Biology subjects

Edassery, S.

Publications and source records attributed to Edassery, S..

5 recordsLinked to original sources

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↗