Compartmentalisation proteomics revealed endolysosomal protein network changes in a goat model of atrial fibrillation

Abstract

Endolysosomes (EL) are known for their role in regulating both intracellular trafficking and proteostasis. EL help facilitate elimination of damaged membrane and cytosolic proteins, protein aggregates, membranous organelles and also play an important role in calcium signalling. Despite the importance of EL, their specific role in cardiovascular disease is not well understood. In particular, it's unclear how EL contribute to atrial pathology over longer time frames. To shed light on this question, we conducted a comprehensive analysis that involved proteomics, transcriptomics, integrated analysis, electron tomography, western blotting, and enzyme assays. To identify the role of EL in atrial fibrillation (AF), we applied a recently published organelle protein isolation method. We used this method to study biopsies from AF goat model and analyse the EL-specific proteins and pathways involved in this condition. Our results revealed the upregulation of the AMPK pathway and the expression of EL-specific proteins that were not found in whole tissue lysates (TL), including GAA, DYNLRB1, CLTB, SIRT3, CCT2, and muscle-specific HSPB2. We also observed structural anomalies, such as autophago-vacuole formation, irregularly shaped mitochondria, and glycogen deposition, which provide insights into the EL's contribution to AF and related pathways and molecular mechanisms. Overall, our findings suggest that EL play an important role in the development of AF over longer time frames, and provide a more detailed understanding of the underlying molecular processes involved.

Lysosomal signalling pathways influence heart rhythm, and regulate atrial function

“…We recently published an omics study focused on endolysosomal organelle proteins that highlights possible changes in lysosome function in AF. Amongst the many regulated proteins detected, we found in our human proteomics lysosomal alpha glucosidase (GAA), that is involved in the lysosomal breakdown of glycogen to be upregulated in AF [36]. In addition to GAA, we also detected the following Rab GTPases to be changed in our human proteomics (Fig.…”

“…Rab7 normally present on late endosomes, is either directly or indirectly involved in each event occurring between early endosomes and lysosomes. RAB7A is a recruiting protein for the tethering molecules by regulating transport pathways and transforming late-endosomes to lysosomes (lysosomal biogenesis) and sorting complex required for transport pathways, after 6 months in AF [50]. Ly-SR distance increase in AF is still unclear, future studies will seek to investigate whether this change could underpin the increase in lysosome-SR distance reported in our study and the potential functional impact of this change on the lysosomal calcium signalling.…”

“…The goat model in this study (female C. hircus) is described in [50], where AF was induced and maintained in female goats (C. hircus) for 6 months (AF goat model was created as methodologically described in [77]. Goat were anesthetized and followed by an open chest experiment (N=4 AF and N=4 sham controls) in order to collect tissue and were euthanized.…”

“…ATP6AP1 (V-type proton ATPase subunit S1), involved in lysosomal acidification was detected (log2 -0.282 fold change in AF). Other proteins with roles in lysosomal function that were detected in our significantly regulated list include: Transmembrane protein 119 (TMEM119, log2 0.542 fold change in AF), Synaptogamin 1 (SYT1, log2 -0.82 fold change in AF), Microtubule-associated protein tau (MAPT, log2 -0.491 fold change in AF), Isoform 2 of Glycogen phosphorylase, muscle form, glycogen metabolizing enzyme (PYGM, log2 -0.97 fold change in AF), Natriuretic peptides A (NPPA, log2 1.106 fold change in AF), Mitogen-activated protein kinase 14 (MAPK14, log2 0.215 fold change in AF and was also upregulated in goat AF studies [36]. Top Canonical Pathways include (Fig.…”