Biochemical studies on lipidosis in Indian children.
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The intracellular movement of cholesterol in mammalian cells may involve complex pathways by which the sterol moves to various cellular sites and mediates transcriptional regulation, enzyme activation, and protein degradation. Current evidence indicates that there are three distinct pathways modulating intracellular cholesterol trafficking. The movement of endogenously synthesized cholesterol from the endoplasmic reticulum appears to be distinct from movement of exogenous, low density lipoprotein (LDL)-derived cholesterol to the plasma membrane. In addition, steroidogenic cells possess a third mechanism by which cholesterol is transported to the mitochondria to initiate steroid hormone synthesis. In this review, we have outlined the current knowledge of cholesterol transport mechanisms and pathways and have described approaches that may help define cholesterol trafficking mechanisms in molecular detail. The use of genetic and molecular biologic techniques can potentially reveal gene products that are involved in intracellular cholesterol transport and regulation as well as those that may secondarily affect this process.
Fluorescent microscopic examination of fibroblasts cultured with low density lipoprotein (LDL) and progesterone (10 micrograms/ml) for 24 h revealed extensive filipin-cholesterol staining of perinuclear lysosomes. Levels of unesterified cholesterol were 2-fold greater than in fibroblasts cultured with LDL alone. Progesterone strongly blocked cholesteryl ester synthesis. When cellular uptake of LDL was monitored in the presence of 58035, a specific inhibitor of acyl-CoA:cholesterol acyltransferase, excess unesterified cholesterol was not stored in lysosomes. Discontinuation of LDL uptake in conjunction with progesterone washout markedly reversed the filipin-cholesterol staining of lysosomes. Reversal of the lysosomal cholesterol lipidosis was associated with a rapid burst of cholesteryl ester synthesis and a normalization of the cellular levels of free and esterified cholesterol. In contrast to normal cells, progesterone removal from Niemann-Pick C fibroblasts did not reverse the lysosomal cholesterol accumulation of these mutant cultures. The metabolic precursor of progesterone, pregnenolone, also induced extensive accumulation of cholesterol in lysosomes. Other steroids induced less vacuolar cholesterol accumulation in the following decreasing order: corticosterone and testosterone, promegestone, RU 486. The relative inhibition of cellular cholesterol esterification by the steroids paralleled their respective abilities to sequester cholesterol in lysosomes rather than their inhibition of acyl-CoA:cholesterol acyltransferase activity in cell-free extracts. The progesterone-related inhibition and restoration of lysosomal cholesterol trafficking is a useful experimental means of studying intracellular cholesterol transport. A particularly important feature of its utility is the facile reversibility of the steroid-induced block. The lysosomal cholesterol lipidosis established with a hydrophobic amine, U18666A, was not as readily reversed.
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Two sisters, now 29 and 24 years old, are described. They presented a congenital storage of, most probably, phospholipids in the histiocytes of the sea-blue type or blue pigmentophages. The granules of these cells showed a PAS positivity and strong positivity for acid phosphatase, but there were negative also for non-specific esterase, naphthol-AS-D-chloracetate esterase and iron acid also for urine mucopolysaccharide. The two cases differed from all the described cases in the absence of hepatosplenomegaly and in the presence of bone changes resembling late spondyloepiphyseal dysplasia or atypical dysostosis multiplex.
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The case of a girl is described who was 3 1/4 years of age and was admitted of the hospital because of hepato-splenomegaly. In addition to this, there were peculiar alterations in the lungs, an increase of lipoids in the blood, a characteristic alteration of the retina, and bone marrow and liver cells storing lipoid. The diagnosis of sphingomyelin lipoidosis (Niemann-Pick) was confirmed by electronmicroscopic and biochemical investigation of a percutaneous liver biopsy specimen.
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Autophagy is a critical mechanism of cellular quality control, orchestrated by selective autophagy receptor (SAR) proteins. Pharmacologically enhancing the cargo-targeting capacity of SARs presents an attractive but underexplored strategy for the precise therapeutic activation of autophagy. Here, we characterize SQ-1, a small-molecule activator of autophagy that engages the prototypical SAR protein p62/sequestosome-1 (SQSTM1). We show that SQ-1 sensitizes p62 to oxidation and promotes its disulfide-mediated oligomerization in response to mitochondrial reactive oxygen species (ROS). This ROS-dependent activation of p62-mediated selective autophagy enhances the clearance of ROS-generating mitochondria and restores cell viability in models of Niemann-Pick type C1 disease, which is marked by impaired autophagic flux. In summary, the unique mode of action of SQ-1 enables self-regulated autophagy activation, offering a potential therapeutic strategy for lysosomal storage disorders and a broader spectrum of age-related diseases characterized by defective autophagy.
We present the results of a structural, histochemical and lipid-chromatographic study of tissues obtained at postmortem from an unusual case of phospholipidosis. A previous biopsy of the appendix and liver (Elleder et al., 1975a) had revealed a predominance of phosphoglyceride storage, principally of lysobisphosphatidic acid (LBPA) postmortem material showed that this lipid was stored exclusively in central neurons. In the spleen and the lymph node, however, sphingomyelin (SP) was shown, histochemically and chromatographically, to be the main lipid stored. Total sphingomyelinase (SPase) activity in the appendix was reduced to about 50% of normal. Neuroaxonal dystrophy (NAD) and a conspicuous discrepancy between the degree of distension of some neurons and their lipid content deserve special mention. The case is contrasted with classical sphingomyelinosis; the complexity of the Niemann-Pick group of diseases is discussed as an indication of the difficulties of classification of any atypical case.
On the basis of a bioptic examination of the appendix, skin and a liver specimen, the diagnosis of phospholipidosis was made in a girl aged 27 months. In contrast to the Niemann-Pick's complex of sphingomyelinoses, phosphoglycerides were stored in larger amounts than spingomyelin. The disease should be undoubtedly included under one heading with the so-called "kephalinosis" [11] and with the cases described by Wiedemann et al. [10]. The terms "Type II phospholipidosis [Baar-Wiedemann's disease]" or, briefly, phosphoglyceridosis, appear to be most adequeate for designating the diseases in question. The disorder can be diagnosed on the basis of iron hematoxylin staining, visualizing all phospholipids. In Niemann-Pick's sfingomyelinosis, alkaline hydrolysis does not alter the colour, whereas in the phosphoglyceridosis under discussion the colour is substantially reduced or even desappears after alkaline hydrolysis.
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NCTR-Balb/c mice are afflicted with a cholesterol lysosomal storage disorder stemming from a defect in intracellular cholesterol processing. The clinical and biochemical abnormalities expressed in the mice resemble Niemann-Pick type C and D disorders in humans. One of the proposed mechanisms to explain the pathophysiology of the disorder implies a defect in the process of membrane transport that normally takes place in the vesicular movement of cholesterol to specific target sites in the cell. Secretory granule formation in pancreatic acinar cells is one of the biological processes known to involve massive membrane flow. Thus, we have undertaken a morphometric study of the regranulation mechanism in the pancreatic acinar cells of the mutant mice, as a way of studying cellular membrane movement. Electron micrographs of pancreatic acinar cells from mutant and normal mice were taken at several time points after extensive degranulation induced by pilocarpine injection. Two hours after stimulation the pancreatic cells demonstrated a complete loss of granules, and at later time points newly formed granules appeared. Identical unit granule volumes were observed in both groups, indicating that the progranules were of normal size. However, the rate of granule formation and maturation was reduced in the mutant mice, which might be the result of a defect in membrane function.
We have shown that ether-linked glycerolipids accumulated in the adrenal, liver, and spleen of a male Chinese infant with Wolman's disease; the increases were mainly in the alkyl and alk-1-enyl glycerolipids that did not contain phosphorus. Alkyldiacylglycerol accounted for a portion of the rise in the neutral alkylglycerols. The spleen also contained increased amounts of ether-linked phosphoglycerides of the alkyl and alk-1-enyl types. Organs from a Niemann-Pick patient were also included in this study; they did not show comparable rises in the content of ether-linked glycerolipids, suggesting the possibility that storage of these compounds may be characteristic of Wolman's disease, or a variant form thereof.
A case of a 27 month old girl suffering from a rare form of lipidosis is described. Clinical symtoms consisted of a moderate hepatosplenomegaly and a progressive psychomotor retardation. Bioptical examination of the liver, appendix and skin revealed a pronounced lipid storage in histiocytes, hepatocytes, vascular endothelium and in peripheral nervous system. Histochemically, a generalized storage of phosphoglycerides and cholesterol was found. It was accompanied with a moderate amount of sphingomyelin and a variable amount of glycolipids (predominantly glycosphingolipids), the latter being stored mainly in the peripheral nervous system and in the vascular endothelium. Chromatographically, an increased concentration of lysobisphosphatidic acid and cholesterol could be detected. The ultrastructure of storage cytosomes was rather pleomorphic often with concentrically lamellar appearance. Further details of the investigation are described and the relation of this case to those described by Baar and Hickmans (1956) and Wiedemann et al. (1972) is stressed. Due to a strong evidence that this group of diseases represents a new type of phospholipid storage disease the name "Phospholipidosis Type II" (Baar-Wiedemann) or "Phosphoglyceridosis" is proposed, whereas "Phospholipidosis Type I" or "Sphingomyelinosis" should be reserved for the classical Niemann-Pick complex.
OBJECTIVE: Diagnosis of hepatocellular carcinoma (HCC) remains challenging for clinicians. Machine learning approaches and big data analyses are viable strategies for identifying HCC diagnostic markers. MATERIALS AND METHODS: In this study, we downloaded mRNA expression profiles of HCC from the GEO database and used random forest and machine learning algorithms, such as least absolute shrinkage and selection operator, to screen for reliable diagnostic genes. Disease Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis enrichment analyses were performed to explore differential gene functions and disease pathways. CIBERSORT was performed to calculate the immune cell infiltration of HCC and the correlation between diagnostic genes and immune cells. Cell experiments were performed to evaluate the function of R-spondin 3 (RSPO3) in HCC cells. Immunohistochemical staining was used to evaluate the protein expression of CD138, CD206 and iNOS. RESULTS: The results indicated that extracellular matrix protein 1 (ECM1), Niemann-Pick C1-Like 1 (NPC1L1) and RSPO3 were down-regulated in HCC compared with the normal group (p < 0.05), which was validated in clinical tissue samples. Moreover, ECM1, NPC1L1 and RSPO3 had high diagnostic values (AUC > 0.75) for HCC in both training and test groups. Immuno-infiltration analysis revealed that ECM1 and RSPO3 were highly positively correlated with neutrophil and macrophage M2 levels, whereas they were negatively correlated with Tregs. RSPO3-si affected cell proliferation and apoptosis in HCC. Furthermore, RSPO3 exhibited a positive correlation with tumour progression, the proportion of plasma cells and M2 macrophages in mice, while showing a negative association with M1 macrophages. CONCLUSION: The present study identified ECM1, NPC1L1 and RSPO3 as new diagnostic biomarkers for HCC based on normal and diseased samples from HCC, meanwhile the pro-oncogenic function of RSPO3 and its regulation on immune infiltration have been confirmed.
We analysed urine and tissue specimens from two nephrotic infantile sialic acid storage disease patients (nISSD) for free and bound sialic acids in comparison to non-nephrotic ISSD patients (ISSD), patients with minimal change nephrosis (nControl) and normal controls (Control). No differences in the excretion of urinary free sialic acid could be detected between ISSD and nISSD urines. Sialyloligosaccharide fractions were only slightly elevated and of apparently normal composition. Owing to glomerular dysfunction, measurable quantities of protein-bound sialic acids were present in nISSD and nControl. In nISSD tissues, free sialic acid was elevated 18-100-fold above control and 3-12-fold above Niemann-Pick A (NPA) samples. The storage of membrane-bound sialic acid was slightly increased compared to control tissues, but equal to those from NPA, thus reflecting an unspecific increase of membranes due to lysosomal storage. According to these results no major biochemical differences were detectable between ISSD and nISSD. The nephrotic syndrome in nISSD could not be related to a general deficit in the sialylation of glycoproteins. Nevertheless, a cell membrane-specific alteration in sialoglycoproteins of glomerular cells might still be possible.