Mapping Cellular Response to Destabilized Transthyretin Reveals Cell- and Amyloidogenic Protein-Specific Signatures

Abstract

In ATTR amyloidosis, transthyretin (TTR) protein is secreted from the liver and deposited as toxic aggregates at downstream target tissues. Despite recent advancements in treatments for ATTR amyloidosis, the mechanisms underlying misfolded TTR-mediated cellular damage remain elusive. In an effort to define early events of TTR-associated stress, we exposed neuronal (SH-SY5Y) and cardiac (AC16) cells to wild-type and destabilized TTR variants (TTRV122I and TTRL55P) and performed transcriptional (RNAseq) and epigenetic (ATACseq) profiling. We subsequently compared TTR-responsive signatures to cells exposed to destabilized antibody light chain protein associated with AL amyloidosis as well as ER stressors (thapsigargin, heat shock). In doing so, we observed overlapping, yet distinct cell type- and amyloidogenic protein-specific signatures, suggesting unique responses to each amyloidogenic variant. Moreover, we identified chromatin level changes in AC16 cells exposed to mutant TTR which resolved upon pre-incubation with kinetic stabilizer tafamidis. Collectively, these data provide insight into the mechanisms underlying amyloid-mediated cellular damage and provide a robust resource representing cellular responses to aggregation-prone proteins and ER stress.

Abnormal global longitudinal strain and reduced serum inflammatory markers in cardiac AL amyloidosis patients without significant amyloid fibril deposition

“…[37] In doing so, we demonstrated that AC16 cells exposed to cardiomyopathy-associated κAL LC displayed a significantly higher number of differentially expressed genes than AC16 cells exposed to non-AL amyloidogenic proteins with no significant overlap in differentially regulated genes between study groups. [37] Herein, we used human induced pluripotent stem cell (iPSC)-derived cardiomyocytes to validate the gene expression changes of clinically relevant genes in cardiac dysfunction-related pathways that are differentially activated upon exposure to a cardiomyopathy-associated κAL LC. We then used this data to guide subsequent interrogation of our clinical dataset for measurable parameters that reflect gene expression changes observed in these cardiac dysfunction-related pathways.…”

“…Previously, we characterized neuronal SH-SY5Y and cardiac AC16 cells to an amyloidogenic, cardiomyopathy-associated kappa 1 LC (cardiomyopathy-associated κAL LC) as compared to amyloidogenic transthyretin (TTR) via RNA sequencing (RNAseq). [37] In doing so, we demonstrated that AC16 cells exposed to cardiomyopathy-associated κAL LC displayed a significantly higher number of differentially expressed genes than AC16 cells exposed to non-AL amyloidogenic proteins with no significant overlap in differentially regulated genes between study groups. [37] Herein, we used human induced pluripotent stem cell (iPSC)-derived cardiomyocytes to validate the gene expression changes of clinically relevant genes in cardiac dysfunction-related pathways that are differentially activated upon exposure to a cardiomyopathy-associated κAL LC.…”

“…2022. [37] Functional predictions were made using the Enrichr gene set enrichment analysis web server [43][44][45] were identified by the presence of elevated cardiac biomarkers per institutional reference ranges, including BNP > 72 mg/dL or NT-proBNP > 899 pg/mL or cardiac troponin I > 0.033 ng/mL. For the final analysis, we defined presumed LC-induced cardiac dysfunction as (1) elevated cardiac biomarkers, (2) normal echocardiographic intraventricular septal thickness (< 11 mm in males and < 10 mm in females), (3) estimated glomerular filtration rate > 60 mL/min/1.73m 2 , (4) absence of late gadolinium enhancement on cardiac magnetic resonance imaging (if performed), and (5) negative endomyocardial biopsy (if performed).…”

“…Our group previously examined transcriptomic changes occurring in AC16 human ventricular cardiomyocyte cells exposed to a cardiomyopathy-associated κAL LC as described above from the Boston University Amyloidosis Center and amyloidogenic transthyretin (TTR) proteins [37]. Here, we performed a post-hoc functional gene set enrichment analysis (fgsea) to evaluate hallmark pathways enriched upon exposure of AC16 cells to a cardiomyopathy-associated κAL LC.…”

A longevity-specific bank of induced pluripotent stem cells from centenarians and their offspring

“…Beginning soon after their initial discovery, iPSCs have been used to model diseases as well as screen drugs for the treatment of amyotrophic lateral sclerosis 9 , spinal muscular atrophy 10 , and other neurodegenerative 11 and muscular 12 disorders. Notably and importantly, these model systems have been applied to and faithfully recapitulate disease pathologies associated with aging that manifest late in life, such as in AD [13][14][15][16][17] and in our own work on familial ATTRamyloidosis [18][19][20][21] . The versatility in these systems to produce any cell and tissue type of the body allows for interrogation of multiple, aging-impacted tissues, many of which have been demonstrated to age at different rates 22 .…”