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Research article
Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration
Aimee Kao
University of California San Francisco
Corresponding Author
ORCiD: https://orcid.org/0000-0002-7686-7968
License:
This work is licensed under a CC BY 4.0 License. Read Full License
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 to process PGRN 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 distinctive, 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 and an increased activity of AEP, in a region-specific manner.
Conclusions - This study demonstrates that multiple lysosomal proteases may work in concert to liberate multi-granulin fragments and granulins. It also implicates both AEP and granulin F in the neurobiology of FTLD-TDP-Pgrn. Modulating progranulin cleavage and granulin production may represent therapeutic strategies for FTLD-Pgrn and other progranulin-related diseases.
Keywords
Progranulin, granulin, frontotemporal lobar degeneration, lysosome, protease, pH, asparagine endopeptidase
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Due to technical limitations, tables 1-2 are only available as downloads in the supplemental files section.
Table 1. PGRN cleavage by lysosomal proteases in vitro
Summary of whether the enzymes tested could cleave progranulin (PGRN) or not along with the potential compartment it may cleave PGRN depending on the pH it processed progranulin in vitro. En, endosomes; Ly, lysosomes; Ex, extracellular.
Table 2. Clinical Information for control and FTLD-TDP-Pgrn subjects
Clinical information for the control and FTLD-TDP-Pgrn subjects. PMI, post-mortem interval; IOC, inferior occipital cortex; MFG, middle frontal gyrus.
This is a list of supplementary files associated with this preprint. Click to download.
- AppendixFigureMohanetal.FINAL.pdf
- TABLESMohanetal.FINAL.pdf
Table 1. PGRN cleavage by lysosomal proteases in vitro Summary of whether the enzymes tested could cleave progranulin (PGRN) or not along with the potential compartment it may cleave PGRN depending on the pH it processed progranulin in vitro. En, endosomes; Ly, lysosomes; Ex, extracellular. Table 2. Clinical Information for control and FTLD-TDP-Pgrn subjects Clinical information for the control and FTLD-TDP-Pgrn subjects. PMI, post-mortem interval; IOC, inferior occipital cortex; MFG, middle frontal gyrus.
- SupplementalFiguresMohanetal9Dec2020.pdf
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This preprint is under consideration at Molecular Neurodegeneration. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research article
Processing of progranulin into granulins involves multiple lysosomal proteases and is affected in frontotemporal lobar degeneration
Aimee Kao
University of California San Francisco
Corresponding Author
ORCiD: https://orcid.org/0000-0002-7686-7968
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Revision
Version 3
Posted 29 Dec, 2020
No community comments so far
Editorial decision: Major revision
On 29 Dec, 2020
Review #4 received
Received 22 Dec, 2020
Review #2 received
Received 21 Dec, 2020
Review #3 received
Received 21 Dec, 2020
Reviewer #4 agreed
On 15 Dec, 2020
Reviewer #2 agreed
On 13 Dec, 2020
Reviewer #3 agreed
On 13 Dec, 2020
Reviewers invited
Invitations sent on 13 Dec, 2020
Reviewer #1 agreed
On 13 Dec, 2020
Review #1 received
Received 13 Dec, 2020
Editor assigned
On 11 Dec, 2020
Submission checks complete
On 11 Dec, 2020
Editor invited
On 11 Dec, 2020
No comments provided
Editorial decision: Major revision
On 14 Oct, 2020
Review #5 received
Received 12 Oct, 2020
Review #4 received
Received 29 Sep, 2020
Reviewer #5 agreed
On 28 Sep, 2020
Review #3 received
Received 27 Sep, 2020
Reviewer #4 agreed
On 22 Sep, 2020
Reviewer #3 agreed
On 21 Sep, 2020
Review #2 received
Received 20 Sep, 2020
Reviewer #2 agreed
On 16 Sep, 2020
Review #1 received
Received 04 Aug, 2020
Reviewers invited
Invitations sent on 31 Jul, 2020
Reviewer #1 agreed
On 31 Jul, 2020
Editor assigned
On 23 Jul, 2020
Submission checks complete
On 22 Jul, 2020
Editor invited
On 22 Jul, 2020
No comments provided
Editorial decision: Revise before peer review
On 18 Jul, 2020
First submitted
On 17 Jul, 2020
Editor assigned
On 17 Jul, 2020
Submission checks complete
On 16 Jul, 2020
Editor invited
On 16 Jul, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Neurology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
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 to process PGRN 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 distinctive, 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 and an increased activity of AEP, in a region-specific manner.
Conclusions - This study demonstrates that multiple lysosomal proteases may work in concert to liberate multi-granulin fragments and granulins. It also implicates both AEP and granulin F in the neurobiology of FTLD-TDP-Pgrn. Modulating progranulin cleavage and granulin production may represent therapeutic strategies for FTLD-Pgrn and other progranulin-related diseases.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Due to technical limitations, tables 1-2 are only available as downloads in the supplemental files section.
Table 1. PGRN cleavage by lysosomal proteases in vitro
Summary of whether the enzymes tested could cleave progranulin (PGRN) or not along with the potential compartment it may cleave PGRN depending on the pH it processed progranulin in vitro. En, endosomes; Ly, lysosomes; Ex, extracellular.
Table 2. Clinical Information for control and FTLD-TDP-Pgrn subjects
Clinical information for the control and FTLD-TDP-Pgrn subjects. PMI, post-mortem interval; IOC, inferior occipital cortex; MFG, middle frontal gyrus.