Hepatocyte-like cells reveal novel role of SERPINA1 in transthyretin amyloidosis

Abstract

Transthyretin (TTR)-related familial amyloid polyneuropathy (ATTR) results from aggregation and extracellular disposition of misfolded TTR mutants. Growing evidence suggests the importance of hepatic chaperones for the modulation of pathogenesis. We took advantage of induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (HLCs) from ATTR patients (ATTR-HLCs) to compare chaperone gene expression to that in HLCs from healthy individuals (H-HLCs). From the set of genes analyzed, chaperones that are predominantly located extracellularly were differently expressed. Expression of the chaperones showed a high correlation with TTR in both ATTR-HLCs and H-HLCs. In contrast, after TTR knockdown, the correlation was mainly affected in ATTR-HLCs suggesting that differences in TTR expression triggers aberrant chaperone expression. Serpin family A member 1 (SERPINA1) was the only extracellular chaperone that was markedly upregulated after TTR knockdown in ATTR-HLCs. Co-immunoprecipitation revealed that SERPINA1 physically interacts with TTR. In vitro assays indicated that SERPINA1 can interfere with TTR aggregation. Taken together, our results suggest that extracellular chaperones play a crucial role in ATTR pathogenesis, in particular SERPINA1, which may affect amyloid formation.

In Vitro and In Vivo Effects of SerpinA1 on the Modulation of Transthyretin Proteolysis

“…Plasmin-mediated proteolysis facilitates the process of TTR aggregation, as observed by the increase of TTR aggregated species (909.7 nm; 8.1%) along with the decrease of the soluble form (13.15 nm; 75.4%) (Figure 2B), comparatively to non-digested samples, in which TTR was only found in the soluble form (9.228 nm; 98.5%) (Figure 2A). In addition, TTR V30M incubated with SerpinA1 revealed the presence of soluble particles exhibiting a large diameter (23.81 nm, 100%) (Figure 2C), probably indicating the formation of TTR-SerpinA1 complex, as described previously [33]. Samples incubated with both plasmin and SerpinA1 presented less abundant and smaller TTR aggregates (537.7 nm; 4.3%) (Figure 2D), as compared to samples only incubated with plasmin (Figure 2B).…”

“…Samples incubated with both plasmin and SerpinA1 presented less abundant and smaller TTR aggregates (537.7 nm; 4.3%) (Figure 2D), as compared to samples only incubated with plasmin (Figure 2B). Besides its function as a serine protease inhibitor, SerpinA1 also functions as an extracellular chaperone and recently, it was reported that SerpinA1 inhibited TTR amyloid Besides its function as a serine protease inhibitor, SerpinA1 also functions as an extracellular chaperone and recently, it was reported that SerpinA1 inhibited TTR amyloid formation in vitro [33]. Thus, the same samples were analyzed by thioflavin T (ThT) assays to evaluate the amyloid nature of the formed species.…”

“…Sci. 2021, 22, 9488 5 of 17 formation in vitro [33]. Thus, the same samples were analyzed by thioflavin T (ThT) assays to evaluate the amyloid nature of the formed species.…”

“…The SerpinA1 mRNA was found to be differentially expressed in hepatocyte-like cells (HLCs) from ATTR patients compared to healthy controls and, a high inverse correlation between SerpinA1 and TTR genes was also observed. Upon TTR knockdown in HLCs the correlation was abolished [33]. Recently, it was demonstrated that SerpinA1 knockdown modulates TTR expression in both cellular and animal models, performing an important role in the development of ATTR amyloidosis [34].…”

Expression of Amyloidogenic Transthyretin Drives Hepatic Proteostasis Remodeling in an Induced Pluripotent Stem Cell Model of Systemic Amyloid Disease

“…Here, we utilize a patient-specific iPSC-based model of ATTR amyloidosis to investigate the contribution of hepatic proteostasis and disease-modifying factors to the distal toxicity observed in patients. Recent attempts have been made to identify transcriptional differences between ATTR amyloidosis and wild-type iPSC-derived HLCs via qRT-PCR ( Niemietz et al., 2018 ). Problematically, the maturational status of examined cells in these studies was not taken into account, and reported results likely reflect distinct differentiation efficiencies between lines.…”