles arise from pharyngeal mesoderm (PM) progenitors. Here, we reveal a hierarchical regulatory network of a set of transcription factors expressed in the PM that initiates heart and craniofacial organogenesis. Genetic perturbation of this network in mice resulted in heart and craniofacial muscle defects, revealing robust cross-regulation between its members. We identified Lhx2 as a previously undescribed player during cardiac and pharyngeal muscle development. Lhx2 and Tcf21 genetically interact with Tbx1, the major determinant in the etiology of DiGeorge/velo-cardio-facial/22q11.2 deletion syndrome. Furthermore, knockout of these genes in the mouse recapitulates specific cardiac features of this syndrome. We suggest that PM-derived cardiogenesis and myogenesis are network properties rather than properties specific to individual PM members. These findings shed new light on the developmental underpinnings of congenital defects.

    View details for DOI 10.1073/pnas.1208690109

    View details for Web of Science ID 000311576300048

    View details for PubMedID 23112163

  • The actin regulator N-WASp is required for muscle-cell fusion in mice PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Gruenbaum-Cohen, Y., Harel, I., Umansky, K., Tzahor, E., Snapper, S. B., Shilo, B., Schejter, E. D. 2012; 109 (28): 11211-11216

    Abstract

    A fundamental aspect of skeletal myogenesis involves extensive rounds of cell fusion, in which individual myoblasts are incorporated into growing muscle fibers. Here we demonstrate that N-WASp, a ubiquitous nucleation-promoting factor of branched microfilament arrays, is an essential contributor to skeletal muscle-cell fusion in developing mouse embryos. Analysis both in vivo and in primary satellite-cell cultures, shows that disruption of N-WASp function does not interfere with the program of skeletal myogenic differentiation, and does not affect myoblast motility, morphogenesis and attachment capacity. N-WASp-deficient myoblasts, however, fail to fuse. Furthermore, our analysis suggests that myoblast fusion requires N-WASp activity in both partners of a fusing myoblast pair. These findings reveal a specific role for N-WASp during mammalian myogenesis. WASp-family elements appear therefore to act as universal mediators of the myogenic cell-cell fusion mechanism underlying formation of functional muscle fibers, in both vertebrate and invertebrate species.

    View details for DOI 10.1073/pnas.1116065109

    View details for Web of Science ID 000306642100042

    View details for PubMedID 22736793

  • The occipital lateral plate mesoderm is a novel source for vertebrate neck musculature DEVELOPMENT Theis, S., Patel, K., Valasek, P., Otto, A., Pu, Q., Harel, I., Tzahor, E., Tajbakhsh, S., Christ, B., Huang, R. 2010; 137 (17): 2961-2971

    Abstract

    In vertebrates, body musculature originates from somites, whereas head muscles originate from the cranial mesoderm. Neck muscles are located in the transition between these regions. We show that the chick occipital lateral plate mesoderm has myogenic capacity and gives rise to large muscles located in the neck and thorax. We present molecular and genetic evidence to show that these muscles not only have a unique origin, but additionally display a distinct temporal development, forming later than any other muscle group described to date. We further report that these muscles, found in the body of the animal, develop like head musculature rather than deploying the programme used by the trunk muscles. Using mouse genetics we reveal that these muscles are formed in trunk muscle mutants but are absent in head muscle mutants. In concordance with this conclusion, their connective tissue is neural crest in origin. Finally, we provide evidence that the mechanism by which these neck muscles develop is conserved in vertebrates.

    View details for DOI 10.1242/dev.049726

    View details for Web of Science ID 000280780900017

    View details for PubMedID 20699298

  • Epidermal progenitors give rise to Merkel cells during embryonic development and adult homeostasis JOURNAL OF CELL BIOLOGY Van Keymeulen, A., Mascre, G., Youseff, K. K., Harel, I., Michaux, C., De Geest, N., Szpalski, C., Achouri, Y., Bloch, W., Hassan, B. A., Blanpain, C. 2009; 187 (1): 91-100

    Abstract

    Merkel cells (MCs) are located in the touch-sensitive area of the epidermis and mediate mechanotransduction in the skin. Whether MCs originate from embryonic epidermal or neural crest progenitors has been a matter of intense controversy since their discovery >130 yr ago. In addition, how MCs are maintained during adulthood is currently unknown. In this study, using lineage-tracing experiments, we show that MCs arise through the differentiation of epidermal progenitors during embryonic development. In adults, MCs undergo slow turnover and are replaced by cells originating from epidermal stem cells, not through the proliferation of differentiated MCs. Conditional deletion of the Atoh1/Math1 transcription factor in epidermal progenitors results in the absence of MCs in all body locations, including the whisker region. Our study demonstrates that MCs arise from the epidermis by an Atoh1-dependent mechanism and opens new avenues for study of MC functions in sensory perception, neuroendocrine signaling, and MC carcinoma.

    View details for DOI 10.1083/jcb.200907080

    View details for Web of Science ID 000270452800012

    View details for PubMedID 19786578

  • Distinct Origins and Genetic Programs of Head Muscle Satellite Cells DEVELOPMENTAL CELL Harel, I., Nathan, E., Tirosh-Finkel, L., Zigdon, H., Guimaraes-Camboa, N., Evans, S. M., Tzahor, E. 2009; 16 (6): 822-832

    Abstract

    Adult skeletal muscle possesses a remarkable regenerative capacity, due to the presence of satellite cells, adult muscle stem cells. We used fate-mapping techniques in avian and mouse models to show that trunk (Pax3(+)) and cranial (MesP1(+)) skeletal muscle and satellite cells derive from separate genetic lineages. Similar lineage heterogeneity is seen within the head musculature and satellite cells, due to their shared, heterogenic embryonic origins. Lineage tracing experiments with Isl1Cre mice demonstrated the robust contribution of Isl1(+) cells to distinct jaw muscle-derived satellite cells. Transplantation of myofiber-associated, Isl1-derived satellite cells into damaged limb muscle contributed to muscle regeneration. In vitro experiments demonstrated the cardiogenic nature of cranial- but not trunk-derived satellite cells. Finally, overexpression of Isl1 in the branchiomeric muscles of chick embryos inhibited skeletal muscle differentiation in vitro and in vivo, suggesting that this gene plays a role in the specification of cardiovascular and skeletal muscle stem cell progenitors.

    View details for DOI 10.1016/j.devcel.2009.05.007

    View details for Web of Science ID 000267203700009

    View details for PubMedID 19531353

  • The contribution of Islet1-expressing splanchnic mesoderm cells to distinct branchiomeric muscles reveals significant heterogeneity in head muscle development DEVELOPMENT Nathan, E., Monovich, A., Tirosh-Finkel, L., Harrelson, Z., Rousso, T., Rinon, A., Harel, I., Evans, S. M., Tzahor, E. 2008; 135 (4): 647-657

    Abstract

    During embryogenesis, paraxial mesoderm cells contribute skeletal muscle progenitors, whereas cardiac progenitors originate in the lateral splanchnic mesoderm (SpM). Here we focus on a subset of the SpM that contributes to the anterior or secondary heart field (AHF/SHF), and lies adjacent to the cranial paraxial mesoderm (CPM), the precursors for the head musculature. Molecular analyses in chick embryos delineated the boundaries between the CPM, undifferentiated SpM progenitors of the AHF/SHF, and differentiating cardiac cells. We then revealed the regionalization of branchial arch mesoderm: CPM cells contribute to the proximal region of the myogenic core, which gives rise to the mandibular adductor muscle. SpM cells contribute to the myogenic cells in the distal region of the branchial arch that later form the intermandibular muscle. Gene expression analyses of these branchiomeric muscles in chick uncovered a distinct molecular signature for both CPM- and SpM-derived muscles. Islet1 (Isl1) is expressed in the SpM/AHF and branchial arch in both chick and mouse embryos. Lineage studies using Isl1-Cre mice revealed the significant contribution of Isl1(+) cells to ventral/distal branchiomeric (stylohyoid, mylohyoid and digastric) and laryngeal muscles. By contrast, the Isl1 lineage contributes to mastication muscles (masseter, pterygoid and temporalis) to a lesser extent, with virtually no contribution to intrinsic and extrinsic tongue muscles or extraocular muscles. In addition, in vivo activation of the Wnt/beta-catenin pathway in chick embryos resulted in marked inhibition of Isl1, whereas inhibition of this pathway increased Isl1 expression. Our findings demonstrate, for the first time, the contribution of Isl1(+) SpM cells to a subset of branchiomeric skeletal muscles.

    View details for DOI 10.1242/dev.007989

    View details for Web of Science ID 000252679600005

    View details for PubMedID 18184728

Stanford Medicine Resources: