PSMD1 and PSMD2 regulate HepG2 cell proliferation and apoptosis via modulating cellular lipid droplet metabolism

Background Obesity and nonalcoholic steatohepatitis (NASH) are well-known risk factors of hepatocellular carcinoma (HCC). The lipid-rich environment enhances the proliferation and metastasis abilities of tumor cells. Previous studies showed the effect of the ubiquitin–proteasome system (UPS) on tumor cell proliferation. However, the underlying mechanism of UPS in regulating the proliferation of lipid-rich tumor cells is not totally clear. Results Here, we identify two proteasome 26S subunits, non-ATPase 1 and 2 (PSMD1 and PSMD2), which regulate HepG2 cells proliferation via modulating cellular lipid metabolism. Briefly, the knockdown of PSMD1 and/or PSMD2 decreases the formation of cellular lipid droplets, the provider of the energy and membrane components for tumor cell proliferation. Mechanically, PSMD1 and PSMD2 regulate the expression of genes related to de novo lipid synthesis via p38-JNK and AKT signaling. Moreover, the high expression of PSMD1 and PSMD2 is significantly correlated with poor prognosis of HCC. Conclusion We demonstrate that PSMD1 and PSMD2 promote the proliferation of HepG2 cells via facilitating cellular lipid droplet accumulation. This study provides a potential therapeutic strategy for the treatment of lipid-rich tumors.

The effect of BACE1-AS on β-amyloid generation by regulating BACE1 mRNA expression

Background The BACE1 antisense transcript (BACE1-AS) is a conserved long noncoding RNA (lncRNA). The level of BACE1-AS is significantly increased and the level of the BACE1 mRNA is slightly increased in subjects with AD. BACE1-AS exerts a significant moderating effect on the expression of the BACE1 mRNA and promotes the formation of Aβ. After the administration of Aβ1-42 to SH-SY5Y cells and C57/BL6J mice, we detected the expression of BACE1-AS, BACE1 mRNA, and BACE1 protein, as well as the concentration of Aβ1-40. Then, we silenced the expression of BACE1-AS in SH-SY5Y and 20E2 cells using siRNAs targeting BACE1-AS and detected its effects on the levels of the BACE1 mRNA and BACE1 protein and Aβ1-40 generation. Results The administration of Aβ1-42 increased the expression of BACE1-AS, BACE1 mRNA and protein, as well as the concentration of Aβ1-40 in SH-SY5Y cells and the brains of C57BL/6J mice. Pretreatment with the BACE1-AS siRNA inhibited the effect of Aβ1-42 on increasing the expression of BACE1-AS and BACE1, as well as the generation of Aβ. Conclusions The mechanism by which exogenous Aβ1-42 induces BACE1 expression and Aβ generation is mediated by BACE1-AS. BACE1-AS is involved in the mechanism regulating BACE1 expression and Aβ generation in APPsw transgenic cells.

Overlapping transcriptional expression response of wheat zinc-induced facilitator-like transporters emphasize important role during Fe and Zn stress

Background Hexaploid wheat is an important cereal crop that has been targeted to enhance grain micronutrient content including zinc (Zn) and iron (Fe). In this direction, modulating the expression of plant transporters involved in Fe and Zn homeostasis has proven to be one of the promising approaches. The present work was undertaken to identify wheat zinc-induced facilitator-like (ZIFL) family of transporters. The wheat ZIFL genes were characterized for their transcriptional expression response during micronutrient fluctuations and exposure to multiple heavy metals. Results The genome-wide analyses resulted in identification of fifteen putative TaZIFL-like genes, which were distributed only on Chromosome 3, 4 and 5. Wheat ZIFL proteins subjected to the phylogenetic analysis showed the uniform distribution along with rice, Arabidopsis and maize. In-silico analysis of the promoters of the wheat ZIFL genes demonstrated the presence of multiple metal binding sites including those which are involved in Fe and heavy metal homeostasis. Quantitative real-time PCR analysis of wheat ZIFL genes suggested the differential regulation of the transcripts in both roots and shoots under Zn surplus and also during Fe deficiency. Specifically, in roots, TaZIFL2.3, TaZIFL4.1, TaZIFL4.2, TaZIFL5, TaZIFL6.1 and TaZIFL6.2 were significantly up-regulated by both Zn and Fe. This suggested that ZIFL could possibly be regulated by both the nutrient stress in a tissue specific manner. When exposed to heavy metals, TaZIFL4.2 and TaZIFL7.1 show significant up-regulation, whereas TaZIFL5 and TaZIFL6.2 remained almost unaffected. Conclusion This is the first report for detailed analysis of wheat ZIFL genes. ZIFL genes also encode for transporter of mugineic acid (TOM) proteins, that are involved in the release of phytosiderophores to enhance Fe/Zn uptake. The detailed expression analysis suggests the varying expression patterns during development of wheat seedlings and also against abiotic/biotic stresses. Overall, this study will lay foundation to prioritize functional assessment of the candidate ZIFL as a putative TOM protein in wheat.