Biology subjects

Edassery, S.

Publications and source records attributed to Edassery, S..

8 recordsLinked to original sources

bioRxiv2026

Neprilysin mediated cleavage of phospholamban dysregulates SERCA in heart failure

BackgroundNeprilysin (NEP) is a zinc-dependent metalloprotease targeted in heart failure therapy to prevent it degrading circulating cardioprotective vasoactive peptides. NEP can also cleave sarcolipin (SLN), the skeletal- and atrial muscle-specific micropeptide regulator of the sarcoplasmic reticulum Ca2+-ATPase (SERCA). A direct pathophysiological role of NEP in ventricular muscle has not been established. MethodsProteomics and immunoblot analysis of human myocardial specimens were used to quantify NEP abundance in failing and non-failing hearts. Heterologous protein expression and biochemical binding assays assessed NEP-mediated cleavage of phospholamban (PLB) and its impact on PLB-SERCA interactions. Functional consequences of NEP expression or inhibition were evaluated in neonatal rat ventricular myocytes and in a human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of heart failure. ResultsWe observed increased NEP abundance in failing human myocardium relative to non-failing controls. We demonstrated that NEP cleaves phospholamban (PLB), disrupting PLB-SERCA interactions. Mutation of PLB (V49A), prevented NEP cleavage and preserved PLB-SERCA binding, indicating V49 is critical for NEP substrate recognition. In neonatal rat ventricular myocytes, NEP expression was associated with faster Ca2+ transient decay kinetics and increased SR Ca2+ load, consistent with reduced SERCA inhibition. Inhibition of NEP in a hiPSC-CM heart failure model attenuated the hypertrophic transcriptional responses and reversed Ca2+-transport dysregulation. ConclusionsThese findings implicate increased NEP expression in the sarcoplasmic reticulum of cardiomyocytes as previously unrecognized maladaptive consequence of heart failure contributing to cardiac dysfunction. In this novel pathophysiological mechanism, increased NEP results in PLB cleavage and loss of regulation of SERCA. While this may relieve SERCA inhibition and augment cellular Ca2+ handling, loss of PLB chronically disrupts hearts dynamic response to adrenergic stress, changing heart rate, or other physiological challenges. The data provide new insight into the cardioprotective effects of pharmacological NEP inhibition in clinical practice, reveal a novel mechanism of action of neprilysin inhibition in cardiomyocytes and may help inform future therapeutic strategies for patients with heart failure. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/732949v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@5ddc5dorg.highwire.dtl.DTLVardef@2e746corg.highwire.dtl.DTLVardef@1dd8273org.highwire.dtl.DTLVardef@19f5635_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2026

A Novel Mechanism of Cardiomyopathy: Toxic Peptides Dysregulate Calcium Transport

A hallmark of dilated cardiomyopathy (DCM) is calcium mishandling, including reduced transport activity of the SERCA calcium pump in cardiac muscle cells. This has focused attention on SERCA as mechanism of disease and potential therapeutic target. Previously, diminished SERCA activity has been attributed to decreased protein expression, but recent studies suggest SERCA levels are unchanged in DCM. Thus, another mechanism must be responsible for the deficit. Since proteolysis is increased and proteosome function is impaired in DCM, we reasoned that accumulation of toxic protein fragments may contribute to SERCA dysfunction. In particular, previous studies showed diverse species of hydrophobic -helices can inhibit SERCA, so we hypothesized that SERCA may become congested with transmembrane peptides that mimic endogenous regulatory partners. We purified cell membranes from non-failing and DCM human ventricles and subjected them to mass spectrometry to identify protein species upregulated in DCM. Select candidates were screened for binding and inhibition of SERCA. Several small membrane proteins and membrane protein fragments bound avidly to SERCA and significantly reduced cellular calcium stores. The data suggest a novel pathophysiological mechanism in which transmembrane protein debris obstructs SERCA function and regulation, contributing to cardiac muscle dysfunction in heart failure.

physiology↗

bioRxiv2025

Heat-shock pathway activation by TRC051384 protects spiral ganglion neurons from noise-induced hearing loss

Noise-induced hearing loss (NIHL) is a major public health problem caused by damage to cochlear hair cells, synapses, and spiral ganglion neurons (SGNs). Since effective treatments are lacking, we investigated cellular stress responses induced by moderate and loud noise in a mouse model of cochlear synaptopathy. RNA sequencing and spatial transcriptomics revealed that noise exposure elicited a robust but transient upregulation of endoplasmic reticulum chaperones and proteasome subunits in SGNs and their supporting cells. To target this response, we administered TRC051384, a small-molecule activator of the heat shock transcription factor Hsf1, prior to noise exposure. TRC051384 crossed the blood-labyrinth barrier and reached the cochlea, induced heat shock protein gene expression, and restored ubiquitin-proteasome function in SGNs. Notably, TRC051384 treatment enhanced auditory brainstem response threshold recovery, preserved Wave I amplitudes, and maintained ribbon synapse density. These findings establish proteotoxic stress in SGNs as a key driver of NIHL and identify HSF1 activation as a promising therapeutic strategy.

neuroscience↗

bioRxiv2025

Calcium-Activated Sarcomere Contractility Drives Cardiomyocyte Maturation and the Response to External Mechanical Cues but is Dispensable for Sarcomere Formation

BackgroundUnderstanding the mechanisms of cardiomyocyte development is critical for fulfilling the potential of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Although myocyte development is known to depend on internal and external mechanical cues, further investigation is required to understand the contributions of different signals and how they are integrated together to generate an adult cardiomyocyte. Here, we address this gap by examining the role of calcium-activated contractility in sarcomere formation and maturation and its influence on the iPSC-CM response to nanopatterns. MethodsWe generated iPSCs with homozygous D65A cardiac troponin C (cTnC) mutations. This mutation prevents calcium binding to site II of cTnC, resulting in tropomyosin blocking strong myosin binding to the thin filament and inhibiting sarcomere contraction. The iPSCs were differentiated into cardiomyocytes and matured in culture over 60 days. Cells were characterized via fluorescence imaging and calcium transient analysis. WT and mutant proteomes were examined via mass spectrometry throughout differentiation and maturation. We also replated partially matured cardiomyocytes onto nanopatterned surfaces to investigate how external mechanical signals affect maturation in contractile versus non-contractile cells. ResultsSurprisingly, we found that sarcomeres formed in the cTnC D65A cardiomyocytes, though these sarcomeres were underdeveloped and disorganized. Mutant cardiomyocytes also exhibited significant proteomic maturation defects and abnormal calcium transients. Plating D65A cardiomyocytes on nanopatterns improved structural and proteomic maturation. However, plating WT cardiomyocytes on nanopatterns led to a reduction in sarcomeric and oxidative phosphorylation protein content. ConclusionsCalcium-activated contractility is dispensable for sarcomerogenesis but critical for cardiomyocyte maturation. In non-contractile, mutant cardiomyocytes, nanopatterns enhance maturation, suggesting that external mechanical cues may partially compensate for defective contractility. However, nanopatterns did not facilitate WT maturation and may have hindered it. In addition to these novel findings, these large mass spectrometry datasets cataloging iPSC-CM maturation represent a useful resource for the cardiovascular community.

bioengineering↗

bioRxiv2023

Exceptional longevity of mammalian ovarian and oocyte macromolecules throughout the reproductive lifespan

The mechanisms contributing to age-related deterioration of the female reproductive system are complex, however aberrant protein homeostasis is a major contributor. We elucidated exceptionally stable proteins, structures, and macromolecules that persist in mammalian ovaries and gametes across the reproductive lifespan. Ovaries exhibit localized structural and cell-type specific enrichment of stable macromolecules in both the follicular and extrafollicular environments. Moreover, ovaries and oocytes both harbor a panel of exceptionally long-lived proteins, including cytoskeletal, mitochondrial, and oocyte-derived proteins. The exceptional persistence of these long-lived molecules suggest a critical role in lifelong maintenance and age-dependent deterioration of reproductive tissues. One sentence summaryExceptionally long-lived macromolecules in mammalian ovaries and oocytes as pillars for lifelong reproductive health span.

physiology↗

bioRxiv2023

Proteomic profiling of regenerated urinary bladder tissue with stem cell seeded scaffold composites in a non-human primate bladder augmentation model

Urinary bladder insult can be caused by environmental, genetic, and developmental factors. Depending upon insult severity, the bladder may lose its ability to maintain capacity and intravesical pressures resulting in renal deterioration. Bladder augmentation enterocystoplasty (BAE) is employed to increase bladder capacity to preserve renal function using autologous bowel tissue as a "patch." To avoid the clinical complications associated with this procedure, we have engineered composite grafts comprised of autologous bone marrow mesenchymal stem cells (MSCs) with CD34+ hematopoietic stem/progenitor cells (HSPCs) co-seeded onto a pliable synthetic scaffold [POCO; poly(1,8-octamethylene-citrate-co-octanol)] or a biological scaffold (SIS; small intestinal submucosa) to regenerate bladder tissue in a baboon bladder augmentation model. We set out to determine the protein expression profile of bladder tissue that has undergone regeneration with the aforementioned stem cell seeded scaffolds along with baboons that underwent BAE. Data demonstrate that POCO and SIS grafted animals share high protein homogeneity between native and regenerated tissues while BAE animals displayed heterogenous protein expression between the tissues following long-term engraftment. We posit that stem cell seeded scaffolds can recapitulate tissue that is almost indistinguishable from native tissue at the protein level and may be used in lieu of procedures such as BAE. Significance of StudyBladder augmentation enterocystoplasty has been used for decades as the gold-standard surgical procedure to treat severely dysfunctional bladders. Unfortunately, bowel (typically ileum) used for augmentation is an anatomical and physiological mismatch to bladder tissue and results in numerous complications including bladder perforation, secondary and tertiary redo surgeries, metabolic imbalances, excess mucus production, and increased risk of cancer. This is in part due to the intestinal protein expression that serves as a starting point and subsequent foundation in the optimization of pseudo bladder tissue. Within the context of this study, we demonstrate that autologous, bone marrow derived mesenchymal stem cells along with primitive hematopoietic stem/progenitor cells can used to regenerate bladder tissue in a large deficit, non-human primate bladder augmentation model. Data demonstrate that this synergistic cellular combination facilitates the promotion of a protein tissue landscape that is nearly identical to native bladder tissue.

bioengineering↗

bioRxiv2022

Relapse-like behavior and nAChR sensitization following intermittent access nicotine self-administration

ABSTRACTMany tobacco smokers consume nicotine intermittently, but the underlying mechanisms and neurobiological changes associated with intermittent nicotine intake are unclear. Understanding intermittent nicotine intake is a high priority, as it could promote therapeutic strategies to attenuate tobacco consumption. We examined nicotine intake behavior and neurobiological changes in male rats that were trained to self-administer nicotine during brief (5 min) trials interspersed with longer (15 min) drug-free periods. Rats readily adapted to intermittent access (IntA) SA following acquisition on a continuous access (ContA) schedule. Probabilistic analysis of IntA nicotine SA suggested reduced nicotine loading behavior compared to ContA, and nicotine pharmacokinetic modeling revealed that rats taking nicotine intermittently may have increased intake to maintain blood levels of nicotine that are comparable to ContA SA. After IntA nicotine SA, rats exhibited an increase in unreinforced responses for nicotine-associated cues (incubation of craving) and specific alterations in the striatal proteome after 7 days without nicotine. IntA nicotine SA also induced nAChR functional upregulation in the interpeduncular nucleus (IPN), and it enhanced nicotine binding in the brain as determined via [11C]nicotine positron emission tomography. Reducing the saliency of the cue conditions during the 5 min access periods attenuated nicotine intake, but incubation of craving was preserved. Together, these results indicate that IntA conditions promote nicotine SA and nicotine seeking after a nicotine-free period.

neuroscience↗

bioRxiv2021

Xenogeneic Fibroblasts Inhibit The Growth Of Breast And Ovarian Cancer Cell Lines In Co-Culture

Cell-based therapies cure some hematologic malignancies, although little information exists on solid cancer cell responses. The study objective was to test the hypothesis that xenogeneic fibroblasts can inhibit the growth of human cancer cell lines in vitro. Seven human cell lines (pancreatic cancer HPAF II; brain cancer U-87 MG; fibrosarcoma; ovarian cancer OVCAR3 and SKOV3; and breast cancer MCF7 and MDA-MB231) were co-cultured with two xenogeneic fibroblast cell lines (CV-1;monkey, Cercopithecus aethiops and DF-1; chicken, Gallus gallus) in a transwell culture system. Cancer cell proliferation was assessed colorimetrically. Different concentrations of breast and ovarian cancer cells were tested. Gene expression induced by DF-1 xenogeneic fibroblasts was assessed by RNAseq of MCF7 breast cancer cells. The proliferation of the majority of the cancer cell lines was altered by co-culture with xenogeneic fibroblasts. Cell proliferation was increased (4-17%) by CV-1; DF-1 increased brain cancer cell proliferation (16%), decreased breast and ovarian cancer cell growth (15 and 26% respectively) but did not affect fibrosarcoma and pancreatic cancer cells. When the initial cancer cell concentrations were lowered 4-fold, growth inhibition of breast and ovarian cancer increased more than 2-fold. DF-1 fibroblasts induced significant differential expression of 484 genes in MCF7 breast cancer cells; 285 genes were down-regulated and 199 genes were upregulated compared to control. Genes involved in the immune response were the major downregulated entities. RNAseq results were validated by qRT-PCR of 12 genes. The results show that xenogeneic fibroblasts can alter the growth and gene expression of cancer cells in vitro. This suggests a potentially novel investigational approach to the control of cancer cell growth.

cancer biology↗