Association with SERCA2a directs phospholamban trafficking to sarcoplasmic reticulum from a nuclear envelope pool

He, Wenbo; Huang, Dong-Ping; Guo, Shuai; Wang, Danning; Guo, Jin; Cala, Steven E.; Chen, Zhenhui

doi:10.1016/j.yjmcc.2020.04.025

Cited by 14 publications

(18 citation statements)

References 64 publications

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“…For example, sAnk1 is peptide (non-regulin family member) that acts to help target SERCA1 to longitudinal SR and to maintain the ultrastructure of longitudinal SR of mouse myofibers [121]; in addition, sAnk1 also acts as a regulin-like peptide inhibitor of SERCA1 activity in a heterologous expression system [11,70]. On the other hand, the SERCA2 protein contributes to targeting PLN to longitudinal SR of cardiomyocytes, via the newly-identified NEST pathway (nuclear ER to SR via T-tubule transit), as reported by Cala and Chen [122,123]. Similarly, SERCA1 contributes to targeting SLN peptides to endoplasmic reticulum of cultured human embryonic kidney cells [35,36,124].…”

Section: Potential Mechanisms To Control Sln Protein Expression and Serca Regulation In Horse Gluteal Musclementioning

confidence: 83%

Sarcolipin Exhibits Abundant RNA Transcription and Minimal Protein Expression in Horse Gluteal Muscle

Autry

Karim

Perumbakkam

et al. 2020

Veterinary Sciences

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Ca2+ regulation in equine muscle is important for horse performance, yet little is known about this species-specific regulation. We reported recently that horse encode unique gene and protein sequences for the sarcoplasmic reticulum (SR) Ca2+-transporting ATPase (SERCA) and the regulatory subunit sarcolipin (SLN). Here we quantified gene transcription and protein expression of SERCA and its inhibitory peptides in horse gluteus, as compared to commonly-studied rabbit skeletal muscle. RNA sequencing and protein immunoblotting determined that horse gluteus expresses the ATP2A1 gene (SERCA1) as the predominant SR Ca2+-ATPase isoform and the SLN gene as the most-abundant SERCA inhibitory peptide, as also found in rabbit skeletal muscle. Equine muscle expresses an insignificant level of phospholamban (PLN), another key SERCA inhibitory peptide expressed commonly in a variety of mammalian striated muscles. Surprisingly in horse, the RNA transcript ratio of SLN-to-ATP2A1 is an order of magnitude higher than in rabbit, while the corresponding protein expression ratio is an order of magnitude lower than in rabbit. Thus, SLN is not efficiently translated or maintained as a stable protein in horse muscle, suggesting a non-coding role for supra-abundant SLN mRNA. We propose that the lack of SLN and PLN inhibition of SERCA activity in equine muscle is an evolutionary adaptation that potentiates Ca2+ cycling and muscle contractility in a prey species domestically selected for speed.

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Section: Potential Mechanisms To Control Sln Protein Expression and Serca Regulation In Horse Gluteal Musclementioning

confidence: 83%

Sarcolipin Exhibits Abundant RNA Transcription and Minimal Protein Expression in Horse Gluteal Muscle

Autry

Karim

Perumbakkam

et al. 2020

Veterinary Sciences

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“…The SL membrane proteins Cx43 (encoded by Gja1 ) and Na V 1.5 (encoded by Scn5a ) are known to be preferentially localized to the intercalated disks (IDs) with the latter also found in surface sarcolemma and transverse tubules [ 56 ]. Following synthesis in the perinuclear region, these proteins are thought to move to the IDs via the canonical secretory protein trafficking (SPT) pathway [ 3 , 20 , 25 ]. In accordance with this notion, mRNAs for these proteins, especially Gja1 , appeared to localize mainly to the nuclei and perinuclear regions of myocytes ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, Ca V 1.2 (encoded by Cacna1c ) localizes to the transverse tubules, while SERCA2a (encoded by Atp2a2 ) and RyR2 (encoded by Ryr2 ) localize to SR membranes [ 4 , 27 ]. Previous studies suggested that trafficking of these proteins may also rely on the canonical SPT mechanism [ 3 , 25 , 44 , 62 ]. Surprisingly, mRNA for several of these proteins, in addition to being present in and around the nuclei, exhibited cell-wide distribution (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In this study, we examined how protein synthesis is spatially organized within cardiac myocytes for membrane proteins with key roles in electrical excitability and contractility localized to both the sarcolemma (SL; namely Ca V 1.2, and Na V 1.5) and sarcoplasmic reticulum (SR; namely SERCA2a and RyR2). It is commonly held that all membrane proteins in cardiac myocytes are synthesized and processed in ER/Golgi, in the perinuclear regions, and then transported to locations of deployment in the SL and SR membranes (i.e., the SPT pathway) [ 3 , 20 , 25 ]. In contrast to such centralized mechanisms, we present evidence for membrane protein synthesis occurring throughout the cardiac myocyte cytosolic space, providing on-site supply of membrane proteins for local use.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, membrane proteins are thought to follow the classical secretory pathway for their synthesis. It is generally thought that messenger RNA (mRNA) for membrane proteins, such as ion channels, are more restricted and only centrally translated in the perinuclear rough endoplasmic reticulum (ER) and newly synthesized proteins are processed in the Golgi network before being trafficked from perinuclear regions to sites of deployment throughout the cell [ 25 ]. Previous studies investigating the trafficking of some cardiac membrane proteins, such as connexin43 (Cx43; encoded by Gja1 ), supported this view [ 49 – 51 ].…”

Section: Introductionmentioning

confidence: 99%

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Distributed synthesis of sarcolemmal and sarcoplasmic reticulum membrane proteins in cardiac myocytes

et al. 2021

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It is widely assumed that synthesis of membrane proteins, particularly in the heart, follows the classical secretory pathway with mRNA translation occurring in perinuclear regions followed by protein trafficking to sites of deployment. However, this view is based on studies conducted in less-specialized cells, and has not been experimentally addressed in cardiac myocytes. Therefore, we undertook direct experimental investigation of protein synthesis in cardiac tissue and isolated myocytes using single-molecule visualization techniques and a novel proximity-ligated in situ hybridization approach for visualizing ribosome-associated mRNA molecules for a specific protein species, indicative of translation sites. We identify here, for the first time, that the molecular machinery for membrane protein synthesis occurs throughout the cardiac myocyte, and enables distributed synthesis of membrane proteins within sub-cellular niches where the synthesized protein functions using local mRNA pools trafficked, in part, by microtubules. We also observed cell-wide distribution of membrane protein mRNA in myocardial tissue from both non-failing and hypertrophied (failing) human hearts, demonstrating an evolutionarily conserved distributed mechanism from mouse to human. Our results identify previously unanticipated aspects of local control of cardiac myocyte biology and highlight local protein synthesis in cardiac myocytes as an important potential determinant of the heart’s biology in health and disease.

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Activation of Ca2+ transport in cardiac microsomes enriches functional sets of ER and SR proteins

et al. 2023

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The importance of sarcoplasmic reticulum (SR) Ca2+-handling in heart has led to detailed understanding of Ca2+-release and re-uptake protein complexes, while less is known about other endoplasmic reticulum (ER) functions in the heart. To more fully understand cardiac SR and ER functions, we analyzed cardiac microsomes based on their increased density through the actions of the SR Ca2+-ATPase (SERCA) and the ryanodine receptor that are highly active in cardiomyocytes. Crude cardiac microsomal vesicles loaded with Ca oxalate produced two higher density subfractions, MedSR and HighSR. Proteins from 20.0 μg of MV, MedSR, and HighSR protein were fractionated using SDS-PAGE, then trypsinized from 20 separate gel pieces, and analyzed by LC–MS/MS to determine protein content. From 62,000 individual peptide spectra obtained, we identified 1105 different proteins, of which 354 were enriched ≥ 2.0-fold in SR fractions compared to the crude membrane preparation. Previously studied SR proteins were all enriched, as were proteins associated with canonical ER functions. Contractile, mitochondrial, and sarcolemmal proteins were not enriched. Comparing the levels of SERCA-positive SR proteins in MedSR versus HighSR vesicles produced a range of SR subfraction enrichments signifying differing levels of Ca2+ leak co-localized in the same membrane patch. All known junctional SR proteins were more enriched in MedSR, while canonical ER proteins were more enriched in HighSR membrane. Proteins constituting other putative ER/SR subdomains also exhibited average Esub enrichment values (mean ± S.D.) that spanned the range of possible Esub values, suggesting that functional sets of proteins are localized to the same areas of the ER/SR membrane. We conclude that active Ca2+ loading of cardiac microsomes, reflecting the combined activities of Ca2+ uptake by SERCA, and Ca2+ leak by RyR, permits evaluation of multiple functional ER/SR subdomains. Sets of proteins from these subdomains exhibited similar enrichment patterns across membrane subfractions, reflecting the relative levels of SERCA and RyR present within individual patches of cardiac ER and SR.

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Association with SERCA2a directs phospholamban trafficking to sarcoplasmic reticulum from a nuclear envelope pool

Cited by 14 publications

References 64 publications

Sarcolipin Exhibits Abundant RNA Transcription and Minimal Protein Expression in Horse Gluteal Muscle

Sarcolipin Exhibits Abundant RNA Transcription and Minimal Protein Expression in Horse Gluteal Muscle

Distributed synthesis of sarcolemmal and sarcoplasmic reticulum membrane proteins in cardiac myocytes

Activation of Ca2+ transport in cardiac microsomes enriches functional sets of ER and SR proteins

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