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Determination of the Pathological Features of NPC1 Variants in a Cellular Complementation Test
(2019)
Niemann-Pick Type C (NP-C) is a rare disorder of lipid metabolism caused by mutations
within the NPC1 and NPC2 genes. NP-C is a neurovisceral disease leading to a heterogeneous,
multisystemic spectrum of symptoms in those affected. Until now, there is no investigative tool to
demonstrate the significance of single variants within the NPC genes. Hence, the aim of the study
was to establish a test that allows for an objective assessment of the pathological potential of NPC1
gene variants. Chinese hamster ovary cells defective in the NPC1 gene accumulate cholesterol in
lysosomal storage organelles. The cells were transfected with NPC1-GFP plasmid vectors carrying
distinct sequence variants. Filipin staining was used to test for complementation of the phenotype.
The known variant p.Ile1061Thr showed a significantly impaired cholesterol clearance after 12 and
24 h compared to the wild type. Among the investigated variants, p.Ser954Leu and p.Glu1273Lys
showed decelerated cholesterol clearance as well. The remaining variants p.Gln60His, p.Val494Met,
and p.Ile787Val showed a cholesterol clearance indistinguishable from wild type. Further, p.Ile1061Thr
acquired an enhanced clearance ability upon 25-hydroxycholesterol treatment. We conclude that the
variants that caused an abnormal clearance phenotype are highly likely to be of clinical relevance.
Moreover, we present a system that can be utilized to screen for new drugs.
Liver diseases are important causes of morbidity and mortality worldwide. The aim of
this study was to identify differentially expressed microRNAs (miRNAs), target genes, and key
pathways as innovative diagnostic biomarkers in liver patients with different pathology and functional
state. We determined, using RT-qPCR, the expression of 472 miRNAs in 125 explanted livers from
subjects with six different liver pathologies and from control livers. ANOVA was employed to
obtain differentially expressed miRNAs (DEMs), and miRDB (MicroRNA target prediction database)
was used to predict target genes. A miRNA–gene differential regulatory (MGDR) network was
constructed for each condition. Key miRNAs were detected using topological analysis. Enrichment
analysis for DEMs was performed using the Database for Annotation, Visualization, and Integrated
Discovery (DAVID). We identified important DEMs common and specific to the different patient
groups and disease progression stages. hsa-miR-1275 was universally downregulated regardless
the disease etiology and stage, while hsa-let-7a*, hsa-miR-195, hsa-miR-374, and hsa-miR-378 were
deregulated. The most significantly enriched pathways of target genes controlled by these miRNAs
comprise p53 tumor suppressor protein (TP53)-regulated metabolic genes, and those involved in
regulation of methyl-CpG-binding protein 2 (MECP2) expression, phosphatase and tensin homolog
(PTEN) messenger RNA (mRNA) translation and copper homeostasis. Our findings show a novel
panel of deregulated miRNAs in the liver tissue from patients with different liver pathologies. These
miRNAs hold potential as biomarkers for diagnosis and staging of liver diseases.