Protective effects and mechanisms of Ndfipl on SH-SY5Y cell apoptosis in an in vitro Parkinson's disease model.

The aim of the current study was to examine the protective effects and mechanisms of Ndfipl on neurocytes in an experimental in vitro Parkinson's disease model induced by MPP+. The cell model was developed with dominant negative expression and suppressed expression of Ndfipl by means of transient transfection of Ndfipl-dominant negative and -inhibitory vectors. In total, four different Ndfipl cell models were established. Different methods were used to analyze the cells. The MTT method was used to detect the effect of Ndfipl on the survival rate and apoptosis of the cells induced by MPP(+). We further studied the roles of Ndfipl in inhibiting MPP(+)-induced SH-SY5Y apoptosis, protection, and ubiquitination of SH-SY5Y cells. Our results showed that Ndfipl reduced apoptosis and improved cell survival rate, indicating that Ndfipl has a neuroprotective effect. Furthermore, we found that Ndfipl binds to Nedd4-1, and that increased expression of Ndfipl significantly reduced Itch expression. We also found that increased ubiquitination played a role in Ndfipl-mediated processes, and that Ndfipl and α-synuclein interact. Additionally, the expression of Ndfipl reduced expression of α-synuclein. In conclusion, Ndfipl plays a significant role in protecting SH-SY5Y cells in in vitro Parkinson's disease models.

CUL4B, NEDD4, and UGT1As involve in the TGF-ß signalling in hepatocellular carcinoma.

UNLABELLED:  Introduction and Aim. TGF-ß signalling is involved in pathogenesis and progress of hepatocellular carcinoma (HCC). This bioinformatics study consequently aims to determine the underlying molecular mechanism of TGF- ß activation in HCC cells. MATERIAL AND METHODS: Dataset GSE10393 was downloaded from Gene Expression Omnibus, including 2 Huh-7 (HCC cell line) samples treated by TGF- ß (100 pmol/L, 48 h) and 2 untreated samples. Differentially expressed genes (DEGs) were screened using Limma package (false discovery rate < 0.05 and |log2 fold change| > 1.5), and then enrichment analyses of function, pathway, and disease were performed. In addition, protein-protein interaction (PPI) network was constructed based on the PPI data from multiple databases including INACT, MINT, BioGRID, UniProt, BIND, BindingDB, and SPIKE databases. Transcription factor (TF)-DEG pairs (Bonferroni adjusted p-value < 0.01) from ChEA database and DEG-DEG pairs were used to construct TF-DEG regulatory network. Furthermore, TF-pathway-DEG complex network was constructed by integrating DEG-DEG pairs, TF-DEG pairs, and DEG-pathway pairs. RESULTS: Totally, 209 DEGs and 30 TFs were identified. The DEGs were significantly enriched in adhesion-related functions. PPI network indicted hub genes such as CUL4B and NEDD4. According to the TF-DEG regulatory network, the two hub genes were targeted by SMAD2, SMAD3, and HNF4A. Besides, the 11 pathways in TF-pathway-DEG network were mainly enriched by UGT1A family and CYP3A7, which were predicted to be regulated by SMAD2, SMAD3, SOX2, TP63, and HNF4A. CONCLUSIONS: TGF- ß might influence biological processes of HCC cells via SMAD2/SMAD3-NEDD4, HNF4A-CUL4B/NEDD4, SOX2/TP63/HNF4A-CYP3A7, and SMAD2/SMAD3/SOX2/TP63/HNF4A-UGT1As regulatory pathways.

NEDD4-1 and PTEN expression in keloid scarring.

Keloid scarring remains a major problem in plastic surgery. The aim of this study was to determine the expression of the PTEN tumor suppressor and NEDD4-1 genes in keloid tissue and explore their effect on the formation of such scarring. Twenty keloid patients were enrolled in the study and underwent surgical removal of keloid tissue. No patient had received chemotherapy and/or radiotherapy prior to treatment. PTEN and NEDD4-1 mRNA expression was detected by reverse transcription PCR, while PTEN protein expression was assessed using immunohistochemistry. Our results showed that levels of PTEN were significantly diminished in keloid samples (P < 0.05), whereas those of NEDD4-1 did not significantly differ between keloid tissue and normal skin (P > 0.05). Furthermore, we found that NEDD4-1 expression is high and inversely correlated with that of PTEN in keloids. Our results suggest that the PTEN/PI3K/AKT pathway may play an important role in keloid formation and reduces PTEN expression in such tissue. Finally, although NEDD4-1 has previously been identified as a factor in keloid susceptibility, and the protein for which it encodes is known to degrade PTEN by catalyzing its polyubiquitylation, the detailed mechanism behind its involvement in keloid formation needs to be further studied.

NEDD4 Regulates PAX7 Levels Promoting Activation of the Differentiation Program in Skeletal Muscle Precursors.

The transcription factor Pax7 regulates skeletal muscle stem cell (satellite cells) specification and maintenance through various mechanisms, including repressing the activity of the muscle regulatory factor MyoD. Hence, Pax7-to-MyoD protein ratios can determine maintenance of the committed-undifferentiated state or activation of the differentiation program. Pax7 expression decreases sharply in differentiating myoblasts but is maintained in cells (re)acquiring quiescence, yet the mechanisms regulating Pax7 levels based on differentiation status are not well understood. Here we show that Pax7 levels are directly regulated by the ubiquitin-ligase Nedd4. Our results indicate that Nedd4 is expressed in quiescent and activated satellite cells, that Nedd4 and Pax7 physically interact during early muscle differentiation-correlating with Pax7 ubiquitination and decline-and that Nedd4 loss of function prevented this effect. Furthermore, even transient nuclear accumulation of Nedd4 induced a drop in Pax7 levels and precocious muscle differentiation. Consequently, we propose that Nedd4 functions as a novel Pax7 regulator, which activity is temporally and spatially controlled to modulate the Pax7 protein levels and therefore satellite cell fate.

Gender flip-flop association between genetic variations of NEDD4L and metabolic syndrome in the Kazakh general population.

Genetic variation is thought to contribute to etiology of metabolic syndrome (MS). Neural precursor cell expressed developmentally downregulated 4-like gene (NEDD4L) is a candidate gene for MS. This study investigated the relationship between variations of NEDD4L and MS in the Kazakh, which is an ideal population to study the genetic mechanisms of complex diseases such as MS. We screened the promoter and exons of NEDD4L in 48 Kazakh individuals with MS to identify representative variations. By genotyping the representative variations [271420T>C (rs2288774), 271454A>G (rs2288775), and 296921-296923delTTG] in the Kazakh general population, we conducted a case-control study. In female subjects, the distribution of genotypes and alleles of rs2288775 and 296921-296923delTTG differed significantly between the MS pacients and controls. In male subjects, the genotype distributions of 296921-296923delTTG were significantly different between the MS pacients and controls in the dominant model (P = 0.047). After adjustment for age, smoking, and drinking, multivariate logistic regression analysis showed that rs2288775 was significantly associated with MS [for the A/A genotype, odds ratio (OR) = 3.296, P = 0.011] in female subjects. For 296921-296923delTTG, the I/D+D/D genotype was the high-risk genotype for MS in female subjects (OR = 2.791, P = 0.035) and was a protective factor for MS in male subjects (OR = 0.580, P = 0.045). The 296921-296923delTTG variation of NEDD4L is a gender flip-flop associated with MS in Kazakh individuals. The A allele of rs2288775 may be an independent risk factor for MS in Kazakh women. The results suggest that the genetic variations of NEDD4L might be involved in the pathogenesis of MS.

Nedd4-2 modulates renal Na+-Cl- cotransporter via the aldosterone-SGK1-Nedd4-2 pathway.

Regulation of renal Na(+) transport is essential for controlling blood pressure, as well as Na(+) and K(+) homeostasis. Aldosterone stimulates Na(+) reabsorption by the Na(+)-Cl(-) cotransporter (NCC) in the distal convoluted tubule (DCT) and by the epithelial Na(+) channel (ENaC) in the late DCT, connecting tubule, and collecting duct. Aldosterone increases ENaC expression by inhibiting the channel's ubiquitylation and degradation; aldosterone promotes serum-glucocorticoid-regulated kinase SGK1-mediated phosphorylation of the ubiquitin-protein ligase Nedd4-2 on serine 328, which prevents the Nedd4-2/ENaC interaction. It is important to note that aldosterone increases NCC protein expression by an unknown post-translational mechanism. Here, we present evidence that Nedd4-2 coimmunoprecipitated with NCC and stimulated NCC ubiquitylation at the surface of transfected HEK293 cells. In Xenopus laevis oocytes, coexpression of NCC with wild-type Nedd4-2, but not its catalytically inactive mutant, strongly decreased NCC activity and surface expression. SGK1 prevented this inhibition in a kinase-dependent manner. Furthermore, deficiency of Nedd4-2 in the renal tubules of mice and in cultured mDCT(15) cells upregulated NCC. In contrast to ENaC, Nedd4-2-mediated inhibition of NCC did not require the PY-like motif of NCC. Moreover, the mutation of Nedd4-2 at either serine 328 or 222 did not affect SGK1 action, and mutation at both sites enhanced Nedd4-2 activity and abolished SGK1-dependent inhibition. Taken together, these results suggest that aldosterone modulates NCC protein expression via a pathway involving SGK1 and Nedd4-2 and provides an explanation for the well-known aldosterone-induced increase in NCC protein expression.