Cardiac fibrosis in mouse expressing DsRed tetramers involves chronic autophagy and proteasome degradation insufficiency

Abstract

Proteinopathy in the heart which often manifests excessive misfolded/aggregated proteins in cardiac myocytes can result in severe fibrosis and heart failure. Here we developed a mouse model, which transgenically express tetrameric DsRed, a red fluorescent protein (RFP), in an attempt to mimic the pathological mechanisms ofcardiac fibrosis. Whilst DsRed is expressed and forms aggregation in most mouse organs, certain pathological defects are specifically recapitulated in cardiac muscle cells including mitochondria damages, aggresome-like residual bodies, excessive ubiquitinated proteins, and the induction of autophagy. The proteinopathy and cellular injuries caused by DsRed aggregates may be due to impaired or overburdened ubiquitin-proteasome system and autophagy-lysosome systems. We further identified that DsRed can be ubiquitinated and associated with MuRF1, a muscle-specific E3 ligase. Concomitantly, an activation of NF-κB signaling and a strong TIMP1 induction were noted, suggesting that RFP-induced fibrosis was augmented by a skewed balance between TIMP1 and MMPs. Taken together, our study highlights the molecular consequences of uncontrolled protein aggregation leading to congestive heart failure, and provides novel insights into fibrosis formation that can be exploited for improved therapy.

Synthetic Monopartite Peptide That Enables the Nuclear Import of Genes Delivered by the Neurotensin-Polyplex Vector

“…In this study, the DsRed2DsRed2 expression was cytotoxic regardless of the use of KPRa or KPSV40. This cytotoxic effect is inherent in the DsRed2 protein, as previously shown in cardiac myocytes of a transgenic mouse and Hela cells . These results indirectly support the safety of NTS-polyplex vector transfection in vivo …”

Mitochondrial Dysfunction as an Underlying Cause of Skeletal Muscle Disorders

“…The UPR in the ER (UPR er ) also affects gene expression related to protein degradation in atrophic muscles [ 125 ]. Uncontrolled protein aggregation due to the impairment or overburdening of the ubiquitin–proteasome and autophagy–lysosome systems leads to mitochondrial damage, aggregation-like residues, hyper-ubiquitinated proteins, and induction of autophagy, leading to muscle fibrotic injury [ 126 ]. Protein quality control is important for muscle cells, and skeletal muscle is not as resistant to protein stress as cardiomyocytes [ 127 ].…”

Structural Insights into the Binding of Red Fluorescent Protein mCherry-Specific Nanobodies

“…Thus, RFPs can be more easily combined with GFP or other FPs to create multicolor imaging experiments [ 13 ]. However, one challenge with RFPs is their tendency to form tetramers, which can result in false-positive binding results [ 14 ]. To address this issue, researchers have developed monomeric RFPs, which have become increasingly popular in life science research.…”