The François Jacob Institute of Biology brings together five departments and three services
The last two years in scientific news
Group leader: Carole Escartin
We study astrocytes, a type of brain glial cells that play key supporting roles for neurons. Under pathological conditions, such as neurodegenerative diseases, astrocytes become reactive. This is defined by morphological changes, but the functional consequences remain unclear (Ben Haim et al., Front. Cell. Neuro., 2015; Escartin et al., Glia, 2019). Given the importance of astrocytes for brain homeostasis, any change in their functions may have major effects on neuron survival.
We develop new molecular tools to modulate and monitor reactive astrocytes in situ, in order to better understand the roles of these complex cells.
1. Viral vectors to selectively modulate astrocyte reactivity in vivoWe identified the JAK2-STAT3 pathway as a key signaling pathway controlling the reactive state of astrocytes in neurodegenerative diseases (Ben Haim et al., J. Neurosci., 2015; Ceyzériat et al., Neuroscience, 2016; Ceyzériat et al., Acta Neuropathol. Com., 2018). As part of a young investigator ANR project, we developed viral vectors targeting this pathway in astrocytes, to specifically activate or deactivate them in vivo. With these molecular tools, it is possible to:
2. Molecular and functional changes in reactive astrocytes in vivoOur earlier in vivo studies of reactive astrocytes induced by the cytokine CNTF, revealed significant changes in multiple important astrocyte functions (Escartin et al. J. Neurosci, 2006; 2007; Seidel et al., Glia, 2015). Thanks to a FRC grant, we further showed that reactive astrocytes alter synaptic transmission and plasticity in the hippocampus (Ceyzériat et al., Acta Neuropathol. Com., 2018). Through grants from ANR and Fondation Maladies Rares, we are now exploring the molecular and functional heterogeneity of reactive astrocytes, and implement multi-omics analysis of reactive glial cells in ND models.
3. Reactive astrocytes as biomarkers for pathological situations Reactive astrocytes appear under pathological conditions, and thus could be used as biomarkers for brain diseases. In collaboration with the brain imaging teams in MIRCen, we showed that reactive astrocytes are detected by positron emission tomography (PET) with radiotracers for TSPO, a protein previously described as a reactive microglia marker (Lavisse et al. J. Neurosci., 2012).
4. Reactive astrocytes as therapeutic targets for neurodegenerative diseasesFinally, through grants from ANR, LECMA/Vaincre Alzheimer, FRC and Neuratris, we assess whether reactive astrocytes impact molecular, cellular, functional and behavioral disease outcomes, in mouse models of Huntington's and Alzheimer's diseases (HD and AD), and more recently of demyelinating disorders. We find that reactive astrocytes are rather beneficial in HD (Escartin et al., J. Neurosci., 2006; Ben Haim et al., J. Neurosci., 2015) while they have mainly deleterious roles in AD (Ceyzériat et al., Acta Neuropathol. Com., 2018 ; Guillemaud et al., Neurobiol Aging, 2020).
Virus-mediated expression of a SOCS3 in astrocytes in an AD mouse model (3xTg) blunts astrocyte reaction and restores synaptic long term potentiation, a form of synaptic plasticity. Ceyzériat et al., Acta Neuropathol. Com., 2018. In collaboration with A. Panatier.
For a complete list of publications, click here.
Questions and (some) answers on reactive astrocytes.Escartin C, Guillemaud O, Carrillo-de Sauvage M.Glia. 2019 Dec;67(12):2221-2247
The complex STATes of astrocyte reactivity: How are they controlled by the JAK-STAT3 pathway? Ceyzériat K, Abjean L, Carrillo-de Sauvage MA, Ben Haim L, Escartin C. Neuroscience. 2016. 330:205-18. Invited Forefront Review.
Elusive roles for reactive astrocytes in neurodegenerative diseases. Ben Haim L, Carrillo-de Sauvage M-A, Ceyzériat K, Escartin C. Front. Cell. Neurosci. 9 : 278. 2015
The neuroprotective agent CNTF decreases neuronal metabolites in the rat striatum : an in vivo multimodal magnetic resonance imaging study.
Carrillo-de Sauvage M-A, Flament J, Bramoulle Y, Ben Haim L, Guillermier M, Berniard A, Auregan G, Houitte D, Brouillet E, Bonvento G, Hantraye P, Valette J, Escartin C.
J Cereb Blood Flow Meta. 2015. 35:917-21.
The JAK/STAT3 pathway is a common inducer of astrocyte reactivity in Alzheimer's and Huntington's disease.Ben Haim L, Ceyzériat K, Carrillo-de Sauvage M-A, Aubry F, Auregan G, Guillermier M, Ruiz M, Petit F, Houitte D, Faivre E, Vandesquille M, Aron-Badin R, Dhenain M, Déglon N, Hantraye P, Brouillet E, Bonvento G, Escartin C.
J Neurosci. 2015. 35(6):2817-29.
Connexin 30 sets synaptic strength by controlling astroglial synapse invasion.
Pannasch U, Freche D, Dallérac G, Ghézali G, Escartin C, Ezan P, Cohen-Salmon M, Benchenane K, Abudara V, Dufour A, Lübke JH, Déglon N, Knott G, Holcman D, Rouach N.
Nat Neurosci. 2014. 17(4):549-58.
Reactive astrocytes overexpress TSPO and are detected by TSPO
Lavisse S, Guillermier M, Hérard AS, Petit F, Delahaye M, Van Camp N, Ben Haim L, Lebon V, Remy P, Dollé F, Delzescaux T, Bonvento G, Hantraye P, Escartin C.
J. Neurosci. 2012. 32(32):10809-18.
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