scholarly journals Autophagy Mechanism, Regulation, Functions, and Disorders

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Mallikarjun Badadani
Keyword(s):  
Lysosomal Enzymes ◽  
Neuromuscular Disorders ◽  
Bafilomycin A1 ◽  
Tor Signaling ◽  
Physiological Conditions ◽  
Membrane Bound ◽  
Foxo Transcription Factors ◽  
Regulation Functions ◽  
Related Proteins ◽  
Chaperone Mediated Autophagy

Autophagy is a self-digesting mechanism responsible for removal of damaged organelles, malformed proteins during biosynthesis, and nonfunctional long-lived proteins by lysosome. Autophagy has been divided into three general types depending on the mechanism by which intracellular materials are delivered into lysosome for degradation that is, microautophagy, chaperone-mediated autophagy (CMA), and macroautophagy. In microautophagy cytoplasm material is sequestered through direct invagination to the lysosomal membrane. Whereas in CMA proteins flagged with pentapeptide motif (KFERQ) were selectively degraded through direct translocation into lysosome. Macroautophagy involves the formation of subcellular double-membrane-bound structures called autophagosomes that contain degradable contents of cytoplasm materials and deliver them into lysosomes for breakdown by lysosomal enzymes. The molecular mechanism of autophagy involves several conserved Atg (autophagy-related) proteins. Systems produce modified complexes Atg8-PE and Atg5-Atg12-Atg16 as autophagy regulators. Autophagy is activated in response to diverse stress and physiological conditions. For example, food deprivation, hyperthermia, and hypoxia are mediated by factors like insulin/IGF-1, m-TOR signaling, FOXO transcription factors, and chaperones. The perturbance in autophagy may lead to several types of cancers, myopathies, and neuromuscular disorders. Several autophagy inducers and inhibitors like 3-methyladenine (3-MA), bafilomycin A1, LY294002 (LY), and Velcade have been used to treat disease is an intense field of study.

Exploring Cardioprotective Potential of Esculetin Against Isoproterenol Induced Myocardial Infarction in Rats: In Vivo and in Vitro Evidence

2021 ◽  
Author(s):  
Pullaiah Chitikela P ◽  
Vinod K Nelson ◽  
Sushma R ◽  
Narasimha Kumar GV ◽  
Thyagaraju K
Keyword(s):  
Myocardial Infarction ◽  
Body Weight ◽  
Lysosomal Enzymes ◽  
H9c2 Cell ◽  
Rna Expression ◽  
Cell Necrosis ◽  
Tnf Α ◽  
Intracellular Ros ◽  
Membrane Bound

Abstract BackgroundEsculetin is a natural coumarin derivative from various plants with multiple pharmacological effects. Hence, the present study was undertaken to explore the cardio protective potential of esculetin against isoproterenol induced myocardial toxicity in rats. Methods The treatment schedule was fixed for 28 days and the rats were divided into five groups of six each. Rats of group I received the normal saline and served as normal control, group II was received ISO (100mg/kg body weight) for last two consecutive days of the study and served as disease control. Groups III and IV received esculetin 10 and 20 mg/kg body weight respectively once a day per oral for 28 days along with ISO for last two consecutive days of the study. Cardiac biomarkers such as CK-MB and LDH, membrane bound Na+ /K+ ATPases activity, myocardial lysosomal enzymes activity and tissue antioxidants status were estimated in the heart tissue samples. The histopathological changes in the myocardium were also assessed. Further, DPPH assay was done to evaluate the free radicals scavenging potential of esculetin. Cytoxicity assay, intracellular ROS levels by DCFDA assay and m-RNA expression of TNF-α, IL-6 and NF-κB by quantitative RT-PCR in H9c2 cell lines.ResultsThe increased levels of CK-MB, LDH, LPO, myocardial lysosomal enzymes and membrane bound Na+ /K+ ATPase levels by ISO administration was significantly increased with concomitant decrease in tissue antioxidant enzymes such as GSH, Catalase, and SOD. Pre-treatment with esculetin for 28 days has significantly decreased the levels of cardiac bio-markers, lysosomal enzymes, membrane bound Na+ /K+ ATPase levels as well as Lipid peroxides which is in contrary to the ISO group. Amelioration of the antioxidant levels were also found in esculetin treated groups. Histopathological examination of heart reveals that myocardial degeneration, mononuclear cell infiltration was noticed in ISO treated rats, whereas the same was restored with esculetin treatment. In H9C2 cell lines esculetin could effectively reduced intracellular ROS inhibition and m-RNA expression of pro-inflammatory cytokines including TNF-α, IL-6 and NF-κB to prevent apoptosis or cell necrosis. Conclusion The study provides the evidence of cardioprotective potentials of esculetin against isoproterenol induced myocardial infarction by antioxidant and myocardial membrane stabilization along with in vitro protection from arsenic induced ROS cell necrosis or apoptosis in H9C2 cells.

scholarly journals Azurophilic Granules of Human Neutrophilic Leukocytes Are Deficient in Lysosome-Associated Membrane Proteins but Retain the Mannose 6-Phosphate Recognition Marker

Blood ◽  
1998 ◽  
Vol 91 (3) ◽  
pp. 1044-1058 ◽  
Author(s):  
A.-M. Cieutat ◽  
P. Lobel ◽  
J.T. August ◽  
L. Kjeldsen ◽  
H. Sengeløv ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Lysosomal Enzymes ◽  
Acid Hydrolases ◽  
Structural Localization ◽  
Dense Bodies ◽  
Neutrophilic Leukocytes ◽  
Azurophil Granule ◽  
Membrane Bound ◽  
Storage Granules ◽  
Mannose 6 Phosphate

Abstract During granulocyte differentiation in the bone marrow (BM), neutrophilic leukocyte precursors synthesize large amounts of lysosomal enzymes. These enzymes are sequestered into azurophilic storage granules until used days later for digestion of phagocytized microorganisms after leukocyte emigration to inflamed tissues. This azurophil granule population has previously been defined as a primary lysosome, ie, a membrane-bound organelle containing acid hydrolases that have not entered into a digestive event. In this study, azurophil granules were purified and shown to contain large amounts of mannose 6-phosphate-containing glycoproteins (Man 6-P GP) but little lysosome-associated membrane proteins (LAMP). In addition, the fine structural localization of Man 6-P GP and LAMP was investigated at various stages of maturation in human BM and blood. Man 6-P GP were present within the azurophilic granules at all stages of maturation and in typical multivesicular bodies (MVB) as well as in multilaminar compartments (MLC), identified by their content of concentric arrays of internal membranes. LAMP was absent in all identified granule populations, but was consistently found in the membranes of vesicles, MVB, and MLC. The latter compartment has not been previously described in this cell type. In conclusion, the azurophilic granules, which contain an abundance of lysosomal enzymes and Man 6-P GP, lack the LAMP glycoproteins. By current criteria, they therefore cannot be classified as lysosomes, but rather may have the functional characteristics of a regulated secretory granule. Rather, the true lysosomes of the resting neutrophil are probably the MVB and MLC. Finally, the typical “dense bodies” or mature lysosomes described in other cells are not present in resting neutrophils.

scholarly journals Lipid droplets maintain lipid homeostasis during anaphase for efficient cell separation in budding yeast

2016 ◽  
Vol 27 (15) ◽  
pp. 2368-2380 ◽  
Author(s):  
Po-Lin Yang ◽  
Tzu-Han Hsu ◽  
Chao-Wen Wang ◽  
Rey-Huei Chen
Keyword(s):  
Cell Separation ◽  
Neutral Lipids ◽  
Budding Yeast ◽  
Acid Synthesis ◽  
Mitotic Exit ◽  
Lipid Homeostasis ◽  
Physiological Conditions ◽  
Division Site ◽  
Quadruple Mutant ◽  
Membrane Bound

The neutral lipids steryl ester and triacylglycerol (TAG) are stored in the membrane-bound organelle lipid droplet (LD) in essentially all eukaryotic cells. It is unclear what physiological conditions require the mobilization or storage of these lipids. Here, we study the budding yeast mutant are1Δ are2Δ dga1Δ lro1Δ, which cannot synthesize the neutral lipids and therefore lacks LDs. This quadruple mutant is delayed at cell separation upon release from mitotic arrest. The cells have abnormal septa, unstable septin assembly during cytokinesis, and prolonged exocytosis at the division site at the end of cytokinesis. Lipidomic analysis shows a marked increase of diacylglycerol (DAG) and phosphatidic acid, the precursors for TAG, in the mutant during mitotic exit. The cytokinesis and separation defects are rescued by adding phospholipid precursors or inhibiting fatty acid synthesis, which both reduce DAG levels. Our results suggest that converting excess lipids to neutral lipids for storage during mitotic exit is important for proper execution of cytokinesis and efficient cell separation.

Dissection of functional domains in Bcl-2α by site-directed mutagenesis

1994 ◽  
Vol 72 (11-12) ◽  
pp. 463-469 ◽  
Author(s):  
Christoph Borner ◽  
Reynald Olivier ◽  
Isabelle Martinou ◽  
Chantal Mattmann ◽  
Jurg Tschopp ◽  
...  
Keyword(s):  
Cell Survival ◽  
Protein Structures ◽  
Cell Types ◽  
Site Directed Mutagenesis ◽  
Functional Domains ◽  
Directed Mutagenesis ◽  
Membrane Attachment ◽  
Alternatively Spliced ◽  
Membrane Bound ◽  
Related Proteins

Bcl-2α is a mitochondrial or perinuclear-associated oncoprotein that prolongs the life span of a variety of cell types by interfering with programmed cell death. How Bcl-2 confers cell survival is unknown, although antioxidant and antiprotease functions have been proposed. In addition, protein structures of Bcl-2 that are crucial for its survival activity are still ill-defined. Bcl-2 can occur as Bcl-2α or Bcl-2β, two alternatively spliced forms which solely differ in their carboxyl termini. The finding that Bcl-2α is active and membrane bound, but Bcl-2β is inactive and cytosolic, indicates that the carboxyl terminus contributes to the survival activity of Bcl-2. This region contains two subdomains, a domain X with unknown function and a hydrophobic stretch reported to mediate membrane assocation of Bcl-2α. Recently Bcl-2-related proteins have been identified. These include Bax that heterodimerizes with Bcl-2 and, when overxpressed, counteracts Bcl-2. Bax contains two highly conserved regions of sequence homology with Bcl-2, referred to as Bcl-2 homology 1 and 2 (BH1 and BH2) domains. Site-directed mutagenesis studies have revealed that both domains are not only novel dimerization motifs for the interaction of Bax with Bcl-2 but also crucial for the survival activity of Bcl-2. Interestingly, the C-terminal end of BH2 encompasses the Bcl-2α/β splice site, as well as part of domain X in Bcl-2α. To better define the role of domain X and the hydrophobic C-terminal stretch of Bcl-2α for its survival activity, we created various deletion and truncation mutations in these regions by site-directed mutagenesis. We show here that membrane attachment and therefore the hydrophobic stretch is not required for the survival activity of Bcl-2, but part of domain X appears to be indispensable.Key words: apoptosis, Bcl-2, mutagenesis, cell survival, functional domains.

The subcellular localization of soluble and membrane-bound lysosomal enzymes in I-cell fibroblasts and in fibroblasts from control individuals

1986 ◽  
Vol 19 (1) ◽  
pp. 95 ◽  
Author(s):  
J.M. van Dongen ◽  
R. Willemsen ◽  
W.J. Visser ◽  
A.T. Hoogeveen ◽  
H.J. Sips ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Lysosomal Enzymes ◽  
Membrane Bound

scholarly journals Azurophilic Granules of Human Neutrophilic Leukocytes Are Deficient in Lysosome-Associated Membrane Proteins but Retain the Mannose 6-Phosphate Recognition Marker

Blood ◽  
1998 ◽  
Vol 91 (3) ◽  
pp. 1044-1058 ◽  
Author(s):  
A.-M. Cieutat ◽  
P. Lobel ◽  
J.T. August ◽  
L. Kjeldsen ◽  
H. Sengeløv ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Lysosomal Enzymes ◽  
Acid Hydrolases ◽  
Structural Localization ◽  
Dense Bodies ◽  
Neutrophilic Leukocytes ◽  
Azurophil Granule ◽  
Membrane Bound ◽  
Storage Granules ◽  
Mannose 6 Phosphate

During granulocyte differentiation in the bone marrow (BM), neutrophilic leukocyte precursors synthesize large amounts of lysosomal enzymes. These enzymes are sequestered into azurophilic storage granules until used days later for digestion of phagocytized microorganisms after leukocyte emigration to inflamed tissues. This azurophil granule population has previously been defined as a primary lysosome, ie, a membrane-bound organelle containing acid hydrolases that have not entered into a digestive event. In this study, azurophil granules were purified and shown to contain large amounts of mannose 6-phosphate-containing glycoproteins (Man 6-P GP) but little lysosome-associated membrane proteins (LAMP). In addition, the fine structural localization of Man 6-P GP and LAMP was investigated at various stages of maturation in human BM and blood. Man 6-P GP were present within the azurophilic granules at all stages of maturation and in typical multivesicular bodies (MVB) as well as in multilaminar compartments (MLC), identified by their content of concentric arrays of internal membranes. LAMP was absent in all identified granule populations, but was consistently found in the membranes of vesicles, MVB, and MLC. The latter compartment has not been previously described in this cell type. In conclusion, the azurophilic granules, which contain an abundance of lysosomal enzymes and Man 6-P GP, lack the LAMP glycoproteins. By current criteria, they therefore cannot be classified as lysosomes, but rather may have the functional characteristics of a regulated secretory granule. Rather, the true lysosomes of the resting neutrophil are probably the MVB and MLC. Finally, the typical “dense bodies” or mature lysosomes described in other cells are not present in resting neutrophils.

scholarly journals Expanding the Clinico-Genetic Spectrum of Myofibrillar Myopathy: Experience From a Chinese Neuromuscular Center

2020 ◽  
Vol 11 ◽  
Author(s):  
Yue-Bei Luo ◽  
Yuyao Peng ◽  
Yuling Lu ◽  
Qiuxiang Li ◽  
Huiqian Duan ◽  
...  
Keyword(s):  
Neuromuscular Disorders ◽  
Myofibrillar Myopathy ◽  
Pathogenic Variants ◽  
Correlation Spectrum ◽  
Genetic Features ◽  
Cardiac Evaluation ◽  
Αb Crystallin ◽  
Hereditary Myopathy ◽  
Related Proteins ◽  
First Time

Background: Myofibrillar myopathy is a group of hereditary neuromuscular disorders characterized by dissolution of myofibrils and abnormal intracellular accumulation of Z disc-related proteins. We aimed to characterize the clinical, physiological, pathohistological, and genetic features of Chinese myofibrillar myopathy patients from a single neuromuscular center.Methods: A total of 18 patients were enrolled. Demographic and clinical data were collected. Laboratory investigations, electromyography, and cardiac evaluation was performed. Routine and immunohistochemistry stainings against desmin, αB-crystallin, and BAG3 of muscle specimen were carried out. Finally, next-generation sequencing panel array for genes associated with hereditary neuromuscular disorders were performed.Results: Twelve pathogenic variants in DES, BAG3, FLNC, FHL1, and TTN were identified, of which seven were novel mutations. The novel DES c.1256C>T substitution is a high frequency mutation. The combined recessively/dominantly transmitted c.19993G>T and c.107545delG mutations in TTN gene cause a limb girdle muscular dystrophy phenotype with the classical myofibrillar myopathy histological changes.Conclusions: We report for the first time that hereditary myopathy with early respiratory failure patient can have peripheral nerve and severe spine involvement. The mutation in Ig-like domain 16 of FLNC is associated with the limb girdle type of filaminopathy, and the mutation in Ig-like domain 18 with distal myopathy type. These findings expand the phenotypic and genotypic correlation spectrum of myofibrillar myopathy.

scholarly journals Exploring cardioprotective potential of esculetin against isoproterenol induced myocardial toxicity in rats: in vivo and in vitro evidence

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Chitikela P. Pullaiah ◽  
Vinod K. Nelson ◽  
Sushma Rayapu ◽  
Narasimha Kumar G V ◽  
Thyagaraju Kedam
Keyword(s):  
Body Weight ◽  
Cell Lines ◽  
Lysosomal Enzymes ◽  
H9c2 Cell ◽  
Rna Expression ◽  
Cell Necrosis ◽  
Tnf Α ◽  
Intracellular Ros ◽  
Membrane Bound

Abstract Background Esculetin is a natural coumarin derivative from various plants with multiple pharmacological effects. Hence, the present study was undertaken to explore the cardio protective potential of esculetin against isoproterenol induced myocardial toxicity in rats. Methods The treatment schedule was fixed for 28 days and the rats were divided into five groups of six each. Rats of group I received the normal saline and served as normal control, group II was received ISO (100 mg/kg body weight) for last two consecutive days of the study and served as disease control. Groups III and IV received esculetin 10 and 20 mg/kg body weight respectively once a day per oral for 28 days along with ISO for last two consecutive days of the study. Cardiac biomarkers such as CK-MB and LDH, membrane bound Na+ /K+ ATPases activity, myocardial lysosomal enzymes activity and tissue antioxidants status were estimated in the heart tissue samples. The histopathological changes in the myocardium were also assessed. Further, DPPH assay was done to evaluate the free radicals scavenging potential of esculetin. Cytoxicity assay, intracellular ROS levels by DCFDA assay and m-RNA expression of TNF-α, IL-6 and NF-κB by quantitative RT-PCR in H9c2 cell lines. Results The increased levels of CK-MB, LDH, LPO, myocardial lysosomal enzymes and membrane bound Na+ /K+ ATPase levels by ISO administration was significantly increased with concomitant decrease in tissue antioxidant enzymes such as GSH, Catalase, and SOD. Pre-treatment with esculetin for 28 days has significantly decreased the levels of cardiac bio-markers, lysosomal enzymes, membrane bound Na+ /K+ ATPase levels as well as Lipid peroxides which is in contrary to the ISO group. Amelioration of the antioxidant levels were also found in esculetin treated groups. Histopathological examination of heart reveals that myocardial degeneration, mononuclear cell infiltration was noticed in ISO treated rats, whereas the same was restored with esculetin treatment. In H9C2 cell lines esculetin could effectively reduced intracellular ROS inhibition and m-RNA expression of pro-inflammatory cytokines including TNF-α, IL-6 and NF-κB to prevent apoptosis or cell necrosis. Conclusion The study provides the evidence of cardioprotective potentials of esculetin against isoproterenol induced myocardial infarction by antioxidant and myocardial membrane stabilization along with in vitro protection from arsenic induced ROS cell necrosis or apoptosis in H9C2 cells.

scholarly journals Protein Composition and Electron Microscopy Structure of Affinity-Purified Human Spliceosomal B Complexes Isolated under Physiological Conditions

2006 ◽  
Vol 26 (14) ◽  
pp. 5528-5543 ◽  
Author(s):  
Jochen Deckert ◽  
Klaus Hartmuth ◽  
Daniel Boehringer ◽  
Nastaran Behzadnia ◽  
Cindy L. Will ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Potential Role ◽  
Protein Composition ◽  
Nuclear Extract ◽  
Physiological Conditions ◽  
Catalytic Activation ◽  
Composition And Structure ◽  
Spliceosome Activation ◽  
Related Proteins

ABSTRACT The spliceosomal B complex is the substrate that undergoes catalytic activation leading to catalysis of pre-mRNA splicing. Previous characterization of this complex was performed in the presence of heparin, which dissociates less stably associated components. To obtain a more comprehensive inventory of the B complex proteome, we isolated this complex under low-stringency conditions using two independent methods. MS2 affinity-selected B complexes supported splicing when incubated in nuclear extract depleted of snRNPs. Mass spectrometry identified over 110 proteins in both independently purified B complex preparations, including ∼50 non-snRNP proteins not previously found in the spliceosomal A complex. Unexpectedly, the heteromeric hPrp19/CDC5 complex and 10 additional hPrp19/CDC5-related proteins were detected, indicating that they are recruited prior to spliceosome activation. Electron microscopy studies revealed that MS2 affinity-selected B complexes exhibit a rhombic shape with a maximum dimension of 420 Å and are structurally more homogeneous than B complexes treated with heparin. These data provide novel insights into the composition and structure of the spliceosome just prior to its catalytic activation and suggest a potential role in activation for proteins recruited at this stage. Furthermore, the spliceosomal complexes isolated here are well suited for complementation studies with purified proteins to dissect factor requirements for spliceosome activation and splicing catalysis.

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