| 1. |
- Zhou, T. K., et al.
(författare)
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Molecular Characterisation of Titin N2A and Its Binding of CARP Reveals a Titin/Actin Cross-linking Mechanism
- 2021
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836. ; 433:9
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Tidskriftsartikel (refereegranskat)abstract
- Striated muscle responds to mechanical overload by rapidly up-regulating the expression of the cardiac ankyrin repeat protein, CARP, which then targets the sarcomere by binding to titin N2A in the I-band region. To date, the role of this interaction in the stress response of muscle remains poorly understood. Here, we characterise the molecular structure of the CARP-receptor site in titin (UN2A) and its binding of CARP. We find that titin UN2A contains a central three-helix bundle fold (ca 45 residues in length) that is joined to N- and C-terminal flanking immunoglobulin domains by long, flexible linkers with partial helical content. CARP binds titin by engaging an a-hairpin in the three-helix fold of UN2A, the C-terminal linker sequence, and the BC loop in Ig81, which jointly form a broad binding interface. Mutagenesis showed that the CARP/N2A association withstands sequence variations in titin N2A and we use this information to evaluate 85 human single nucleotide variants. In addition, actin co-sedimentation, co-transfection in C2C12 cells, proteomics on heart lysates, and the mechanical response of CARP-soaked myofibrils imply that CARP induces the cross-linking of titin and actin myofilaments, thereby increasing myofibril stiffness. We conclude that CARP acts as a regulator of force output in the sarcomere that preserves muscle mechanical performance upon overload stress. Crown Copyright (C) 2021 Published by Elsevier Ltd. All rights reserved.
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| 2. |
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| 3. |
- Liang, Y., et al.
(författare)
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Desmosomal COP9 regulates proteome degradation in arrhythmogenic right ventricular dysplasia/cardiomyopathy
- 2021
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Ingår i: Journal of Clinical Investigation. - : American Society for Clinical Investigation. - 0021-9738 .- 1558-8238. ; 131:11
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Tidskriftsartikel (refereegranskat)abstract
- Dysregulated protein degradative pathways are increasingly recognized as mediators of human disease. This mechanism may have particular relevance to desmosomal proteins that play critical structural roles in both tissue architecture and cell-cell communication, as destabilization/breakdown of the desmosomal proteome is a hallmark of genetic-based desmosomal-targeted diseases, such as the cardiac disease arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). However, no information exists on whether there are resident proteins that regulate desmosomal proteome homeostasis. Here, we uncovered a cardiac constitutive photomorphogenesis 9 (COP9) desmosomal resident protein complex, composed of subunit 6 of the COP9 signalosome (CSN6), that enzymatically restricted neddylation and targeted desmosomal proteome degradation. CSN6 binding, localization, levels, and function were affected in hearts of classic mouse and human models of ARVD/C affected by desmosomal loss and mutations, respectively. Loss of desmosomal proteome degradation control due to junctional reduction/loss of CSN6 and human desmosomal mutations destabilizing junctional CSN6 were also sufficient to trigger ARVD/C in mice. We identified a desmosomal resident regulatory complex that restricted desmosomal proteome degradation and disease.
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| 4. |
- Marrocco, V., et al.
(författare)
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PKC and PKN in heart disease
- 2019
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Ingår i: Journal of Molecular and Cellular Cardiology. - : Elsevier BV. - 0022-2828. ; 128, s. 212-226
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Tidskriftsartikel (refereegranskat)abstract
- The protein kinase C (PKC) and closely related protein kinase N (PKN) families of serine/threonine protein kinases play crucial cellular roles. Both kinases belong to the AGC subfamily of protein kinases that also include the CAMP dependent protein kinase (PKA), protein kinase B (PKB/AKT), protein kinase G (PKG) and the ribosomal protein S6 kinase (S6K). Involvement of PKC family members in heart disease has been well documented over the years, as their activity and levels are mis-regulated in several pathological heart conditions, such as ischemia, diabetic cardiomyopathy, as well as hypertrophic or dilated cardiomyopathy. This review focuses on the regulation of PKCs and PKNs in different pathological heart conditions and on the influences that PKC/PKN activation has on several physiological processes. In addition, we discuss mechanisms by which PKCs and the closely related PKNs are activated and turned-off in hearts, how they regulate cardiac specific downstream targets and pathways, and how their inhibition by small molecules is explored as new therapeutic target to treat cardiomyopathies and heart failure.
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| 5. |
- Franke, Barbara, et al.
(författare)
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Molecular basis for the fold organization and sarcomeric targeting of the muscle atrogin MuRF1
- 2014
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Ingår i: Open Biology. - London, United Kingdom : The Royal Society Publishing. - 2046-2441. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- MuRF1 is an E3 ubiquitin ligase central to muscle catabolism. It belongs to the TRIM protein family characterized by a tripartite fold of RING, B-box and coiled-coil (CC) motifs, followed by variable C-terminal domains. The CC motif is hypothesized to be responsible for domain organization in the fold as well as for high-order assembly into functional entities. But data on CC from this family that can clarify the structural significance of this motif are scarce. We have characterized the helical region from MuRF1 and show that, contrary to expectations, its CC domain assembles unproductively, being the B2- and COS-boxes in the fold (respectively flanking the CC) that promote a native quaternary structure. In particular, the C-terminal COS-box seemingly forms an α-hairpin that packs against the CC, influencing its dimerization. This shows that a C-terminal variable domain can be tightly integrated within the conserved TRIM fold to modulate its structure and function. Furthermore, data from transfected muscle show that in MuRF1 the COS-box mediates the in vivo targeting of sarcoskeletal structures and points to the pharmacological relevance of the COS domain for treating MuRF1-mediated muscle atrophy.
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