Article

Alzheimer and Parkinson Diagnoses in Progranulin Null Mutation Carriers in an Extended Founder Family

University of Antwerp, Antwerpen, Flemish, Belgium
JAMA Neurology (Impact Factor: 7.42). 10/2007; 64(10):1436-46. DOI: 10.1001/archneur.64.10.1436
Source: PubMed

ABSTRACT

Progranulin gene (PGRN) haploinsufficiency was recently associated with ubiquitin-positive frontotemporal lobar degeneration linked to chromosome 17q21 (FTLDU-17).
To assess whether PGRN genetic variability contributed to other common neurodegenerative brain diseases, such as Alzheimer disease (AD) or Parkinson disease (PD).
Mutation analysis of PGRN.
Memory Clinic of the Middelheim General Hospital. Patients We analyzed 666 Belgian patients with AD and 255 with PD.
Results of PGRN sequencing, PGRN transcript analysis, short tandem repeat genotyping, and neuropathologic analysis.
We identified 2 patients with AD and 1 patient with PD who carried the null mutation IVS0 + 5G>C, which we reported earlier in an extensively characterized Belgian founder family, DR8, segregating FTLDU. Postmortem pathologic diagnosis of the patient with PD revealed both FTLDU and Lewy body pathologic features. In addition, we identified in PGRN only 1 other null mutation, the nonsense mutation p.Arg535X, in 1 patient with probable AD. However, in vitro analysis predicted a PGRN C-truncated protein, although it remains to be elucidated if this shortened transcript leads to haploinsufficiency.
Our mutation data indicated that null mutations are rare in patients with AD (3/666 = 0.45%) and PD (1/255 = 0.39%). Also, AD and PD clinical diagnoses in patients who carry PGRN null mutations likely result from etiologic heterogeneity rather than PGRN haploinsufficiency.

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Available from: Nathalie Brouwers, Aug 14, 2014
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    • "Black arrowheads indicate fragments that are reduced and gray arrowheads indicate fragments that are increased during processing of the GRN p.C105R mutant protein. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPTimmortalized by Ebstein Barr virus transformation of lymphocytes collected from whole blood on lithium heparin according to standard procedures (Brouwers, et al., 2007), were cultured in RPMI 1640 medium. Sequence chromatogram of GRN g.99C>A and GRN g.103G>A. "
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    ABSTRACT: Progranulin (GRN) is a secreted growth factor involved in various cellular functions and loss-of-function mutations are a major cause of frontotemporal lobar degeneration (FTLD) with TDP-43 positive pathology. The majority of FTLD-related GRN mutations are nonsense mutations resulting in reduced GRN expression. Non-synonymous GRN missense mutations have been described as risk factor for neurodegenerative brain diseases, but their pathogenic nature remains largely elusive. We identified a double missense mutation in GRN leading to amino acid changes p.D33E and p.G35R in a FTLD patient from Turkish origin. Biochemical and cell biological analysis of the double-mutation together with two sofar uncharacterised GRN missense mutations (p.C105R and p.V514M) revealed a reduced secretion efficiency of the GRN p.D33E/p.G35R and p.C105R proteins. Furthermore, loss of the conserved cysteine residue affects protein folding and altered proteolytic processing by neutrophil elastase and proteinase 3. Our data indicate that the described variants may cause a loss-of-function, albeit to a lesser extent than GRN null mutations, and hence could be considered as low penetrant risk factors for neurodegenerative diseases.
    Full-text · Article · Dec 2015 · Neurobiology of aging
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    • "HEK 293FT and microglia BV-2 cells were maintained in DMEM Glutamax cell culture media (Life Technologies), supplemented with 10% fetal calf serum (Sigma Aldrich) and non-essential amino acids (Life Technologies). Epstein Barr virus transformed lymphoblast cells [12,59] were cultured in RPMI 1640 medium (Life Technologies), supplemented with 10% fetal calf serum (Sigma Aldrich) and glutamine (Life Technologies). 5 × 105 cells per ml were seeded and treated with 0.5 μM (LCLs) or 0.13 μM (BV-2) 5-aza-2′-deoxycytidine (DAC, Sigma Aldrich), dissolved in DMSO. Due to the low half-life of DAC, the cell culture media and DAC was replaced daily. "
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    ABSTRACT: Background Frontotemporal lobar degeneration (FTLD) is a heterogeneous group of neurodegenerative diseases associated with personality changes and progressive dementia. Loss-of-function mutations in the growth factor progranulin (GRN) cause autosomal dominant FTLD, but so far the pathomechanism of sporadic FTLD is unclear. Results We analyzed whether DNA methylation in the GRN core promoter restricts GRN expression and, thus, might promote FTLD in the absence of GRN mutations. GRN expression in human lymphoblast cell lines is negatively correlated with methylation at several CpG units within the GRN promoter. Chronic treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (DAC) strongly induces GRN mRNA and protein levels. In a reporter assay, CpG methylation blocks transcriptional activity of the GRN core promoter. In brains of FTLD patients several CpG units in the GRN promoter are significantly hypermethylated compared to age-matched healthy controls, Alzheimer and Parkinson patients. These CpG motifs are critical for GRN promoter activity in reporter assays. Furthermore, DNA methyltransferase 3a (DNMT3a) is upregulated in FTLD patients and overexpression of DNMT3a reduces GRN promoter activity and expression. Conclusion These data suggest that altered DNA methylation is a novel pathomechanism for FTLD that is potentially amenable to targeted pharmacotherapy.
    Full-text · Article · May 2013
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    • "Among the missense mutations studied, two (p.P248L and p.R432C) were reported to lead to decreased secretion, and one (p.C139R) reduces PGRN production, stability and patient plasma levels [7,25,32]. p.S120Y, is unlikely to be pathogenic since it is found in control patients [37,38] was found to promote neurite outgrowth similar to WT rPGRN. In contrast, rPGRN with p.C139R, p.R432C or p.P248L mutations did not stimulate neurite outgrowth, suggesting that these mutations adversely affect PGRN function and may be pathogenic, which would be consistent with previous genetic studies [39,40]. "
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    ABSTRACT: Progranulin (PGRN), a widely secreted growth factor, is involved in multiple biological functions, and mutations located within the PGRN gene (GRN) are a major cause of frontotemporal lobar degeneration with TDP-43-positive inclusions (FLTD-TDP). In light of recent reports suggesting PGRN functions as a protective neurotrophic factor and that sortilin (SORT1) is a neuronal receptor for PGRN, we used a Sort1-deficient (Sort1 −/− ) murine primary hippocampal neuron model to investigate whether PGRN’s neurotrophic effects are dependent on SORT1. We sought to elucidate this relationship to determine what role SORT1, as a regulator of PGRN levels, plays in modulating PGRN’s neurotrophic effects. As the first group to evaluate the effect of PGRN loss in Grn knockout primary neuronal cultures, we show neurite outgrowth and branching are significantly decreased in Grn −/− neurons compared to wild-type (WT) neurons. More importantly, we also demonstrate that PGRN overexpression can rescue this phenotype. However, the recovery in outgrowth is not observed following treatment with recombinant PGRN harboring missense mutations p.C139R, p.P248L or p.R432C, indicating that these mutations adversely affect the neurotrophic properties of PGRN. In addition, we also present evidence that cleavage of full-length PGRN into granulin peptides is required for increased neuronal outgrowth, suggesting that the neurotrophic functions of PGRN are contained within certain granulins. To further characterize the mechanism by which PGRN impacts neuronal morphology, we assessed the involvement of SORT1. We demonstrate that PGRN induced-outgrowth occurs in the absence of SORT1 in Sort1 −/− cultures. We demonstrate that loss of PGRN impairs proper neurite outgrowth and branching, and that exogenous PGRN alleviates this impairment. Furthermore, we determined that exogenous PGRN induces outgrowth independent of SORT1, suggesting another receptor(s) is involved in PGRN induced neuronal outgrowth.
    Full-text · Article · Jul 2012 · Molecular Neurodegeneration
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