N-butyldeoxynojirimycin (miglustat) ameliorates pulmonary fibrosis through inhibition of nuclear translocation of Smad2/3.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. The disease involves excessive accumulation of fibroblasts and myofibroblasts, and myofibroblasts differentiated by pro-fibrotic factors promote the deposition of extracellular matrix proteins such as collagen and fibronectin. Transforming growth factor-ß1 is a pro-fibrotic factor that promotes fibroblast-to-myofibroblast differentiation (FMD). Therefore, inhibition of FMD may be an effective strategy for IPF treatment. In this study, we screened the anti-FMD effects of various iminosugars and showed that some compounds, including N-butyldeoxynojirimycin (NB-DNJ, miglustat, an inhibitor of glucosylceramide synthase (GCS)), a clinically approved drug for treating Niemann-Pick disease type C and Gaucher disease type 1, inhibited TGF-ß1-induced FMD by inhibiting the nuclear translocation of Smad2/3. N-butyldeoxygalactonojirimycin having GCS inhibitory effect did not attenuate the TGF-ß1-induced FMD, suggesting that NB-DNJ exerts the anti-FMD effects by GCS inhibitory effect independent manner. N-butyldeoxynojirimycin did not inhibit TGF-ß1-induced Smad2/3 phosphorylation. In a mouse model of bleomycin (BLM)-induced pulmonary fibrosis, intratracheal or oral administration of NB-DNJ at an early fibrotic stage markedly ameliorated lung injury and deterioration of respiratory functions, such as specific airway resistance, tidal volume, and peak expiratory flow. Furthermore, the anti-fibrotic effects of NB-DNJ in the BLM-induced lung injury model were similar to those of pirfenidone and nintedanib, which are clinically approved drugs for the treatment of IPF. These results suggest that NB-DNJ may be effective for IPF treatment.

Proteomic analysis of subcellular compartments containing disseminated alpha-synuclein seeds.

The pathological form of a-synuclein (a-syn) is transmitted through neural circuits in the brains of Parkinson disease (PD) patients and amplifies misfolded a-syn, further forming intracellular deposits. However, the details of a-syn pre-formed fibrils (PFFs) transmission in vivo have not been fully elucidated. By inoculating Quantum dots (QD)-labeled a-syn PFFs (QD-a-syn PFFs) into the unilateral striatum, we detected QD-a-syn PFFs in brain homogenates obtained from the ipsilateral and contralateral sides of the inoculated site and further obtained QD-a-syn PFFs enriched-particles with fluorescence-activated organelle sorting. Proteomic analysis suggested that QD-a-syn PFFs-enriched particles in the contralateral side were associated with component proteins of synapse. In contrast, QD-a-syn PFFs-enriched particles in the ipsilateral side were associated with proteins belonging to ER components. Immunostaining of brain sections confirmed that QD-a-syn PFFs in the contralateral side were co-localized with synaptic vesicle marker proteins in the cortex and striatum. Additionally, QD-a-syn PFFs in the ipsilateral side were more co-localized with ER marker proteins compared to the contralateral side. These results correspond to proteomic analysis. This study provides potential candidates for the subcellular localization of a-syn PFFs in vivo during the dissemination phase of seeds. These subcellular compartments could be involved in the transmission of seeds.

Tyrosine-phosphorylation and activation of glucosylceramide synthase by v-Src: Its role in survival of HeLa cells against ceramide.

Sphingolipids represent a family of cellular lipid-molecules that regulate physiological and pathophysiological processes. Glucosylceramide (GlcCer), the simplest glycosphingolipid (GSL), is synthesized from ceramide and UDP-glucose by GlcCer synthase (GCS). Both GlcCer (and resulting GSLs) and ceramide regulate various cellular functions including cell death and multiple drug resistance. Src family tyrosine kinases are up-regulated in various human cancer cells. We examined the effect of v-Src expression on GCS activity, the formation of 4-nitrobenzo-2-oxa-1,3-diazole (NBD)-labeled GlcCer from NBD-ceramide, and the effect of tyrosine132 mutation in GCS on ceramide-induced cytotoxicity in HeLa cells. Expression of v-Src increased the formation of NBD-GlcCer in both intact cells without marked changes in other sphingolipid metabolites and cell homogenates without changing affinities of NBD-ceramide and UDP-glucose. Expression of v-Src also increased tyrosine-phosphorylated levels in GCS proteins in HeLa and HEK293T cells. In HEK293T cells transiently expressing the GCS mutant, GCS-Y132F-HA, showing replacement of the tyrosine132 residue with phenylalanine, tyrosine-phosphorylated levels in GCS proteins were significantly lower than those in control cells expressing the GCS-wild-type-HA. The formation of NBD-GlcCer in HeLa cells stably expressing GCS-Y132F-HA was significantly lower than that in the control. Ceramide-induced cytotoxicity in HeLa-GCS-Y132F-HA cells was significantly greater than in the control. In this study, we showed for the first time that expression of v-Src up-regulated GCS activity via tyrosine phosphorylation of the enzyme in a post-translational manner. Mechanisms of Src-induced resistance to ceramide-induced cytotoxicity are discussed in relation to the Src-induced up-regulation of GCS activity.

Development of a new doubly-labeled fluorescent ceramide probe for monitoring the metabolism of sphingolipids in living cells.

A new ceramide analog, 1, containing two fluorescent dyes, NBD in the N-acyl part and KFL5 in the alkyl part, was synthesized. The fluorescence from both NBD and KFL5 was detected in living cells in a time-dependent manner. A multi-wavelength fluorescence detector was used to detect ceramide metabolites including sphingosine, sphingosine-1-phosphate, glucosylceramide, and sphingomyelin, which are connected to the fluorescent dyes, simultaneously in a single TLC plate.