scholarly journals Autophagy: molecular machinery, regulation, and implications for renal pathophysiology

2009 ◽  
Vol 297 (2) ◽  
pp. F244-F256 ◽  
Author(s):  
Sudharsan Periyasamy-Thandavan ◽  
Man Jiang ◽  
Patricia Schoenlein ◽  
Zheng Dong
Keyword(s):  
Mammalian Cells ◽  
Cellular Response ◽  
Nutrient Deprivation ◽  
Experimental Conditions ◽  
Induce Cell Death ◽  
The Core ◽  
Molecular Machinery ◽  
Response To Stress ◽  
Membrane Bound ◽  
And Function

Autophagy is a cellular process of “self-eating.” During autophagy, a portion of cytoplasm is enveloped in double membrane-bound structures called autophagosomes, which undergo maturation and fusion with lysosomes for degradation. At the core of the molecular machinery of autophagy is a specific family of genes or proteins called Atg. Originally identified in yeast, Atg orthologs are now being discovered in mammalian cells and have been shown to play critical roles in autophagy. Traditionally, autophagy is recognized as a cellular response to nutrient deprivation or starvation whereby cells digest cytoplasmic organelles and macromolecules to recycle nutrients for self-support. However, studies during the last few years have indicated that autophagy is a general cellular response to stress. Interestingly, depending on experimental conditions, especially stress levels, autophagy can directly induce cell death or act as a mechanism of cell survival. In this review, we discuss the molecular machinery, regulation, and function of autophagy. In addition, we analyze the recent findings of autophagy in renal systems and its possible role in renal pathophysiology.

Early signalling events of autophagy

2013 ◽  
Vol 55 ◽  
pp. 1-15 ◽  
Author(s):  
Laura E. Gallagher ◽  
Edmond Y.W. Chan
Keyword(s):  
Protein Kinase ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Mammalian Cells ◽  
Mammalian Target Of Rapamycin ◽  
Interacting Protein ◽  
The Core ◽  
Autophagy Gene ◽  
Autophagy Induction ◽  
Cellular Pathways

Autophagy is a conserved cellular degradative process important for cellular homoeostasis and survival. An early committal step during the initiation of autophagy requires the actions of a protein kinase called ATG1 (autophagy gene 1). In mammalian cells, ATG1 is represented by ULK1 (uncoordinated-51-like kinase 1), which relies on its essential regulatory cofactors mATG13, FIP200 (focal adhesion kinase family-interacting protein 200 kDa) and ATG101. Much evidence indicates that mTORC1 [mechanistic (also known as mammalian) target of rapamycin complex 1] signals downstream to the ULK1 complex to negatively regulate autophagy. In this chapter, we discuss our understanding on how the mTORC1–ULK1 signalling axis drives the initial steps of autophagy induction. We conclude with a summary of our growing appreciation of the additional cellular pathways that interconnect with the core mTORC1–ULK1 signalling module.

Spatial control of actin-based motility through plasmalemmal PtdIns(4,5)P2-rich raft assemblies.

2005 ◽  
Vol 72 ◽  
pp. 119-127 ◽  
Author(s):  
Tamara Golub ◽  
Caroni Pico
Keyword(s):  
Protein Kinase ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Lipid Rafts ◽  
Patch Clustering ◽  
Pkc Protein Kinase C ◽  
Membrane Bound ◽  
And Function ◽  
Cytoskeleton Dynamics ◽  
Syndrome Protein

The interactions of cells with their environment involve regulated actin-based motility at defined positions along the cell surface. Sphingolipid- and cholesterol-dependent microdomains (rafts) order proteins at biological membranes, and have been implicated in most signalling processes at the cell surface. Many membrane-bound components that regulate actin cytoskeleton dynamics and cell-surface motility associate with PtdIns(4,5)P2-rich lipid rafts. Although raft integrity is not required for substrate-directed cell spreading, or to initiate signalling for motility, it is a prerequisite for sustained and organized motility. Plasmalemmal rafts redistribute rapidly in response to signals, triggering motility. This process involves the removal of rafts from sites that are not interacting with the substrate, apparently through endocytosis, and a local accumulation at sites of integrin-mediated substrate interactions. PtdIns(4,5)P2-rich lipid rafts can assemble into patches in a process depending on PtdIns(4,5)P2, Cdc42 (cell-division control 42), N-WASP (neural Wiskott-Aldrich syndrome protein) and actin cytoskeleton dynamics. The raft patches are sites of signal-induced actin assembly, and their accumulation locally promotes sustained motility. The patches capture microtubules, which promote patch clustering through PKA (protein kinase A), to steer motility. Raft accumulation at the cell surface, and its coupling to motility are influenced greatly by the expression of intrinsic raft-associated components that associate with the cytosolic leaflet of lipid rafts. Among them, GAP43 (growth-associated protein 43)-like proteins interact with PtdIns(4,5)P2 in a Ca2+/calmodulin and PKC (protein kinase C)-regulated manner, and function as intrinsic determinants of motility and anatomical plasticity. Plasmalemmal PtdIns(4,5)P2-rich raft assemblies thus provide powerful organizational principles for tight spatial and temporal control of signalling in motility.

Bleeding Time in Rats: A Comparison of Different Experimental Conditions

1982 ◽  
Vol 48 (01) ◽  
pp. 108-111 ◽  
Author(s):  
Elisabetta Dejana ◽  
Silvia Villa ◽  
Giovanni de Gaetano
Keyword(s):  
Platelet Function ◽  
Bleeding Time ◽  
Platelet Dysfunction ◽  
Experimental Conditions ◽  
Platelet Number ◽  
Coagulation Defects ◽  
Tail Tip ◽  
And Function ◽  
Storage Pool Disease ◽  
Type Of Anaesthesia

SummaryThe tail bleeding time (BT) in rats definitely varies according to the method applied. Of the various variables that may influence BT, we have evaluated the position (horizontal or vertical) of the tail, the environment (air or saline), the temperature (4°, 23° or 37° C) and the type of anaesthesia. Transection of the tail tip cannot be used to screen drugs active on platelet function since it is sensitive to coagulation defects. Template BT in contrast is not modified by heparin and is sensitive to defects of platelet number and function (“storage pool disease”, dipyridamole-like drugs, exogenous prostacyclin). In contrast the test fails to detect aspirin-induced platelet dysfunction. The evidence reported indicates that thromboxane A2-prostacyclin balance is not a factor regulating BT. Aspirin treatment however may be a precipitating factor when associated with other abnormalities of platelet function.Template BT is a valid screening test for platelet disorders and for antiplatelet drugs.

Use of Flexible Materials with a Novel Pressure Driven Equibiaxial Cell Stretching Device for Mechanical Stimulation of Single Mammalian Cells

2003 ◽  
Vol 773 ◽  
Author(s):  
James D. Kubicek ◽  
Stephanie Brelsford ◽  
Philip R. LeDuc
Keyword(s):  
Cell Fate ◽  
Mechanical Stimulation ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Single Cells ◽  
Complex Nature ◽  
Cellular Behavior ◽  
Cell Stretching ◽  
Stimulation Of ◽  
Pressure Driven

AbstractMechanical stimulation of single cells has been shown to affect cellular behavior from the molecular scale to ultimate cell fate including apoptosis and proliferation. In this, the ability to control the spatiotemporal application of force on cells through their extracellular matrix connections is critical to understand the cellular response of mechanotransduction. Here, we develop and utilize a novel pressure-driven equibiaxial cell stretching device (PECS) combined with an elastomeric material to control specifically the mechanical stimulation on single cells. Cells were cultured on silicone membranes coated with molecular matrices and then a uniform pressure was introduced to the opposite surface of the membrane to stretch single cells equibiaxially. This allowed us to apply mechanical deformation to investigate the complex nature of cell shape and structure. These results will enhance our knowledge of cellular and molecular function as well as provide insights into fields including biomechanics, tissue engineering, and drug discovery.

scholarly journals xCELLanalyzer: A Framework for the Analysis of Cellular Impedance Measurements for Mode of Action Discovery

2019 ◽  
Vol 24 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Raimo Franke ◽  
Bettina Hinkelmann ◽  
Verena Fetz ◽  
Theresia Stradal ◽  
Florenz Sasse ◽  
...  
Keyword(s):  
Data Analysis ◽  
Bioactive Compounds ◽  
Mode Of Action ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Label Free ◽  
Synthesis Inhibitor ◽  
Analysis Pipeline ◽  
Bioactive Natural Products ◽  
Data Analysis Pipeline

Mode of action (MoA) identification of bioactive compounds is very often a challenging and time-consuming task. We used a label-free kinetic profiling method based on an impedance readout to monitor the time-dependent cellular response profiles for the interaction of bioactive natural products and other small molecules with mammalian cells. Such approaches have been rarely used so far due to the lack of data mining tools to properly capture the characteristics of the impedance curves. We developed a data analysis pipeline for the xCELLigence Real-Time Cell Analysis detection platform to process the data, assess and score their reproducibility, and provide rank-based MoA predictions for a reference set of 60 bioactive compounds. The method can reveal additional, previously unknown targets, as exemplified by the identification of tubulin-destabilizing activities of the RNA synthesis inhibitor actinomycin D and the effects on DNA replication of vioprolide A. The data analysis pipeline is based on the statistical programming language R and is available to the scientific community through a GitHub repository.

scholarly journals Influence of spatial structure on protein damage susceptibility: a bioinformatics approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maximilian Fichtner ◽  
Stefan Schuster ◽  
Heiko Stark
Keyword(s):  
Amino Acids ◽  
Molecular Medicine ◽  
Protein Damage ◽  
Aging Research ◽  
Form And Function ◽  
The Core ◽  
And Function ◽  
Thermophilic Organisms ◽  
Damage Susceptibility ◽  
Protein Shell

AbstractAging research is a very popular field of research in which the deterioration or decline of various physiological features is studied. Here we consider the molecular level, which can also have effects on the macroscopic level. The proteinogenic amino acids differ in their susceptibilities to non-enzymatic modification. Some of these modifications can lead to protein damage and thus can affect the form and function of proteins. For this, it is important to know the distribution of amino acids between the protein shell/surface and the core. This was investigated in this study for all known structures of peptides and proteins available in the PDB. As a result, it is shown that the shell contains less susceptible amino acids than the core with the exception of thermophilic organisms. Furthermore, proteins could be classified according to their susceptibility. This can then be used in applications such as phylogeny, aging research, molecular medicine, and synthetic biology.

scholarly journals ADP-Ribosylation Factor (ARF) Interaction Is Not Sufficient for Yeast GGA Protein Function or Localization

2002 ◽  
Vol 13 (9) ◽  
pp. 3078-3095 ◽  
Author(s):  
Annette L. Boman ◽  
Paul D. Salo ◽  
Melissa J. Hauglund ◽  
Nicole L. Strand ◽  
Shelly J. Rensink ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Protein Localization ◽  
Carboxypeptidase Y ◽  
Minor Role ◽  
Temperature Sensitive ◽  
Adp Ribosylation ◽  
And Function ◽  
Adp Ribosylation Factor

Golgi-localized γ-ear homology domain, ADP-ribosylation factor (ARF)-binding proteins (GGAs) facilitate distinct steps of post-Golgi traffic. Human and yeast GGA proteins are only ∼25% identical, but all GGA proteins have four similar domains based on function and sequence homology. GGA proteins are most conserved in the region that interacts with ARF proteins. To analyze the role of ARF in GGA protein localization and function, we performed mutational analyses of both human and yeast GGAs. To our surprise, yeast and human GGAs differ in their requirement for ARF interaction. We describe a point mutation in both yeast and mammalian GGA proteins that eliminates binding to ARFs. In mammalian cells, this mutation disrupts the localization of human GGA proteins. Yeast Gga function was studied using an assay for carboxypeptidase Y missorting and synthetic temperature-sensitive lethality between GGAs andVPS27. Based on these assays, we conclude that non-Arf-binding yeast Gga mutants can function normally in membrane trafficking. Using green fluorescent protein-tagged Gga1p, we show that Arf interaction is not required for Gga localization to the Golgi. Truncation analysis of Gga1p and Gga2p suggests that the N-terminal VHS domain and C-terminal hinge and ear domains play significant roles in yeast Gga protein localization and function. Together, our data suggest that yeast Gga proteins function to assemble a protein complex at the late Golgi to initiate proper sorting and transport of specific cargo. Whereas mammalian GGAs must interact with ARF to localize to and function at the Golgi, interaction between yeast Ggas and Arf plays a minor role in Gga localization and function.

Antimicrobial mode of action of secretions from the metapleural gland ofMytmecia gulosa(Australian bull ant)

1995 ◽  
Vol 41 (2) ◽  
pp. 136-144 ◽  
Author(s):  
J. A. Mackintosh ◽  
J. E. Trimble ◽  
A. J. Beattie ◽  
D. A. Veal ◽  
M. K. Jones ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antimicrobial Agents ◽  
Structural Integrity ◽  
Phospholipid Bilayer ◽  
Active Components ◽  
Cytoplasmic Matrix ◽  
Metapleural Glands ◽  
Total Leakage ◽  
Membrane Bound ◽  
And Function

Secretions from exocrine metapleural glands of Myrmecia gulosa (Australian bull ant) exhibit broad-spectrum antimicrobial activity. Treatment of the yeast Candida albicans with metapleural secretion resulted in the rapid and total leakage of K+ions from cells within 10 min. Ultrastructural analysis of the bacteria Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa, and cells and protoplasts of Candida albicans demonstrated gross damage of the cell membrane and aggregation of the cytoplasmic matrix of treated cells. Degradation of membrane-bound organelles was also observed in Candida albicans. The antimicrobially active components of metapleural secretions were nonpolar and interacted with the phospholipid bilayer, causing damage to the structural integrity of liposomes and the release of carboxyfluorescein. The data suggest that the antimicrobial agents in metapleural secretion act primarily by disrupting the structure and function of the phospholipid bilayer of the cytoplasmic membrane.Key words: ant metapleural secretion, antimicrobial, Candida albicans, cytoplasmic membrane.

scholarly journals Secreted CXCL12 (SDF-1) forms dimers under physiological conditions

2012 ◽  
Vol 442 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Paramita Ray ◽  
Sarah A. Lewin ◽  
Laura Anne Mihalko ◽  
Sasha-Cai Lesher-Perez ◽  
Shuichi Takayama ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Extracellular Space ◽  
Mammalian Cells ◽  
Cell Signalling ◽  
Xenograft Model ◽  
Physiological Conditions ◽  
Cxc Chemokine ◽  
Chemokine Ligand ◽  
Chemokine Cxcl12 ◽  
And Function

Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.

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