scholarly journals Mauve/LYST limits fusion of lysosome-related organelles and promotes centrosomal recruitment of microtubule nucleating proteins

2021 ◽  
Vol 56 (7) ◽  
pp. 1000-1013.e6
Author(s):  
Ramona Lattao ◽  
Hélène Rangone ◽  
Salud Llamazares ◽  
David M. Glover
Keyword(s):  
Lysosome Related Organelles

scholarly journals Orchestration of Primary Hemostasis by Platelet and Endothelial Lysosome-Related Organelles

2020 ◽  
Vol 40 (6) ◽  
pp. 1441-1453 ◽  
Author(s):  
Ellie Karampini ◽  
Ruben Bierings ◽  
Jan Voorberg
Keyword(s):  
Endothelial Cells ◽  
Intracellular Signaling ◽  
Protein Complexes ◽  
Biological Properties ◽  
Bleeding Disorders ◽  
Granule Formation ◽  
Primary Hemostasis ◽  
Granule Maturation ◽  
Lysosome Related Organelles ◽  
Von Willebrand

Megakaryocyte-derived platelets and endothelial cells store their hemostatic cargo in α- and δ-granules and Weibel-Palade bodies, respectively. These storage granules belong to the lysosome-related organelles (LROs), a heterogeneous group of organelles that are rapidly released following agonist-induced triggering of intracellular signaling pathways. Following vascular injury, endothelial Weibel-Palade bodies release their content into the vascular lumen and promote the formation of long VWF (von Willebrand factor) strings that form an adhesive platform for platelets. Binding to VWF strings as well as exposed subendothelial collagen activates platelets resulting in the release of α- and δ-granules, which are crucial events in formation of a primary hemostatic plug. Biogenesis and secretion of these LROs are pivotal for the maintenance of proper hemostasis. Several bleeding disorders have been linked to abnormal generation of LROs in megakaryocytes and endothelial cells. Recent reviews have emphasized common pathways in the biogenesis and biological properties of LROs, focusing mainly on melanosomes. Despite many similarities, LROs in platelet and endothelial cells clearly possess distinct properties that allow them to provide a highly coordinated and synergistic contribution to primary hemostasis by sequentially releasing hemostatic cargo. In this brief review, we discuss in depth the known regulators of α- and δ-granules in megakaryocytes/platelets and Weibel-Palade bodies in endothelial cells, starting from transcription factors that have been associated with granule formation to protein complexes that promote granule maturation. In addition, we provide a detailed view on the interplay between platelet and endothelial LROs in controlling hemostasis as well as their dysfunction in LRO related bleeding disorders.

scholarly journals Reinvestigation of the dysbindin subunit of BLOC-1 (biogenesis of lysosome-related organelles complex-1) as a dystrobrevin-binding protein

2006 ◽  
Vol 395 (3) ◽  
pp. 587-598 ◽  
Author(s):  
Ramin Nazarian ◽  
Marta Starcevic ◽  
Melissa J. Spencer ◽  
Esteban C. Dell'Angelica
Keyword(s):  
Recombinant Proteins ◽  
Binding Protein ◽  
Coiled Coil ◽  
Direct Interaction ◽  
Muscle Pathology ◽  
Binding Assays ◽  
Genetic Studies ◽  
Binding Interface ◽  
Lysosome Related Organelles

Dysbindin was identified as a dystrobrevin-binding protein potentially involved in the pathogenesis of muscular dystrophy. Subsequently, genetic studies have implicated variants of the human dysbindin-encoding gene, DTNBP1, in the pathogeneses of Hermansky–Pudlak syndrome and schizophrenia. The protein is a stable component of a multisubunit complex termed BLOC-1 (biogenesis of lysosome-related organelles complex-1). In the present study, the significance of the dystrobrevin–dysbindin interaction for BLOC-1 function was examined. Yeast two-hybrid analyses, and binding assays using recombinant proteins, demonstrated direct interaction involving coiled-coil-forming regions in both dysbindin and the dystrobrevins. However, recombinant proteins bearing the coiled-coil-forming regions of the dystrobrevins failed to bind endogenous BLOC-1 from HeLa cells or mouse brain or muscle, under conditions in which they bound the Dp71 isoform of dystrophin. Immunoprecipitation of endogenous dysbindin from brain or muscle resulted in robust co-immunoprecipitation of the pallidin subunit of BLOC-1 but no specific co-immunoprecipitation of dystrobrevin isoforms. Within BLOC-1, dysbindin is engaged in interactions with three other subunits, named pallidin, snapin and muted. We herein provide evidence that the same 69-residue region of dysbindin that is sufficient for dystrobrevin binding in vitro also contains the binding sites for pallidin and snapin, and at least part of the muted-binding interface. Functional, histological and immunohistochemical analyses failed to detect any sign of muscle pathology in BLOC-1-deficient, homozygous pallid mice. Taken together, these results suggest that dysbindin assembled into BLOC-1 is not a physiological binding partner of the dystrobrevins, likely due to engagement of its dystrobrevin-binding region in interactions with other subunits.

scholarly journals Prognostic Significance of Reduced BCAS4 expression in Bone Marrow Cells of Patients with Myelodysplastic Syndromes

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4258-4258
Author(s):  
Masayuki Shiseki ◽  
Mayuko Ishii ◽  
Mari Ohwashi ◽  
Kentaro Yoshinaga ◽  
Naoki Mori ◽  
...  
Keyword(s):  
Risk Factors ◽  
Bone Marrow ◽  
Mononuclear Cells ◽  
Bone Marrow Cells ◽  
Risk Groups ◽  
Older Age ◽  
Expression Level ◽  
Expression Of Genes ◽  
Kaplan Meier ◽  
Lysosome Related Organelles

Deletion of long arm of chromosome 20 (del(20q)) is commonly observed in myelodysplastic syndromes (MDS). Reduced expression of genes located within the common deleted region (CDR) of del(20q) due to haploinsufficiency may play a role in molecular pathogenesis of MDS. In the previous study, we examined expression of genes located within the CDR which we determined using array-CGH, in bone marrow mononuclear cells in MDS patients with or without del(20q), indicating that BCAS4 expression was significantly reduced in bone marrow cells in MDS patients with or without del(20q). The BCAS4 gene, which was identified as a fusion transcript expressed in MCF7 cells, encodes 23kD protein. Although function of BCAS4 protein remains unclear, it could be a member of "cappuccino" family, which belong to lysosome-related organelles. Abnormality of genes encoding lysosome-related organelles cause variety of congenital disorders, including the Hermansky-Pudlak syndromes, which is characterized by oculocutaneous albinism and bleeding tendency due to platelet dysfunction as a result of lysosome abnormalities. In the present study we investigated clinical implication of BCAS4 expression level in MDS patients. Mononuclear cells separated from bone marrow samples taken at the time of MDS diagnosis were used for analysis. Written informed consent was obtained from patients before study. To analyze BCAS4 expression, quantitative RT-PCR was performed using cDNA from mononuclear cells as template by the TaqMan probe method (Applied Biosystems) with co-amplification of the endogenous control gene, human GAPDH (Applied Biosystems). Samples from 103 MDS patients, 64 males and 39 females with median age of 67 years (range: 20-91 years), with (n=14) or without (n=89) del(20q), were examined in the present study. Patients were classified as RCUD (n=12), RCMD (n=55), RARS (n=9), RAEB-1 (n=10), and RAEB-2 (n=13), according to WHO 2008 classification, and in RAEB-T (n=4) according to FAB classification. They also were categorized in four IPSS risk groups, low risk (n=30), intermediate-1 risk (n=46), intermediate-2 risk (n=18), and high risk (n=9). There was no significant difference in relative BCAS4 expression level between patients with del(20q) and those without del(20q), and among WHO subtypes. Higher IPSS risk groups (INT-2 and High) showed trend in association with reduced BCAS4 expression compared with lower IPSS risk groups (Low and INT-1) (P=0.104). We analyzed impact of BCAS4 expression on overall survival (OS). Based on BCAS4 expression level, 103 patients were divided into four groups, highest (Q1), intermediate (Q2, Q3), and lowest (Q4) quartiles. The Kaplan-Meier analysis demonstrated that Q4 showed significantly worse OS compared with remaining quartiles (Q1-Q3) (log-rank test, P=0.0031). The estimated 2-year OS rates in Q1-3 group and Q4 group were 75.1% and 48.9%, respectively. According to the COX proportional hazards model, univariate analysis showed lower BCAS4 expression (Q4 vs Q1-Q3) was associated with worse OS (hazard ratio 3.43, 95%CI 1.89-6.11, P=0.0001) as well as older age (65 years or older vs less than 65 years), and higher IPSS risk groups (INT-2 and High vs Low and INT-1). Multivariate analysis indicated that lower BCAS4 expression showed trend for association with worse OS (hazard ratio 1.90, 95%CI 0.96-3.64, P=0.0651) by analyzing with two variables (older age and higher IPSS groups). Next, we investigated whether OS is predicted by combination of three variables, BCAS4 expression level, IPSS risk groups, and age at diagnosis. We defined lower BCAS4 expression (Q4), higher IPSS (INT-2 and High), and older age (65 years or older), as risk factors. The Kaplan-Meier analysis showed that survival curves were well separated according to number of risk factors (0, 1, and 2 or more) (P<0.0001). The estimated 1-year, 2-year, and 5-year survival rates were 100%, 100%, and 86.5% in patients without risk factor, 75%, 70.2%, and 51.7% in patients with one risk factor, and 54%, 34.3%, and 11.4% in patients with two or more risk factors. The present study demonstrated that reduced BCAS4 expression is associated with inferior clinical outcome, indicating that BCAS4 expression level could be a useful prognostic marker in MDS, especially by combination with IPSS risk and patients age at diagnosis. Disclosures Tanaka: Bristol-Myers Squibb: Research Funding.

scholarly journals Dysbindin deficiency Alters Cardiac BLOC-1 Complex and Myozap Levels in Mice

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2390
Author(s):  
Ankush Borlepawar ◽  
Nesrin Schmiedel ◽  
Matthias Eden ◽  
Lynn Christen ◽  
Alexandra Rosskopf ◽  
...  
Keyword(s):  
Direct Interaction ◽  
Cardiomyocyte Hypertrophy ◽  
Loss Of Function ◽  
Interaction Partners ◽  
Lysosome Related Organelles ◽  
The Stability ◽  
Schizophrenia Susceptibility

Dysbindin, a schizophrenia susceptibility marker and an essential constituent of BLOC-1 (biogenesis of lysosome-related organelles complex-1), has recently been associated with cardiomyocyte hypertrophy through the activation of Myozap-RhoA-mediated SRF signaling. We employed sandy mice (Dtnbp1_KO), which completely lack Dysbindin protein because of a spontaneous deletion of introns 5–7 of the Dtnbp1 gene, for pathophysiological characterization of the heart. Unlike in vitro, the loss-of-function of Dysbindin did not attenuate cardiac hypertrophy, either in response to transverse aortic constriction stress or upon phenylephrine treatment. Interestingly, however, the levels of hypertrophy-inducing interaction partner Myozap as well as the BLOC-1 partners of Dysbindin like Muted and Pallidin were dramatically reduced in Dtnbp1_KO mouse hearts. Taken together, our data suggest that Dysbindin’s role in cardiomyocyte hypertrophy is redundant in vivo, yet essential to maintain the stability of its direct interaction partners like Myozap, Pallidin and Muted.

Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease

2011 ◽  
Vol 439 (3) ◽  
pp. 349-378 ◽  
Author(s):  
Anthony J. Morgan ◽  
Frances M. Platt ◽  
Emyr Lloyd-Evans ◽  
Antony Galione
Keyword(s):  
Molecular Mechanisms ◽  
Cellular Processes ◽  
Late Endosomes ◽  
Wide Range ◽  
Health And Disease ◽  
Lysosome Related Organelles ◽  
Cellular Compartments ◽  
Endosomal Vesicles ◽  
Intracellular Targets

Endosomes, lysosomes and lysosome-related organelles are emerging as important Ca2+ storage cellular compartments with a central role in intracellular Ca2+ signalling. Endocytosis at the plasma membrane forms endosomal vesicles which mature to late endosomes and culminate in lysosomal biogenesis. During this process, acquisition of different ion channels and transporters progressively changes the endolysosomal luminal ionic environment (e.g. pH and Ca2+) to regulate enzyme activities, membrane fusion/fission and organellar ion fluxes, and defects in these can result in disease. In the present review we focus on the physiology of the inter-related transport mechanisms of Ca2+ and H+ across endolysosomal membranes. In particular, we discuss the role of the Ca2+-mobilizing messenger NAADP (nicotinic acid adenine dinucleotide phosphate) as a major regulator of Ca2+ release from endolysosomes, and the recent discovery of an endolysosomal channel family, the TPCs (two-pore channels), as its principal intracellular targets. Recent molecular studies of endolysosomal Ca2+ physiology and its regulation by NAADP-gated TPCs are providing exciting new insights into the mechanisms of Ca2+-signal initiation that control a wide range of cellular processes and play a role in disease. These developments underscore a new central role for the endolysosomal system in cellular Ca2+ regulation and signalling.

scholarly journals Interaction of Hermansky-Pudlak Syndrome Genes in the Regulation of Lysosome-Related Organelles

Traffic ◽  
2006 ◽  
Vol 7 (7) ◽  
pp. 779-792 ◽  
Author(s):  
Rashi Gautam ◽  
Edward K. Novak ◽  
Jian Tan ◽  
Kazumasa Wakamatsu ◽  
Shosuke Ito ◽  
...  
Keyword(s):  
Hermansky Pudlak Syndrome ◽  
Lysosome Related Organelles
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