scholarly journals Intercellular transport of lysosomal acid lipase mediates lipoprotein cholesteryl ester metabolism in a human vascular endothelial cell-fibroblast coculture system.

1990 ◽  
Vol 1 (9) ◽  
pp. 661-674 ◽  
Author(s):  
G N Sando ◽  
G P Ma ◽  
K A Lindsley ◽  
Y P Wei

We present results from studies of human cell culture models to support the premise that the extracellular transport of lysosomal acid lipase has a function in lipoprotein cholesteryl ester metabolism in vascular tissue. Vascular endothelial cells secreted a higher fraction of cellular acid lipase than did smooth muscle cells and fibroblasts. Acid lipase and lysosomal beta-hexosaminidase were secreted at approximately the same rate from the apical and basolateral surface of an endothelial cell monolayer. Stimulation of secretion with NH4Cl did not affect the polarity. We tested for the ability of secreted endothelial lipase to interact with connective tissue cells and influence lipoprotein cholesterol metabolism in a coculture system in which endothelial cells on a micropore filter were suspended above a monolayer of acid lipase-deficient (Wolman disease) fibroblasts. After 5-7 d, acid lipase activity in the fibroblasts reached 10%-20% of the level in normal cells; cholesteryl esters that had accumulated from growth in serum were cleared. Addition of mannose 6-phosphate to the coculture medium blocked acid lipase uptake and cholesterol clearance, indicating that lipase released from endothelial cells was packaged into fibroblast lysosomes by a phosphomannosyl receptor-mediated pathway. Supplementation of the coculture medium with serum was not required for lipase uptake and cholesteryl ester hydrolysis by the fibroblasts, but was necessary for cholesterol clearance. Results from our coculture model suggest that acid lipase may be transported from intact endothelium to cells in the lumen or the wall of a blood vessel. We postulate that delivery of acid hydrolases and lipoproteins to a common endocytic compartment may occur and have an impact on cellular lipoprotein processing.

1999 ◽  
Vol 2 (6) ◽  
pp. 574-576 ◽  
Author(s):  
Zuhal Akçören ◽  
Safiye Göğüş ◽  
Nurten Koçak ◽  
Figen Gürakan ◽  
Hasan Özen ◽  
...  

Cholesteryl ester storage disease (CESD) is rare and characterized by accumulation of cholesteryl esters and triglycerides in many tissues due to the deficiency of lysosomal acid lipase. We report a 3½-year-old child with CESD. The diagnosis was indicated by liver biopsy and confirmed by reduced acid lipase activity in leukocytes.


2007 ◽  
Vol 293 (6) ◽  
pp. H3340-H3347 ◽  
Author(s):  
Eun Jin Lim ◽  
Eric J. Smart ◽  
Michal Toborek ◽  
Bernhard Hennig

Polychlorinated biphenyls (PCBs) may contribute to the pathology of atherosclerosis by activating inflammatory responses in vascular endothelial cells. Endothelial nitric oxide synthase (eNOS) is colocalized with caveolae and is a critical regulator of vascular homeostasis. PCBs may be proatherogenic by causing dysfunctional eNOS signaling. The objective of this study was to investigate the role of caveolin-1 in PCB-induced endothelial dysfunction with a focus on mechanisms associated with eNOS signaling. Cells derived from an immortalized human vascular endothelial cell line were treated with PCB77 to study nitrotyrosine formation through eNOS signaling. Phosphorylation studies of eNOS, caveolin-1, and kinases, such as Src, phosphatidylinositol 3-kinase (PI3K), and Akt, were conducted in cells containing either functional or small-interfering RNA-silenced caveolin-1 protein. We also investigated caveolin-1-regulated mechanisms associated with PCB-induced markers of peroxynitrite formation and DNA binding of NF-κB. Cellular exposure to PCB77 increased eNOS phosphorylation and nitric oxide production, as well as peroxynitrite levels. A subsequent PCB-induced increase in NF-κB DNA binding may have implications in oxidative stress-mediated inflammatory mechanisms. The activation of eNOS by PCB77 treatment was blocked by inhibitors of the Src/PI3K/Akt pathway. PCB77 also increased phosphorylation of caveolin-1, indicating caveolae-dependent endocytosis. Caveolin-1 silencing abolished both the PCB-stimulated Akt and eNOS phosphorylation, suggesting a regulatory role of caveolae in PCB-induced eNOS signaling. These findings suggest that PCB77 induces eNOS phosphorylation in endothelial cells through a Src/PI3K/Akt-dependent mechanism, events regulated by functional caveolin-1. Our data provide evidence that caveolae may play a critical role in regulating vascular endothelial cell activation and toxicity induced by persistent environmental pollutants such as coplanar PCBs.


2011 ◽  
Vol 286 (35) ◽  
pp. 30624-30635 ◽  
Author(s):  
Kristin L. Bowden ◽  
Nicolas J. Bilbey ◽  
Leanne M. Bilawchuk ◽  
Emmanuel Boadu ◽  
Rohini Sidhu ◽  
...  

1998 ◽  
Vol 39 (7) ◽  
pp. 1382-1388 ◽  
Author(s):  
Franco Pagani ◽  
Rajalakshmi Pariyarath ◽  
Rodolfo Garcia ◽  
Cristiana Stuani ◽  
Alberto B. Burlina ◽  
...  

2020 ◽  
Vol 61 (8) ◽  
pp. 1192-1202
Author(s):  
Francis Rajamohan ◽  
Allan R. Reyes ◽  
Meihua Tu ◽  
Nicole L. Nedoma ◽  
Lise R. Hoth ◽  
...  

Lysosomal acid lipase (LAL) is a serine hydrolase that hydrolyzes cholesteryl ester (CE) and TGs delivered to the lysosomes into free cholesterol and fatty acids. LAL deficiency due to mutations in the LAL gene (LIPA) results in accumulation of TGs and cholesterol esters in various tissues of the body leading to pathological conditions such as Wolman’s disease and CE storage disease (CESD). Here, we present the first crystal structure of recombinant human LAL (HLAL) to 2.6 Å resolution in its closed form. The crystal structure was enabled by mutating three of the six potential glycosylation sites. The overall structure of HLAL closely resembles that of the evolutionarily related human gastric lipase (HGL). It consists of a core domain belonging to the classical α/β hydrolase-fold family with a classical catalytic triad (Ser-153, His-353, Asp-324), an oxyanion hole, and a “cap” domain, which regulates substrate entry to the catalytic site. Most significant structural differences between HLAL and HGL exist at the lid region. Deletion of the short helix, 238NLCFLLC244, at the lid region implied a possible role in regulating the highly hydrophobic substrate binding site from self-oligomerization during interfacial activation. We also performed molecular dynamic simulations of dog gastric lipase (lid-open form) and HLAL to gain insights and speculated a possible role of the human mutant, H274Y, leading to CESD.


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