Alpha kinase 3 signaling at the M-band maintains sarcomere integrity and proteostasis in striated muscle
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ABSTRACT:
PROVIDER: PRJNA889737 | ENA |
REPOSITORIES: ENA
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Project description:Muscle contraction is driven by the molecular machinery of the sarcomere. While the constituent components of the sarcomere are well characterized, it is less clear how the activity and turnover of sarcomeric proteins is regulated. In particular, phosphorylation is critical regulator of muscle function. Thus, identification of regulatory kinases is key to understanding the sarcomere function. Pathogenic variants in alpha kinase 3 (ALPK3) cause cardiomyopathy and musculoskeletal disease, but little is known about this atypical kinase. Here we show that ALPK3 localizes to the M-Band of the sarcomere and define the ALPK3-dependent phosphoproteome. ALPK3 deficiency disrupted sarcomeric organization and calcium kinetics in hPSC-derived cardiomyocytes and reduced force generation in cardiac organoids. Phosphoproteomic profiling identified ALPK3-dependant phospho-peptides that were enriched for sarcomeric components of the M-band and the ubiquitin-binding protein SQSTM1. Analysis of the ALPK3 interactome confirmed binding to M-band proteins including SQSTM1. Importantly, in hPSC-derived cardiomyocytes modeling ALPK3 deficiency and cardiomyopathic ALPK3 mutations, sarcomeric organization and M-band localization of SQSTM1 were abnormal. These data suggest ALPK3 has an integral role in maintaining sarcomere integrity and proteostasis in striated muscle. We propose this mechanism may underly disease pathogenesis in patients with ALPK3 variants.
2023-01-10 | GSE215304 | GEO
Project description:Muscle contraction is driven by the molecular machinery of the sarcomere. As phosphorylation is a critical regulator of muscle function, the identification of regulatory kinases is important for understanding sarcomere biology. Pathogenic variants in alpha kinase 3 (ALPK3) cause cardiomyopathy and musculoskeletal disease, but little is known about this atypical kinase. Here we show that ALPK3 is an essential component of the M-band of the sarcomere and define the ALPK3-dependent phosphoproteome. ALPK3 deficiency impaired contractility both in human cardiac organoids and in the hearts of mice harboring a pathogenic truncating Alpk3 variant. ALPK3-dependent phosphopeptides were enriched for sarcomeric components of the M-band and the ubiquitin-binding protein sequestosome-1 (SQSTM1) (also known as p62). Analysis of the ALPK3 interactome confirmed binding to M-band proteins including SQSTM1. In human pluripotent stem cell-derived cardiomyocytes modeling cardiomyopathic ALPK3 mutations, sarcomeric organization and M-band localization of SQSTM1 were abnormal suggesting that this mechanism may underly disease pathogenesis.
| S-EPMC11358020 | biostudies-literature
Project description:The sarcomere is the muscle contractile unit, whose assembly and disassembly are intimately linked to changes in myofiber size and function. Mutations in sarcomeric proteins are common causes of myopathies, ranging from severe neonatal to adult-onset forms. Here, we identify HECTD1 as an E3 ubiquitin ligase necessary for sarcomere maintenance. We show that silencingHectd1 in myotubesreduces the levels of proteins critical for sarcomere integrity including a-actin, titin, troponins, tropomyosins, and several myosin heavy chain isoforms. We further establish that Hectd1 ubiquitylates and stabilizes the molecular chaperones KLHL40/41, that when dysfunctional destabilize nebulin and other sarcomere thin filament proteins (causing nemaline myopathy). Consequently, skeletal muscle-specific Hectd1 knockout mice (Hectd1 mKO) show progressive muscle weakness, exercise intolerance, and unresolved tissue remodeling. Molecular and histological analysis of Hectd1 mKO muscle revealed subsarcolemmal storage of the scaffold protein desmin, mitochondrial abnormalities, and severe sarcomere disorganization. This work uncovers Hectd1 as an E3 ligase critical for sarcomere assembly, and a novel diagnostic gene for myopathy with features of nemaline and desmin myopathy.
2024-07-26 | GSE272775 | GEO
Project description:The esophagus is a muscular tube which transports swallowed content from the oral cavity and the pharynx to the stomach. Early in mouse development, an entire layer of the esophagus, the muscularis externa, consists of differentiated smooth muscle cells. Starting shortly after mid-gestation till about two weeks after birth, the muscularis externa almost entirely consists of striated muscle. This proximal-to-distal replacement of smooth muscle by the striated muscle depends on a number of factors. To identify the nature of the hypothetical “proximal” (mainly striated muscle originating) and “distal” (mainly smooth muscle originating) signals that govern the striated-for-smooth muscle replacement, we compared the esophagus of Myf5:MyoD null fetuses completely lacking striated muscle to the normal control using cDNA microarray analysis, followed by a comprehensive databases search. Here we provide an insight into the nature of “proximal” and “distal” signals that govern the striated-for-smooth muscle replacement in the esophagus.
2018-11-01 | GSE122017 | GEO
Project description:Styxl2, a poorly characterized pseudophosphatase, was identified as a transcriptional target of the Jak1-Stat1 pathway during myoblast differentiation in culture. Styxl2 is specifically expressed in vertebrate striated muscles. By gene knockdown in zebrafish or genetic knockout in mice, we found that Styxl2 plays an essential role in maintaining sarcomere integrity in developing muscles. To further reveal the functions of Styxl2 in adult muscles, we generated two inducible knockout mouse models: one with Styxl2 being deleted in mature myofibers to assess its role in sarcomere maintenance, and the other in adult muscle satellite cells (MuSCs) to assess its role in de novo sarcomere assembly. We find that Styxl2 is not required for sarcomere maintenance but functions in de novo sarcomere assembly during injury-induced muscle regeneration. Mechanistically, Styxl2 interacts with non-muscle myosin IIs, enhances their ubiquitination, and targets them for autophagy-dependent degradation. Without Styxl2, the degradation of non-muscle myosin IIs is delayed, which leads to defective sarcomere assembly and force generation. Thus, Styxl2 promotes de novo sarcomere assembly by interacting with non-muscle myosin IIs and facilitating their autophagic degradation.
2024-03-31 | GSE262242 | GEO
Project description:We show that striated muscle-expressed genes affected by reduction in UNC-120/SRF activity are not similarly affected by absence of the FHOD-1 formin. This suggests FHOD-1 does not affect striated muscle development via promotion of UNC-120/SRF-dependent transcription.
2020-09-19 | GSE158232 | GEO
Project description:Imbalances in endoplasmic reticulum (ER) proteostasis are associated with etiologically-diverse degenerative diseases linked to excessive extracellular protein misfolding and aggregation. Reprogramming of the ER proteostasis environment through genetic activation of the Unfolded Protein Response (UPR)-associated transcription factor ATF6 attenuates secretion and extracellular aggregation of amyloidogenic proteins. Here, we employed a screening approach that included complementary arm-specific UPR reporters and medium-throughput transcriptional profiling to identify non-toxic small molecules that phenocopy the ATF6-mediated reprogramming of the ER proteostasis environment. Comprehensive transcriptome analysis was employed to validate the capacity of three prioritized compounds to remodel the ER proteostasis environment, and to assess the prefential activation of ATF6 transcriptional targets relative to targets of the IRE1/XBP1s and PERK arms of the UPR. HEK293T-Rex and HEK293-DAX cells were treated for 6 hr with vehicle (DMSO), 1 µM Tg, 10 mM TMP (in HEK293DAX), or 10 µM 132, 147 or 263 in biological triplicate at 37 ÌC
2016-07-21 | E-GEOD-84636 | biostudies-arrayexpress
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) proteostasis through the activation of transcription factors such as XBP1s and ATF6. The functional consequences of these transcription factors for ER proteostasis remain poorly defined. Here, we describe methodology that enables orthogonal, small molecule-mediated activation of the UPR-associated transcription factors XBP1s and/or ATF6 in the same cell independent of stress. We employ transcriptomics and quantitative proteomics to evaluate ER proteostasis network remodeling owing to the XBP1s and/or ATF6 transcriptional programs. Furthermore, we demonstrate that the three ER proteostasis environments accessible by activating XBP1s and/or ATF6 differentially influence the folding, trafficking, and degradation of destabilized ER client proteins without globally affecting the endogenous proteome. Our data reveal how the ER proteostasis network is remodeled by the XBP1s and/or ATF6 transcriptional programs at the molecular level and demonstrate the potential for selectively restoring aberrant ER proteostasis of pathologic, destabilized proteins through arm-selective UPR-activation. The unfolded protein response adapts endoplasmic reticulum (ER) proteostasis via stress-responsive transcription factors including XBP1s and ATF6. Here, R. Luke Wiseman and colleagues implement technology for the orthogonal, ligand-dependent activation of XBP1s and/or ATF6 in a single cell. They characterize how XBP1s and/or ATF6 activation impacts ER proteostasis pathway composition and function. Adapted ER environments influence the proteostasis of destabilized protein variants without affecting the endogenous proteome. The work informs the development of proteostasis environment-adapting therapeutics for protein misfolding-related diseases. In order to activate both XBP1s and ATF6 in the same cell, we incorporated DHFR.ATF6 and tet-inducible XBP1s into a HEK293T-REx cell line stably expressing the tet-repressor. The HEK293DYG control cell line expresses tet-inducible eGFP and DHFR.YFP and is used as a control to demonstrate that the addition of doxycycline (dox) and trimethoprim (TMP) do not induce UPR genes. HEK293DYG cells were treated for 12 h with vehicle or 1 μg/mL dox and 10 μM TMP in biological triplicate. Cells were harvested and RNA was extracted using the RNeasy Mini Kit (Qiagen). Genomic DNA was removed by on-column digestion using the RNase-free DNase Set (Qiagen). Data from HEK293DYG cells showed no significant overlap in the ligand-treated transcriptomes obtained from HEK293DAX cells.
2013-04-23 | E-GEOD-44950 | biostudies-arrayexpress
Project description:Cardiac development relies on proper cardiomyocyte differentiation including expression and assembly of cell-type specific actomyosin subunits into a functional cardiac sarcomere. Control of this process involves not only promoting expression of cardiac sarcomere subunits but also repressing expression of non-cardiac myofibril paralogs. This level of transcriptional control requires broadly expressed multiprotein machines that modify and remodel the chromatin landscape to restrict transcription machinery access. Prominent among these is the Nucleosome Remodeling and Deacetylase (NuRD) complex, which includes the catalytic core subunit CHD4. Here, we demonstrate that direct CHD4-mediated repression of skeletal and smooth muscle myofibril isoforms is required for normal cardiac sarcomere formation, function, and embryonic survival early in gestation. Through transcriptomic and system genome-wide analyses of CHD4 localization, we identified novel CHD4 binding sites in smooth muscle myosin heavy chain, fast skeletal α-actin, and the fast skeletal troponin complex genes. We further demonstrate that in the absence of CHD4, cardiomyocytes in the developing heart form a hybrid muscle cell that contains cardiac, skeletal and smooth muscle myofibril components. These misexpressed paralogs intercalate into the nascent cardiac sarcomere to disrupt sarcomere formation and cause impaired cardiac function in utero. These results demonstrate the genomic and physiological requirements for CHD4 in mammalian cardiac development.
2018-05-15 | GSE109012 | GEO
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) proteostasis through the activation of transcription factors such as XBP1s and ATF6. The functional consequences of these transcription factors for ER proteostasis remain poorly defined. Here, we describe methodology that enables orthogonal, small molecule-mediated activation of the UPR-associated transcription factors XBP1s and/or ATF6 in the same cell independent of stress. We employ transcriptomics and quantitative proteomics to evaluate ER proteostasis network remodeling owing to the XBP1s and/or ATF6 transcriptional programs. Furthermore, we demonstrate that the three ER proteostasis environments accessible by activating XBP1s and/or ATF6 differentially influence the folding, trafficking, and degradation of destabilized ER client proteins without globally affecting the endogenous proteome. Our data reveal how the ER proteostasis network is remodeled by the XBP1s and/or ATF6 transcriptional programs at the molecular level and demonstrate the potential for selectively restoring aberrant ER proteostasis of pathologic, destabilized proteins through arm-selective UPR-activation. The unfolded protein response adapts endoplasmic reticulum (ER) proteostasis via stress-responsive transcription factors including XBP1s and ATF6. Here, R. Luke Wiseman and colleagues implement technology for the orthogonal, ligand-dependent activation of XBP1s and/or ATF6 in a single cell. They characterize how XBP1s and/or ATF6 activation impacts ER proteostasis pathway composition and function. Adapted ER environments influence the proteostasis of destabilized protein variants without affecting the endogenous proteome. The work informs the development of proteostasis environment-adapting therapeutics for protein misfolding-related diseases. In order to activate both XBP1s and ATF6 in the same cell, we incorporated DHFR.ATF6 and tet-inducible XBP1s into a HEK293T-REx cell line stably expressing the tet-repressor. Selection of a single colony resulted in the HEK293DAX cell line in which XBP1s is induced by doxycycline and DHFR.ATF6 is activated by trimethoprim (TMP; TMP-dependent DHFR.ATF6 activation in HEK293DAX cells will henceforth be referred to as ATF6 activation for simplicity). HEK293DAX cells were treated for 12 h with vehicle, 1 ?g/mL dox, 10 ?M TMP, or both in biological triplicate. Cells were harvested and RNA was extracted using the RNeasy Mini Kit (Qiagen). Genomic DNA was removed by on-column digestion using the RNase-free DNase Set (Qiagen). Data from HEK293DYG cells showed no significant overlap in the ligand-treated transcriptomes obtained from the control HEK293DYG cells.
2013-04-23 | E-GEOD-44949 | biostudies-arrayexpress