Periostin C-Terminal Is Intrinsically Disordered and Interacts with 143 Proteins in an In Vitro Epidermal Model of Atopic Dermatitis

Abstract

Human periostin is a 78–91 kDa matricellular protein implicated in extracellular matrix remodeling, tumor development, metastasis, and inflammatory diseases like atopic dermatitis, psoriasis, and asthma. The protein consists of six domains, including an N-terminal Cys-rich CROPT domain, four fasciclin-1 domains, and a C-terminal domain. The exons encoding the C-terminal domain may be alternatively spliced by shuffling four exons, generating ten variants of unknown function. Here, we investigate the structure and interactome of the full-length variant of the C-terminal domain with no exons spliced out. The structural analysis showed that the C-terminal domain lacked a tertiary structure and was intrinsically disordered. In addition, we show that the motif responsible for heparin-binding is in the conserved very C-terminal part of periostin. Pull-down confirmed three known interaction partners and identified an additional 140 proteins, among which nine previously have been implicated in atopic dermatitis. Based on our findings, we suggest that the C-terminal domain of periostin facilitates interactions between connective tissue components in concert with the four fasciclin domains.

Targeted Antisense Oligonucleotide-Mediated Skipping of Murine Postn Exon 17 Partially Addresses Fibrosis in D2.mdx Mice

“…These structural changes have implications for the interaction of Periostin isoforms with fibrotic proteins within the ECM. While previous works on Periostin structure have primarily focused on the unstructured nature of its C-terminal region, which nonetheless participates in biological functions by binding to ECM components [ 32 ], the use of AlphaFold AI prediction software (V2) [ 33 ] has not been used to compare isoform variants. Our findings using a Phyre2 (V2.0) intensive analysis align with previous observations regarding the disordered tertiary arrangement of secondary structure elements in Periostin and extend to non-full-length isoforms.…”

“…In previous studies, the Periostin C-terminal region was associated with a network of 143 potential protein interactors, with a particular emphasis on syndecan-1 and syndecan-4, whose binding depends on the presence of the full-length C-terminal region [ 32 ]. These heparin sulphate proteoglycans are reported to interact with the heparin-binding site located within the arginine-rich motif at the distal end of the Postn C-terminal region.…”

Development of a top-down MS assay for specific identification of human periostin isoforms

“…Recombinant periostin isoforms 1-10 were expressed and purified as previously described ( Rusbjerg-Weberskov et al, 2023 ). Briefly, the recombinant periostin isoforms were expressed in a truncated form containing an N-terminal Twin-Strep-tag ® , a TEV cleavage site, the FAS1-4 domain, and the C-terminal domain.…”

“…Variation occurs from splicing of the similarly sized exons 17, 18, 19, and 21 that encode part of the C-terminal domain ( Figure 1 ). The C-terminal domain of periostin is disordered ( Rusbjerg-Weberskov et al, 2023 ) and constitute 11%–26% of the protein depending on the isoform.…”

DataSheet1.docx

“…The C-terminal domain of all isoforms contains an arginine-rich motif, RRRLREGRS, in the very terminal and is present in all isoforms (Figure 1). Thus, enrichment of the C-terminal regions after CNBr cleavage could rely on the heparin-binding ability inferred by this motif (Rusbjerg-Weberskov et al, 2023). The advantage of exploiting this common heparinbinding site is the hypothesized unbiased enrichment of all isoforms, which is essential for its compatibility with the assay.…”