Interaction of hIAPP with Model Raft Membranes and Pancreatic β‐Cells: Cytotoxicity of hIAPP Oligomers

Weise, Katrin; Radovan, Diana; Gohlke, Andrea; Opitz, N.; Winter, Roland

doi:10.1002/cbic.201000039

Cited by 74 publications

(88 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One example is pancreatic beta cell failure related to the formation of islet amyloid deposit of the 37-residue natively unfolded human islet amyloid polypeptide (IAPP). Negatively charged lipid membranes and lipid rafts favor the binding of IAPP and also promote its aggregation (39). A positively charged N terminus is considered responsible for the partial insertion of IAPP into negatively charged lipid membranes, a process mainly driven by electrostatic interactions (39).…”

Section: Discussionmentioning

confidence: 99%

Diabetes and Pancreatic Exocrine Dysfunction Due to Mutations in the Carboxyl Ester Lipase Gene-Maturity Onset Diabetes of the Young (CEL-MODY)

Johansson

Torsvik

Bjørkhaug

et al. 2011

Journal of Biological Chemistry

110

View full text Add to dashboard Cite

CEL-maturity onset diabetes of the young (MODY), diabetes with pancreatic lipomatosis and exocrine dysfunction, is due to dominant frameshift mutations in the acinar cell carboxyl ester lipase gene (CEL). As Cel knock-out mice do not express the phenotype and the mutant protein has an altered and intrinsically disordered tandem repeat domain, we hypothesized that the disease mechanism might involve a negative effect of the mutant protein. In silico analysis showed that the pI of the tandem repeat was markedly increased from pH 3.3 in wild-type (WT) to 11.8 in mutant (MUT) human CEL. By stably overexpressing CEL-WT and CEL-MUT in HEK293 cells, we found similar glycosylation, ubiquitination, constitutive secretion, and quality control of the two proteins. The CEL-MUT protein demonstrated, however, a high propensity to form aggregates found intracellularly and extracellularly. Different physicochemical properties of the intrinsically disordered tandem repeat domains of WT and MUT proteins may contribute to different short and long range interactions with the globular core domain and other macromolecules, including cell membranes. Thus, we propose that CEL-MODY is a protein misfolding disease caused by a negative gain-of-function effect of the mutant proteins in pancreatic tissues.Most monogenic forms of diabetes are due to mutations in genes expressed in the pancreatic beta cell. Previously, Raeder et al.(1) reported a novel monogenic syndrome caused by mutations in the carboxyl ester lipase gene (CEL) (OMIM 609812; CEL-MODY 2 or MODY8), characterized by dominantly inherited childhood-onset pancreatic exocrine dysfunction and diabetes mellitus from adulthood. Notably, this gene is not transcribed in beta cells but is mainly expressed in pancreatic acinar tissue (2, 3) and lactating mammary glands (4, 5). The CEL enzyme (EC 3.1.1.13), also known as bile salt-stimulated/dependent lipase, is secreted into the intestine and activated by bile salts, playing a role in the hydrolysis and absorption of cholesterol-and lipid-soluble vitamins (6).The human CEL gene is ϳ10 kb in size and consists of 11 exons. In the last exon, there is a variable number of tandem repeats (VNTR) where the 33-bp nearly identical segments are repeated usually between 7 and 23 times (1, 7-9). The VNTR of the most common CEL allele has 16 repeats, thereby encoding a protein consisting of 745 amino acids with a predicted molecular mass of ϳ79 kDa. The rat Cel is secreted from the acinar cells and is thought to follow the classical pathway of secretory proteins (for review see Ref.3). In the endoplasmic reticulum (ER), the protein is co-translationally N-glycosylated at a conserved Asn residue (Asn-210), serving as a client protein for the molecular chaperone GRP94 and being associated with ER membranes (10, 11). The VNTR-encoded protein C terminus is heavily O-glycosylated in the mature protein, probably on Thr residues before or after PVPP motifs in the first 10 repeats (12). The O-glycosylation sites are present in a region enriched in the amino ...

show abstract

Section: Discussionmentioning

confidence: 99%

Diabetes and Pancreatic Exocrine Dysfunction Due to Mutations in the Carboxyl Ester Lipase Gene-Maturity Onset Diabetes of the Young (CEL-MODY)

Johansson

Torsvik

Bjørkhaug

et al. 2011

Journal of Biological Chemistry

110

View full text Add to dashboard Cite

show abstract

“…Pore formation has been proposed to be a key for membrane disruption (21)(22)(23), but a carpeting, detergent-like mechanism has also been advocated (24,25). There is experimental evidence that intermediates permeabilize membranes (26)(27)(28), whereas other studies implicate fibril growth at the membrane surface (29,30). The structural requirements for membrane activity are also not completely clear.…”

Section: Significancementioning

confidence: 99%

“…We examined two more complicated model systems: total brain extract lipids (TBE-lipids) and a ternary system consisting of DOPC, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol at a 1:2:1 ratio. TBE-lipids have been widely used as models of the plasma membrane and have been used in studies of IAPP-membrane interactions (28,(39)(40)(41). They are considerably more complex than standard one-or two-component model membrane systems.…”

Section: Folded Monomeric Proteins Are Less Effective At Inducing Modelmentioning

confidence: 99%

See 1 more Smart Citation

Islet amyloid polypeptide toxicity and membrane interactions

Cao

Abedini

Wang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

130

143

View full text Add to dashboard Cite

Islet amyloid polypeptide (IAPP) is responsible for amyloid formation in type 2 diabetes and contributes to the failure of islet cell transplants, however the mechanisms of IAPP-induced cytotoxicity are not known. Interactions with model anionic membranes are known to catalyze IAPP amyloid formation in vitro. Human IAPP damages anionic membranes, promoting vesicle leakage, but the features that control IAPP-membrane interactions and the connection with cellular toxicity are not clear. Kinetic studies with wildtype IAPP and IAPP mutants demonstrate that membrane leakage is induced by prefibrillar IAPP species and continues over the course of amyloid formation, correlating additional membrane disruption with fibril growth. Analyses of a set of designed mutants reveal that membrane leakage does not require the formation of β-sheet or α-helical structures. A His-18 to Arg substitution enhances leakage, whereas replacement of all of the aromatic residues via a triple leucine mutant has no effect. Biophysical measurements in conjunction with cytotoxicity studies show that nonamyloidogenic rat IAPP is as effective as human IAPP at disrupting standard anionic model membranes under conditions where rat IAPP does not induce cellular toxicity. Similar results are obtained with more complex model membranes, including ternary systems that contain cholesterol and are capable of forming lipid rafts. A designed point mutant, I26P-IAPP; a designed double mutant, G24P, I26P-IAPP; a double N-methylated variant; and pramlintide, a US Food and Drug Administration-approved IAPP variant all induce membrane leakage, but are not cytotoxic, showing that there is no one-to-one relationship between disruption of model membranes and induction of cellular toxicity.

show abstract

“…First, hIAPP 16 -37 has an MMP-9 cleavage site between residues 25-26 and co-incubation of hIAPP 16 -37 with MMP-9 leads to non-amyloidogenic and non-cytotoxic fragments. Second, it has been speculated that early aggregates (oligomers) of hIAPP are the major cytotoxic species and that fully aggregated hIAPP is inert (43)(44)(45)(46)(47). We observed that hIAPP 16 -37 aggregates much faster than fulllength hIAPP and one could speculate that it therefore reaches the inert aggregated state more quickly.…”

Section: Discussionmentioning

confidence: 62%

Matrix Metalloproteinase-9 Protects Islets from Amyloid-induced Toxicity

Meier

Zraika

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background: MMP-9 cleaves hIAPP, the major constituent of islet amyloid deposits. Results: MMP-9-cleaved hIAPP fragments are largely non-amyloidogenic and non-cytotoxic. MMP-9 overexpression in amyloid-prone islets reduces amyloid deposition and the associated toxicity. Conclusion: MMP-9 protects islets from amyloid-induced toxicity. Significance: MMP-9 activation specifically in islets might be a novel strategy to limit ␤-cell loss in type 2 diabetes.

show abstract

Interaction of hIAPP with Model Raft Membranes and Pancreatic β‐Cells: Cytotoxicity of hIAPP Oligomers

Cited by 74 publications

References 62 publications

Diabetes and Pancreatic Exocrine Dysfunction Due to Mutations in the Carboxyl Ester Lipase Gene-Maturity Onset Diabetes of the Young (CEL-MODY)

Diabetes and Pancreatic Exocrine Dysfunction Due to Mutations in the Carboxyl Ester Lipase Gene-Maturity Onset Diabetes of the Young (CEL-MODY)

Islet amyloid polypeptide toxicity and membrane interactions

Matrix Metalloproteinase-9 Protects Islets from Amyloid-induced Toxicity

Contact Info

Product

Resources

About