scholarly journals Aziridine-2,3-Dicarboxylate-Based Cysteine Cathepsin Inhibitors Induce Cell Death in Leishmania major Associated with Accumulation of Debris in Autophagy-Related Lysosome-Like Vacuoles

2010 ◽  
Vol 54 (12) ◽  
pp. 5028-5041 ◽  
Author(s):  
Uta Schurigt ◽  
Caroline Schad ◽  
Christin Glowa ◽  
Ulrike Baum ◽  
Katja Thomale ◽  
...  
Keyword(s):  
Cell Death ◽  
Leishmania Major ◽  
Cysteine Proteinase ◽  
Membrane Integrity ◽  
New Drugs ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cysteine Cathepsins ◽  
Cysteine Cathepsin ◽  
Microscopic Studies

ABSTRACT The papain-like cysteine cathepsins expressed by Leishmania play a key role in the life cycle of these parasites, turning them into attractive targets for the development of new drugs. We previously demonstrated that two compounds of a series of peptidomimetic aziridine-2,3-dicarboxylate [Azi(OBn)2]-based inhibitors, Boc-(S)-Leu-(R)-Pro-(S,S)-Azi(OBn)2 (compound 13b) and Boc-(R)-Leu-(S)-Pro-(S,S)-Azi(OBn)2 (compound 13e), reduced the growth and viability of Leishmania major and the infection rate of macrophages while not showing cytotoxicity against host cells. In the present study, we characterized the mode of action of inhibitors 13b and 13e in L. major. Both compounds targeted leishmanial cathepsin B-like cysteine cathepsin cysteine proteinase C, as shown by fluorescence proteinase activity assays and active-site labeling with biotin-tagged inhibitors. Furthermore, compounds 13b and 13e were potent inducers of cell death in promastigotes, characterized by cell shrinkage, reduction of mitochondrial transmembrane potential, and increased DNA fragmentation. Transmission electron microscopic studies revealed the enrichment of undigested debris in lysosome-like organelles participating in micro- and macroautophagy-like processes. The release of digestive enzymes into the cytoplasm after rupture of membranes of lysosome-like vacuoles resulted in the significant digestion of intracellular compartments. However, the plasma membrane integrity of compound-treated promastigotes was maintained for several hours. Taken together, our results suggest that the induction of cell death in Leishmania by cysteine cathepsin inhibitors 13b and 13e is different from mammalian apoptosis and is caused by incomplete digestion in autophagy-related lysosome-like vacuoles.

Structure and host–actinomycete interactions in developing root nodules of Comptonia peregrina

1978 ◽  
Vol 56 (5) ◽  
pp. 502-531 ◽  
Author(s):  
William Newcomb ◽  
R. L. Peterson ◽  
Dale Callaham ◽  
John G. Torrey
Keyword(s):  
Host Cell ◽  
Root Nodules ◽  
Host Cells ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Host Plasma Membrane ◽  
Soil Actinomycete

Correlated fluorescence, bright-field, transmission electron, and scanning electron microscopic studies were made on developing root nodules of Comptonia peregrina (L.) Coult. (Myricaceae) produced by a soil actinomycete which invades the root and establishes a symbiosis leading to fixation of atmospheric dinitrogen. After entering the host via a root hair infection, the hyphae of the endophyte perforate root cortical cells by local degradation of host cell walls and penetration of the host cytoplasm. The intracellular hyphae are always surrounded by host plasma membrane and a thick polysaccharide material termed the capsule. (For convenience, term intracellular refers to the endophyte being inside a Comptonia cell as distinguished from being intercellular, i.e.. between host cells, even though the former is actually extracellular as the endophyte is separated from the host cytoplasm by the host plasmalemma.) Numerous profiles of vesiculate rough endoplasmic reticulum (RER) occur near the growing hyphae. Although the capsule shows a positive Thiery reaction indicating its polysaccharide nature, the fibrillar contents of the RER do not, leaving uncertain whether the capsule results from polymers derived from the RER. Amyloplasts of the cortical cells lose their starch deposits during hyphal proliferation. The hyphae branch extensively in specific layers of the cortex, penetrating much of the host cytoplasm. At this stage, hyphal ends become swollen and form septate club-shaped vesicles within the periphery of the host cells. Lipid-like inclusions and Thiery-positive particles, possibly glycogen, are observed in the hyphae at this time. Associated with hyphal development is an increase in average host cell volume, although nuclear volume appears to remain constant. Concomitant with vesicle maturation, the mitochondrial population increases sharply, suggesting a possible relationship to vesicle function. The intimate interactions between host and endophyte during development of the symbiotic relationship are emphasized throughout.

scholarly journals Coiling Phagocytosis of Trypanosomatids and Fungal Cells

1998 ◽  
Vol 66 (9) ◽  
pp. 4331-4339 ◽  
Author(s):  
M. G. Rittig ◽  
K. Schröppel ◽  
K.-H. Seack ◽  
U. Sander ◽  
E.-N. N’Diaye ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Saccharomyces Cerevisiae ◽  
Legionella Pneumophila ◽  
Leishmania Major ◽  
Posterior Pole ◽  
Host Cells ◽  
Human Monocytes ◽  
Eukaryotic Microorganisms ◽  
Microscopic Studies

ABSTRACT Coiling phagocytosis has previously been studied only with the bacteria Legionella pneumophila and Borrelia burgdorferi, and the results were inconsistent. To learn more about this unconventional phagocytic mechanism, the uptake of various eukaryotic microorganisms by human monocytes, murine macrophages, and murine dendritic cells was investigated in vitro by video and electron microscopy. Unconventional phagocytosis of Leishmania spp. promastigotes, Trypanosoma cruzi trypomastigotes,Candida albicans hyphae, and zymosan particles fromSaccharomyces cerevisiae differed in (i) morphology (rotating unilateral pseudopods with the trypanosomatids, overlapping bilateral pseudopods with the fungi), (ii) frequency (high withLeishmania; occasional with the fungi; rare with T. cruzi), (iii) duration (rapid with zymosan; moderate with the trypanosomatids; slow with C. albicans), (iv) localization along the promastigotes (flagellum of Leishmania major andL. aethiopica; flagellum or posterior pole of L. donovani), and (v) dependence on complement (strong with L. major and L. donovani; moderate with the fungi; none with L. aethiopica). All of these various types of unconventional phagocytosis gave rise to similar pseudopod stacks which eventually transformed to a regular phagosome. Further video microscopic studies with L. major provided evidence for a cytosolic localization, synchronized replication, and exocytic release of the parasites, extending traditional concepts about leishmanial infection of host cells. It is concluded that coiling phagocytosis comprises phenotypically similar consequences of various disturbances in conventional phagocytosis rather than representing a single separate mechanism.

scholarly journals After one year of the COVID-19 pandemic and hundreds of suggested drugs, will cathepsin L inhibitors be the solution?

Avicenna ◽  
2021 ◽  
Vol 2022 (1) ◽  
Author(s):  
Amr Ahmed ◽  
Mohammad Nezami ◽  
Abdullah Alkattan ◽  
Ahmed Mohamed ◽  
Omar Alshazly ◽  
...  
Keyword(s):  
Active Sites ◽  
Viral Infections ◽  
Cathepsin L ◽  
Docking Studies ◽  
Host Cells ◽  
Endosomal Membrane ◽  
Cysteine Cathepsins ◽  
Cathepsin Activity ◽  
Cysteine Cathepsin ◽  
One Year

Cysteine cathepsins are defined as lysosomal enzymes that are members of the papain family. Cysteine cathepsins (Cts) prevalently exist in whole organisms, varying from prokaryotes to mammals, and possess greatly conserved cysteine residues in their active sites. Cts are engaged in the digestion of cellular proteins, activation of zymogens, and remodeling of the extracellular matrix (ECM). Host cells are entered by SARS-CoV-2 via endocytosis. Cathepsin L and phosphatidylinositol 3-phosphate 5-kinase are crucial in endocytosis by cleaving the spike protein, which permits viral membrane fusion with the endosomal membrane and succeeds in the release of the viral genome to the host cell. Therefore, inhibition of cathepsin L may be advantageous in terms of decreasing infection caused by SARS-CoV-2. Coordinate inhibition of multiple Cts and lysosomal function by different drugs and biological agents might be of value for some purposes, such as a parasite or viral infections and antineoplastic applications. Zn2+ deficiency or dysregulation leads to exaggerated cysteine cathepsin activity, increasing the autoimmune/inflammatory response. For this purpose, Zn2+ metal can be safely combined with a drug that increases the anti-proteolytic effect of endogenous Zn2+, lowering the excessive activity of some CysCts. Biguanide derivative complexes with Zn2+ have been found to be promising inhibitors of CysCts protease reactions. Molecular docking studies of cathepsin L inhibited by the metformin-Zn+2 complex have been performed, showing two strong key interactions (Cys-25&His-163) and an extra H-bond with Asp-163 compared to cocrystallized Zn+2 (PDB ID 4axl).

scholarly journals Trichomonas vaginalis Polyamine Metabolism Is Linked to Host Cell Adherence and Cytotoxicity

2005 ◽  
Vol 73 (5) ◽  
pp. 2602-2610 ◽  
Author(s):  
Ana F. Garcia ◽  
M. Benchimol ◽  
J. F. Alderete
Keyword(s):  
Host Cell ◽  
Trichomonas Vaginalis ◽  
Cysteine Proteinase ◽  
Growth Arrest ◽  
Electron Microscopic Examination ◽  
Host Cells ◽  
Polyamine Metabolism ◽  
Cell Adherence ◽  
Electron Microscopic ◽  
Control Versus

ABSTRACT Trichomonas vaginalis secretes putrescine that is readily detected in vaginal secretions. We wanted to examine the effect of decreased putrescine synthesis by inhibition of ornithine decarboxylase (ODC) on T. vaginalis. One reason is because inhibition of Tritrichomonas foetus ODC results in growth arrest, destruction of hydrogenosomes, and decreased amounts of hydrogenosomal enzymes. Treatment of T. vaginalis T016 with ≥20 mM 1,4-diamino-2-butanone (DAB) to inhibit ODC resulted in growth arrest, which was reversed by addition of exogenous putrescine. No similar reversal of growth arrest was achieved with the polyamines spermine or spermidine or with iron. Electron microscopic examination of control versus DAB-treated trichomonads did not reveal any adverse effects on the number and integrity of hydrogenosomes. Further, the adhesins AP65, AP51, and AP33 mediating binding to immortalized vaginal epithelial cells (VECs) share identity to enzymes of the hydrogenosome organelle, and there was no difference in amounts of adhesins between control versus DAB-treated T. vaginalis parasites. Likewise, similar patterns and extent of fluorescence were evident for the prominent AP65 adhesin. Surprisingly, DAB treatment increased by 4- to 20-fold above untreated trichomonads handled identically the level of adherence mediated by adhesins. Interestingly, the enhanced attachment to VECs was reversed by exogenous putrescine added to DAB-treated trichomonads. Equally noteworthy was that DAB-treated T. vaginalis with enhanced adherence did not possess the previously reported ability to kill host cells in a contact-dependent fashion mediated by cysteine proteinases, and total cysteine proteinase activity patterns were identical between control and DAB-treated trichomonads. Overall, these data suggest that polyamine metabolism and secreted putrescine are linked to host cell adherence and cytotoxicity.

scholarly journals The Natural History of Uterine Leiomyomas: Light and Electron Microscopic Studies of Fibroid Phases, Interstitial Ischemia, Inanosis, and Reclamation

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Gordon P. Flake ◽  
Alicia B. Moore ◽  
Deloris Sutton ◽  
Grace E. Kissling ◽  
John Horton ◽  
...  
Keyword(s):  
Cell Death ◽  
Uterine Leiomyomas ◽  
Electron Microscopic ◽  
Nutritional Deprivation ◽  
Limited Life ◽  
Microscopic Studies ◽  
History Of ◽  
End Stage ◽  
Dying Cells ◽  
Phagocytic Reaction

We propose, and offer evidence to support, the concept that many uterine leiomyomas pursue a self-limited life cycle. This cycle can be arbitrarily divided on the basis of morphologic assessment of the collagen content into 4 phases: (1) proliferation, (2) proliferation and synthesis of collagen, (3) proliferation, synthesis of collagen, and early senescence, and (4) involution. Involution occurs as a result of both vascular and interstitial ischemia. Interstitial ischemia is the consequence of the excessive elaboration of collagen, resulting in reduced microvascular density, increased distance between myocytes and capillaries, nutritional deprivation, and myocyte atrophy. The end stage of this process is an involuted tumor with a predominance of collagen, little to no proliferative activity, myocyte atrophy, and myocyte cell death. Since many of the dying cells exhibit light microscopic and ultrastructural features that appear distinct from either necrosis or apoptosis, we refer to this process as inanosis, because it appears that nutritional deprivation, or inanition, is the underlying cause of cell death. The disposal of myocytes dying by inanosis also differs in that there is no phagocytic reaction, but rather an apparent dissolution of the cell, which might be viewed as a process of reclamation as the molecular contents are reclaimed and recycled.

scholarly journals Genes required for the engulfment of cell corpses during programmed cell death in Caenorhabditis elegans.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 79-94 ◽  
Author(s):  
R E Ellis ◽  
D M Jacobson ◽  
H R Horvitz
Keyword(s):  
Cell Death ◽  
Caenorhabditis Elegans ◽  
Programmed Cell Death ◽  
Nematode Caenorhabditis Elegans ◽  
Electron Microscopic ◽  
New Genes ◽  
Microscopic Studies ◽  
A Cell ◽  
Cell Corpse ◽  
Dying Cells

Abstract After programmed cell death, a cell corpse is engulfed and quickly degraded by a neighboring cell. For degradation to occur, engulfing cells must recognize, phagocytose and digest the corpses of dying cells. Previously, three genes were known to be involved in eliminating cell corpses in the nematode Caenorhabditis elegans: ced-1, ced-2 and nuc-1. We have identified five new genes that play a role in this process: ced-5, ced-6, ced-7, ced-8 and ced-10. Electron microscopic studies reveal that mutations in each of these genes prevent engulfment, indicating that these genes are needed either for the recognition of corpses by other cells or for the initiation of phagocytosis. Based upon our study of double mutants, these genes can be divided into two sets. Animals with mutations in only one of these sets of genes have relatively few unengulfed cell corpses. By contrast, animals with mutations in both sets of genes have many unengulfed corpses. These observations suggest that these two sets of genes are involved in distinct and partially redundant processes that act in the engulfment of cell corpses.

scholarly journals A holistic insight of mycobacteriophage induced changes in mycobacterial cells

2021 ◽  
Author(s):  
Fatema Calcuttawala ◽  
Rahul Shaw ◽  
Arpita Sarbajna ◽  
Moumita Dutta ◽  
Saptarshi Sinha ◽  
...  
Keyword(s):  
Cell Death ◽  
Electron Microscopic Examination ◽  
Cellular Level ◽  
Electron Microscopic ◽  
Major Mechanism ◽  
Membrane Pores ◽  
Transmission Electron ◽  
Before And After ◽  
Microscopic Studies ◽  
Induced Changes

Mycobacteriophages are phages that interact with mycobacteria resulting in their killing. Although lysis is the major mechanism by which mycobacteriophages cause cell death, other mechanisms may also be involved. The present study was in i tiated with the objective of investigating the changes that take place at the cellular level following the infection of mycobacterial cells by phage D29.  To investigate th is issue, we took recourse to performing immunofluorescence and electron microscopic studies . Transmission electron microscopic examination reveal ed the adsorption of phages on to the surface of mycobacteria , f ollowing which penetration of the tail through the thick mycol o ic acid layer was seen . At later time points discrete populations of cells at different stages of lysis we re observed , which comprised of complete ly lys ed cells , in which the cells were fragmented and those at the early onset stage exhibited formation of membrane pores through which the phages and intracellular contents were released.   SEM results also indicate d that phages may come out through the entire surface of the cell, or alternatively through gaps in the surface. In some of the images we observed structures that apparently resembled membrane blebs which are normally encountered when cells undergo programmed cell death (PCD). In addition, we observed significant increase in DNA fragmentation as well as membrane depolarization, which are also indicative of occurrence of PCD. As several bacterial PCD pathways are mediated by the toxin-antitoxin (TA) modules, the expression profile of all the TA systems was examined before and after phage infection. Apart from specifically addressing the issue of PCD in mycobacteriophage infected cells, this investigation has led to the development of facile tools necessary for investigating mycobacteriophage-mycobacteria interactions by means of microscopic methods.

Vascular regression during the formation of the free digits in the avian limb bud: a comparative study in chick and duck embryos

Development ◽  
1985 ◽  
Vol 85 (1) ◽  
pp. 239-250
Author(s):  
J. M. Hurle ◽  
E. Colvee ◽  
M. A. Fernandez-Teran
Keyword(s):  
Cell Death ◽  
Blood Vessels ◽  
Mesenchymal Cell ◽  
Limb Bud ◽  
Death Process ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Cell Death Process

The pattern and structure of the blood vessels of the interdigital spaces of the leg bud have been studied by means of Indian ink injections and transmission electron microscopy in the chick and duck embryos. The results show that in the chick the interdigital necrotic process responsible for the freeing of the digits is followed by regression of the blood vessels. In the webbed foot of the duck, the interdigital necrotic processes are not followed by vascular regression. Transmission electron microscopic studies show that both in the chick and in the duck, interdigital blood vessels are immature structures lacking basal lamina. Dead cells of presumably endothelial origin were detected in the lumen of the regressing blood vessels of the chick but not in the duck. However, the intensity of this cell death process does not appear to be high enough to account by itself for the disappearance of the interdigital blood vessels. The possible relationships between interdigital mesenchymal cell death and vascular regression are discussed.

Sign in / Sign up

Export Citation Format

Share Document