Explore the vast range of titles available.

Progranulin (PGRN) is predominantly expressed by microglia in the brain, and genetic and experimental evidence suggests a critical role in Alzheimer's disease (AD). We asked whether PGRN expression is changed in a disease severity‐specific manner in AD. We measured PGRN in cerebrospinal fluid (CSF) in two of the best‐characterized AD patient cohorts, namely the Dominant Inherited Alzheimer's Disease Network (DIAN) and the Alzheimer's Disease Neuroimaging Initiative (ADNI). In carriers of AD causing dominant mutations, cross‐sectionally assessed CSF PGRN increased over the course of the disease and significantly differed from non‐carriers 10 years before the expected symptom onset. In late‐onset AD, higher CSF PGRN was associated with more advanced disease stages and cognitive impairment. Higher CSF PGRN was associated with higher CSF soluble TREM2 (triggering receptor expressed on myeloid cells 2) only when there was underlying pathology, but not in controls. In conclusion, we demonstrate that, although CSF PGRN is not a diagnostic biomarker for AD, it may together with sTREM2 reflect microglial activation during the disease. Synopsis Neuroinflammation and microgliosis are key pathological features of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) protein levels analysis in large AD patients' cohorts reveals that CSF levels of Progranulin (PGRN) together with soluble TREM2 may serve as a microglia activity marker in AD. CSF PGRN increases in carriers of autosomal‐dominant AD from the Dominant Inherited Alzheimer's Disease Network (DIAN), causing dominant mutations 10 years before the expected symptom onset. CSF PGRN increases in late‐onset AD patients from the Alzheimer's disease Neuroimaging Initiative (ADNI) cohort during the course of the disease and is associated with cognitive decline. CSF PGRN and CSF soluble TREM2 (sTREM2), both of which have key regulatory functions in microglia, are associated specifically when there is underlying neurodegeneration. CSF PGRN together with CSF sTREM2 may serve as microglial activity markers and could be used to prove target engagement in clinical trials aiming to modulate microglial activity. Graphical Abstract Neuroinflammation and microgliosis are key pathological features of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) protein levels analysis in large AD patients' cohorts reveals that CSF levels of Progranulin (PGRN) together with soluble TREM2 may serve as a microglia activity marker in AD.

Background Pathogenic heterozygous mutations in the progranulin gene ( GRN ) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. Methods Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. Results We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers ( p  = 0.007) with a trend in non-carriers ( p  = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. Conclusions These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

BackgroundTriple negative breast cancer (TNBC) is characterized by invasiveness and short survival. Identifying novel TNBC-targeted therapies, to potentiate standard of care (SOC) therapy, is an unmet need. Progranulin (PGRN/GP88) is a biological driver of tumorigenesis, survival, and drug resistance in several cancers including breast cancer (BC). PGRN/GP88 tissue expression is an independent prognostic factor of recurrence while elevated serum PGRN/GP88 level is associated with poor outcomes. Since PGRN/GP88 expression is elevated in 30% TNBC, we investigated the involvement of progranulin on TNBC.MethodsThe effect of inhibiting PGRN/GP88 expression in TNBC cells by siRNA was investigated. The effects of a neutralizing anti-human PGRN/GP88 monoclonal antibody AG01 on the proliferation and migration of two TNBC cell lines expressing PGRN/GP88 were then examined in vitro and in vivo.ResultsInhibition of GP88 expression by siRNA and AG01 treatment to block PGRN/GP88 action reduced proliferation and migration in a dose-dependent fashion in MDA-MB-231 and HS578-T cells. Western blot analysis showed decreased expression of phosphorylated protein kinases p-Src, p-AKT, and p-ERK upon AG01 treatment, as well as inhibition of tumor growth and Ki67 expression in vivo.ConclusionPGRN/GP88 represents a therapeutic target with companion diagnostics. Blocking PGRN/GP88 with antibody treatment may provide novel-targeted solutions in TNBC treatment which could eventually address the issue of toxicity and unresponsiveness associated with SOC.

Background Chronic kidney disease (CKD) is a prevalent global health issue characterized by progressive renal dysfunction and fibrosis, often leading to end-stage renal failure. Renal fibrosis, a hallmark of CKD, is driven by complex immune responses, including macrophage polarization and inflammatory signaling pathways. Progranulin (PGRN), a glycoprotein involved in inflammation and tissue repair, has emerged as a key regulator in various fibrotic diseases. However, the precise role of PGRN in macrophage polarization and renal fibrosis in CKD remains unclear and warrants further investigation. Methods Renal tissue samples from CKD patients and unilateral ureteral obstruction (UUO)-induced mice were analyzed using immunohistochemistry, immunofluorescence, Western blotting, and qRT-PCR to assess fibrosis, macrophage infiltration, and key markers of autophagy and inflammation. Recombinant PGRN (rPGRN) was administered in vivo to assess its effects on renal fibrosis, macrophage polarization, and autophagic flux. To evaluate the role of PGRN, PGRN knockout (PGRN −/− ) mice were also utilized. The effects of PGRN on autophagic flux and mitochondrial dynamics were studied using mCherry-GFP-LC3 dual-labeling, and macrophage polarization was analyzed by flow cytometry and cytokine profiling. Results PGRN expression is significantly elevated in CKD patients and UUO mice and is associated with increased macrophage infiltration and renal fibrosis. rPGRN administration in vivo aggravated fibrosis and promoted M2 macrophage polarization. In contrast, PGRN −/− mice showed reduced renal fibrosis, significantly reduced collagen deposition, and reduced expression of pro-fibrotic cytokines. In addition, the mitochondrial function of PGRN −/− renal fibrosis mice was improved, the mtDNA content of mouse kidney tissue was increased, the results of electron microscopy showed that the mitochondrial structure was relatively normal, the mitochondrial biogenesis related genes PGC1α, TOMM20 and Fis1 were up-regulated, and the levels of MFN2 and Drp1 were significantly reduced. In addition, autophagy related gene LC3 was decreased and P62 protein level was increased in PGRN −/− model mice. Mechanically, PGRN interacts with autophagy related proteins ATG5 and ATG12 to regulate autophagy flux through the PI3K-Akt signaling pathway and promote the polarization of M2 macrophages. Conclusion PGRN plays a critical role in driving renal fibrosis by regulating macrophage polarization, autophagy, and mitochondrial dynamics. Our findings suggest that PGRN exacerbates CKD progression by promoting M2 macrophage polarization and disrupting autophagic processes, highlighting PGRN as a potential therapeutic target for the treatment of CKD and renal fibrosis.

Progranulin is a pro-protein that is necessary for maintaining lysosomal function. Loss-of-function progranulin ( GRN ) mutations are a dominant cause of frontotemporal dementia (FTD). Brains of people with FTD due to GRN mutations accumulate lysosomal storage material and exhibit increased expression of lysosomal transcripts, which may be driven by TFEB and related transcription factors. While this may be a compensatory response to lysosomal impairment, overproduction of lysosomal proteins may also contribute to FTD pathogenesis. To investigate how TFEB may contribute to disease in people with GRN mutations, we analyzed the effects of TFEB overexpression in progranulin-insufficient cells and mice. We generated GRN knockout HEK-293 cells ( GRN KO cells), which exhibited increased nuclear localization of TFEB and expression of lysosomal transcripts, but impaired autophagy. TFEB overexpression in GRN KO cells further increased lysosomal transcripts and partially normalized autophagy. We next injected an AAV vector expressing mouse Tfeb (AAV-TFEB) into the thalamus of Grn –/– mice, which accumulates lysosomal storage material. AAV-TFEB increased lysosomal transcripts and reduced immunoreactivity for SCMAS, a marker of lysosomal storage material, in Grn –/– thalamus. These data show that TFEB activity alleviates some autophagy-lysosomal deficits caused by progranulin insufficiency, suggesting potential utility of lysosome-based therapies for GRN -associated diseases.

Background 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 C57BL/6 mouse strain background leads to very mild phenotypes, and pathways regulating PGRN deficiency phenotypes remain to be elucidated. Methods We generated PGRN-deficient mice in the FVB/N background and compared PGRN deficiency phenotypes between C57BL/6 and FVB/N backgrounds via immunostaining, western blot, RNA-seq, and proteomics approaches. We demonstrated a novel pathway in modifying PGRN deficiency phenotypes using inhibitor treatment and AAV-mediated overexpression in mouse models. Results 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 C57BL/6 background. sPLA2-IIA inhibition rescues PGRN deficiency phenotypes, while 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. Conclusions Our studies establish a better mouse model for FTLD- GRN and uncover novel pathways modifying PGRN deficiency phenotypes.

Progranulin (PGRN), which is produced in neurons and microglia, is a neurotrophic and anti-inflammatory glycoprotein. Human loss-of-function mutations cause frontotemporal dementia, and PGRN knockout (KO) mice are a model for dementia. In addition, PGRN KO mice exhibit severe phenotypes in models of traumatic or ischemic central nervous system (CNS) disorders, including traumatic brain injury (TBI). It is unknown whether restoration of progranulin expression in neurons (and not in microglia) might be sufficient to prevent excessive TBI-evoked brain damage. To address this question, we generated mice with Nestin-Cre-driven murine PGRN expression in a PGRN KO line (PGRN-KO NestinGrn ) to rescue PGRN in neurons. PGRN expression analysis in primary CNS cell cultures from naïve mice and in (non-) injured brain tissue from PGRN-KO NestinGrn revealed expression of PGRN in neurons but not in microglia. After experimental TBI, examination of the structural brain damage at 5 days post-injury (dpi) showed that the TBI-induced loss of brain tissue and hippocampal neurons was exacerbated in PGRN-KO Grnflfl mice (PGRN knockout with the mGrn fl-STOP-fl allele, Cre-negative), as expected, whereas the tissue damage in PGRN-KO NestinGrn mice was similar to that in PGRN-WT mice. Analysis of CD68 + immunofluorescent microglia and Cd68 mRNA expression showed that excessive microglial activation was rescued in PGRN-KO NestinGrn mice, and the correlation of brain injury with Cd68 expression suggested that Cd68 was a surrogate marker for excessive brain injury caused by PGRN deficiency. The results show that restoring neuronal PGRN expression was sufficient to rescue the exacerbated neuropathology of TBI caused by PGRN deficiency, even in the absence of microglial PGRN. Hence, endogenous microglial PGRN expression was not essential for the neuroprotective or anti-inflammatory effects of PGRN after TBI in this study. Graphical Abstract

Progranulin (PGRN), encoded by the GRN gene in humans, is a secreted growth factor implicated in a multitude of processes ranging from regulation of inflammation to wound healing and tumorigenesis. The clinical importance of PGRN became especially evident in 2006, when heterozygous mutations in the GRN gene, resulting in haploinsufficiency, were found to be one of the main causes of frontotemporal lobar degeneration (FTLD). FTLD is a clinically heterogenous disease that results in the progressive atrophy of the frontal and temporal lobes of the brain. Despite significant research, the exact function of PGRN and its mechanistic relationship to FTLD remain unclear. However, growing evidence suggests a role for PGRN in the lysosome—most striking being that homozygous GRN mutation leads to neuronal ceroid lipofuscinosis, a lysosomal storage disease. Since this discovery, several links between PGRN and the lysosome have been established, including the existence of two independent lysosomal trafficking pathways, intralysosomal processing of PGRN into discrete functional peptides, and direct and indirect regulation of lysosomal hydrolases. Here, we summarize the cellular functions of PGRN, its roles in the nervous system, and its link to multiple neurodegenerative diseases, with a particular focus dedicated to recent lysosome-related mechanistic developments.

Loss-of-function mutations in GRN cause frontotemporal lobar degeneration (FTLD). Patients with GRN mutations present with a uniform subtype of TAR DNA-binding protein 43 (TDP-43) pathology at autopsy (FTLD-TDP type A); however, age at onset and clinical presentation are variable, even within families. We aimed to identify potential genetic modifiers of disease onset and disease risk in GRN mutation carriers. The study was done in three stages: a discovery stage, a replication stage, and a meta-analysis of the discovery and replication data. In the discovery stage, genome-wide logistic and linear regression analyses were done to test the association of genetic variants with disease risk (case or control status) and age at onset in patients with a GRN mutation and controls free of neurodegenerative disorders. Suggestive loci (p<1 × 10−5) were genotyped in a replication cohort of patients and controls, followed by a meta-analysis. The effect of genome-wide significant variants at the GFRA2 locus on expression of GFRA2 was assessed using mRNA expression studies in cerebellar tissue samples from the Mayo Clinic brain bank. The effect of the GFRA2 locus on progranulin concentrations was studied using previously generated ELISA-based expression data. Co-immunoprecipitation experiments in HEK293T cells were done to test for a direct interaction between GFRA2 and progranulin. Individuals were enrolled in the current study between Sept 16, 2014, and Oct 5, 2017. After quality control measures, statistical analyses in the discovery stage included 382 unrelated symptomatic GRN mutation carriers and 1146 controls free of neurodegenerative disorders collected from 34 research centres located in the USA, Canada, Australia, and Europe. In the replication stage, 210 patients (67 symptomatic GRN mutation carriers and 143 patients with FTLD without GRN mutations pathologically confirmed as FTLD-TDP type A) and 1798 controls free of neurodegenerative diseases were recruited from 26 sites, 20 of which overlapped with the discovery stage. No genome-wide significant association with age at onset was identified in the discovery or replication stages, or in the meta-analysis. However, in the case-control analysis, we replicated the previously reported TMEM106B association (rs1990622 meta-analysis odds ratio [OR] 0·54, 95% CI 0·46–0·63; p=3·54 × 10−16), and identified a novel genome-wide significant locus at GFRA2 on chromosome 8p21.3 associated with disease risk (rs36196656 meta-analysis OR 1·49, 95% CI 1·30–1·71; p=1·58 × 10−8). Expression analyses showed that the risk-associated allele at rs36196656 decreased GFRA2 mRNA concentrations in cerebellar tissue (p=0·04). No effect of rs36196656 on plasma and CSF progranulin concentrations was detected by ELISA; however, co-immunoprecipitation experiments in HEK293T cells did suggest a direct binding of progranulin and GFRA2. TMEM106B-related and GFRA2-related pathways might be future targets for treatments for FTLD, but the biological interaction between progranulin and these potential disease modifiers requires further study. TMEM106B and GFRA2 might also provide opportunities to select and stratify patients for future clinical trials and, when more is known about their potential effects, to inform genetic counselling, especially for asymptomatic individuals. National Institute on Aging, National Institute of Neurological Disorders and Stroke, Canadian Institutes of Health Research, Italian Ministry of Health, UK National Institute for Health Research, National Health and Medical Research Council of Australia, and the French National Research Agency.

Purpose Spinal cord injury (SCI) often results in significant and catastrophic dysfunction and disability and imposes a huge economic burden on society. This study aimed to determine whether progranulin (PGRN) plays a role in the progressive damage following SCI and evaluate the potential for development of a PGRN derivative as a new therapeutic target in SCI. Methods PGRN-deficient ( Gr −/− ) and wild-type (WT) littermate mice were subjected to SCI using a weight-drop technique. Local PGRN expression following injury was evaluated by Western blotting and immunofluorescence. Basso Mouse Scale (BMS), inclined grid walking test, and inclined plane test were conducted at indicated time points to assess neurological recovery. Inflammation and apoptosis were examined by histology (Hematoxylin and Eosin (H&E) staining and Nissl staining, TUNEL assays, and immunofluorescence), Western blotting (from whole tissue protein for iNOS/p-p65/Bax/Bcl-2), and ex vivo ELISA (for TNFα/IL-1β/IL-6/IL-10). To identify the prophylactic and therapeutic potential of targeting PGRN, a PGRN derived small protein, Atsttrin, was conjugated to PLGA-PEG-PLGA thermosensitive hydrogel and injected into intrathecal space prior to SCI. BMS was recorded for neurological recovery and Western blotting was applied to detect the inflammatory and apoptotic proteins. Results After SCI, PGRN was highly expressed in activated macrophage/microglia and peaked at day 7 post-injury. Grn −/− mice showed a delayed neurological recovery after SCI at day 21, 28, 35, and 42 post-injury relative to WT controls. Histology, TUNEL assay, immunofluorescence, Western blotting, and ELISA all indicated that Grn −/− mice manifested uncontrolled and expanded inflammation and apoptosis. Administration of control-released Atsttrin could improve the neurological recovery and the pro-inflammatory/pro-apoptotic effect of PGRN deficiency. Conclusion PGRN deficiency exacerbates SCI by promoting neuroinflammation and cellular apoptosis, which can be alleviated by Atsttrin. Collectively, our data provide novel evidence of using PGRN derivatives as a promising therapeutic approach to improve the functional recovery for patients with spinal cord injury.