Strategies to prevent cleavage of the linker region between ligand-binding repeats 4 and 5 of the LDL receptor

Strøm, Thea Bismo; Bjune, Katrine; Leren, Trond P.

doi:10.1093/hmg/ddz164

Cited by 3 publications

(2 citation statements)

References 28 publications

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“…Our data showing that LDLR is cleaved by BMP1 in human primary hepatocytes adds further weight to this proteolytic cleavage event being of physiological relevance. The CTF of LDLR resulting from BMP1 cleavage has been identified in extracts from multiple human liver samples and human adrenal gland and the NTF was detected in human urine, likely due to clearance from plasma by the kidneys [ 3 , 22 ]. However, as mouse LDLR is not cleaved by BMP1 due to the critical Asp193 being replaced by Val, studies in mice expressing wild‐type LDLR would not reveal whether cleavage of the receptor by BMP1 has an impact on plasma LDL‐C metabolism.…”

Section: Discussionmentioning

confidence: 99%

Proteolysis of the low‐density lipoprotein receptor in hepatocytes is mediated by BMP1 but not by other astacin proteases

Kellett,

Fisher,

Aldworth

et al. 2023

FEBS Letters

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Bone morphogenetic protein 1 (BMP1), a member of the astacin family of zinc‐metalloproteases, proteolytically cleaves the low‐density lipoprotein receptor (LDLR) within its ligand‐binding domain, reducing the binding and cellular uptake of LDL‐cholesterol. Here, we aimed to determine whether astacin proteases other than BMP1 may also cleave LDLR. Although human hepatocytes express all six astacin proteases, including the meprins and mammalian tolloid, we found through pharmacological inhibition and genetic knockdown that only BMP1 contributed to the cleavage of LDLR in its ligand‐binding domain. We also found that the minimum amino acid change required to render mouse LDLR susceptible to cleavage by BMP1 is mutation at the P1′ and P2 positions of the cleavage site. When expressed in cells, the resulting humanised‐mouse LDLR internalised LDL‐cholesterol. This work provides insight into the biological mechanisms regulating LDLR function.

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Section: Discussionmentioning

confidence: 99%

Proteolysis of the low‐density lipoprotein receptor in hepatocytes is mediated by BMP1 but not by other astacin proteases

Kellett,

Fisher,

Aldworth

et al. 2023

FEBS Letters

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“…However, there is evidence that BMP1 is involved in cleaving the LDLR in human primary hepatocytes and in human liver and adrenal samples [ 37 , 61 , 63 ], and the 36–40 kDa N-terminal fragment is present in human urine, likely due to clearance from the blood plasma by the kidneys [ 61 ]. Both 14-mer synthetic peptides and antibodies directed against the linker region between LA repeats 4 and 5 prevented cleavage of LDLR by BMP1, providing proof of principle that blocking the action of BMP1 on LDLR could represent a novel approach to reducing plasma LDL-cholesterol [ 64 ].…”

Section: Ldlr Regulationmentioning

confidence: 99%

Post-translational regulation of the low-density lipoprotein receptor provides new targets for cholesterol regulation

Aldworth,

Hooper

2024

Biochemical Society Transactions

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The amount of the low-density lipoprotein receptor (LDLR) on the surface of hepatocytes is the primary determinant of plasma low-density lipoprotein (LDL)-cholesterol level. Although the synthesis and cellular trafficking of the LDLR have been well-documented, there is growing evidence of additional post-translational mechanisms that regulate or fine tune the surface availability of the LDLR, thus modulating its ability to bind and internalise LDL-cholesterol. Proprotein convertase subtilisin/kexin type 9 and the asialoglycoprotein receptor 1 both independently interact with the LDLR and direct it towards the lysosome for degradation. While ubiquitination by the E3 ligase inducible degrader of the LDLR also targets the receptor for lysosomal degradation, ubiquitination of the LDLR by a different E3 ligase, RNF130, redistributes the receptor away from the plasma membrane. The activity of the LDLR is also regulated by proteolysis. Proteolytic cleavage of the transmembrane region of the LDLR by γ-secretase destabilises the receptor, directing it to the lysosome for degradation. Shedding of the extracellular domain of the receptor by membrane-type 1 matrix metalloprotease and cleavage of the receptor in its LDL-binding domain by bone morphogenetic protein-1 reduces the ability of the LDLR to bind and internalise LDL-cholesterol at the cell surface. A better understanding of how the activity of the LDLR is regulated will not only unravel the complex biological mechanisms controlling LDL-cholesterol metabolism but also could help inform the development of alternative pharmacological intervention strategies for the treatment of hypercholesterolaemia.

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Bone morphogenetic protein 1 cleaves the linker region between ligand-binding repeats 4 and 5 of the LDL receptor and makes the LDL receptor non-functional

Strøm

Bjune

Leren

2019

Human Molecular Genetics

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The cell-surface low-density lipoprotein receptor (LDLR) internalizes low-density lipoprotein (LDL) by receptor-mediated endocytosis and plays a key role in the regulation of plasma cholesterol levels. The ligand-binding domain of the LDLR contains seven ligand-binding repeats of approximately 40 residues each. Between ligand-binding repeats 4 and 5, there is a 10-residue linker region that is subject to enzymatic cleavage. The cleaved LDLR is unable to bind LDL. In this study, we have screened a series of enzyme inhibitors in order to identify the enzyme that cleaves the linker region. These studies have identified bone morphogenetic protein 1 (BMP1) as being the cleavage enzyme. This conclusion is based upon the use of the specific BMP1 inhibitor UK 383367, silencing of the BMP1 gene by the use of siRNA or CRISPR/Cas9 technology and overexpression of wild-type BMP1 or the loss-of-function mutant E214A-BMP1. We have also shown that the propeptide of BMP1 has to be cleaved at RSRR120↓ by furin-like proprotein convertases for BMP1 to have an activity towards the LDLR. Targeting BMP1 could represent a novel strategy to increase the number of functioning LDLRs in order to lower plasma LDL cholesterol levels. However, a concern by using BMP1 inhibitors as cholesterol-lowering drugs could be the risk of side effects based on the important role of BMP1 in collagen assembly.

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Strategies to prevent cleavage of the linker region between ligand-binding repeats 4 and 5 of the LDL receptor

Cited by 3 publications

References 28 publications

Proteolysis of the low‐density lipoprotein receptor in hepatocytes is mediated by BMP1 but not by other astacin proteases

Proteolysis of the low‐density lipoprotein receptor in hepatocytes is mediated by BMP1 but not by other astacin proteases

Post-translational regulation of the low-density lipoprotein receptor provides new targets for cholesterol regulation

Bone morphogenetic protein 1 cleaves the linker region between ligand-binding repeats 4 and 5 of the LDL receptor and makes the LDL receptor non-functional

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