Mutation-Induced Deamidation of Corneal Dystrophy-Related Transforming Growth Factor β-Induced Protein

Nielsen, Nadia Sukusu; Juhl, Dennis Wilkens; Poulsen, Ebbe Toftgaard; Lukassen, Marie V.; Poulsen, Emil Christian; Risør, Michael W.; Scavenius, Carsten; Enghild, Jan J.

doi:10.1021/acs.biochem.7b00668

Cited by 4 publications

(6 citation statements)

References 54 publications

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“…The double bands seen for the A546D and A546D/P551Q FAS1-4 domains (Fig. 2 A ) are, as shown previously (26), because of deamidations. The deamidations did not affect HtrA1 specificity and activity because both bands were degraded to the same extent.…”

Section: Resultssupporting

confidence: 87%

The serine protease HtrA1 cleaves misfolded transforming growth factor β–induced protein (TGFBIp) and induces amyloid formation

Poulsen

Nielsen

Scavenius

et al. 2019

Journal of Biological Chemistry

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The serine protease high-temperature requirement protein A1 (HtrA1) is associated with protein-misfolding disorders such as Alzheimer's disease and transforming growth factor β–induced protein (TGFBIp)–linked corneal dystrophy. In this study, using several biochemical and biophysical approaches, including recombinant protein expression, LC-MS/MS and 2DE analyses, and thioflavin T (ThT) fluorescence assays for amyloid fibril detection, and FTIR assays, we investigated the role of HtrA1 both in normal TGFBIp turnover and in corneal amyloid formation. We show that HtrA1 can cleave WT TGFBIp but prefers amyloidogenic variants. Corneal TGFBIp is extensively processed in healthy people, resulting in C-terminal degradation products spanning the FAS1-4 domain of TGFBIp. We show here that HtrA1 cleaves the WT FAS1-4 domain only inefficiently, whereas the amyloidogenic FAS1-4 mutations transform this domain into a considerably better HTRA1 substrate. Moreover, HtrA1 cleavage of the mutant FAS1-4 domains generated peptides capable of forming in vitro amyloid aggregates. Significantly, these peptides have been previously identified in amyloid deposits in vivo , supporting the idea that HtrA1 is a causative agent for TGFBIp-associated amyloidosis in corneal dystrophy. In summary, our results indicate that TGFBIp is an HtrA1 substrate and that some mutations in the gene encoding TGFBIp cause aberrant HtrA1-mediated processing that results in amyloidogenesis in corneal dystrophies.

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Section: Resultssupporting

confidence: 87%

The serine protease HtrA1 cleaves misfolded transforming growth factor β–induced protein (TGFBIp) and induces amyloid formation

Poulsen

Nielsen

Scavenius

et al. 2019

Journal of Biological Chemistry

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“…TGFβI encodes an ECM protein induced by TGFβ that interacts with collagen . Recent studies have shown that mutations in TGFβI in humans cause a condition known as granular corneal dystrophy, which is characterized by opaque deposits in the corneal stroma . Therefore, its upregulation in our data suggests that TGFβI may play a role in organizing collagen fibrils synthesized by the corneal endothelium and keratocytes during early development.…”

Section: Resultsmentioning

confidence: 61%

Transcriptomic analysis of differential gene expression during chick periocular neural crest differentiation into corneal cells

Lwigale

2019

Developmental Dynamics

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Background: Multipotent neural crest cells (NCC) contribute to the corneal endothelium and keratocytes during ocular development, but the molecular mechanisms that underlie this process remain poorly understood. We performed RNA-Seq analysis on periocular neural crest (pNC), corneal endothelium, and keratocytes and validated expression of candidate genes by in situ hybridization. Results: RNA-Seq profiling revealed enrichment of genes between pNC and neural crest-derived corneal cells, which correspond to pathways involved in focal adhesion, ECM-receptor interaction, cell adhesion, melanogenesis, and MAPK signaling. Comparisons of candidate NCC genes to ocular gene expression revealed that majority of the NCC genes are expressed in the pNC, but they are either differentially expressed or maintained during corneal development. Several genes involved in RA, TGFβ, and Wnt signaling pathways and their modulators are also differentially expressed. We identified differentially expressed transcription factors as potential downstream candidates that may instruct expression of genes involved in establishing corneal endothelium and keratocyte identities. Conclusion: Combined, our data reveal novel changes in gene expression profiles as pNC differentiate into highly specialized corneal endothelial cells and keratocytes. These data serve as platform for further analyses of the molecular networks involved in NCC differentiation into corneal cells, and provide insights into genes involved in corneal dysgenesis and adult diseases.

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“…For FAS1-4, the same stability ranking was obtained using both urea and thermal denaturation, emphasizing the robustness of the conclusions. In addition, deamidation rates as a measure of structural integrity were similar for corresponding FAS1-4 and TGFBIp mutants (Nielsen et al, 2017).…”

Section: The Fas1-4 Domain Mimics Many Properties Of Full-length Tgfbip Making It An Excellent Model Systemmentioning

confidence: 79%

Biochemical mechanisms of aggregation in TGFBI-linked corneal dystrophies

Nielsen

Poulsen

Lukassen

et al. 2020

Progress in Retinal and Eye Research

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Transforming growth factor-β-induced protein (TGFBIp), an extracellular matrix protein, is the second most abundant protein in the corneal stroma. In this review, we summarize the current knowledge concerning the expression, molecular structure, binding partners, and functions of human TGFBIp. To date, 74 mutations in the transforming growth factor-β-induced gene (TGFBI) are associated with amyloid and amorphous protein deposition in TGFBI-linked corneal dystrophies. We discuss the current understanding of the biochemical mechanisms of TGFBI-linked corneal dystrophies and propose that mutations leading to granular corneal dystrophy (GCD) decrease the solubility of TGFBIp and affect the interactions between TGFBIp and components of the corneal stroma, whereas mutations associated with lattice corneal dystrophy (LCD) lead to a destabilization of the protein that disrupts proteolytic turnover, especially by the serine protease HtrA1. Future research should focus on TGFBIp function in the cornea, confirmation of the biochemical mechanisms in vivo, and the development of disease models. Future therapies for TGFBI-linked corneal dystrophies might include topical agents that regulate protein aggregation or gene therapy that targets the mutant allele by CRISPR/Cas9 technology.

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Mutation-Induced Deamidation of Corneal Dystrophy-Related Transforming Growth Factor β-Induced Protein

Cited by 4 publications

References 54 publications

The serine protease HtrA1 cleaves misfolded transforming growth factor β–induced protein (TGFBIp) and induces amyloid formation

The serine protease HtrA1 cleaves misfolded transforming growth factor β–induced protein (TGFBIp) and induces amyloid formation

Transcriptomic analysis of differential gene expression during chick periocular neural crest differentiation into corneal cells

Biochemical mechanisms of aggregation in TGFBI-linked corneal dystrophies

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