Cellular and Molecular Mechanisms for the Bone Response to Mechanical Loading

2001 ◽  
Vol 11 (s1) ◽  
pp. S128-S136 ◽  
Author(s):  
Susan A. Bloomfield
Keyword(s):  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Interstitial Fluid Flow ◽  
Effector Cells ◽  
Bone Response ◽  
Osteogenic Response ◽  
Mechanical Signal ◽  
Endocrine Factors ◽  
Key Steps

To define the cellular and molecular mechanisms for the osteogenic response of bone to increased loading, several key steps must be defined: sensing of the mechanical signal by cells in bone, transduction of the mechanical signal to a biochemical one, and transmission of that biochemical signal to effector cells. Osteocytes are likely to serve as sensors of loading, probably via interstitial fluid flow produced during loading. Evidence is presented for the role of integrins, the cell’s actin cytoskeleton, G proteins, and various intracellular signaling pathways in transducing that mechanical signal to a biochemical one. Nitric oxide, prostaglandins, and insulin-like growth factors all play important roles in these pathways. There is growing evidence for modulation of these mechanotransduction steps by endocrine factors, particularly parathyroid hormone and estrogen. The efficiency of this process is also impaired in the aged animal, yet what remains undefined is at what step mechanotransduction is affected.

Microglia in cerebral ischemia: molecular actions and interactionsThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigator's Forum.

2006 ◽  
Vol 84 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Aaron Y. Lai ◽  
Kathryn G. Todd
Keyword(s):  
Cerebral Ischemia ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Extracellular Signals ◽  
Messenger Molecules ◽  
Membrane Bound ◽  
The Subject ◽  
Survey Review ◽  
Selection Of

The precise role of microglia in stroke and cerebral ischemia has been the subject of debate for a number of years. Microglia are capable of synthesizing numerous soluble and membrane-bound biomolecules, some known to be neuroprotective, some neurotoxic, whereas others have less definitive bioactivities. The molecular mechanisms through which microglia activate these molecules have thus become an important area of ischemia research. Here we provide a survey review that summarizes the key actions of microglial factors in cerebral ischemia including complement proteins, chemokines, pro-inflammatory cytokines, neurotrophic factors, hormones, and proteinases, as well several important messenger molecules that play a part in how these factors respond to extracellular signals during ischemic injuries. We also provide some new perspectives on how microglial intracellular signaling may contribute to the seemingly contradictory roles of several microglial effector molecules.

scholarly journals Role of Calcium and EPAC in Norepinephrine-Induced Ghrelin Secretion

Endocrinology ◽  
2014 ◽  
Vol 155 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Bharath K. Mani ◽  
Jen-Chieh Chuang ◽  
Lilja Kjalarsdottir ◽  
Ichiro Sakata ◽  
Angela K. Walker ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Intracellular Signaling ◽  
Endocrine Cells ◽  
Molecular Mechanisms ◽  
Phosphodiesterase Inhibitor ◽  
Intracellular Signaling Pathways ◽  
Ghrelin Secretion ◽  
Kinase A

Ghrelin is an orexigenic hormone secreted principally from a distinct population of gastric endocrine cells. Molecular mechanisms regulating ghrelin secretion are mostly unknown. Recently, norepinephrine (NE) was shown to enhance ghrelin release by binding to β1-adrenergic receptors on ghrelin cells. Here, we use an immortalized stomach-derived ghrelin cell line to further characterize the intracellular signaling pathways involved in NE-induced ghrelin secretion, with a focus on the roles of Ca2+ and cAMP. Several voltage-gated Ca2+ channel (VGCC) family members were found by quantitative PCR to be expressed by ghrelin cells. Nifedipine, a selective L-type VGCC blocker, suppressed both basal and NE-stimulated ghrelin secretion. NE induced elevation of cytosolic Ca2+ levels both in the presence and absence of extracellular Ca2+. Ca2+-sensing synaptotagmins Syt7 and Syt9 were also highly expressed in ghrelin cell lines, suggesting that they too help mediate ghrelin secretion. Raising cAMP with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine also stimulated ghrelin secretion, although such a cAMP-mediated effect likely does not involve protein kinase A, given the absence of a modulatory response to a highly selective protein kinase A inhibitor. However, pharmacological inhibition of another target of cAMP, exchange protein-activated by cAMP (EPAC), did attenuate both basal and NE-induced ghrelin secretion, whereas an EPAC agonist enhanced basal ghrelin secretion. We conclude that constitutive ghrelin secretion is primarily regulated by Ca2+ influx through L-type VGCCs and that NE stimulates ghrelin secretion predominantly through release of intracellular Ca2+. Furthermore, cAMP and its downstream activation of EPAC are required for the normal ghrelin secretory response to NE.

scholarly journals Analysis of the Placental Tissue Transcriptome of Normal and Preeclampsia Complicated Pregnancies

Acta Naturae ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 71-83 ◽  
Author(s):  
E. A. Trifonova ◽  
T. V. Gabidulina ◽  
N. I. Ershov ◽  
V. N. Serebrova ◽  
A. Yu. Vorozhishcheva ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Ischemia Reperfusion ◽  
Placental Tissue ◽  
Immunological Tolerance ◽  
Leading Role ◽  
New Genes ◽  
Genome Wide ◽  
Differential Gene

Preeclampsia is one of the most severe gestational complications which is one of the leading causes of maternal and perinatal morbidity and mortality. A growth in the incidence of severe and combined forms of the pathology has been observed in recent years. According to modern concepts, inadequate cytotrophoblast invasion into the spiral arteries of the uterus and development of the ischemia-reperfusion syndrome in the placental tissue play the leading role in the development of preeclampsia, which is characterized by multipleorgan failure. In this regard, our work was aimed at studying the patterns of placental tissue transcriptome that are specific to females with PE and with physiological pregnancy, as well as identifying the potential promising biomarkers and molecular mechanisms of this pathology. We have identified 63 genes whose expression proved to differ significantly in the placental tissue of females with PE and with physiological pregnancy. A cluster of differentially expressed genes (DEG) whose expression level is increased in patients with preeclampsia includes not only the known candidate genes that have been identified in many other genome-wide studies (e.g., LEP, BHLHB2, SIGLEC6, RDH13, BCL6), but also new genes (ANKRD37, SYDE1, CYBA, ITGB2, etc.), which can be considered as new biological markers of preeclampsia and are of further interest. The results of a functional annotation of DEG show that the development of preeclampsia may be related to a stress response, immune processes, the regulation of cell-cell interactions, intracellular signaling cascades, etc. In addition, the features of the differential gene expression depending on preeclampsia severity were revealed. We have found evidence of the important role of the molecular mechanisms responsible for the failure of immunological tolerance and initiation of the pro-inflammatory cascade in the development of severe preeclampsia. The results obtained elaborate the concept of the pathophysiology of preeclampsia and contain the information necessary to work out measures for targeted therapy of this disease.

scholarly journals Molecular Background of Leak K+ Currents: Two-Pore Domain Potassium Channels

2010 ◽  
Vol 90 (2) ◽  
pp. 559-605 ◽  
Author(s):  
Péter Enyedi ◽  
Gábor Czirják
Keyword(s):  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Detailed Examination ◽  
Resting Membrane Potential ◽  
Membrane Stretch ◽  
Physiological Processes ◽  
Pore Domain ◽  
K Currents

Two-pore domain K+ (K2P) channels give rise to leak (also called background) K+ currents. The well-known role of background K+ currents is to stabilize the negative resting membrane potential and counterbalance depolarization. However, it has become apparent in the past decade (during the detailed examination of the cloned and corresponding native K2P channel types) that this primary hyperpolarizing action is not performed passively. The K2P channels are regulated by a wide variety of voltage-independent factors. Basic physicochemical parameters (e.g., pH, temperature, membrane stretch) and also several intracellular signaling pathways substantially and specifically modulate the different members of the six K2P channel subfamilies (TWIK, TREK, TASK, TALK, THIK, and TRESK). The deep implication in diverse physiological processes, the circumscribed expression pattern of the different channels, and the interesting pharmacological profile brought the K2P channel family into the spotlight. In this review, we focus on the physiological roles of K2P channels in the most extensively investigated cell types, with special emphasis on the molecular mechanisms of channel regulation.

scholarly journals Modifying muscle mass – the endocrine perspective

2006 ◽  
Vol 191 (2) ◽  
pp. 349-360 ◽  
Author(s):  
A M Solomon ◽  
P M G Bouloux
Keyword(s):  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Specific Reference ◽  
Exciting Field ◽  
Medical Disorders ◽  
Age Related ◽  
Health And Disease ◽  
Endocrine Factors ◽  
Atrophy And Hypertrophy

This review describes the major hormonal factors that determine the balance between human skeletal muscle anabolism and catabolism in health and disease, with specific reference to age-related muscle loss (sarcopenia). The molecular mechanisms associated with muscle hypertrophy are described, and the central role of the satellite cell highlighted. The biological dynamics of satellite cells, varying between states of quiescence, proliferation and differentiation are strongly influenced by local endocrine factors. The molecular mechanisms of muscle atrophy are examined focussing on the causes of sarcopenia and associations with systemic medical disorders. In addition, evidence is provided that the mechanisms of atrophy and hypertrophy are unlikely to be simple opposites. Novel endocrine mechanisms underpinning mechano-transduction include IGF-I subtypes that may differentiate between endocrine and mechanical signals; their interaction with classical endocrine factors is an active area of translational research. Recently acquired knowledge on the mechanism of anabolic effects of androgens is also reviewed. The increasingly recognised role of myostatin, a negative regulator of muscle function, is described, as well as its potential as a therapeutic target. Strategies to counter age-related sarcopenia thus represent an exciting field of future investigation.

scholarly journals Tetraspanin CD63 Bridges Autophagic and Endosomal Processes To Regulate Exosomal Secretion and Intracellular Signaling of Epstein-Barr Virus LMP1

2017 ◽  
Vol 92 (5) ◽  
Author(s):  
Stephanie N. Hurwitz ◽  
Mujeeb R. Cheerathodi ◽  
Dingani Nkosi ◽  
Sara B. York ◽  
David G. Meckes
Keyword(s):  
Host Cell ◽  
Intracellular Signaling ◽  
Epstein Barr Virus ◽  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Cell Protein ◽  
Viral Oncoprotein ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT The tetraspanin protein CD63 has been recently described as a key factor in extracellular vesicle (EV) production and endosomal cargo sorting. In the context of Epstein-Barr virus (EBV) infection, CD63 is required for the efficient packaging of the major viral oncoprotein latent membrane protein 1 (LMP1) into exosomes and other EV populations and acts as a negative regulator of LMP1 intracellular signaling. Accumulating evidence has also pointed to intersections of the endosomal and autophagy pathways in maintaining cellular secretory processes and as sites for viral assembly and replication. Indeed, LMP1 can activate the mammalian target of rapamycin (mTOR) pathway to suppress host cell autophagy and facilitate cell growth and proliferation. Despite the growing recognition of cross talk between endosomes and autophagosomes and its relevance to viral infection, little is understood about the molecular mechanisms governing endosomal and autophagy convergence. Here, we demonstrate that CD63-dependent vesicle protein secretion directly opposes intracellular signaling activation downstream of LMP1, including mTOR-associated proteins. Conversely, disruption of normal autolysosomal processes increases LMP1 secretion and dampens signal transduction by the viral protein. Increases in mTOR activation following CD63 knockout are coincident with the development of serum-dependent autophagic vacuoles that are acidified in the presence of high LMP1 levels. Altogether, these findings suggest a key role of CD63 in regulating the interactions between endosomal and autophagy processes and limiting cellular signaling activity in both noninfected and virally infected cells. IMPORTANCE The close connection between extracellular vesicles and viruses is becoming rapidly and more widely appreciated. EBV, a human gamma herpesvirus that contributes to the progression of a multitude of lymphomas and carcinomas in immunocompromised or genetically susceptible populations, packages its major oncoprotein, LMP1, into vesicles for secretion. We have recently described a role of the host cell protein CD63 in regulating intracellular signaling of the viral oncoprotein by shuttling LMP1 into exosomes. Here, we provide strong evidence of the utility of CD63-dependent EVs in regulating global intracellular signaling, including mTOR activation by LMP1. We also demonstrate a key role of CD63 in coordinating endosomal and autophagic processes to regulate LMP1 levels within the cell. Overall, this study offers new insights into the complex intersection of cellular secretory and degradative mechanisms and the implications of these processes in viral replication.

scholarly journals Notch Signaling Regulation in Autoinflammatory Diseases

2020 ◽  
Vol 21 (22) ◽  
pp. 8847
Author(s):  
Rossella Gratton ◽  
Paola Maura Tricarico ◽  
Adamo Pio d'Adamo ◽  
Anna Monica Bianco ◽  
Ronald Moura ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Cell Fate ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Notch Pathway ◽  
Autoinflammatory Diseases ◽  
Cellular Processes ◽  
Core Components

Notch pathway is a highly conserved intracellular signaling route that modulates a vast variety of cellular processes including proliferation, differentiation, migration, cell fate and death. Recently, the presence of a strict crosstalk between Notch signaling and inflammation has been described, although the precise molecular mechanisms underlying this interplay have not yet been fully unravelled. Disruptions in Notch cascade, due both to direct mutations and/or to an altered regulation in the core components of Notch signaling, might lead to hypo- or hyperactivation of Notch target genes and signaling molecules, ultimately contributing to the onset of autoinflammatory diseases. To date, alterations in Notch signaling have been reported as associated with three autoinflammatory disorders, therefore, suggesting a possible role of Notch in the pathogenesis of the following diseases: hidradenitis suppurativa (HS), Behçet disease (BD), and giant cell arteritis (GCA). In this review, we aim at better characterizing the interplay between Notch and autoinflammatory diseases, trying to identify the role of this signaling route in the context of these disorders.

scholarly journals The Gut Microbiome Influences Host Endocrine Functions

2019 ◽  
Vol 40 (5) ◽  
pp. 1271-1284 ◽  
Author(s):  
Marialetizia Rastelli ◽  
Patrice D Cani ◽  
Claude Knauf
Keyword(s):  
Gut Microbiome ◽  
Molecular Mechanisms ◽  
Peptide Yy ◽  
Host Cells ◽  
Bioactive Lipids ◽  
Gut Peptides ◽  
Endocrine Factors ◽  
Host Metabolism ◽  
The Impact

AbstractThe gut microbiome is considered an organ contributing to the regulation of host metabolism. Since the relationship between the gut microbiome and specific diseases was elucidated, numerous studies have deciphered molecular mechanisms explaining how gut bacteria interact with host cells and eventually shape metabolism. Both metagenomic and metabolomic analyses have contributed to the discovery of bacterial-derived metabolites acting on host cells. In this review, we examine the molecular mechanisms by which bacterial metabolites act as paracrine or endocrine factors, thereby regulating host metabolism. We highlight the impact of specific short-chain fatty acids on the secretion of gut peptides (i.e., glucagon-like peptide-1, peptide YY) and other metabolites produced from different amino acids and regulating inflammation, glucose metabolism, or energy homeostasis. We also discuss the role of gut microbes on the regulation of bioactive lipids that belong to the endocannabinoid system and specific neurotransmitters (e.g., γ-aminobutyric acid, serotonin, nitric oxide). Finally, we review the role of specific bacterial components (i.e., ClpB, Amuc_1100) also acting as endocrine factors and eventually controlling host metabolism. In conclusion, this review summarizes the recent state of the art, aiming at providing evidence that the gut microbiome influences host endocrine functions via several bacteria-derived metabolites.

CD8+ T cell dysfunction by TOX intoxication: a protumorigenic event in the tumor microenvironment

2021 ◽  
Author(s):  
Nilesh Kumar Sharma ◽  
Sachin C Sarode ◽  
Gargi S Sarode ◽  
Shankargouda Patil
Keyword(s):  
T Cells ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
High Mobility ◽  
Cancer Therapeutics ◽  
Effector Cells ◽  
T Effector Cells ◽  
Epigenetic Remodeling ◽  
Cellular Components

Accumulating evidence suggests the role of cellular components in achieving antitumor to protumor microenvironments. Among the various types of cells within the tumor niche, the state of CD8+ T cells apparently changes from cytotoxic T effector cells and memory T cells to exhausted CD8+ T cells. These changes in the phenotype of CD8+ T cells promote the protumor microenvironment. Recently, comprehensive experimental data delineated the role of thymocyte selection-associated high-mobility group-box protein (TOX), which regulates the transcriptional process and epigenetic remodeling, with implications in tumor and chronic viral infections. This perspective summarizes the molecular mechanisms that link CD8+ T cells, TOX, and transcriptional and epigenetic reprogramming as well as future directions for determining new avenues of cancer therapeutics.

scholarly journals Natural Products and Obesity: A Focus on the Regulation of Mitotic Clonal Expansion during Adipogenesis

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1157 ◽  
Author(s):  
Eugene Chang ◽  
Choon Kim
Keyword(s):  
Cell Cycle ◽  
Natural Products ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Inhibitory Effects ◽  
Health Crisis ◽  
Health Complications ◽  
Key Steps

Obesity is recognized as a worldwide health crisis. Obesity and its associated health complications such as diabetes, dyslipidemia, hypertension, and cardiovascular diseases impose a big social and economic burden. In an effort to identify safe, efficient, and long-term effective methods to treat obesity, various natural products with potential for inhibiting adipogenesis were revealed. This review aimed to discuss the molecular mechanisms underlying adipogenesis and the inhibitory effects of various phytochemicals, including those from natural sources, on the early stage of adipogenesis. We discuss key steps (proliferation and cell cycle) and their regulators (cell-cycle regulator, transcription factors, and intracellular signaling pathways) at the early stage of adipocyte differentiation as the mechanisms responsible for obesity.

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