Thomas E Willnow

Max-Delbrück-Centrum für Molekulare Medizin, Berlín, Berlin, Germany

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Publications (162)1357.12 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The proneurotrophin receptor sortilin is a protein with dual functions, being involved in intracellular protein transport, as well as cellular signal transduction. The relevance of the receptor for various neuronal disorders, such as dementia, seizures, and brain injury, is well established. In contrast, little is known about the role of sortilin in immune cells and inflammatory diseases. The aim of our study was to elucidate the distribution of sortilin in different immune cell types in mice and humans and to analyze its function in autoimmune CNS inflammation. Sortilin was expressed most profoundly in murine and human macrophages and dendritic cells and to a much lesser extent in B and T cells. In dendritic cells, sortilin had an impact on Ag processing. Accordingly, sortilin was highly expressed by infiltrated perivascular myeloid cells, mainly in vessel cuffs, in the CNS of patients suffering from multiple sclerosis, the most common inflammatory autoimmune disease of the CNS. Yet, sortilin gene-targeted mice (Sort1(-/-)) and chimeras deficient in sortilin in the immune system were as susceptible as wild-type littermates to T cell-dependent experimental autoimmune encephalomyelitis. Considering our results and recent data from other investigators, we conclude that the proneurotrophin receptor sortilin plays a role in innate, rather than in adaptive, immune processes and, thus, not in autoimmune neuroinflammation.
    The Journal of Immunology 11/2015; DOI:10.4049/jimmunol.1403156 · 4.92 Impact Factor
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    ABSTRACT: During forebrain development, LRP2 promotes morphogen signaling as an auxiliary SHH receptor. However, in the developing retina, LRP2 assumes the opposing function, mediating endocytic clearance of SHH and antagonizing morphogen action. LRP2-mediated clearance prevents spread of SHH activity from the central retina into the retinal margin to protect quiescent progenitor cells in this niche from mitogenic stimuli. Loss of LRP2 in mice increases the sensitivity of the retinal margin for SHH, causing expansion of the retinal progenitor cell pool and hyperproliferation of this tissue. Our findings document the ability of LRP2 to act, in a context-dependent manner, as activator or inhibitor of the SHH pathway. Our current findings uncovered LRP2 activity as the molecular mechanism imposing quiescence of the retinal margin in the mammalian eye and suggest SHH-induced proliferation of the retinal margin as cause of the large eye phenotype observed in mouse models and patients with LRP2 defects.
    Developmental Cell 10/2015; DOI:10.1016/j.devcel.2015.09.001 · 9.71 Impact Factor
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    ABSTRACT: SORLA is a neuronal sorting receptor implicated both in sporadic and familial forms of AD. SORLA reduces the amyloidogenic burden by two mechanisms, either by rerouting internalized APP molecules from endosomes to the trans-Golgi network (TGN) to prevent proteolytic processing or by directing newly produced Aβ to lysosomes for catabolism. Studies in cell lines suggested that the interaction of SORLA with cytosolic adaptors retromer and GGA is required for receptor sorting to and from the TGN. However, the relevance of anterograde or retrograde trafficking forSORLAactivity in vivo remained largely unexplored. Here, we generated mouse models expressing SORLA variants lacking binding sites for GGA or retromer to query this concept in the brain. Disruption of retromer binding resulted in a retrograde-sorting defect with accumulation of SORLA in endosomes and depletion from the TGN, and in an overall enhanced APP processing. In contrast, disruption of the GGA interaction did not impact APP processing but caused increased brain Aβ levels, a mechanism attributed to a defect in anterograde lysosomal targeting of Aβ. Our findings substantiated the significance of adaptormediated sorting for SORLA activities in vivo, and they uncovered that anterograde and retrograde sorting paths may serve discrete receptor functions in amyloidogenic processes.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 09/2015; 35(37):12703-13. DOI:10.1523/JNEUROSCI.0427-15.2015 · 6.34 Impact Factor
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    ABSTRACT: The furosemide-sensitive Na(+)-K(+)-2Cl(-)-cotransporter (NKCC2) is crucial for NaCl reabsorption in kidney thick ascending limb (TAL) and drives the urine concentrating mechanism. NKCC2 activity is modulated by N-terminal phosphorylation and dephosphorylation. Serine-threonine kinases that activate NKCC2 have been identified, but less is known about phosphatases that deactivate NKCC2. Inhibition of calcineurin phosphatase has been shown to stimulate transport in the TAL and the distal convoluted tubule. Here, we identified NKCC2 as a target of the calcineurin Aβ isoform. Short-term cyclosporine administration in mice augmented the abundance of phospho-NKCC2, and treatment of isolated TAL with cyclosporine increased the chloride affinity and transport activity of NKCC2. Because sorting-related receptor with A-type repeats (SORLA) may affect NKCC2 phosphoregulation, we used SORLA-knockout mice to test whether SORLA is involved in calcineurin-dependent modulation of NKCC2. SORLA-deficient mice showed more calcineurin Aβ in the apical region of TAL cells and less NKCC2 phosphorylation and activity compared with littermate controls. In contrast, overexpression of SORLA in cultured cells reduced the abundance of endogenous calcineurin Aβ. Cyclosporine administration rapidly normalized the abundance of phospho-NKCC2 in SORLA-deficient mice, and a functional interaction between calcineurin Aβ and SORLA was further corroborated by binding assays in rat kidney extracts. In summary, we have shown that calcineurin Aβ and SORLA are key components in the phosphoregulation of NKCC2. These results may have clinical implications for immunosuppressive therapy using calcineurin inhibitors. Copyright © 2015 by the American Society of Nephrology.
    Journal of the American Society of Nephrology 05/2015; DOI:10.1681/ASN.2014070728 · 9.34 Impact Factor
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    ABSTRACT: Most lysosomal enzymes require mannose 6-phosphate (M6P) residues for efficient receptor-mediated lysosomal targeting. Although the lack of M6P residues results in missorting and hypersecretion, selected lysosomal enzymes reach normal levels in lysosomes of various cell types suggesting the existence of M6P-independent transport routes. Here, we quantify the lysosomal proteome in M6P-deficient mouse fibroblasts (PT(ki) ) using Stable Isotope Labeling by Amino acids in Cell culture (SILAC)-based comparative mass spectrometry, and find unchanged amounts of 20 % of lysosomal enzymes, including cathepsin D and B (Ctsd, Ctsb). Examination of fibroblasts from a new mouse line lacking both M6P and sortilin, a candidate for M6P-independent transport of lysosomal enzymes, revealed that sortilin does not act as cargo receptor for Ctsb and Ctsd. Using fibroblast lines deficient for endocytic lipoprotein receptors we could demonstrate that both LDL receptor and Lrp1 mediate the internalization of non-phosphorylated Ctsb and Ctsd. Furthermore, the presence of Lrp1 inhibitor increased the secretion of Ctsd from PT(ki) cells. These findings establish Lrp1 and LDL receptors in M6P-independent secretion-recapture targeting mechanism for lysosomal enzymes. This article is protected by copyright. All rights reserved.
    Traffic 03/2015; 16(7). DOI:10.1111/tra.12284 · 4.35 Impact Factor
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    ABSTRACT: Balancing trophic and apoptotic cues is critical for development and regeneration of neuronal circuits. Here we identify SorCS2 as a proneurotrophin (proNT) receptor, mediating both trophic and apoptotic signals in conjunction with p75(NTR). CNS neurons, but not glia, express SorCS2 as a single-chain protein that is essential for proBDNF-induced growth cone collapse in developing dopaminergic processes. SorCS2- or p75(NTR)-deficient in mice caused reduced dopamine levels and metabolism and dopaminergic hyperinnervation of the frontal cortex. Accordingly, both knockout models displayed a paradoxical behavioral response to amphetamine reminiscent of ADHD. Contrary, in PNS glia, but not in neurons, proteolytic processing produced a two-chain SorCS2 isoform that mediated proNT-dependent Schwann cell apoptosis. Sciatic nerve injury triggered generation of two-chain SorCS2 in p75(NTR)-positive dying Schwann cells, with apoptosis being profoundly attenuated in Sorcs2(-/-) mice. In conclusion, we have demonstrated that two-chain processing of SorCS2 enables neurons and glia to respond differently to proneurotrophins.
    Neuron 06/2014; 82(5):1074-1087. DOI:10.1016/j.neuron.2014.04.022 · 15.05 Impact Factor
  • Anne-Sophie Carlo · Anders Nykjaer · Thomas E Willnow ·
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    ABSTRACT: Sortilin is a sorting receptor that directs target proteins, such as growth factors, signaling receptors, and enzymes, to their destined location in secretory or endocytic compartments of cells. The activity of sortilin is essential for proper function of not only neurons but also non-neuronal cell types, and receptor (dys)function emerges as a major cause of malignancies, including hypercholesterolemia, retinal degeneration, neuronal cell loss in stroke and spinal cord injury, or Alzheimer's disease and other neurodegenerative disorders. In this article, we describe the molecular mechanisms of sortilin action in protein sorting and signaling and how modulation of receptor function may offer novel therapeutic strategies for treatment of common diseases of the cardiovascular and nervous systems.
    Journal of Molecular Medicine 05/2014; 92(9). DOI:10.1007/s00109-014-1152-3 · 5.11 Impact Factor
  • Vanessa Schmidt · Anne‐Sophie Carlo · Thomas E. Willnow ·
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    ABSTRACT: Unlabelled: Alzheimer disease (AD) is the most common neurodegenerative disease affecting millions of patients worldwide. According to the amyloid cascade hypothesis, the formation of neurotoxic oligomers composed of amyloid-β (Aβ) peptides is the main mechanism that causes synaptic dysfunction and, eventually, neuronal cell death in this condition. Intriguingly, apolipoprotein E (apoE), the most important genetic risk factor for sporadic AD, emerges as a key factor that contributes to many aspects of the amyloid cascade including the clearance of Aβ from brain interstitial fluid and the ability of this peptide to form neurotoxic oligomers. Central to the activity of apoE in the healthy and in the diseased brain are apoE receptors that interact with this protein to mediate its multiple cellular and systemic effects. This review describes the molecular interactions that link apoE and its cellular receptors with neuronal viability and function, and how defects in these pathways in the brain promote neurodegeneration. For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article.
    Wiley Interdisciplinary Reviews Systems Biology and Medicine 05/2014; 6(3). DOI:10.1002/wsbm.1262 · 3.21 Impact Factor
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    ABSTRACT: The low-density lipoprotein (LDL) receptor-related protein 2 (LRP2) is a multifunctional cell surface receptor expressed in the embryonic neuroepithelium. Loss of LRP2 in the developing murine central nervous system (CNS) causes impaired closure of the rostral neural tube at embryonic stage (E) 9.0. Similar neural tube defects (NTDs) have previously been attributed to impaired folate metabolism in mice. We therefore asked whether LRP2 might be required for delivery of folate to neuroepithelial cells during neurulation. Uptake assays in whole embryo cultures showed that LRP2 deficient neuroepithelial cells are unable to mediate uptake of folate bound to soluble folate receptor 1 (sFOLR1). Consequently, folate concentrations are significantly reduced in Lrp2(-/-) embryos compared to control littermates. Moreover, the folic acid dependent gene Alx3 is significantly down regulated in Lrp2 mutants. In conclusion, we show that LRP2 is essential for cellular folate uptake in the developing neural tube, a crucial step for proper neural tube closure.
    Journal of Cell Science 03/2014; 127(10). DOI:10.1242/jcs.140145 · 5.43 Impact Factor

  • Acta Physiologica 03/2014; 210:44-44. · 4.38 Impact Factor
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    ABSTRACT: SORLA/SORL1 is a unique neuronal sorting receptor for the amyloid precursor protein that has been causally implicated in both sporadic and autosomal dominant familial forms of Alzheimer's disease (AD). Brain concentrations of SORLA are inversely correlated with amyloid-β (Aβ) in mouse models and AD patients, suggesting that increasing expression of this receptor could be a therapeutic option for decreasing the amount of amyloidogenic products in affected individuals. We characterize a new mouse model in which SORLA is overexpressed, and show a decrease in Aβ concentrations in mouse brain. We trace the underlying molecular mechanism to the ability of this receptor to direct lysosomal targeting of nascent Aβ peptides. Aβ binds to the amino-terminal VPS10P domain of SORLA, and this binding is impaired by a familial AD mutation in SORL1. Thus, loss of SORLA's Aβ sorting function is a potential cause of AD in patients, and SORLA may be a new therapeutic target for AD drug development.
    Science translational medicine 02/2014; 6(223):223ra20. DOI:10.1126/scitranslmed.3007747 · 15.84 Impact Factor
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    ABSTRACT: Multiple sclerosis (MS) is a chronic neuro-inflammatory disorder, which is marked by the invasion of the central nervous system by monocyte-derived macrophages and autoreactive T cells across the brain vasculature. Data from experimental animal models recently implied that the passage of leukocytes across the brain vasculature is preceded by their traversal across the blood-cerebrospinal fluid barrier (BCSFB) of the choroid plexus. The correlation between the presence of leukocytes in the CSF of patients suffering from MS and the number of inflammatory lesions as detected by magnetic resonance imaging suggests that inflammation at the choroid plexus contributes to the disease, although in a yet unknown fashion. We here provide first insights into the involvement of the choroid plexus in the onset and severity of the disease and in particular address the role of the tight junction protein claudin-3 (CLDN3) in this process. Detailed analysis of human post-mortem brain tissue revealed a selective loss of CLDN3 at the choroid plexus in MS patients compared to control tissues. Importantly, mice that lack CLDN3 have an impaired BCSFB and experience a more rapid onset and exacerbated clinical signs of experimental autoimmune encephalomyelitis, which coincides with enhanced levels of infiltrated leukocytes in their CSF. Together, this study highlights a profound role for the choroid plexus in the pathogenesis of multiple sclerosis, and implies that CLDN3 may be regarded as a crucial and novel determinant of BCSFB integrity.
    Acta Neuropathologica 12/2013; 128(2). DOI:10.1007/s00401-013-1227-1 · 10.76 Impact Factor
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    ABSTRACT: SORCS3 is an orphan receptor of the VPS10P domain receptor family, a group of sorting and signaling receptors central to many pathways in control of neuronal viability and function. SORCS3 is highly expressed in the CA1 region of the hippocampus, but the relevance of this receptor for hippocampal activity remained absolutely unclear. Here, we show that SORCS3 localizes to the postsynaptic density and that loss of receptor activity in gene-targeted mice abrogates NMDA receptor-dependent and -independent forms of long-term depression (LTD). Consistent with a loss of synaptic retraction, SORCS3-deficient mice suffer from deficits in behavioral activities associated with hippocampal LTD, particularly from an accelerated extinction of fear memory. A possible molecular mechanism for SORCS3 in synaptic depression was suggested by targeted proteomics approaches that identified the ability of SORCS3 to functionally interact with PICK1, an adaptor that sorts glutamate receptors at the postsynapse. Faulty localization of PICK1 in SORCS3-deficient neurons argues for altered glutamate receptor trafficking as the cause of altered synaptic plasticity in the SORCS3-deficient mouse model. In conclusion, our studies have identified a novel function for VPS10P domain receptors in control of synaptic depression and suggest SORCS3 as a novel factor modulating aversive memory extinction.
    PLoS ONE 09/2013; 8(9):e75006. DOI:10.1371/journal.pone.0075006 · 3.23 Impact Factor
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    ABSTRACT: Sorting-related receptor with A-type repeats (SORLA) is a sorting receptor for the amyloid precursor protein (APP) that prevents breakdown of APP into Aβ peptides, a hallmark of Alzheimer's disease (AD). Several cytosolic adaptors have been shown to interact with the cytoplasmic domain of SORLA, thereby controlling intracellular routing of SORLA/APP complexes in cell lines. However, the relevance of adaptor-mediated sorting of SORLA for amyloidogenic processes in vivo remained unexplored. We focused on the interaction of SORLA with phosphofurin acidic cluster sorting protein (PACS) 1, an adaptor that shuttles proteins between transGolgi network (TGN) and endosomes. Using PACS1 knockdown studies in neuronal cell lines and investigations in transgenic mice expressing a PACS1-binding defective mutant of SORLA, we document that disruption of SORLA and PACS1 interaction results in the inability of SORLA/APP complexes to sort to the TGN in neurons, and in increased APP processing in the brain. Loss of PACS1 also impairs proper expression of the cation-independent mannose-6 phosphate receptor and its target cathepsin B, a protease that breaks down Aβ. Thus, our data identified the importance of PACS1-dependent protein sorting for control of amyloidogenic burden via both SORLA-dependent and SORLA-independent mechanisms.
    Molecular and Cellular Biology 09/2013; 33(21). DOI:10.1128/MCB.00628-13 · 4.78 Impact Factor
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    ABSTRACT: Stimulation of neurons with brain-derived neurotrophic factor (BDNF) results in robust induction of SORLA, an intracellular sorting receptor of the VPS10P domain receptor gene family. However, the relevance of SORLA for BDNF-induced neuronal responses has not previously been investigated. We now demonstrate that SORLA is a sorting factor for the tropomyosin-related kinase receptor B (TrkB) that facilitates trafficking of this BDNF receptor between synaptic plasma membranes, post-synaptic densities, and cell soma, a step critical for neuronal signal transduction. Loss of SORLA expression results in impaired neuritic transport of TrkB and in blunted response to BDNF in primary neurons; and it aggravates neuromotoric deficits caused by low BDNF activity in a mouse model of Huntington's disease. Thus, our studies revealed a key role for SORLA in mediating BDNF trophic signaling by regulating the intracellular location of TrkB.
    PLoS ONE 08/2013; 8(8):e72164. DOI:10.1371/journal.pone.0072164 · 3.23 Impact Factor
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    Thomas E Willnow · Olav M Andersen ·
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    ABSTRACT: Excessive proteolytic breakdown of the amyloid precursor protein (APP) to neurotoxic amyloid β peptides (Aβ) by secretases in the brain is a molecular cause of Alzheimer disease (AD). According to current concepts, the complex route whereby APP moves between the secretory compartment, the cell surface and endosomes to encounter the various secretases determines its processing fate. However, the molecular mechanisms that control the intracellular trafficking of APP in neurons and their contribution to AD remain poorly understood. Here, we describe the functional elucidation of a new sorting receptor SORLA that emerges as a central regulator of trafficking and processing of APP. SORLA interacts with distinct sets of cytosolic adaptors for anterograde and retrograde movement of APP between the trans-Golgi network and early endosomes, thereby restricting delivery of the precursor to endocytic compartments that favor amyloidogenic breakdown. Defects in SORLA and its interacting adaptors result in transport defects and enhanced amyloidogenic processing of APP, and represent important risk factors for AD in patients. As discussed here, these findings uncovered a unique regulatory pathway for the control of neuronal protein transport, and provide clues as to why defects in this pathway cause neurodegenerative disease.
    Journal of Cell Science 06/2013; 126(13). DOI:10.1242/jcs.125393 · 5.43 Impact Factor
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    ABSTRACT: A growing body of evidence suggests a role for soluble alpha-amyloid precursor protein (sAPPalpha) in pathomechanisms of Alzheimer disease (AD). This cleavage product of APP was identified to have neurotrophic properties. However, it remained enigmatic what proteins, targeted by sAPPalpha, might be involved in such neuroprotective actions. Here, we used high-resolution two-dimensional polyacrylamide gel electrophoresis to analyze proteome changes downstream of sAPPalpha in neurons. We present evidence that sAPPalpha regulates expression and activity of CDK5, a kinase that plays an important role in AD pathology. We also identified the cytoprotective chaperone ORP150 to be induced by sAPPalpha as part of this protective response. Finally, we present functional evidence that the sAPPalpha receptor SORLA is essential to mediate such molecular functions of sAPPalpha in neurons.
    PLoS ONE 06/2013; 8(6):e65920. DOI:10.1371/journal.pone.0065920 · 3.23 Impact Factor
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    ABSTRACT: Apolipoprotein E (APOE) is the major risk factor for sporadic Alzheimer's disease. Among other functions, APOE is proposed to sequester neurotoxic amyloid-β (Aβ) peptides in the brain, delivering them to cellular catabolism via neuronal APOE receptors. Still, the receptors involved in this process remain controversial. Here, we identified the pro-neurotrophin receptor sortilin as major endocytic pathway for clearance of APOE/Aβ complexes in neurons. Sortilin binds APOE with high affinity. Lack of receptor expression in mice results in accumulation of APOE and of Aβ in the brain and in aggravated plaque burden. Also, primary neurons lacking sortilin exhibit significantly impaired uptake of APOE/Aβ complexes despite proper expression of other APOE receptors. Despite higher than normal brain APOE levels, sortilin-deficient animals display anomalies in brain lipid metabolism (e.g., accumulation of sulfatides) seen in APOE-deficient mice, indicating functional deficiency in cellular APOE uptake pathways. Together, our findings identified sortilin as an essential neuronal pathway for APOE-containing lipoproteins in vivo and suggest an intriguing link between Aβ catabolism and pro-neurotrophin signaling converging on this receptor.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 01/2013; 33(1):358-70. DOI:10.1523/JNEUROSCI.2425-12.2013 · 6.34 Impact Factor
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Publication Stats

9k Citations
1,357.12 Total Impact Points


  • 1997-2015
    • Max-Delbrück-Centrum für Molekulare Medizin
      • • Research Team Molecular Cardiovascular Research
      • • Experimental and Clinical Research Center (ECRC)
      Berlín, Berlin, Germany
  • 2004-2012
    • Charité Universitätsmedizin Berlin
      • Institute of Vegetative Anatomy
      Berlín, Berlin, Germany
  • 2010
    • University of Dundee
      Dundee, Scotland, United Kingdom
  • 1999-2007
    • Aarhus University
      • • Department of Medical Biochemistry
      • • Institute of Anatomy
      Aars, Region North Jutland, Denmark
    • Wolfson Childrens Hospital
      Jacksonville, Florida, United States
  • 2003
    • St. Jude Children's Research Hospital
      Memphis, Tennessee, United States
  • 2002-2003
    • Freie Universität Berlin
      Berlín, Berlin, Germany
    • Wroclaw Medical University
      • Faculty of Pharmacy
      Wrocław, Lower Silesian Voivodeship, Poland
  • 2000-2002
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 1996
    • CUNY Graduate Center
      New York, New York, United States
  • 1994-1996
    • University of Texas Southwestern Medical Center
      • Department of Molecular Genetics
      Dallas, TX, United States
    • University of Texas at Dallas
      • Biochemistry
      Richardson, Texas, United States