Insulin-degrading enzyme is not secreted from cultured cells

Eun Suk Song; David W. Rodgers; Louis B. Hersh

doi:10.1038/s41598-018-20597-6

Insulin-degrading enzyme is not secreted from cultured cells

Eun Suk Song, David W. Rodgers, Louis B. Hersh

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer's disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released at the same relative level, indicating that extracellular IDE results from a loss of cell integrity, not secretion. Lovastatin increases IDE release from BV-2 cells as reported, but this release is mirrored by LDH release. Cell viability assays indicate lovastatin causes a loss of cell integrity, explaining its effect on IDE release. IDE is present in an exosome-enriched fraction from BV-2 cell conditioned media, however it represents only ~0.01% of the total cellular enzyme and is unlikely to be a significant source of IDE. These results call into question the secretion of IDE and its importance in extracellular peptide degradation.

Original language	English
Article number	2335
Journal	Scientific Reports
Volume	8
Issue number	1
DOIs	https://doi.org/10.1038/s41598-018-20597-6
State	Published - Dec 1 2018

Bibliographical note

Funding Information:
Tis work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486).

Funding Information:
This work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486).

Publisher Copyright:
© 2018 The Author(s).

ASJC Scopus subject areas

General

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1038/s41598-018-20597-6

Cite this

@article{96d50536a9de4c9a8cfe0378cfa5ecc3,

title = "Insulin-degrading enzyme is not secreted from cultured cells",

abstract = "Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer's disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released at the same relative level, indicating that extracellular IDE results from a loss of cell integrity, not secretion. Lovastatin increases IDE release from BV-2 cells as reported, but this release is mirrored by LDH release. Cell viability assays indicate lovastatin causes a loss of cell integrity, explaining its effect on IDE release. IDE is present in an exosome-enriched fraction from BV-2 cell conditioned media, however it represents only ~0.01% of the total cellular enzyme and is unlikely to be a significant source of IDE. These results call into question the secretion of IDE and its importance in extracellular peptide degradation.",

author = "Song, {Eun Suk} and Rodgers, {David W.} and Hersh, {Louis B.}",

note = "Funding Information: Tis work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486). Funding Information: This work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486). Publisher Copyright: {\textcopyright} 2018 The Author(s).",

year = "2018",

month = dec,

day = "1",

doi = "10.1038/s41598-018-20597-6",

language = "English",

volume = "8",

number = "1",

}

TY - JOUR

T1 - Insulin-degrading enzyme is not secreted from cultured cells

AU - Song, Eun Suk

AU - Rodgers, David W.

AU - Hersh, Louis B.

N1 - Funding Information: Tis work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486). Funding Information: This work was supported by National Institutes of Health grants GM 11787 (to LBH) and NS38041 (to DWR) and National Science Foundation grant IIA-1355438 (to DWR). We acknowledge use of facilities in the Kentucky Center for Structural Biology as well as support from and use of core facilities belonging to the Center for Molecular Medicine (National Institutes of Health grant P20 GM103486). Publisher Copyright: © 2018 The Author(s).

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer's disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released at the same relative level, indicating that extracellular IDE results from a loss of cell integrity, not secretion. Lovastatin increases IDE release from BV-2 cells as reported, but this release is mirrored by LDH release. Cell viability assays indicate lovastatin causes a loss of cell integrity, explaining its effect on IDE release. IDE is present in an exosome-enriched fraction from BV-2 cell conditioned media, however it represents only ~0.01% of the total cellular enzyme and is unlikely to be a significant source of IDE. These results call into question the secretion of IDE and its importance in extracellular peptide degradation.

AB - Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer's disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released at the same relative level, indicating that extracellular IDE results from a loss of cell integrity, not secretion. Lovastatin increases IDE release from BV-2 cells as reported, but this release is mirrored by LDH release. Cell viability assays indicate lovastatin causes a loss of cell integrity, explaining its effect on IDE release. IDE is present in an exosome-enriched fraction from BV-2 cell conditioned media, however it represents only ~0.01% of the total cellular enzyme and is unlikely to be a significant source of IDE. These results call into question the secretion of IDE and its importance in extracellular peptide degradation.

UR - http://www.scopus.com/inward/record.url?scp=85041655291&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85041655291&partnerID=8YFLogxK

U2 - 10.1038/s41598-018-20597-6

DO - 10.1038/s41598-018-20597-6

M3 - Article

C2 - 29402917

AN - SCOPUS:85041655291

VL - 8

IS - 1

M1 - 2335

ER -

Insulin-degrading enzyme is not secreted from cultured cells

Abstract

Bibliographical note

ASJC Scopus subject areas

UN SDGs

Access to Document

Other files and links

Fingerprint

Cite this