Folding-related Dimerization of Human Cystatin C

Ekiel, Irena; Abrahamson, Magnus

doi:10.1074/jbc.271.3.1314

Cited by 122 publications

(119 citation statements)

References 40 publications

(34 reference statements)

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“…L68Q cystatin C, the cystatin C variant causing hereditary cystatin C amyloid angiopathy, has an increased propensity to form dimers compared with that of wt cystatin C, since the mutation lowers the energy barrier for the transition through destabilization of the monomeric structure and stabilization of the unfolded intermediate (22). However, also wt cystatin C has been shown to dimerize in vitro and the rate of the process could be increased by raising the temperature, lowering the pH, or using conditions of mild chemical denaturation (40). Transformation of monomeric wt cystatin C into amyloid fibrils in vitro has also been described, but the system used required a very low pH of 2.0 and did not allow detection of any molecular intermediates of the transformation (28).…”

Section: Discussionmentioning

confidence: 99%

Fibrillogenic Oligomers of Human Cystatin C Are Formed by Propagated Domain Swapping

Wahlbom

Wang

Lindström

et al. 2007

Journal of Biological Chemistry

116

132

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Cystatin C and the prion protein have been shown to form dimers via three-dimensional domain swapping, and this process has also been hypothesized to be involved in amyloidogenesis. Production of oligomers of other amyloidogenic proteins has been reported to precede fibril formation, suggesting oligomers as intermediates in fibrillogenesis. A variant of cystatin C, with a Leu 68 3 Gln substitution, is highly amyloidogenic, and carriers of this mutation suffer from massive cerebral amyloidosis leading to brain hemorrhage and death in early adulthood. This work describes doughnut-shaped oligomers formed by wild type and L68Q cystatin C upon incubation of the monomeric proteins. Purified oligomers of cystatin C are shown to fibrillize faster and at a lower concentration than the monomeric protein, indicating a role of the oligomers as fibril-assembly intermediates. Moreover, the present work demonstrates that three-dimensional domain swapping is involved in the formation of the oligomers, because variants of monomeric cystatin C, stabilized against three-dimensional domain swapping by engineered disulfide bonds, do not produce oligomers upon incubation under non-reducing conditions. Redox experiments using wild type and stabilized cystatin C strongly suggest that the oligomers, and thus probably the fibrils as well, are formed by propagated domain swapping rather than by assembly of domain-swapped cystatin C dimers.

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Section: Discussionmentioning

confidence: 99%

Fibrillogenic Oligomers of Human Cystatin C Are Formed by Propagated Domain Swapping

Wahlbom

Wang

Lindström

et al. 2007

Journal of Biological Chemistry

116

132

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“…It was previously shown that recombinant normal cystatin C dimerizes when exposed to denaturing agents, low pH, or high temperature (43). Although these conditions are similar to those leading to protein unfolding, it was demonstrated that cystatin C dimers are formed by association of native, properly folded proteins (43).…”

Section: Source Of Proteasementioning

confidence: 99%

“…Although these conditions are similar to those leading to protein unfolding, it was demonstrated that cystatin C dimers are formed by association of native, properly folded proteins (43). The dimers and aggregates of the variant recombinant protein were formed at normal body temperature, nearly 25°C lower than that needed for the wild type cystatin C dimerization (25).…”

Section: Source Of Proteasementioning

confidence: 99%

“…The variant cystatin C formed dimers at concentrations lower than those necessary for dimerization of the wild type protein. Upon dimerization, cystatin C looses its cysteine protease inhibitory activity, indicating that the association may involve the active site (43). Cystatin C may acquire a nonfunctional dimeric form while in specific cellular compartments and upon secretion dissociate into its active monomeric form.…”

Section: Source Of Proteasementioning

confidence: 99%

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Instability of the Amyloidogenic Cystatin C Variant of Hereditary Cerebral Hemorrhage with Amyloidosis, Icelandic Type

Wei

Berman

Castaño

et al. 1998

Journal of Biological Chemistry

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A cystatin C variant with L68Q substitution and a truncation of 10 NH 2 -terminal residues is the major constituent of the amyloid deposited in the cerebral vasculature of patients with the Icelandic form of hereditary cerebral hemorrhage with amyloidosis (HCHWA-I). Variant and wild type cystatin C production, processing, secretion, and clearance were studied in human cell lines stably overexpressing the cystatin C genes. Immunoblot and mass spectrometry analyses demonstrated monomeric cystatin C in cell homogenates and culture media. While cystatin C formed concentration-dependent dimers, the HCHWA-I variant dimerized at lower concentrations than the wild type protein. Amino-terminal sequence analysis revealed that the variant and normal proteins produced and secreted are the full-length cystatin C.Pulse-chase experiments demonstrated similar levels of normal and variant cystatin C production and secretion. However, the secreted variant cystatin C exhibited an increased susceptibility to a serine protease in conditioned media and in human cerebrospinal fluid, explaining its depletion from the cerebrospinal fluid of HCHWA-I patients. Thus, the amino acid substitution may induce unstable cystatin C with intact inhibitory activity and predisposition to self-aggregation and amyloid fibril formation.

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“…The mechanisms controlling the intracellular inhibition of cysteine proteinases in endosomes and lysosomes with cystatin C entering the endosomal -lysosomal pathway by endocytotic uptake may include dimerisation (Ekiel and Abrahamson, 1996;Merz et al, 1997), proteolytic fragmentation by cathepsin D (Lenarčič et al, 1991) or neutrophilic granulocyte elastase (Abrahamson et al, 1991). Some of these mechanisms may operate already in the pericellular microenvironment and may restrict the inhibitory function of the secreted cystatin C against the proteolytic activity of cell surface associated and/or secreted enzymes (Křepela et al, 1998).…”

mentioning

confidence: 99%

Cysteine proteinase inhibitor cystatin C in squamous cell carcinoma of the head and neck: relation to prognosis

et al. 2004

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To determine the role of the cysteine proteinase inhibitor cystatin C in the invasive behavior of squamous cell carcinoma of the head and neck (SCCHN), Cystatin C protein level was measured in 82 pairs of primary tumour tissue and adjacent noncancerous mucosa, using the enzyme-linked immunosorbent assay. The median level of cystatin C in tumour tissue was 1.18 times lower than that in corresponding mucosa (P ¼ 0.031). In normal mucosa samples, the cystatin C level was influenced by the site of sampling: it was lower in nonlaryngeal tissue samples (oral cavity, oro-or hypopharynx) than in laryngeal samples (P ¼ 0.004). The tumour cystatin C level correlated inversely with pN-stage (P ¼ 0.047), whereas a trend of lower cystatin C levels was observed in the group with extranodal tumour extension compared to those with no extranodal spread (P ¼ 0.069). In univariate analysis, the patients with low tumour cystatin C levels exhibited poor disease-free survival (DFS, P ¼ 0.013) and disease-specific survival (DSS, P ¼ 0.013). In multivariate analysis, the most powerful predictor of survival was pN-stage (DFS: P ¼ 0.040, HR 2.78; DSS: P ¼ 0.011, HR 4.36,), followed by the cystatin C level (DFS: P ¼ 0.043, HR 0.22; DSS: P ¼ 0.067, HR 0.25). When comparing the prognostic strength of cystatin C to that of stefin A, another cysteine proteinase inhibitor, which emerged as the most significant prognosticator for survival in our previous study analysing the same cohort of patients, stefin A proved to be significantly more reliable predictor for both DFS and DSS than cystatin C. Our results indicate that cystatin C is implicated in the invasive behavior of SCCHN, and that there are variations in regulation of proteolytic pathways under nonmalignant conditions, inherent to individual subsites inside the upper aerodigestive tract. The correlation between high cystatin C levels and improved survival concurs with the concept of the protective role of high levels of cysteine proteinase inhibitors in tissue homogenates that has been previously suggested by the survival results in breast and lung carcinoma as well as SCCHN.

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Folding-related Dimerization of Human Cystatin C

Cited by 122 publications

References 40 publications

Fibrillogenic Oligomers of Human Cystatin C Are Formed by Propagated Domain Swapping

Fibrillogenic Oligomers of Human Cystatin C Are Formed by Propagated Domain Swapping

Instability of the Amyloidogenic Cystatin C Variant of Hereditary Cerebral Hemorrhage with Amyloidosis, Icelandic Type

Cysteine proteinase inhibitor cystatin C in squamous cell carcinoma of the head and neck: relation to prognosis

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