Multi-Granulin Domain Peptides Bind to Pro-Cathepsin D and Stimulate Its Enzymatic Activity More Effectively Than Progranulin <i>in Vitro</i>

Butler, Victoria; Cortopassi, Wilian A.; Gururaj, Sushmitha; Wang, Austin L.; Pierce, Olivia M; Jacobson, Matthew P.; Kao, Aimee W.

doi:10.1021/acs.biochem.9b00275

Cited by 34 publications

(36 citation statements)

References 35 publications

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“…1c). CTSD has also been implicated in multiple neurodegenerative diseases and was previously demonstrated to associate with PGRN, affecting both CTSD levels and activity [14,[34][35][36][37][38][39]. One recent study reported that prolonged incubation (16 hours) of PGRN with CTSD at pH 3.5 can lead to PGRN cleavage, although low molecular weight granulin-sized bands were not observed [20].…”

Section: Resultsmentioning

confidence: 99%

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Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration

Mohan

Sampognaro

Argouarch

et al. 2020

Preprint

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Background: Progranulin loss-of-function mutations are linked to frontotemporal lobar degeneration with TDP-43 positive inclusions (FTLD-TDP-Pgrn). Progranulin (PGRN) is an intracellular and secreted pro-protein that is proteolytically cleaved into individual granulin peptides, which are increasingly thought to contribute to FTLD-TDP-Pgrn disease pathophysiology. Intracellular PGRN is processed into granulins in the endo-lysosomal compartments. Therefore, to better understand the conversion of intracellular PGRN into granulins, we systematically tested the ability of different classes of endo-lysosomal proteases at a range of pH setpoints.Results: In vitro cleavage assays identified multiple enzymes that can process human PGRN into multi- and single-granulin fragments in a pH-dependent manner. We confirmed the role of cathepsin B and cathepsin L in PGRN processing and showed that these and several previously unidentified lysosomal proteases (cathepsins E, G, K, S and V) are able to process PGRN in variable, pH-dependent manners. In addition, we have demonstrated a new role for asparagine endopeptidase (AEP) in processing PGRN, with AEP having the unique ability to liberate granulin F from the pro-protein. Brain tissue from individuals with FTLD-TDP-Pgrn show increased PGRN processing to granulin F, correlating with increased activity of AEP, in a region-specific manner. Conclusions: This study demonstrates that multiple lysosomal proteases may work in concert to liberate granulins and implicates both AEP and granulin F in the neurobiology of FTLD-TDP-Pgrn. Modulating progranulin cleavage may represent a new strategy to modulate PGRN and granulin levels in disease.

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Section: Resultsmentioning

confidence: 99%

“…1a). Fragments consisting of multiple granulins have also been previously described [12,13], and these multi-granulin fragments (MGFs) exert biological activities as well [14]. PGRN is secreted into the extracellular matrix where proteases, such as neutrophil elastase, may process PGRN [6,8,15].…”

Section: Introductionmentioning

confidence: 99%

Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration

Mohan

Sampognaro

Argouarch

et al. 2020

Preprint

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“…A few have also argued that increased proteolysis of PGRN as a reason for haploinsufficiency, which will directly correlate with increased GRN levels (57). A more recent study established that more effective proteolytic processing of cathepsin D, an aspartyl protease that is known to cleave PGRN, occurs in the presence of GRNs (92), which seem to support the idea that generation of GRNs to be the reason for decreased availability of PGRN. Results presented in this study establish a potential mechanism by which GRNs directly interact with TDP-43CTD and modulate the latter's ability to aggregate and/or phase separate (Fig 6).…”

Section: Discussionmentioning

confidence: 96%

Granulins modulate liquid-liquid phase separation and aggregation of TDP-43 C-terminal domain

Bhopatkar

Uversky

Rangachari

2019

Preprint

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Tar DNA binding protein (TDP-43) has emerged as a key player in many neurodegenerative pathologies including frontotemporal lobar degeneration (FTLD) and amyotropic lateral sclerosis (ALS). Important hallmarks of FTLD and ALS are the toxic cytoplasmic inclusions of Cterminal fragments of TDP-43 (TDP-43CTD), which are formed upon proteolytic cleavage of fulllength TDP-43 in the nucleus and subsequent transport to the cytoplasm. TDP-43CTD is also known to form stress granules (SGs) by coacervating with RNA in cytoplasm under stress conditions and are believed to be involved in modulating the pathologies. Among other factors affecting these pathologies, the pleiotropic protein called progranulin (PGRN) has gained significant attention lately. The haploinsufficiency of PGRN, caused by autosomal dominant mutations in GRN gene, results in its loss-of-function linked to FTLD and ALS. But precisely how the protein contributes to the pathology remains unknown. Recently, cleavage to GRNs were observed to be a significant part of FTLD and ALS progression with specific GRNs exacerbating TDP-43-induced toxicity in C.elegans. In this report, we show that GRNs -3 and -5 directly interact with TDP-43CTD to modulate latter's aggregation or stress granule formation in disparate ways in vitro. These results constitute the first observation of direct interaction between GRNs and TDP-43 and suggest a mechanism by which the loss of PGRN function could lead to FTLD and ALS.

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“…In vitro , progranulin added to recombinant cathepsin D protects this protein from high temperature-induced denaturation/degradation ( Beel et al, 2017 ). Progranulin stabilizes the propeptide of cathepsin D, promoting autocatalysis at the active site ( Butler et al, 2019 ). In the absence of progranulin, levels of cathepsin D (both pro and mature) accumulate, although enzyme activity decreases, a key indicator of lysosomal dysfunction ( Götzl et al, 2018 ).…”

Section: Progranulinmentioning

confidence: 99%

Secreted Chaperones in Neurodegeneration

Chaplot

Jarvela

Lindberg

2020

Front. Aging Neurosci.

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Protein homeostasis, or proteostasis, is a combination of cellular processes that govern protein quality control, namely, protein translation, folding, processing, and degradation. Disruptions in these processes can lead to protein misfolding and aggregation. Proteostatic disruption can lead to cellular changes such as endoplasmic reticulum or oxidative stress; organelle dysfunction; and, if continued, to cell death. A majority of neurodegenerative diseases involve the pathologic aggregation of proteins that subverts normal neuronal function. While prior reviews of neuronal proteostasis in neurodegenerative processes have focused on cytoplasmic chaperones, there is increasing evidence that chaperones secreted both by neurons and other brain cells in the extracellular – including transsynaptic – space play important roles in neuronal proteostasis. In this review, we will introduce various secreted chaperones involved in neurodegeneration. We begin with clusterin and discuss its identification in various protein aggregates, and the use of increased cerebrospinal fluid (CSF) clusterin as a potential biomarker and as a potential therapeutic. Our next secreted chaperone is progranulin; polymorphisms in this gene represent a known genetic risk factor for frontotemporal lobar degeneration, and progranulin overexpression has been found to be effective in reducing Alzheimer’s- and Parkinson’s-like neurodegenerative phenotypes in mouse models. We move on to BRICHOS domain-containing proteins, a family of proteins containing highly potent anti-amyloidogenic activity; we summarize studies describing the biochemical mechanisms by which recombinant BRICHOS protein might serve as a therapeutic agent. The next section of the review is devoted to the secreted chaperones 7B2 and proSAAS, small neuronal proteins which are packaged together with neuropeptides and released during synaptic activity. Since proteins can be secreted by both classical secretory and non-classical mechanisms, we also review the small heat shock proteins (sHsps) that can be secreted from the cytoplasm to the extracellular environment and provide evidence for their involvement in extracellular proteostasis and neuroprotection. Our goal in this review focusing on extracellular chaperones in neurodegenerative disease is to summarize the most recent literature relating to neurodegeneration for each secreted chaperone; to identify any common mechanisms; and to point out areas of similarity as well as differences between the secreted chaperones identified to date.

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Multi-Granulin Domain Peptides Bind to Pro-Cathepsin D and Stimulate Its Enzymatic Activity More Effectively Than Progranulin in Vitro

Cited by 34 publications

References 35 publications

Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration

Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration

Granulins modulate liquid-liquid phase separation and aggregation of TDP-43 C-terminal domain

Secreted Chaperones in Neurodegeneration

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