Wnt Signaling as a Potential Therapeutic Target for Frontotemporal Dementia

Department of Psychiatry and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA.
Neuron (Impact Factor: 15.98). 09/2011; 71(6):955-7. DOI: 10.1016/j.neuron.2011.09.002
Source: PubMed

ABSTRACT Progranulin mutations result in frontotemporal dementia, but the underlying pathophysiology has remained largely unexplained. New data by Geschwind and colleagues in this issue of Neuron uncovered that the Wnt/FZD2 signaling pathway is an early and critical contributor to disease pathology.

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    ABSTRACT: Frontotemporal dementia (FTD) accounts for ∼50% of dementia cases before the age of 60. Up to 40% of FTD patients have a familial history (Goldman et al., 2005 and van Swieten and Heutink, 2008) due to mutations in the microtubule-associated protein tau gene (MAPT), progranulin gene (GRN), or C9orf72 gene (Baker et al., 2006, Cruts et al., 2006, DeJesus-Hernandez et al., 2011, Hutton et al., 1998 and Renton et al., 2011). The majority of FTD-causing mutations in GRN are predicted to result in functional null alleles, causing haploinsufficiency. Progranulin (PGRN) has neurotrophic function in vitro and in vivo. Although PGRN−/− mice are viable, they do not recapitulate all the features of FTD (Kayasuga et al., 2007).
    12/2014; 2(1). DOI:10.1016/j.stemcr.2014.12.001
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    ABSTRACT: To understand how haploinsufficiency of progranulin (PGRN) causes frontotemporal dementia (FTD), we created induced pluripotent stem cells (iPSCs) from patients carrying the GRNIVS1+5G > C mutation (FTD-iPSCs). FTD-iPSCs were fated to cortical neurons, the cells most affected in FTD. Although generation of neuroprogenitors was unaffected, their further differentiation into CTIP2-, FOXP2-, or TBR1-TUJ1 double-positive cortical neurons, but not motorneurons, was significantly decreased in FTD-neural progeny. Zinc finger nuclease-mediated introduction of GRN cDNA into the AAVS1 locus corrected defects in cortical neurogenesis, demonstrating that PGRN haploinsufficiency causes inefficient cortical neuron generation. RNA sequencing analysis confirmed reversal of the altered gene expression profile following genetic correction. We identified the Wnt signaling pathway as one of the top defective pathways in FTD-iPSC-derived neurons, which was reversed following genetic correction. Differentiation of FTD-iPSCs in the presence of a WNT inhibitor mitigated defective corticogenesis. Therefore, we demonstrate that PGRN haploinsufficiency hampers corticogenesis in vitro.


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Jun 3, 2014