Emerging roles of micropeptides in calcium cycling dysregulation and atrial fibrillation: A review.
Micropeptides are shaking up the way researchers think about calcium cycling and atrial fibrillation. This new review in the International Journal of Biological Macromolecules digs into how a handful of tiny, membrane-bound peptides—like phospholamban (PLB), sarcolipin (SLN), dwarf open reading frame (DWORF), myoregulin (MLN), endoregulin (ELN), and another-regulin (ALN)—directly influence the SERCA calcium pump. SERCA sits at the heart of cardiac muscle relaxation. When its function gets thrown off, arrhythmias like atrial fibrillation become a lot more likely.
Int J Biol Macromol
by Pani P, Swalsingh G, Sadayappan S et al.
“Emerging roles of micropeptides in calcium cycling dysregulation and atrial fibrillation: A review. Pani P(1), Swalsingh G(1), Sadayappan S(2), Bal NC(3). Author information: (1)School of Biotechnology, KIIT University, Bhubaneswar, Odisha, 751024, India. (2)Department of Cellular & Molecular Medicine, Sarver Heart Center, University of Arizona College of Medicine, Tucson, AZ, 85721, USA. (3)School of Biotechnology, KIIT University, Bhubaneswar, Odisha, 751024, India. Electronic address: naresh.bal@kiitbiotech.ac.in. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia globally, marked by chaotic electrical impulses and irregular atrial contraction. At the cellular level, defective calcium (Ca+2) handling plays a central role in AF pathogenesis, with the sarco/endoplasmic reticulum Ca+2-ATPase (SERCA) pump being a critical determinant of intracellular Ca+2 reuptake and myocardial relaxation. Recent research has uncovered a class of small transmembrane micropeptides, phospholamban (PLB), sarcolipin (SLN), dwarf open reading frame (DWORF), myoregulin (MLN), endoregulin (ELN) and another-regulin (ALN), that directly modulate SERCA activity. Interestingly, these micropeptides exhibit chamber-specific expression and diverse regulatory mechanisms, functioning as inhibitors, uncouplers or facilitators of SERCA activity and are increasingly linked to atrial arrhythmogenesis. This review synthesizes current understanding on function of SERCA micropeptides, highlighting their distinct roles in atrial versus ventricular excitation-contraction (E-C) coupling. We explore evidence from genetically modified animal models and patient-derived data to elucidate how dysregulation of these peptides, particularly SLN and PLB, contributes to abnormal EC-coupling like Ca+2 cycling, delayed afterdepolarizations, oxidative stress and atrial remodeling. We also examine the influence of systemic metabolic regulators, such as thyroid hormones, catecholamines, dexamethasone and various exercise paradigms on micropeptide expression and function, offering insight into their intersection with AF progression. By dissecting the spatial, temporal and metabolic regulation of SERCA micropeptides, this review aims to offer current understanding about chamber-specific modulation of Ca+2 homeostasis and use these insights towards treatment of AF. Copyright © 2026 Elsevier B.V. All rights reserved. Conflict of interest statement: Declaration of competing interest None.”
Here’s what stands out:
These micropeptides act as on/off switches, brakes, or even boosters for SERCA activity. Some inhibit it, some uncouple it, and others ramp it up.
The expression patterns are chamber-specific. That means different peptides are running the show in the atria versus the ventricles—details that matter for both basic and translational research.
Dysregulation of SLN and PLB in particular shows up in abnormal calcium cycling, oxidative stress, and the electrical chaos that drives atrial fibrillation.
It’s not just genetics. The review highlights how exercise, hormones like thyroid and catecholamines, and even steroids like dexamethasone can tweak micropeptide expression and function.
Researchers are also working with animal models and patient tissue to map out exactly how these peptides interact in the real world. It’s a complex web, but the direction is clear: understanding and manipulating these micropeptides could offer new research pathways for atrial fibrillation.
Key takeaway: Peptides aren’t just bystanders in cardiac biology—they’re regulators with real potential for targeted studies. For more on the growing field, check out the peptide research index.
Cardiac peptide research is just getting started. The next wave of insights won’t be boring.
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