Medicine and Health Sciences Commons^™

Targeting Oncogenic Gαq/11 In Uveal Melanoma, Dominic Lapadula, Jeffrey L Benovic

Department of Biochemistry and Molecular Biology Faculty Papers

Uveal melanoma is the most common intraocular cancer in adults and arises from the transformation of melanocytes in the uveal tract. While treatment of the primary tumor is often effective, 36–50% of patients develop metastatic disease primarily to the liver. While various strategies have been used to treat the metastatic disease, there remain no effective treatments that improve survival. Significant insight has been gained into the pathways that are altered in uveal melanoma, with mutually exclusive activating mutations in the GNAQ and GNA11 genes being found in over 90% of patients. These genes encode the alpha subunits of the hetetrotrimeric …

Leptin Activation Of Metabolically-Related Hypothalamic Neurons, Kailee Hixon

Undergraduate Honors Theses

Obesity is often associated with multiple other clinical conditions, including hypertension and cardiovascular disease. Currently, more than one-third of the world’s population is classified as obese. Leptin is a neuropeptide that is released from adipose cells and is responsible for reducing appetite and increasing metabolism. Leptin also has a role in the activation of cardiovascular and metabolic pre-sympathetic neurons and has been reported to increase blood pressure and heart rate. Thus, understanding the activation of the autonomic nervous system by leptin has implications in the development and safety of drugs to avoid activation of cardiovascular pre-sympathetic neurons. This is important …

Diverse And Converging Roles Of Erk1/2 And Erk5 Pathways On Mesenchymal To Epithelial Transition In Breast Cancer, Akshita B. Bhatt, Thomas D. Wright, Van Barnes, Suravi Chakrabarty, Margarite D. Matossian, Erin Lexner, Deniz A. Ucar, Lucio Miele, Patrick T. Flaherty, Matthew E. Burow, Jane E. Cavanaugh

School of Medicine Faculty Publications

The epithelial to mesenchymal transition (EMT) is characterized by a loss of cell polarity, a decrease in the epithelial cell marker E-cadherin, and an increase in mesenchymal markers including the zinc-finger E-box binding homeobox (ZEB1). The EMT is also associated with an increase in cell migration and anchorage-independent growth. Induction of a reversal of the EMT, a mesenchymal to epithelial transition (MET), is an emerging strategy being explored to attenuate the metastatic potential of aggressive cancer types, such as triple-negative breast cancers (TNBCs) and tamoxifen-resistant (TAMR) ER-positive breast cancers, which have a mesenchymal phenotype. Patients with these aggressive cancers have …

Role Of Na/K-Atpase Non-Enzymatic Signaling In Renal Proximal Tubule Sodium Transport, Shreya Tapan Mukherji

Theses, Dissertations and Capstones

The renal proximal tubule (RPT) is the center stage for renal handling of Na+ , a potent determinant of systemic Na+ and volume homeostasis in health and disease. In the RPT, through its classic ion-pumping function, Na + /K+ -ATPase (NKA) generates the Na+ gradient that drives apical Na+ absorption, mostly through Na+ /H+ exchanger (NHE3). In contrast, pharmacological evidence suggests that the activation of the NKA non-enzymatic signaling function, through Src and other signaling partners, triggers a cellular redistribution of NKA and NHE3 that decreases transcellular Na+ flux in cultured RPT cells. However, the physiological relevance of the nonenzymatic …

Janus Kinase 1 Drives Endoplasmic Reticulum Stress-Induced Transcriptional Reprogramming In Astrocytes, Savannah Graham Sims

Graduate Theses, Dissertations, and Problem Reports

Neurological and neurodegenerative diseases are heterogenous and devastating diseases with limited therapeutic options and no cures. The broad, long-term goal of this project was to elucidate therapeutic targets for neurodegenerative conditions that attenuate damaging inflammation while leaving the beneficial immune response intact and avoiding broad immunosuppression. Inflammation and the accumulation of misfolded proteins are associated with a wide variety of neurological diseases. Here, we have examined how the accumulation of misfolded proteins shapes inflammatory signaling in the glial cell population astrocytes. Astrocytes are the most populous cell in the central nervous system (CNS) and provide physical and trophic support to …

Neutrophil Signaling During Myocardial Infarction Wound Repair, Michael J. Daseke, Upendra Chalise, Mediha Becirovic-Agic, Jeffrey D. Salomon, Leah M. Cook, Adam J. Case, Merry L. Lindsey

Journal Articles: Cellular & Integrative Physiology

Neutrophils are key effector cells of the innate immune system, serving as a first line of defense in the response to injury and playing essential roles in the wound healing process. Following myocardial infarction (MI), neutrophils infiltrate into the infarct region to propagate inflammation and begin the initial phase of cardiac wound repair. Pro-inflammatory neutrophils release proteases to degrade extracellular matrix (ECM), a necessary step for the removal of necrotic myocytes as a prelude for scar formation. Neutrophils transition their phenotype over time to regulate MI inflammation resolution and stabilize scar formation. Neutrophils contribute to the evolution from inflammation to …

Bmp And Tgfß Use And Release In Bone Regeneration, Zeynep Bal, Junichi Kushioka, Joe Kodama, Takashi Kaito, Hideki Yoshikawa, Petek Korkusuz, Feza Korkusuz

Turkish Journal of Medical Sciences

A fracture that does not unite in nine months is defined as nonunion. Nonunion is common in fragmented fractures and large bone defects where vascularization is impaired. The distal third of the tibia, the scaphoid bone or the talus fractures are furthermore prone to nonunion. Open fractures and spinal fusion cases also need special monitoring for healing. Bone tissue regeneration can be attained by autografts, allografts, xenografts and synthetic materials, however their limited availability and the increased surgical time as well as the donor site morbidity of autograft use, and lower probability of success, increased costs and disease transmission and …

Physiological And Pharmacological Roles Of Melatonin In The Pathophysiologicalcomponents Of Cellular Injury After Ischemic Stroke, Ertuğrul Kiliç, Berrak Çağlayan, Mustafa Caglar Beker

Turkish Journal of Medical Sciences

Apart from its metabolic or physiological functions, melatonin has a potent cytoprotective activity in the physiological and pathological conditions. It is synthetized by the pineal gland and released into the blood circulation but particularly cerebrospinal fluid in a circadian manner. It can also easily diffuse through cellular membranes due its small size and lipophilic structure. Its cytoprotective activity has been linked to its potent free radical scavenger activity with the desirable characteristics of a clinically- reliable antioxidant. Melatonin detoxifies oxygen and nitrogen-based free radicals and oxidizing agents, including the highly toxic hydroxyl-and peroxynitrite radicals, initiating cellular damage. However, the cytoprotective …

Protein Carbonylation Of An Amino Acid Residue Of The Na/K‐Atpase Α1 Subunit Determines Na/K‐Atpase Signaling And Sodium Transport In Renal Proximal Tubular Cells, Yanling Yan, Anna P. Shapiro, Brahma R. Mopidevi, Muhammad Chaudhry, Kyle Maxwell, Steven T. Haller, Christopher A. Drummond, David J. Keendey, Jiang Tian, Deepak Malhorta, Zijian Xie, Joseph I. Shapiro Md, Jiang Liu

Muhammad Chaudhry

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ATPase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ATPase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ATPase/c‐Src signaling and subsequent regulation of active transepithelial ²²Na⁺ transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ATPase signaling and sodium handling.

Methods and Results Stable pig α1 knockdown LLC‐PK1‐originated PY‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with …

Characterization Of The Tgfb Pathway And Its Role In Prostaglandin Metabolism In C. Elegans, Muhan Hu

All ETDs from UAB

Cell to cell communication is fundamental to all life processes, from fertilization to death. The TGFߟ superfamily is a large family of proteins that is involved in a wide array of physiological and pathological processes, including development, wound healing, immune system function, cancer, and reproduction. This group of signaling peptides is well conserved across many organisms, from basic nematode to humans. While many studies have aimed to delineate the functions of TGFߟ, they have also unveiled the complexity of this multifunctional family of ligands. In this thesis, I take advantage of the simple C. elegans model system to study the …

Epidermal Growth Factor Receptor (Egfr) Inhibition By Polychlorinated Biphenyls Contributes To Non-Alcoholic Fatty Liver Disease (Nafld)., Josiah Hardesty

Electronic Theses and Dissertations

This dissertation describes how poly-chlorinated biphenyls (PCBs) exacerbate the pathogenesis of non-alcoholic fatty liver disease (NAFLD). While PCBs were banned in 1979, they still persist in contaminated biota, including food, and are detected in human plasma and adipose. The body burden of PCBs is associated with elevation of liver enzymes and necrosis markers in humans, characteristic of NAFLD. PCB exposure in high-fat diet fed mice leads to steatohepatitis that recapitulate the findings seen in exposed humans. The global estimate of people diagnosed with NAFLD is up to 1 in 4 people, unrelated to dietary or genetic factors. The hepatic mechanisms …

Protein Carbonylation Of An Amino Acid Residue Of The Na/K‐Atpase Α1 Subunit Determines Na/K‐Atpase Signaling And Sodium Transport In Renal Proximal Tubular Cells, Yanling Yan, Anna P. Shapiro, Brahma R. Mopidevi, Muhammad Chaudhry, Kyle Maxwell, Steven T. Haller, Christopher A. Drummond, David J. Keendey, Jiang Tian, Deepak Malhorta, Zijian Xie, Joseph I. Shapiro Md, Jiang Liu

Jiang Liu

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ATPase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ATPase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ATPase/c‐Src signaling and subsequent regulation of active transepithelial ²²Na⁺ transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ATPase signaling and sodium handling.

Methods and Results Stable pig α1 knockdown LLC‐PK1‐originated PY‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with …

Protein Carbonylation Of An Amino Acid Residue Of The Na/K‐Atpase Α1 Subunit Determines Na/K‐Atpase Signaling And Sodium Transport In Renal Proximal Tubular Cells, Yanling Yan, Anna P. Shapiro, Brahma R. Mopidevi, Muhammad Chaudhry, Kyle Maxwell, Steven T. Haller, Christopher A. Drummond, David J. Keendey, Jiang Tian, Deepak Malhorta, Zijian Xie, Joseph I. Shapiro Md, Jiang Liu

Zijian Xie

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ATPase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ATPase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ATPase/c‐Src signaling and subsequent regulation of active transepithelial ²²Na⁺ transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ATPase signaling and sodium handling.

Methods and Results Stable pig α1 knockdown LLC‐PK1‐originated PY‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with …

Protein Carbonylation Of An Amino Acid Residue Of The Na/K‐Atpase Α1 Subunit Determines Na/K‐Atpase Signaling And Sodium Transport In Renal Proximal Tubular Cells, Yanling Yan, Anna P. Shapiro, Brahma R. Mopidevi, Muhammad Chaudhry, Kyle Maxwell, Steven T. Haller, Christopher A. Drummond, David J. Keendey, Jiang Tian, Deepak Malhorta, Zijian Xie, Joseph I. Shapiro Md, Jiang Liu

Yanling Yan

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ATPase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ATPase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ATPase/c‐Src signaling and subsequent regulation of active transepithelial ²²Na⁺ transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ATPase signaling and sodium handling.

Methods and Results Stable pig α1 knockdown LLC‐PK1‐originated PY‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with …

The Trade-Off Between Dietary Salt And Cardiovascular Disease; A Role For Na/K-Atpase Signaling?, Joe X. Xie, Anna Pearl Shapiro, Joseph I. Shapiro Md

Joseph I Shapiro MD

It has been postulated for some time that endogenous digitalis-like substances, also called cardiotonic steroids (CTS), exist, and that these substances are involved in sodium handling. Within the past 20 years, these substances have been unequivocally identified and measurements of circulating and tissue concentrations have been made. More recently, it has been identified that CTS also mediate signal transduction through the Na/K-ATPase, and consequently been implicated in profibrotic pathways. This review will discuss the mechanism of CTS in renal sodium handling and a potential “trade-off” effect from their role in inducing tissue fibrosis.

Carbonylationmodificationregulatesna/K-Atpasesignalingandsaltsensitivity:Areviewandahypothesis, Preeya Shah Phd, Rebecca Martin, Yanling Yan, Joseph I. Shapiro Md, Jiang Liu

Jiang Liu

Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal …

Carbonylationmodificationregulatesna/K-Atpasesignalingandsaltsensitivity:Areviewandahypothesis, Preeya Shah Phd, Rebecca Martin, Yanling Yan, Joseph I. Shapiro Md, Jiang Liu

Joseph I Shapiro MD

Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal …

Carbonylationmodificationregulatesna/K-Atpasesignalingandsaltsensitivity:Areviewandahypothesis, Preeya Shah Phd, Rebecca Martin, Yanling Yan, Joseph I. Shapiro Md, Jiang Liu

Yanling Yan

Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal …

Memory Potential, Molecular Characterization, And Translational Applications Of The Novel Theo/Tceo T Cell Phenotype, Todd Bartkowiak, Todd Bartkowiak

Dissertations & Theses (Open Access)

T cells comprise a substantial arm of the immune system and are exquisitely adapted to combat pathogens and tumors. The inflammatory environment largely dictates the nature of T cell response. A hallmark of T cell-mediated immunity is formation of immunological memory; the ability to respond more potently to re-encounter with pathogens. The immune system is also capable of recognizing tumors as foreign, much like viral or bacterial pathogens. Tumors have evolved, though, to generate an immunosuppressive environment to avoid destruction. The field of immunotherapy seeks to overcome immune suppression, in part by targeting T cell co-receptors on the cell surface …

Na/K-Atpase Signaling And Salt Sensitivity: The Role Of Oxidative Stress, Jiang Liu, Yanling Yan, Ying Nie

Yanling Yan

Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium reabsorption in renal proximal tubules, from cardiotonic steroids-mediated to reactive oxygen species (ROS)-mediated Na/K-ATPase signaling that contributes to experimental salt sensitivity.

Na/K-Atpase Signaling And Salt Sensitivity: The Role Of Oxidative Stress, Jiang Liu, Yanling Yan, Ying Nie

Jiang Liu

Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium reabsorption in renal proximal tubules, from cardiotonic steroids-mediated to reactive oxygen species (ROS)-mediated Na/K-ATPase signaling that contributes to experimental salt sensitivity.

Metabolic Regulation Of Cellular Signaling, Rashid John Darbandi

Theses and Dissertations (ETD)

Using the biochemically tractable Xenopus oocyte model system, we have previously characterized a novel metabolic regulation of cell death. We found that glucose-6-phosphate (G6P) via the pentose phosphate pathway leads to increased nicotinamide adenine dinucleotide phosphate (NADPH) levels, a subsequent increase in cytosolic acetyl-coenzyme A and activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). We recently identified coenzyme A (CoA), derived from the breakdown of acetyl-CoA, as the key metabolic signal that mediates a novel mechanism of calmodulindependent activation of CaMKII. CoA binds directly to the calmodulin (CaM) binding domain (CaMBD) of CaMKII resulting in its activation and downstream inhibitory phosphorylation …

Na/K-Atpase Signaling And Salt Sensitivity: The Role Of Oxidative Stress, Jiang Liu, Yanling Yan, Ying Nie

Biochemistry and Microbiology

Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium reabsorption in renal proximal tubules, from cardiotonic steroids-mediated to reactive oxygen species (ROS)-mediated Na/K-ATPase signaling that contributes to experimental salt sensitivity.

Protein Carbonylation Of An Amino Acid Residue Of The Na/K‐Atpase Α1 Subunit Determines Na/K‐Atpase Signaling And Sodium Transport In Renal Proximal Tubular Cells, Yanling Yan, Anna P. Shapiro, Brahma R. Mopidevi, Muhammad Chaudhry, Kyle Maxwell, Steven T. Haller, Christopher A. Drummond, David J. Keendey, Jiang Tian, Deepak Malhorta, Zijian Xie, Joseph I. Shapiro Md, Jiang Liu

Biochemistry and Microbiology

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ATPase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ATPase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ATPase/c‐Src signaling and subsequent regulation of active transepithelial ²²Na⁺ transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ATPase signaling and sodium handling.

Methods and Results Stable pig α1 knockdown LLC‐PK1‐originated PY‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with …

Carbonylation Modification Regulates Na/K-At Pasesignaling And Salt Sensitivity: A Review And A Hypothesis, Preeya Shah Phd, Rebecca Martin, Yanling Yan, Joseph I. Shapiro Md, Jiang Liu

Biochemistry and Microbiology

Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal …

Signaling In Effector Lymphocytes: Insights Toward Safer Immunotherapy, Kamalakannan Rajasekaran, Matthew J. Riese, Sridhar Rao, Li Wang, Monica Thakar, Charles Sentman, Subramaniam Malarkannan

Dartmouth Scholarship

Receptors on T and NK cells systematically propagate highly complex signaling cascades that direct immune effector functions, leading to protective immunity. While extensive studies have delineated hundreds of signaling events that take place upon receptor engagement, the precise molecular mechanism that differentially regulates the induction or repression of a unique effector function is yet to be fully defined. Such knowledge can potentiate the tailoring of signal transductions and transform cancer immunotherapies. Targeted manipulations of signaling cascades can augment one effector function such as antitumor cytotoxicity while contain the overt generation of pro-inflammatory cytokines that contribute to treatment-related toxicity such as …

Epicardial Cell Engraftment And Signaling Promote Cardiac Repair After Myocardial Infarction, Krithika Rao

Graduate College Dissertations and Theses

The epicardium is a single layer of epithelial (mesothelial) cells that covers the entire heart surface, but whose function in adult mammals is poorly understood. Defining the role of epicardial cells during homeostasis, growth and injury has potential to provide new treatment strategies for human diseases that result in heart failure, due to extensive loss of viable cardiac tissue. We hypothesized that epicardial cells contribute to repair as transplantable progenitor cells for cellular regeneration and as a source of secreted growth factors for cell protection after myocardial infarction.

Adult epicardial cells were prospectively isolated as uncommitted epithelial cells using epithelial-specific …

Intracellular Information Processing Through Encoding And Decoding Of Dynamic Signaling Features., Hirenkumar K Makadia, James S. Schwaber, Rajanikanth Vadigepalli

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Cell signaling dynamics and transcriptional regulatory activities are variable within specific cell types responding to an identical stimulus. In addition to studying the network interactions, there is much interest in utilizing single cell scale data to elucidate the non-random aspects of the variability involved in cellular decision making. Previous studies have considered the information transfer between the signaling and transcriptional domains based on an instantaneous relationship between the molecular activities. These studies predict a limited binary on/off encoding mechanism which underestimates the complexity of biological information processing, and hence the utility of single cell resolution data. Here we pursue a …

Effects Of Cardiotonic Steroids On Dermal Collagen Synthesis And Wound Healing, Nasser El-Okdi, Sleiman Smaili, Vanamala Raju, Amjad Shidyak, Shalini Gupta, Larisa Fedorova, Jihad Elkareh, Sankaridrug Periyasamy, Anna Shapiro, M. Kahaleh, Deepak Malhotra, Jingwei Xie, Khew Chin, Joseph Shapiro

Jingwei Xie

We previously reported that cardiotonic steroids stimulate collagen synthesis by cardiac fibroblasts in a process that involves signaling through the Na-K-ATPase pathway (Elkareh et al. Hypertension 49: 215–224, 2007). In this study, we examined the effect of cardiotonic steroids on dermal fibroblasts collagen synthesis and on wound healing. Increased collagen expression by human dermal fibroblasts was noted in response to the cardiotonic steroid marinobufagenin in a dose- and time-dependent fashion. An eightfold increase in collagen synthesis was noted when cells were exposed to 10 nM marinobufagenin for 24 h (P < 0.01). Similar increases in proline incorporation were seen following treatment with digoxin, ouabain, and marinobufagenin (10 nM × 24 h, all results P < 0.01 vs. control). The coadministration of the Src inhibitor PP2 or N-acetylcysteine completely prevented collagen stimulation by marinobufagenin. …

The Trade-Off Between Dietary Salt And Cardiovascular Disease; A Role For Na/K-Atpase Signaling?, Joe X. Xie, Anna Pearl Shapiro, Joseph I. Shapiro Md

Biochemistry and Microbiology

It has been postulated for some time that endogenous digitalis-like substances, also called cardiotonic steroids (CTS), exist, and that these substances are involved in sodium handling. Within the past 20 years, these substances have been unequivocally identified and measurements of circulating and tissue concentrations have been made. More recently, it has been identified that CTS also mediate signal transduction through the Na/K-ATPase, and consequently been implicated in profibrotic pathways. This review will discuss the mechanism of CTS in renal sodium handling and a potential “trade-off” effect from their role in inducing tissue fibrosis.