Tissue chaperoning—the expanded functions of fetuin-A beyond inhibition of systemic calcification

Rudloff, Stefan; Jahnen-Dechent, Willi; Huynh‐Do, Uyen

doi:10.1007/s00424-022-02688-6

Cited by 24 publications

(14 citation statements)

References 137 publications

(174 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Accordingly, we showed increased asialofetuin-A in neuroinflammation. The third mechanism refers to fetuin-A consumption during inhibition of dystrophic calcification attesting to its general role in tissue chaperoning (67,68). Inflammation causes cell damage with release of calcium and phosphate from damaged cells that promotes dystopic calcification while simultaneous energy depletion leads to diminished formation of pyrophosphate (69,70).…”

Section: Discussionmentioning

confidence: 99%

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with severity of CNS inflammation in children

Ricken

Can

Gräber

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

BackgroundFetuin-A is a liver derived plasma protein showing highest serum concentrations in utero, preterm infants and neonates. Fetuin-A is also present in cerebrospinal fluid (CSF). The origin of CSF fetuin-A, blood-derived via the blood brain barrier or synthesized intrathecally, is presently unclear. Fetuin-A prevents ectopic calcification by stabilizing calcium and phosphate as colloidal calciprotein particles mediating their transport and clearance. Thus, fetuin-A plays a suppressive role in inflammation. Fetuin-A is a negative acute-phase protein, serving as a biomarker for MS. Here we studied the association of pediatric inflammatory CNS diseases with fetuin-A glycosylation and phosphorylation.MethodsPaired blood and CSF samples from 66 children were included in the study. Concentration measurements were performed using a commercial human fetuin-A/AHSG ELISA. Of 60 pairs, 23 pairs were analyzed by SDS-PAGE following glycosidase digestion with PNGase-F and Sialidase-AU. Phosphorylation was analyzed in 30 pairs by Phos-Tag™ acrylamide electrophoresis following alkaline phosphatase digestion.Results and DiscussionMean serum and CSF fetuin-A levels were 0.30 ± 0.06 mg/ml and 0.644 ± 0.55 µg/ml, respectively. This study showed that serum fetuin-A levels decreased in inflammation corroborating its role as a negative acute-phase protein. Blood-brain barrier disruption was associated with elevated fetuin-A in CSF. A strong positive correlation was found between the CSF fetuin-A/serum fetuin-A ratio and the CSF albumin/serum albumin ratio, suggesting predominantly transport across the blood-brain barrier rather than intrathecal fetuin-A synthesis. Sialidase digestion showed increased asialofetuin-A levels in serum and CSF samples from children with neuroinflammatory diseases. Desialylation enhanced hepatic fetuin-A clearance via the asialoglycoprotein receptor thus rapidly reducing serum levels during inflammation. Phosphorylation of fetuin-A was more abundant in serum samples than in CSF, suggesting that phosphorylation may regulate fetuin-A influx into the CNS. These results may help establish Fetuin-A as a potential biomarker for neuroinflammatory diseases.

show abstract

Section: Discussionmentioning

confidence: 99%

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with severity of CNS inflammation in children

Ricken

Can

Gräber

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The fetuin-B structure allowed modeling of the complete structure of fetuin-A, which was later confirmed by AlphaFold2 21 . This novel fetuin-A model suggested that the hitherto undefined intrinsically unfolded C-terminal region should also occupy an important role in protein-mineral binding apart from the amino-terminal cystatin-like domain identified earlier 9 , 19 , 22 because it harbors several more putative Ser/Thr phosphorylation sites. This is in line with the current understanding of the role of intrinsically disordered proteins in biomineralization 23 .…”

Section: Introductionmentioning

confidence: 89%

Application of the mineral-binding protein fetuin-A for the detection of calcified lesions

Dzhanaev¹,

Hasberg²,

Gorgels³

et al. 2023

Theranostics

Self Cite

View full text Add to dashboard Cite

Rationale: Calcium plays an essential role in the biology of vertebrates. Calcium content in body fluids is maintained within a narrow physiologic range by feedback control. Phosphate is equally important for metabolism and is likewise controlled, albeit over a wider range. This results in a nearly supersaturated state of calcium phosphate in body liquids driving mineral precipitation in soft tissues, which is actively prevented by calcification inhibitors. The hepatic plasma protein fetuin-A is a circulating mineralization inhibitor regulating calcium phosphate crystal growth and calcified matrix metabolism. Ectopic mineralization is associated with many pathological conditions aggravating their outcome. Current diagnostic methods lack sensitivity towards microcalcifications representing the initial stages of the process. Given the irreversibility of established calcifications, novel diagnostic tools capable of detecting nascent calcium phosphate deposits are highly desirable. Methods: We designed fluorescent fusion proteins consisting of fetuin-A coupled to a green or red fluorescent protein derivate, mEmerald or mRuby3, respectively. The proteins were expressed in mammalian cell lines. Sequence optimization resolved folding issues and increased sensitivity of mineral binding. Chimeric proteins were tested for their ability to detect calcifications in cell cultures and tissue sections retrieved from calcification-prone mice. Results: We employed novel genetically labeled fetuin-A-based fluorescent proteins for the detection of ectopic calcifications. We show that fetuin-A-based imaging agents are non-toxic and suitable for live imaging of microcalcifications beyond the detection limit of conventional staining techniques. The ability of fetuin-A to preferentially bind nascent calcium phosphate crystals allowed the resolution of histopathological detail of early kidney damage that went previously undetected. Endogenous expression of fetuin-A fluorescent fusion proteins allowed extended live imaging of calcifying cells with unprecedented sensitivity and specificity. Conclusion: Ectopic microcalcifications represent a major clinical concern lacking effective diagnostic and treatment options. In this paper, we describe novel highly sensitive fetuin-A-based fluorescent probes for imaging microcalcifications. We show that fusion proteins consisting of a fetuin-A mineral binding moiety and a fluorescent protein are superior to the routine methods for detecting calcifications. They also surpass in continuous live cell imaging the chemically fluorescence labeled fetuin-A, which we established previously.

show abstract

“…Accordingly, we showed increased asialofetuin-A in neuroinflammation. The third mechanism refers to fetuin-A consumption during inhibition of dystrophic calcification attesting to its general role in tissue chaperoning [66,67]. Inflammation causes cell damage with release of calcium and phosphate from damaged cells that promotes dystopic calcification while simultaneous energy depletion leads to diminished formation of pyrophosphate [68,69].…”

Section: Plos Onementioning

confidence: 99%

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with CNS inflammation in children

et al. 2022

Self Cite

View full text Add to dashboard Cite

Fetuin-A is a liver derived plasma protein showing highest serum concentrations in utero, preterm infants, and neonates. Fetuin-A is also present in cerebrospinal fluid (CSF). The origin of CSF fetuin-A, blood-derived via the blood-CSF barrier or synthesized intrathecally, is presently unclear. Fetuin-A prevents ectopic calcification by stabilizing calcium and phosphate as colloidal calciprotein particles mediating their transport and clearance. Thus, fetuin-A plays a suppressive role in inflammation. Fetuin-A is a negative acute-phase protein under investigation as a biomarker for multiple sclerosis (MS). Here we studied the association of pediatric inflammatory CNS diseases with fetuin-A glycosylation and phosphorylation. Paired blood and CSF samples from 66 children were included in the study. Concentration measurements were performed using a commercial human fetuin-A/AHSG ELISA. Of 60 pairs, 23 pairs were analyzed by SDS-PAGE following glycosidase digestion with PNGase-F and Sialidase-AU. Phosphorylation was analyzed in 43 pairs by Phos-TagTM acrylamide electrophoresis following alkaline phosphatase digestion. Mean serum and CSF fetuin-A levels were 0.30 ± 0.06 mg/ml and 0.644 ± 0.55 μg/ml, respectively. This study showed that serum fetuin-A levels decreased in inflammation corroborating its role as a negative acute-phase protein. Blood-CSF barrier disruption was associated with elevated fetuin-A in CSF. A strong positive correlation was found between the CSF fetuin-A/serum fetuin-A quotient and the CSF albumin/serum albumin quotient, suggesting predominantly transport across the blood-CSF barrier rather than intrathecal fetuin-A synthesis. Sialidase digestion showed increased asialofetuin-A levels in serum and CSF samples from children with neuroinflammatory diseases. Desialylation enhanced hepatic fetuin-A clearance via the asialoglycoprotein receptor thus rapidly reducing serum levels during inflammation. Phosphorylation of fetuin-A was more abundant in serum samples than in CSF, suggesting that phosphorylation may regulate fetuin-A influx into the CNS. These results may help establish Fetuin-A as a potential biomarker for neuroinflammatory diseases.

show abstract

Tissue chaperoning—the expanded functions of fetuin-A beyond inhibition of systemic calcification

Cited by 24 publications

References 137 publications

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with severity of CNS inflammation in children

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with severity of CNS inflammation in children

Application of the mineral-binding protein fetuin-A for the detection of calcified lesions

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with CNS inflammation in children

Contact Info

Product

Resources

About