The SERCA-PLN-DWORF axis in cardiometabolic disease: mechanisms and therapeutic perspectives

Abstract

Intracellular calcium (Ca²⁺) homeostasis is a central determinant of cardiometabolic physiology, integrating excitation-contraction coupling, metabolic signaling, and stress adaptation across multiple organs. The sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA), regulated by the micropeptides phospholamban (PLN) and dwarf open reading frame (DWORF), governs ER/SR Ca²⁺ reuptake and thereby shapes Ca²⁺-dependent signaling dynamics. Dysregulation of the SERCA-PLN-DWORF axis is increasingly recognized as a shared pathogenic mechanism in type 2 diabetes-related complications, including diabetic cardiomyopathy and heart failure with preserved ejection fraction (HFpEF), where reduced SERCA2a activity prolongs diastolic Ca²⁺ clearance and promotes calcineurin-NFAT activation and mitochondrial Ca²⁺ overload. In the liver, loss of SERCA2b activity promotes chronic ER stress, Ca²⁺-phosphoinositide complex formation, insulin resistance, and fibrotic activation, thereby linking Ca²⁺ dysregulation to progressive metabolic liver injury in metabolic dysfunction-associated fatty liver disease (MAFLD) and steatohepatitis (MASH). These observations position Ca²⁺ dysregulation as a unifying mechanism across the cardiometabolic disease continuum, spanning myocardial dysfunction, systemic insulin resistance, and progressive fatty liver disease. Therapeutic strategies targeting the SERCA-PLN-DWORF axis, including SERCA activators, PLN-directed antisense oligonucleotides, DWORF gene therapy, and CRISPR-based modulation, have demonstrated efficacy in preclinical models by improving Ca²⁺ handling and alleviating metabolic or contractile stress. Further studies are required to determine the translational feasibility, long-term safety, and optimal patient subsets for SERCA-targeted interventions in cardiometabolic disease.

Fig. 1

Integrated Overview of Intracellular Ca²⁺ Handling and SERCA Regulation. This schematic representation summarizes the major pathways coordinating intracellular Ca²⁺ flux in excitable and non-excitable cells, emphasizing the β-adrenergic receptor (β-AR)–PLN–SERCA regulatory axis. β-AR activation stimulates Gsα–adenylyl cyclase signaling to elevate cAMP, which activates PKA and phosphorylates PLN at Ser¹⁶, relieving its inhibition of SERCA. Concurrently, Ca²⁺ influx through L-type Ca²⁺ channels triggers CaMKII-dependent phosphorylation of PLN at Thr¹⁷, further enhancing SERCA-mediated Ca²⁺ reuptake into the SR/ER. In its dephosphorylated state, PLN stabilizes SERCA in a low-affinity (E2) conformation, limiting Ca²⁺ sequestration, whereas phosphorylation or pentamerization inactivates PLN inhibition. Ca²⁺ release occurs through ryanodine (RyR) and IP₃ receptors, the latter activated via GPCR–PLCβ–IP₃ signaling. ER Ca²⁺ depletion engages STIM1/2-mediated activation of ORAI channels, inducing store-operated Ca²⁺ entry (SOCE). Cytosolic Ca²⁺ is cleared by PMCAs and buffered by mitochondria (via MCU/NCLX) and lysosomes (via TRPML channels), while Golgi Ca²⁺/Mn²⁺-ATPases maintain secretory pathway stores. Elevated cytosolic Ca²⁺ activates calcineurin (CnA) and CaMK, which regulate transcriptional co-activators such as CRTC2 and FOXO to coordinate metabolic, stress-adaptive, and survival programs. Collectively, these integrated Ca²⁺ circuits ensure tight control of signaling amplitude and duration, with the PLN–SERCA module acting as a central determinant of Ca²⁺ clearance, excitation–contraction coupling, and organellar homeostasis across physiological and metabolic contexts

Fig. 2

Tissue-specific and structural regulation of SERCA by micropeptides. A Tissue-specific control of SERCA isoforms. Distinct SERCA isoforms exhibit specialized micropeptide regulation across tissues. In cardiac muscle, SERCA2a is repressed by phospholamban (PLN) and activated by DWORF, which competitively displaces PLN. In non-excitable cells, SERCA2b interacts with another-regulin (ALN), whereas SERCA3, expressed in epithelial and endothelial cells, is modulated by endoregulin (ELN). Each isoform drives ATP-dependent Ca²⁺ uptake into the SR or ER, counterbalanced by RyR or IP₃R-mediated Ca²⁺ release, ensuring precise, tissue-adapted control of Ca²⁺ cycling for contraction, secretion, and metabolic homeostasis. B Structural basis of PLN and DWORF regulation. SERCA’s transmembrane helices (green) form a hydrophobic groove that binds PLN (pink), which inhibits Ca²⁺ transport via key residues Pro¹⁵, Leu³¹, and Asn³⁴. DWORF (blue) occupies the same binding pocket but acts antagonistically, displacing PLN and enhancing Ca²⁺ sequestration. This competitive interaction underscores the opposing regulatory roles of PLN and DWORF and identifies DWORF as a potential therapeutic activator of SERCA in muscle and metabolic disease

Fig. 3

Dysregulation of the SERCA2a–PLN–DWORF Axis in Heart Failure. A Healthy myocardium. β-adrenergic stimulation activates Gsα–AC–cAMP–PKA signaling, leading to PLN phosphorylation at Ser¹⁶ (by PKA) and Thr¹⁷ (by CaMKII). Phosphorylated PLN (pPLN) disengages from SERCA2a, enabling efficient Ca²⁺ reuptake into the SR and proper myofilament relaxation. DWORF further enhances SERCA2a activity by displacing PLN from its inhibitory site, maintaining balanced Ca²⁺ cycling between RyR-mediated release and SERCA2a-mediated sequestration. B Failing myocardium. Impaired β-adrenergic signaling reduces PKA activation and PLN phosphorylation, while pathogenic PLN variants (e.g., R14del) remain constitutively inhibitory. DWORF downregulation and SERCA2a suppression exacerbate SR Ca²⁺ reuptake failure, causing cytosolic Ca²⁺ overload and defective diastolic relaxation. RyR hyperactivity promotes persistent Ca²⁺ leak, driving contractile dysfunction and arrhythmogenesis characteristic of heart failure

Fig. 4

Dysregulation of the SERCA2b–PLN Axis in Hepatic Ca²⁺ Homeostasis and Its Role in MAFLD/MASH Progression. A Healthy liver. In hepatocytes and stellate cells, SERCA2b maintains ER Ca²⁺ storage and cytosolic balance, while PLN inhibition is minimal. Alternative regulators such as ELN and ALN fine-tune SERCA2b activity to preserve ER–mitochondria coupling and suppress the unfolded protein response (UPR). Proper Ca²⁺ homeostasis sustains protein folding, redox balance, and mitochondrial integrity, preventing ER stress and supporting lipid metabolism and cell survival. B MAFLD and MASH. Impaired PI3K–AKT and Gsα–cAMP–PKA signaling keeps PLN unphosphorylated, suppressing SERCA2b activity. Resultant ER Ca²⁺ depletion and cytosolic Ca²⁺ overload trigger UPR activation (BiP, PERK, ATF6, IRE1) and formation of Ca²⁺–PIP complexes, which sequester PIPs and block AKT membrane recruitment, worsening insulin resistance. Disrupted ER–mitochondrial Ca²⁺ coupling causes mitochondrial Ca²⁺ overload, ROS accumulation, and MAM destabilization, promoting apoptosis and release of DAMPs that activate Kupffer cells and inflammation. In stellate cells, reduced SERCA2b further enhances TGF-β–driven fibrogenesis, leading to collagen deposition and fibrosis. Collectively, these Ca²⁺-dependent maladaptations drive hepatic apoptosis, inflammation, and fibrotic remodeling—key hallmarks of MAFLD/MASH pathogenesis

Fig. 5

Therapeutic modulation of the SERCA–PLN–DWORF axis in cardiac and hepatic Ca²⁺ Homeostasis. This schematic illustration summarizes major therapeutic strategies targeting the PLN–SERCA–DWORF regulatory network and Ca²⁺ signaling pathways. In the heart, β-adrenergic activation increases cAMP and PKA-mediated phosphorylation of PLN (Ser¹⁶/Thr¹⁷), relieving its inhibition on SERCA2a and promoting Ca²⁺ reuptake. In PLN-R14del cardiomyopathy, mutant PLN resists phosphorylation and forms toxic oligomers; ASO or CRISPR/Cas9 approaches silence or correct the mutant allele, while AAV-DWORF gene delivery restores SERCA2a function by competitively displacing PLN. Additional interventions include istaroxime (direct SERCA2a activator) and AAV1-SERCA2a therapy, both improving contractile Ca²⁺ cycling. Rycal compounds stabilize RyR to prevent SR Ca²⁺ leak, and CaMKII inhibitors protect against hyperphosphorylation-induced dysfunction. In the liver, SERCA2b supports ER Ca²⁺ homeostasis and can be therapeutically enhanced by CDN1163, atractylenolide II (via FXR activation), or AAV-SERCA2b expression. Restoration of ER Ca²⁺ levels alleviates stress signaling and preserves mitochondrial–ER coupling. Pharmacologic SOCE inhibitors targeting STIM1/ORAI further prevent cytosolic Ca²⁺ overload. Downstream, Ca²⁺-activated calcineurin (CnA) and CaMK pathways modulate transcriptional regulators CRTC2 and FOXO, linking Ca²⁺ homeostasis to metabolic and stress adaptation. Together, these interventions underscore the therapeutic potential of SERCA activation, PLN inhibition, and DWORF augmentation as convergent strategies to normalize intracellular Ca²⁺ cycling in cardiac and hepatic diseases

Fig. 6

Translational and Clinical Landscape of SERCA–PLN–DWORF-Targeted Therapies in Heart and Liver. This figure summarizes the current and emerging therapeutic strategies targeting the PLN–SERCA–DWORF axis across major organ systems. In the heart, AAV1-mediated SERCA2a gene therapy (CUPID trials) has established clinical proof-of-concept and is being extended to HFpEF. DWORF gene therapy remains in preclinical development for advanced heart failure, while PLN-R14del cardiomyopathies are under investigation for ASO and CRISPR-based correction to relieve SERCA inhibition. The small-molecule activator istaroxime has completed phase II trials, showing benefits in acute heart failure. In addition, peptide-based therapeutics are emerging as a versatile modality for direct modulation of SERCA regulatory proteins. Phospho-mimetic PLN inhibitors alleviate diastolic Ca²⁺ clearance defects in HFpEF and diabetic cardiomyopathy, while engineered mini-DWORF analogs competitively displace PLN to enhance SERCA activity in pressure-overload and metabolic heart disease. These peptides provide a protein-level strategy to restore cardiomyocyte Ca²⁺ homeostasis and complement existing gene- and small-molecule approaches. In the liver, FXR agonists (Phase III for NASH) and GLP-1 receptor agonists indirectly enhance SERCA2b activity, alleviating ER stress and metabolic dysfunction. Antifibrotic agents and AAV-based SERCA2b or DWORF gene therapies are being explored for hepatic Ca²⁺ disorders and fibrosis. Safety monitoring includes circulating BiP (GRP78) and biopsy-based ER stress and SERCA2b markers. Collectively, these strategies underscore a multi-organ therapeutic framework centered on restoring Ca²⁺ homeostasis via SERCA activation, PLN suppression, and DWORF augmentation—offering a unified pathway for treating cardiometabolic and fibrotic diseases