Project description:Gene expression microarrays were used to identify how the mRNA phenotype of NSC-34 cells responds to PGRN expression levels. PGRN expression correlated well with molecular phenotypes that included mRNA pathways associated with the regulation of the cytoskeleton Gene expression profile was determined using Illumina Mouse Whole-Genome Expression BeadChips (MouseWG-6 v2.0
Project description:Multiple FTD patient-specific iPSC lines were generated for the first time, Human neurons of progranulin haploinsufficiency have been established. PGRN S116X neurons are more sensitive to kinase inhibitors-induced cell stress, which can be rescued by ectopic progranulin expression, revealing progranulin-dependent cellular defects in FTD. Microarray analysis reveals that the serine/threonine kinase S6K2 (RPS6KB2) and other genes involved in MAPK signaling are dysregulated specifically in neurons with progranulin deficiency. 32 independent human neuronal cultures were analyzed in this study
Project description:Progranulin (PGRN) is critical in supporting a healthy CNS. Its haploinsufficiency results in frontotemporal dementia, while in experimental models of age-related neurodegenerative diseases, the targeted expression of PGRN greatly slows the onset of disease phenotypes. Nevertheless, much remains unclear about how PGRN affects its target cells. In previous studies we found that PGRN showed a remarkable ability to support the survival of NSC-34 motor neuron cells under conditions that would otherwise lead to their apoptosis. Here we used the same model to investigate other phenotypes of PGRN expression in NSC-34 cells. PGRN significantly influenced morphological differentiation, resulting in cells with enlarged cell bodies and extended projections. At a molecular level this correlated with pathways associated with the cytoskeleton and synaptic differentiation. Depletion of PGRN led to increased expression of several neurotrophic receptors, which may represent a homeostatic mechanism to compensate for loss of neurotrophic support from PGRN. The exception was RET, a neurotrophic tyrosine receptor kinase, which, when PGRN levels are high, shows increased expression and enhanced tyrosine phosphorylation. Other receptor tyrosine kinases also showed higher tyrosine phosphorylation when PGRN was elevated, suggesting a generalized enhancement of receptor activity. PGRN was found to bind to multiple plasma membrane proteins, including RET, as well as proteins in the ER/Golgi apparatus/lysosome pathway. Understanding how these various pathways contribute to PGRN action may provide routes toward improving neuroprotective therapies.
Project description:NSC-34 cells produced by fusing mouse embryonic spinal cord motor neuron with neuroblastoma cells expressing reduced level of PGRN (NSC-34/ShPGRN), NSC-34 cells overexpressing hPGRN(NSC-34-/hPGRN) or vector controls were compared in triplicate
Project description:Progranulin is a secreted pro-protein that is trafficked to lysosomes and exerts protective effects in the brain. Progranulin (GRN) mutations, most of which cause progranulin haploinsufficiency, are a major genetic cause of frontotemporal dementia (FTD). Restoring progranulin to people with GRN mutations is a promising treatment strategy, but understanding progranulin’s mechanism of action may enable design of optimal progranulin-based therapies. Progranulin restrains inflammation and promotes neuronal growth and survival, but the mechanisms underlying these effects are unclear. Progranulin is constitutively secreted and interacts with various signaling receptors, but is also taken up and trafficked to lysosomes, where it is necessary for maintaining normal lysosomal function. In previous work, we showed that progranulin acts in lysosomes to promote neuronal survival, but it is not clear if progranulin enhances neuronal growth by acting in lysosomes or through extracellular signaling. To address this question, we employed lentiviral vectors expressing either progranulin (PGRN) or a non-secreted, lysosome-targeted progranulin (L-PGRN). Using lentiviral vectors driven by non-selective (PGK), neuron-selective (hSyn), or astrocyte-selective (GFAP) promoters, we found that delivering L-PGRN to astrocytes, but not neurons, promoted dendritic outgrowth in primary hippocampal cultures. Using transwell co-cultures of astrocytes and neurons, we found that neurons cultured with L-PGRN–transduced astrocytes had greater dendritic outgrowth than those cultured with GFP-transduced astrocytes. Bulk RNA sequencing of primary astrocytes indicated that L-PGRN reduced transcriptomic pathways associated with inflammation and cellular reactivity. Consistent with this result, we found that reducing the number of astrocytes in hippocampal cultures increased dendritic outgrowth and occluded the pro-growth effects of L-PGRN. These data show that under these culture conditions, progranulin secretion is not required to promote dendritic outgrowth. Instead, progranulin may act via a non-cell–autonomous mechanism to suppress secretion of factors from astrocytes that restrain neuronal growth. These data add to a growing body of evidence that progranulin can act on astrocytes to promote neuronal health.
Project description:Description: Progranulin deficiency is associated with neurodegeneration in humans and in mice. We performed a deep proteomic screen of the pre-frontal cortex in aged (13-15 months) female progranulin-deficient mice (GRN-/-) and mice with a neuron-specific inducible overexpression of progranulin (SLICK-GRN-OE with tamoxifen) versus the respective control mice (Grn+/+ and SLICK-Grn without Tamoxifen). The data set shows progranulin-dependent alterations of protein expression in the cortex of mice.
Project description:Multiple FTD patient-specific iPSC lines were generated for the first time, Human neurons of progranulin haploinsufficiency have been established. PGRN S116X neurons are more sensitive to kinase inhibitors-induced cell stress, which can be rescued by ectopic progranulin expression, revealing progranulin-dependent cellular defects in FTD. Microarray analysis reveals that the serine/threonine kinase S6K2 (RPS6KB2) and other genes involved in MAPK signaling are dysregulated specifically in neurons with progranulin deficiency.
Project description:Progranulin (GRN) mutations cause frontotemporal dementia (FTD), but GRN's function in the CNS remains largely unknown. To identify the pathways downstream of GRN, we used weighted genome co-expression network analysis (WGCNA) to develop a systems-level view of transcriptional alterations in a human neural progenitor model of GRN-deficiency. This highlighted key pathways such as apoptosis and ubiquitination in GRN deficient human neurons, while revealing an unexpected major role for the Wnt signaling pathway, which was confirmed by analysis of gene expression data from postmortem FTD brain. Furthermore, we observed that the Wnt receptor Fzd2 was one of only a few genes up-regulated at 6 weeks in a GRN knockout mouse, and that FZD2 reduction caused increased apoptosis, while its upregulation promoted neuronal survival in vitro. Together, these in vitro and in vivo data point to an adaptive role for altered Wnt signaling in GRN deficiency-mediated FTD, representing a potential therapeutic target.
Project description:Progranulin (GRN) mutations cause frontotemporal dementia (FTD), but GRN's function in the CNS remains largely unknown. To identify the pathways downstream of GRN, we used weighted genome co-expression network analysis (WGCNA) to develop a systems-level view of transcriptional alterations in a human neural progenitor model of GRN-deficiency. This highlighted key pathways such as apoptosis and ubiquitination in GRN deficient human neurons, while revealing an unexpected major role for the Wnt signaling pathway, which was confirmed by analysis of gene expression data from postmortem FTD brain. Furthermore, we observed that the Wnt receptor Fzd2 was one of only a few genes up-regulated at 6 weeks in a GRN knockout mouse, and that FZD2 reduction caused increased apoptosis, while its upregulation promoted neuronal survival in vitro. Together, these in vitro and in vivo data point to an adaptive role for altered Wnt signaling in GRN deficiency-mediated FTD, representing a potential therapeutic target. We therefore developed an in vitro model of GRN deficiency using primary human neural stem cells in which shRNA was used to diminish GRN levels to 50% or below. We developed a tetracycline inducible system in which transactivator protein rtTA3 and PuroR genes were constituitively expressed under the UBC promoter, while RFP and shRNA were regulated by an inducible tet-On CMV promoter (Gossen and Bujard, 1992). To control for off-target effects, two hairpins against GRN were used, and a scrambled hairpin was used as a control.
Project description:Haploinsufficiency of the progranulin (PGRN) protein is a leading cause of frontotemporal lobar degeneration (FTLD). Mouse models have been developed to study PGRN functions. However, PGRN deficiency in the commonly used C56BL/6 mouse strain background leads to very mild phenotypes, and pathways regulating PGRN deficiency phenotypes remain to be elucidated. We generated PGRN-deficient mice in the FVB/N background and compared PGRN deficiency phenotypes between C56BL/6 and FVB/N background via immunostaining, western blot, RNA-seq, and proteomics approaches. We also identified sPLA2-IIA as a novel binding partner of PGRN and demonstrated the importance of sPLA2-IIA in modifying PGRN deficiency phenotypes using inhibitor treatment and AAV-mediated overexpression in mouse models. We report that PGRN loss in the FVB/N mouse strain results in earlier onset and stronger FTLD-related and lysosome-related phenotypes. We found that PGRN interacts with sPLA2-IIA, a member of the secreted phospholipase A2 (sPLA2) family member and a key regulator of inflammation that is expressed in FVB/N but not C56BL/6 background. sPLA2-IIA inhibition rescues PGRN deficiency phenotypes and sPLA2-IIA overexpression drives enhanced gliosis and lipofuscin accumulation in PGRN-deficient mice. Additionally, RNA-seq and proteomics analysis revealed that mitochondrial pathways are upregulated in the PGRN-deficient C57BL/6 mice but not in the FVB/N mice. Our studies establish a better mouse model for FTLD-GRN and uncover novel pathways modifying PGRN deficiency phenotypes.