Calcium signalling in chondrogenesis: Implications for cartilage repair

Calcium signalling in chondrogenesis: Implications for cartilage repair
Article in Frontiers in bioscience (Scholar edition) · January 2013
DOI: 10.2741/S374 · Source: PubMed
Csaba Matta1, Róza Zákány1
1Department of Anatomy, Histology and Embryology, University of Debrecen, Medical and Health Science Centre, Nagyerdei krt. b98, Debrecen, Hungary, H-4032

 

ABSTRACT

Undifferentiated mesenchymal stem cells (MSCs) represent an important source for cell-based tissue regeneration techniques that require differentiation towards specific lineages, including chondrocytes. Chondrogenesis, the process by which committed mesenchymal cells differentiate into chondrocytes, is controlled by complex but not yet completely understood signalling mechanisms that involve many components, including intracellular signalling pathways, as well as plasma membrane receptors and ion channels. Some of these signalling components are Ca2+ sensitive. Although the Ca2+-signalling toolkit of undifferentiated MSCs and mature chondrocytes are extensively studied, the adaptation of these components during differentiation and their role in chondrogenesis is not adequately established. In this review, various aspects of Ca2+ signalling are discussed in MSCs and in mature chondrocytes including spatial and temporal aspects, as well as Ca2+ entry and elimination processes, with implications for their involvement in chondrogenesis. A better understanding of these pathways is envisaged to provide a more efficient differentiation of MSCs towards chondrocytes that may lead to the development of better cartilage tissue engineering techniques.

Biology of signalling receptors in human articular chondrocytes

Biology of signalling receptors in human articular chondrocytes

Implications for chondrogenesis and cartilage repair

Faculty of Health Sciences – Department of Clinical Medicine
Ann Kristin Hansen
A dissertation for the degree of Philosophiae Doctor – December 2017

 

Osteoarthritis (OA) is characterised by gradual destruction of articular cartilage and leads to painful and dysfunctional knee-, hip- or hand-joints. With the increasing life expectancy and obesity, the prevalence is expected to rise. In the younger population, joint pain and disability can result from local cartilage defects resulting from injury or disease. After the introduction of autologous chondrocyte implantation (ACI) as a treatment option for localised cartilage defects in the late 80’s, cell‑based repair techniques have been extensively explored through clinical trials aiming to improve long‑term clinical outcomes. However, the role of ACI remains that of postponing joint replacement in patients with localised defects, and despite persistent research on cartilage repair strategies, there is no available treatment to halt or reverse the degenerative process of OA once initiated. The focus of this thesis has thus been to gather new basic knowledge on cartilage functions in the context of cell signalling receptors.
In the first study, we have explored the effects of the powerful inflammatory mediator leukotriene B₄ (LTB₄) on human articular chondrocytes based on studies indicating that this mediator could hold a key role in inflammatory joint diseases. When cyclooxygenase (COX) inhibitors are prescribed to reduce inflammation and pain e.g. in patients with OA, there is a shunting from the prostaglandin- to the leukotriene axis with subsequent upregulation of LTB₄. We demonstrated that chondrocytes
express both the high‑affinity (BLT1) and the low‑affinity (BLT2) LTB₄ receptors by immunolabelling and gene expression. By Western blot, we showed that the high‑affinity BLT1 receptor is active. Upon stimulation of chondrocyte cultures by the ligand, we found no effect on biological functions such as release of inflammatory mediators, proliferation, cartilage gene expression or matrix formation. The overall results suggest that the leukotriene axis is not very active in cartilage, and that the role seen in other inflammatory diseases is probably linked to the ability of LTB₄ to recruit neutrophils, a mechanism that is less prominent in osteoarthritis pathology. In the second paper, we investigated the influence of the active hormonal form of vitamin D, 1α,25(OH)₂D₃, on chondrocyte functions and evaluated potential modulating effects on inflammation as suggested by clinical studies showing improved pain scores after vitamin D supplementation. By immunolabelling and gene‑expression, we found that the expression of vitamin D receptor (VDR) in native cartilage is elusive, but that receptor expression increase upon dedifferentiation and during inflammatory conditions. We also demonstrated that 1α‑hydroxylase, the enzyme catalysing the
conversion of 25(OH)D₃ to 1α,25(OH)₂D₃, is expressed in cartilage and that the expression persists through cellular dedifferentiation and redifferentiation. In monolayer cultures the 25(OH)D₃ was converted to 1α,25(OH)₂D₃ in a dose dependent matter, and exposing chondrocytes to both 25(OH)D₃ and 1α,25(OH)2Dincreased their proliferation rate. The proteoglycan genes ACAN and VCAN displayed an inverse expression pattern, and matrix production was diminished in chondrocytes treated with 25(OH)D₃ or 1α,25(OH)₂D₃. The results imply that cartilage can contribute to the increased level
of 1α,25(OH)₂D₃ seen in synovial fluid of OA patients, but 25(OH)D₃ or 1α,25(OH)₂D₃ may only exert effects on chondrocytes upon dedifferentiation or during inflammatory conditions. The third paper aimed at identifying biomarkers of intrinsic chondrogenic potential in chondrocyte cultures established from 17 donors undergoing ACI treatment. Patient‑derived chondrocytes cultures were grouped according to their chondrogenic abilities in scaffold‑free 3D cultures, as evaluated by
the Bern score. The groupwise expression of cell‑surface molecules including integrins, cell adhesion molecules and growth factor receptors were measured using flow cytometry or gene expression. The gene expression of TGF‑β receptor 3 was inversely related to chondrogenic potential, while all other molecules tested had a uniform expression pattern among all donors. A global proteomic profiling of cell‑associated proteins using tandem‑mass‑tag technology pointed at prolyl 4‑hydroxylase, a pivotal enzyme in collagen triple helix formation, as a biomarker potentially linked to chondrogenic potential.

Mitochondrial calcium uniporter in Drosophila transfers calcium between the endoplasmic reticulum and mitochondria in oxidative stress-induced cell death

Mitochondrial calcium uniporter in Drosophila transfers calcium between the endoplasmic reticulum and mitochondria in oxidative stress-induced cell death
Received for publication, October 31, 2016, and in revised form, July 13, 2017, Published, Papers in Press, July 18, 2017, DOI 10.1074/jbc.M116.765578
Sekyu Choi‡1, Xianglan Quan§1,2, Sunhoe Bang‡1,3, Heesuk Yoo‡3, Jiyoung Kim‡, Jiwon Park‡3, Kyu-Sang Park§4, and Jongkyeong Chung‡3,5
From the ‡National Creative Research Initiatives Center for Energy Homeostasis Regulation, Institute of Molecular Biology and Genetics and School of Biological Sciences, Seoul National University, Seoul 08826, Korea and the §Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 26426, Korea
Edited by John M. Denu

 

Mitochondrial calcium plays critical roles in diverse cellular processes ranging from energy metabolism to cell death. Previous
studies have demonstrated that mitochondrial calcium uptake is mainly mediated by the mitochondrial calcium uniporter (MCU) complex. However, the roles of the MCU complex in calcium transport, signaling, and dysregulation by oxidative
stress still remain unclear. Here, we confirmed that Drosophila MCU contains evolutionarily conserved structures and requires essential MCU regulator (EMRE) for its calcium channel activities. We generated Drosophila MCU loss-of-function mutants, which lacked mitochondrial calcium uptake in response to caffeine stimulation. Basal metabolic activities were not significantly affected in these MCU mutants, as observed in examinations of body weight, food intake, body sugar level, and starvation-induced autophagy. However, oxidative stress-induced increases in mitochondrial calcium, mitochondrial membrane potential depolarization, and cell death were prevented in these mutants. We also found that inositol 1,4,5-trisphosphate receptor genetically interacts with Drosophila MCU and effectively modulates mitochondrial calcium uptake upon oxidative stress. Taken together, these results support the idea that Drosophila MCU is responsible for endoplasmic reticulum-to-mitochondrial calcium transfer and for cell death due to mitochondrial dysfunction under oxidative stress.

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Abstract 12435: Mitochondrial Calcium Flux Modulates Pacemaker Activity in Embryonic Stem Cell-Derived Cardiomyocytes

Abstract 12435: Mitochondrial Calcium Flux Modulates Pacemaker Activity in Embryonic Stem Cell-Derived Cardiomyocytes

 

An XieAnyu ZhouHong LiuGuangbin ShiKenneth R BohelerSamuel C Dudley

 

Abstract

 

Introduction: Ca2+ release from the sarcoplasmic reticulum (SR) is known to contribute to spontaneous activity via the cytoplasmic Na+-Ca2+ exchanger (NCX). Mitochondria are known to participate in Ca2+ cycling. We studied the role of mitochondrial Ca2+ flux in spontaneously activity of embryonic stem cells (ESC)-derived CMs.

Methods: CMs were derived from wild type (Wt) and ryanodine receptor type 2 knockout (RYR2-/-) mouse ESCs and differentiated for 19-21 days. Action potentials (APs) were recorded by perforated whole cell current-clamp. Cytoplasmic Ca2+ transients were determined by fluorescent imaging. Mitochondrial Ca2+ transients were monitored simultaneously with APs.

Results: While If blocker, 10μM ivabradine, had no significant effect on the automaticity, SR Ca2+ handling inhibitors, 10 μM ryanodine and 2 μM 2-APB, reduced the spontaneous beating rate to 56% and 73% respectively in Wt CMs. Inhibition of mitochondrial Ca2+ flux by 10 μM Ru360 showed a similar inhibitory effect on the pacemaker activity.To isolate the contribution of mitochondrial Ca2+, we used RYR2-/- CMs. In RYR2-/- CMs, beating rate was dependent on SR Ca2+ uptake and release from IP3 and the Na+/Ca2+ exchange current but was independent of sarcolemmal Ca2+ influx through L-type Ca2+ channels. In these cells, MCU inhibition by pharmacological or molecular biological means reduced beating rate. Depolarizing mitochondria prevented spontaneous beating. The mitochondrial NCX blocker, 1 or 3μM CGP-37157, terminated AP firings.

Conclusions: Mitochondrial Ca2+ cycling plays a role in spontaneous beating activity in embryonic stem (ES) cell-derived cardiomyocytes. Mitochondrial dysfunction may contribute to altered pacemaker activity in cardiomyopathy.

 

Author Disclosures: A. Xie: None. A. Zhou: None. H. Liu: None. G. Shi: None. K.R. Boheler: None. S.C. Dudley: None.
© 2015 by American Heart Association, Inc.

Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015

Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015

: a systematic analysis for the Global Burden of Disease Study 2015

 

GBD 2015 Disease and Injury Incidence and Prevalence Collaborators*

 

Introduction

Although substantial progress has been made toward reducing mortality and extending life expectancy throughout the world over the past few decades, the epidemiological transition is manifest in the growing importance of non-fatal diseases, outcomes, and injuries which pose, partly as a consequence of decreasing death rates, a rising challenge to the ability of the world’s population to live in full health. Complementing information on deaths by age, sex, cause, geography, and time with equally detailed information on disease incidence, prevalence, and severity is key to a balanced debate in health policy. For this reason, the Global Burden of Disease (GBD) Study uses the disability adjusted life-year (DALY), combining years of life lost (YLLs) due to mortality and years lived with disability (YLDs) in a single metric. One DALY can be thought of as one lost year of healthy life. The sum of DALYs in a population can be thought of as the gap between the population’s present health status and an ideal situation where the entire population lives to an advanced age, free of disease. Assessments of how different diseases lead to multimorbidity and reductions in functional health status are important for both health system planning 1 and a broader range of social policy issues such as the appropriate age for retirement in some countries.2,3 Many challenges in making standardised estimates of non-fatal health outcomes are similar to those affecting mortality estimates (including variations in case definitions, data collection methods, variable quality of data collection, conflicting data, and missing data) but are compounded by more sparse and varied data sources, the need to characterise each disease by its disabling sequelae or consequence(s), and the need to quantify the severity of these consequences. The standardised approach of the annual GBD updates addresses these measurement problems to enhance comparability between causes by geography and over time.

 

 

Sending ammonia signals

Sending ammonia signals
By Steve Edelson, Executive Editor

 

Ammonia has long been viewed as a toxic cellular by-product of glutamine metabolism that has little or no functionality. New findings by a group at Pfizer Inc. now suggest this may not always be the case. The team found that in tumors, ammonia functions as a diffusible signal that can trigger autophagy in neighboring cancer cells, which enables them to be better prepared to counter external stressors such as chemotherapeutics.1 The results suggest that disrupting glutamine
metabolism to reduce ammonia could be explored as a therapeutic strategy. The challenge will be figuring out how to therapeutically target the underlying pathways. In the presence of oxygen, normal cells extract as much energy as possible from glucose primarily through mitochondrial oxidative phosphorylation. In contrast, the majority of tumors grow mostly through glycolysis, a less efficient but faster process that involves converting glucose to lactate in the cytosol. As a result, the mitochondria of tumor cells are not used to generate ATP—instead, they work overtime producing intermediates for the
synthesis of nucleic and fatty acids via the tricarboxylic acid (TCA) cycle (see Figure 1, “Ammonia as a stress signal in cancer”).
One of the substrates for the TCA cycle, α-ketoglutarate, is generated from glutamine in the mitochondria following two deamination reactions. As a by-product, two molecules of ammonia are released.

Uncoupling the Warburg effect from cancer

Uncoupling the Warburg effect from cancer
Ayaz Najafov and Dario R. Alessi1
Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland

 

A remarkable trademark of most tumors is their ability to break down glucose by glycolysis at a vastly higher rate than in normal tissues, even when oxygen is copious. This phenomenon, known as the Warburg effect, enables rapidly dividing tumor
cells to generate essential biosynthetic building blocks such as nucleic acids, amino acids, and lipids from glycolytic intermediates to permit growth and duplication of cellular components during division (1). An assumption dominating research in this area is that the Warburg effect is specific to cancer.

Q’s next: the diverse functions of glutamine in metabolism, cell biology and cancer

Q’s next: the diverse functions of glutamine in metabolism, cell biology and cancer

RJ DeBerardinis1,2 and T Cheng1

1 Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA and 2 McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA

 

Several decades of research have sought to characterize tumor cell metabolism in the hope that tumor-specific activities can be exploited to treat cancer. Having originated from Warburg’s seminal observation of aerobic glycolysis in tumor cells, most of this attention has focused on glucose metabolism. However, since the 1950s cancer biologists have also recognized the importance of glutamine (Q) as a tumor nutrient. Glutamine contributes to essentially every core metabolic task of proliferating tumor cells: it participates in bioenergetics, supports cell defenses against oxidative stress and complements glucose metabolism in the production of macromolecules. The interest in glutamine metabolism has been heightened further by the recent findings that c-myc controls glutamine uptake and degradation, and that glutamine itself exerts influence over a number of signaling pathways that contribute to tumor growth. These observations are stimulating a renewed effort to understand the regulation of glutamine metabolism in tumors and to develop strategies to target glutamine metabolism in cancer. In this study, we review the protean roles of glutamine in cancer, both in the direct support of tumor growth and in mediating some of the complex effects on whole-body metabolism that are characteristic of tumor progression.

Oncogene (2010) 29, 313–324; doi:10.1038/onc.2009.358; published online 2 November 2009

 

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Glutamine and Cancer

Glutamine and Cancer

Wiley W. Souba, M.D., Sc.D.

From the Division of Surgical Oncology, Department of Surgery, Massachusetts General
Hospital, Harvard Medical School, Boston, Massachusetts

 

Objective
This overview on glutamine and cancer discusses the importance of glutamine for tumor growth, summarizes the alterations in interorgan glutamine metabolism that develop in the tumor-bearing host, and reviews the potential benefits of glutamine nutrition in the patient with cancer.

Summary Background Data
Glutamine is the most abundant amino acid in the blood and tissues. It is essential for tumor growth and marked changes in organ glutamine metabolism are characteristic of the host with cancer. Because host glutamine depletion has adverse effects, it is important to study the regulation of glutamine metabolism in cancer and to evaluate the impact of glutamine nutrition in the tumor-bearing state.

Methods
Data from a variety of investigations on glutamine metabolism and nutrition related to the host with cancer were compiled and summarized.

Results
Numerous studies on glutamine metabolism in cancer indicate that many tumors are avid glutamine consumers in vivo and in vitro. As a consequence of progressive tumor growth, host glutamine depletion develops and becomes a hallmark. This glutamine depletion occurs in part because the tumor behaves as a “glutamine trap” but also because of cytokine-mediated alterations in glutamine metabolism in host tissues. Animal and human studies that have investigated the use of glutamine-supplemented nutrition in the host with cancer suggest that pharmacologic doses of dietary glutamine may be beneficial.

Conclusions
Understanding the control of glutamine metabolism in the tumor-bearing host not only improves the knowledge of metabolic regulation in the patient with cancer but also will lead to improved nutritional support regimens targeted to benefit the host.


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Calcium, cancer and killing: The role of calcium in killing cancer cells by cytotoxic T lymphocytes and natural killer cells

Calcium, cancer and killing: The role of calcium in killing cancer cells by cytotoxic T lymphocytes and natural killer cells

Abstract

Killing cancer cells by cytotoxic T lymphocytes (CTL) and by natural killer (NK) cells is of vital importance. Cancer cell proliferation and apoptosis depend on the intracellular Ca2+ concentration, and the expression of numerous ion channels with the ability to control intracellular Ca2+ concentrations has been correlated with cancer. A rise of intracellular Ca2+ concentrations is also required for efficient CTL and NK cell function and thus for killing their targets, in this case cancer cells. Here, we review the data on Ca2+-dependent killing of cancer cells by CTL and NK cells. In addition, we discuss emerging ideas and present a model how Ca2+ may be used by CTL and NK cells to optimize their cancer cell killing efficiency. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.

© 2012 Elsevier B.V. All rights reserved

 

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