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Endosomal and Lysosomal Electrophysiology
Published in Bruno Gasnier, Michael X. Zhu, Ion and Molecule Transport in Lysosomes, 2020
Xiaoli Zhang, Mingxue Gu, Meiqin Hu, Yexin Yang, Haoxing Xu
Individual enlarged LELs can be isolated manually by using patch-pipettes (Dong et al., 2008; Saito et al., 2007). The identity of lysosomes can be confirmed using fluorescent markers for lysosomes, e.g., Lamp1. In the planar patch-clamp method developed by the group of Wahl and Biel, vacuolin-enlarged LELs are isolated through centrifugation, loaded into a recording chamber, and recorded by a half-automated electrophysiology setup (Schieder et al., 2010).
Neisseria gonorrhoeae
Published in Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward, Case Studies in Infectious Disease, 2010
Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward
Both N. gonorrhoeae and N. meningitidis secrete an IgA1 protease. The enzyme cleaves IgA1 at the hinge region to produce Fab and Fc fragments. While it is logical to assume that IgA1 protease contributes to the virulence of the gonococcus by subverting the protective effects of sIgA it should be realized that half of sIgA is of subclass 2 that is resistant to IgA1 protease. Moreover, it has been demonstrated that experimental urethral infections of male volunteers with an IgA1 protease-negative mutant of N. gonorrhoeae matching the parent strain in expression of Opa proteins, LOS, and pilin was indistinguishable from that of the parent strain. A role for IgA1 protease may lie in its ability to cleave lysosome-associated membrane protein 1 (h-lamp-1). As their name implies h-lamp-1and h-lamp-2 are found in the membranes of mature lysosomes but also in the membranes of phagosomes/endosomes. Their functions are not fully understood but they are thought to protect the membrane from the action of degradative enzymes within the lysosome and appear to be required for fusion of lysosomes with phagosomes. It has been shown that gonococcal IgA1 protease can cleave the less glycosylated form of h-lamp-1 found in epithelial cell phagosomes/endosomes, which may enable the bacteria to escape into the cytosol of the cell and prolong their intracellular survival.
Amyloid Production by Human Monocyte Cultures
Published in Gilles Grateau, Robert A. Kyle, Martha Skinner, Amyloid and Amyloidosis, 2004
B. Kluve-Beckerman, N. Magy, J. J. Liepnieks, M. D. Benson
Monocytes maintained under amyloid-forming conditions, but not control monocytes, demonstrate formation of large lysosomal (Lamp-1-staining) structures. If cells are not permeabilized prior to immunocytochemistry, only weak intracellular Lamp-1 staining is detected, whereas stronger extracellular staining associated with structures that look like disrupted vesicles is seen. Extracellular lysosomal staining of this nature is present only in cultures actively producing amyloid. We speculate that large lysosomal-derived vesicles transport nascent amyloid to the cell surface.
Cigarette smoke extract-induced inflammatory response via inhibition of the TFEB-mediated autophagy in NR8383 cells
Published in Experimental Lung Research, 2023
Shu-wen Xu, Yu-jie Zhang, Wen-mei Liu, Xin-fang Zhang, Yuan Wang, Shui-ying Xiang, Jing-chao Su, Zi-bing Liu
Lysosomes are organelles for the degradation stage of autophagy, and the degradation function of it largely depends on its acidic environment. Lysosome-associated membrane protein 1 (LAMP1), a highly glycosylated protein, mainly locates on lysosomal membranes, which not only maintains the structural integrity of lysosomes but acid environment in lysosomes.19 As the result showed, compared with the control group, the fluorescence intensity of LAMP1 protein and Lyso-Tracker Red staining in the CSE group significantly decreased (P < 0.01, Figure 2C&D), revealing that the relative level of lysosomes was decreased and the acidic environment of lysosomes was destroyed, respectively. These results indicated that lysosomes were impaired in the CSE group, which may be involved in the impairment of autophagy degradation.
Deciphering cross-species reactivity of LAMP-1 antibodies using deep mutational epitope mapping and AlphaFold
Published in mAbs, 2023
Tiphanie Pruvost, Magali Mathieu, Steven Dubois, Bernard Maillère, Emmanuelle Vigne, Hervé Nozach
In this study, we explored the molecular determinants of the binding of two LAMP-1-specific antibodies. While LAMP-1 comprises 50% of all lysosomal membrane proteins and is widely used as a cell surface marker of lymphocyte activation and degranulation, its exact role remains uncertain.23,24 LAMP-1 is a physiologically essential protein involved in stabilizing lysosomes and regulating autophagy to prevent embryonic lethality. Previous studies have demonstrated limited cell surface expression of LAMP-1 in normal tissues and moderate-to-high membrane expression in a number of breast, colorectal, gastric, prostate, lung, and ovarian tumors,24 making it a target of interest for oncology applications. Some evidence point to a role for LAMP-1 in tumor progression.25,26
Misrouting of glucagon and stathmin-2 towards lysosomal system of α-cells in glucagon hypersecretion of diabetes
Published in Islets, 2022
Farzad Asadi, Savita Dhanvantari
To more fully explore the connection between lysosomal trafficking and glucagon hypersecretion in diabetes, we hypothesized that glucagon may be secreted through Lamp1+ lysosomes, which have been implicated in the secretion of lysosomal cargo.26 We therefore immunostained αTC1-6 cells for the lysosomal transmembrane protein, Lamp1, together with Stmn2and glucagon (Figure 7B). Lamp1+ immunofluoresence was prominent at the cell membrane along with significant Stmn2 (Figure 7C) and glucagon (Figure 7D) immunofluorescence. Pearson’s correlation analysis showed a strong colocalization between Lamp1 and Stmn2 (Figure 7C; PCC 0.63 ± 0.04), and a high moderate colocalization between Lamp1 and glucagon (Figure 7D; PCC 0.50 ± 0.03). There was also strong co-localization between glucagon and LAMP1 in normal mouse islets (Figure 7E; PCC 0.79 ± 0.05).