Lysosome and Lysosome-related Organelles Responsible for Specialized Functions in Higher Organisms, with Special Emphasis on Vacuolar-type proton ATPase

2003 ◽  
Vol 28 (5) ◽  
pp. 455-463 ◽  
Author(s):  
Ge-Hong Sun-Wada ◽  
Yoh Wada ◽  
Masamitsu Futai
Keyword(s):  
Proton Atpase ◽  
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 Hph1 and Hph2 Are Novel Components of the Sec63/Sec62 Posttranslational Translocation Complex That Aid in Vacuolar Proton ATPase Biogenesis

2010 ◽  
Vol 10 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Francisco J. Piña ◽  
Allyson F. O'Donnell ◽  
Silvere Pagant ◽  
Hai Lan Piao ◽  
John P. Miller ◽  
...  
Keyword(s):  
Environmental Stress ◽  
Complex Function ◽  
Content Type ◽  
Growth Defects ◽  
Proton Atpase ◽  
Vacuolar Acidification ◽  
Atpase Subunits ◽  
Specific Proteins ◽  
A Subunit ◽  
Split Ubiquitin

ABSTRACT Hph1 and Hph2 are homologous integral endoplasmic reticulum (ER) membrane proteins required for Saccharomyces cerevisiae survival under environmental stress conditions. To investigate the molecular functions of Hph1 and Hph2, we carried out a split-ubiquitin-membrane-based yeast two-hybrid screen and identified their interactions with Sec71, a subunit of the Sec63/Sec62 complex, which mediates posttranslational translocation of proteins into the ER. Hph1 and Hph2 likely function in posttranslational translocation, as they interact with other Sec63/Sec62 complex subunits, i.e., Sec72, Sec62, and Sec63. hph1 Δ hph2 Δ cells display reduced vacuole acidification; increased instability of Vph1, a subunit of vacuolar proton ATPase (V-ATPase); and growth defects similar to those of mutants lacking V-ATPase activity. sec71 Δ cells exhibit similar phenotypes, indicating that Hph1/Hph2 and the Sec63/Sec62 complex function during V-ATPase biogenesis. Hph1/Hph2 and the Sec63/Sec62 complex may act together in this process, as vacuolar acidification and Vph1 stability are compromised to the same extent in hph1 Δ hph2 Δ and hph1 Δ hph2 Δ sec71 Δ cells. In contrast, loss of Pkr1, an ER protein that promotes posttranslocation assembly of Vph1 with V-ATPase subunits, further exacerbates hph1 Δ hph2 Δ phenotypes, suggesting that Hph1 and Hph2 function independently of Pkr1-mediated V-ATPase assembly. We propose that Hph1 and Hph2 aid Sec63/Sec62-mediated translocation of specific proteins, including factors that promote efficient biogenesis of V-ATPase, to support yeast cell survival during environmental stress.

Pendrin immunoreactivity in the gill epithelium of a euryhaline elasmobranch

2002 ◽  
Vol 283 (4) ◽  
pp. R983-R992 ◽  
Author(s):  
Peter M. Piermarini ◽  
Jill W. Verlander ◽  
Ines E. Royaux ◽  
David H. Evans
Keyword(s):  
Collecting Duct ◽  
Apical Region ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Gill Epithelium ◽  
Dasyatis Sabina ◽  
Proton Atpase ◽  
Atlantic Stingray ◽  
Freshwater Stingray ◽  
Gill Lamellae

Pendrin is an anion exchanger in the cortical collecting duct of the mammalian nephron that appears to mediate apical Cl−/HCO[Formula: see text]exchange in bicarbonate-secreting intercalated cells. The goals of this study were to determine 1) if pendrin immunoreactivity was present in the gills of a euryhaline elasmobranch (Atlantic stingray, Dasyatis sabina), and 2) if branchial pendrin immunoreactivity was influenced by environmental salinity. Immunoblots detected pendrin immunoreactivity in Atlantic stingray gills; pendrin immunoreactivity was greatest in freshwater stingrays compared with freshwater stingrays acclimated to seawater (seawater acclimated) and marine stingrays. Using immunohistochemistry, pendrin-positive cells were detected on both gill lamellae and interlamellar regions of freshwater stingrays but were more restricted to interlamellar regions in seawater-acclimated and marine stingray gills. Pendrin immunolabeling in freshwater stingray gills was more apical, discrete, and intense compared with seawater-acclimated and marine stingrays. Regardless of salinity, pendrin immunoreactivity occurred on the apical region of cells rich with basolateral vacuolar-proton-ATPase, and not in Na+-K+-ATPase-rich cells. We suggest that a pendrin-like transporter may contribute to apical Cl−/HCO[Formula: see text] exchange in gills of Atlantic stingrays from both freshwater and marine environments.

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.

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