Dataset Information

Functional analysis of Niemann-Pick disease type C family protein, NPC1a, in Drosophila melanogaster.

ABSTRACT: During embryonic gonad coalescence, primordial germ cells (PGCs) follow a carefully choreographed migratory route circumscribed by guidance signals towards somatic gonadal precursor cells (SGPs). In Drosophila melanogaster, SGP-derived Hedgehog (Hh), which serves as a guidance cue for the PGCs, is potentiated by mesodermally restricted HMGCoA-reductase (Hmgcr) and the ABC transporter Multi-drug-resistant-49 (Mdr49). Given the importance of cholesterol modification in the processing and long-distance transmission of the Hh ligand, we have analyzed the involvement of the Niemann-Pick disease type C-1a (NPC1a) protein, a cholesterol transporter, in germ cell migration and Hedgehog signaling. We show that mesoderm-specific inactivation of Npc1a results in germ cell migration defects. Similar to Mdr49, PGC migration defects in the Npc1a embryos are ameliorated by a cholesterol-rich diet. Consistently, reduction in Npc1a weakens the ability of ectopic HMG Coenzyme A reductase (Hmgcr) to induce germ cell migration defects. Moreover, compromising Npc1a levels influences Hh signaling adversely during wing development, a process that relies upon long-range Hh signaling. Last, doubly heterozygous embryos (Mdr49/Npc1a) display enhanced germ cell migration defects when compared with single mutants (Npc1a/+ or Mdr49/+), supporting cooperative interaction between the two.

SUBMITTER: Bialistoky T

PROVIDER: S-EPMC6550021 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Functional analysis of Niemann-Pick disease type C family protein, NPC1a, in <i>Drosophila melanogaster</i>.

Bialistoky Tzofia T Manry Diane D Smith Peyton P Ng Christopher C Kim Yunah Y Zamir Sol S Moyal Victoria V Kalifa Rachel R Schedl Paul P Gerlitz Offer O Deshpande Girish G

Development (Cambridge, England) 20190515 10

During embryonic gonad coalescence, primordial germ cells (PGCs) follow a carefully choreographed migratory route circumscribed by guidance signals towards somatic gonadal precursor cells (SGPs). In <i>Drosophila melanogaster</i>, SGP-derived Hedgehog (Hh), which serves as a guidance cue for the PGCs, is potentiated by mesodermally restricted HMGCoA-reductase (Hmgcr) and the ABC transporter Multi-drug-resistant-49 (Mdr49). Given the importance of cholesterol modification in the processing and lo ...[more]

PMID: 31092503

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Project description:OBJECTIVES:The aim of this study was to comprehensively evaluate the auditory phenotype in Niemann-Pick disease, type C1 (NPC1), to understand better the natural history of this complex, heterogeneous disorder, and to define further the baseline auditory deficits associated with NPC1 so that use of potentially ototoxic interventions (e.g., 2-hydroxypropyl-ß-cyclodextrin) may be more appropriately monitored and understood. DESIGN:Fifty patients with NPC1 ranging in age from 4 months to 21 years (mean = 9.3 years) enrolled in a natural history/observational study at the National Institutes of Health. The auditory test battery included, when possible, immittance audiometry, pure-tone and speech audiometry, otoacoustic emission testing, and a neurotologic auditory brainstem response study. Longitudinal data were collected on a subset of patients. RESULTS:Over half of the cohort exhibited hearing loss involving the high frequencies ranging from a slight to moderate degree, and 74% of patients presented with clinically significant hearing loss involving the frequencies most important to speech understanding (0.5, 1, 2, 4 kHz). Despite the heterogeneity of the sample, results among patients were sufficiently consistent to implicate retrocochlear dysfunction in the majority (66%) of individuals, with (22%) or without (44%) accompanying cochlear involvement. Some patients (10%) presented with a profile for auditory neuropathy spectrum disorder. The combination of cross-sectional and longitudinal data indicates these patients are at risk for a progressive decline in auditory function. CONCLUSIONS:This is the largest cohort of patients with NPC1 evaluated comprehensively for auditory dysfunction, and results implicate the pathological processes of NPC1 in the manifestation of hearing loss. Patients with NPC1 should be monitored audiologically throughout their lives, beginning at the time of diagnosis. Clinicians and researchers should be aware of this historically overlooked aspect of the phenotype.

Project description:BackgroundNiemann-Pick disease, type C1 (NPC1) is an ultrarare, recessive, lethal, lysosomal disease characterized by progressive cerebellar ataxia and cognitive impairment. Although the NPC1 phenotype is heterogeneous with variable age of onset, classical NPC1 is a pediatric disorder. Currently there are no therapies approved by the FDA and therapeutics trials for NPC1 are complicated by disease rarity, heterogeneity, and the relatively slow rate of neurological decline. Thus, identification of disease relevant biomarkers is necessary to provide tools that can support drug development efforts for this devastating neurological disease.MethodsProximal extension assays (O-link® Explore 1536) were used to compare cerebrospinal fluid (CSF) samples from individuals with NPC1 enrolled in a natural history study and non-NPC1 comparison samples. Relative expression levels of 1467 proteins were determined, and candidate protein biomarkers were identified by evaluating fold-change and adjusted Kruskal-Wallis test p-values. Selected proteins were orthogonally confirmed using ELISA. To gain insight into disease progression and severity we evaluated the altered protein expression with respect to clinically relevant phenotypic aspects: NPC Neurological Severity Score (NPC1 NSS), Annual Severity Increment Score (ASIS) and age of neurological onset.ResultsThis study identified multiple proteins with altered levels in CSF from individuals with NPC1 compared to non-NPC1 samples. These included proteins previously shown to be elevated in NPC1 (NEFL, MAPT, CHIT1, CALB1) and additional proteins confirmed by orthogonal assays (PARK7, CALB2/calretinin, CHI3L1/YKL-40, MIF, CCL18 and ENO2). Correlations with clinically relevant phenotypic parameters demonstrated moderate negative (p = 0.0210, r = -0.41) and possible moderate positive (p = 0.0631, r = 0.33) correlation of CSF CALB2 levels with age of neurological onset and ASIS, respectively. CSF CHI3L1 levels showed a moderate positive (p = 0.0183, r = 0.40) correlation with the concurrent NPC1 NSS. A strong negative correlation (p = 0.0016, r = -0.648) was observed between CSF CCL18 and age of neurological onset for childhood/adolescent cases. CSF CCL18 levels also showed a strong positive correlation (p = 0.0017, r = 0.61) with ASIS.ConclusionOur study identified and validated multiple proteins in CSF from individuals with NPC1 that are candidates for further investigation in a larger cohort. These analytes may prove to be useful as supportive data in therapeutic trials.Trial registrationsNCT00344331, NCT00001721, NCT02931682.

Project description:Background and aimsHepatic cholesterol deposition drives inflammation and fibrosis in non-alcoholic steatohepatitis (NASH). The Niemann-Pick type C2 (NPC2) protein plays an important role in regulating intracellular cholesterol trafficking and homeostasis. We hypothesized that intravenous NPC2 supplementation reduces cholesterol accumulation, hepatic inflammation and fibrogenesis in a nutritional NASH rat model.MethodsRats were fed a high-fat, high-cholesterol (HFHC) diet for four weeks resulting in moderately severe NASH. Animals were treated with intravenous NPC2 or placebo twice weekly for either the last two weeks or the entire four weeks. End-points were liver/body- and spleen/body weight ratios, histopathological NASH scores, fibrosis, serum liver enzymes, cholesterol, lipoproteins, cytokines, and quantitative polymerase chain reaction derived hepatic gene expression related to cholesterol metabolism, inflammation, and fibrosis.ResultsHFHC rats developed hepatomegaly, non-fibrotic NASH histopathology, elevated liver enzymes, serum cholesterol, and pro-inflammatory cytokines. Their sterol regulatory element binding factor 2 (SREBF2) and low-density lipoprotein receptor (LDL-R) mRNAs were down-regulated compared with rats on standard chow. NPC2 did not improve liver weight, histopathology, levels of serum liver enzymes or pro-inflammatory tumor necrosis factor-α (TNFα), Interleukin (IL)-6, or IL-1β in HFHC rats. Two weeks of NPC2 treatment lowered hepatic TNFα and COL1A1 mRNA expression. However, this effect was ultimately reversed following additional two weeks of treatment. Four weeks NPC2 treatment of rats raised ATP-binding cassette A1 (ABCA1) and low-density lipoprotein receptor (LDLR) mRNAs in the liver, concurrent with a strong tendency towards higher serum high-density lipoprotein (HDL). Furthermore, the peroxisome proliferator activated receptor-ɣ (PPARG) gene expression was reduced.ConclusionsNPC2 proved inefficient at modifying robust hepatic NASH end-points in a HFHC NASH model. Nonetheless, our data suggest that hepatic ABCA1 expression and reverse cholesterol transport were upregulated by NPC2 treatment, thus presenting putative therapeutic effects in diseases associated with deregulated lipid metabolism.

Dataset Information

Functional analysis of Niemann-Pick disease type C family protein, NPC1a, in Drosophila melanogaster.

Publications

Functional analysis of Niemann-Pick disease type C family protein, NPC1a, in <i>Drosophila melanogaster</i>.

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