Changes in phosphatidylinositol 3-kinase 55 kDa gamma expression and subcellular localization may be caspase 6 dependent in paraquat-induced SH-SY5Y apoptosis

LncRNA JHDM1D-AS1 Suppresses MPP + -Induced Neuronal Injury in Parkinson's Disease via miR-134-5p/PIK3R3 Axis

Parkinson's disease (PD) is a multi-factorial neurodegenerative disease. Long noncoding RNAs (lncRNAs) have been revealed to be involved in the process of PD. Herein, this study aimed to investigate the potential function and mechanism of JHDM1D-AS1 (JHDM1D antisense 1) in PD process. 1-Methyl-4-phenylpyridinium (MPP +)-induced SK-N-SH cells were used to conduct expression and function analyses. Levels of genes and proteins were examined using real-time reverse transcription PCR (RT-qPCR) and Western blot. Cell viability and apoptosis were determined using CCK-8 assay, flow cytometry, and Western blot, respectively. ELISA analysis was performed for the detection of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. The contents of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured using commercial kits. The direct interactions between miR-134-5p and PIK3R3 (Phosphoinositide-3-Kinase Regulatory Subunit 3) or JHDM1D-AS1 were verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. JHDM1D-AS1 expression was decreased by MPP + in SK-N-SH cells in a dose- or time-dependent manner. Functionally, JHDM1D-AS1 overexpression attenuated MPP + -evoked neuronal apoptosis, inflammation, and oxidative stress. Mechanistically, JHDM1D-AS1 competitively bound to miR-134-5p to upregulate the expression of its target PIK3R3. Rescue experiments suggested that miR-134-5p upregulation reversed the inhibitory effects of JHDM1D-AS1 on MPP + -induced neuronal injury. Moreover, inhibition of miR-134-5p protected neurons against MPP + -induced neuronal apoptosis, inflammation, and oxidative stress, which were abolished by PIK3R3 silencing. JHDM1D-AS1 protected against MPP + -induced neuron injury via miR-134-5p/PIK3R3 axis, suggesting the potential involvement of this axis in PD process.

P55PIK Regulates P53-Dependent Apoptosis in Cancer Cells by Interacting with P53 DNA-Specific Domain

Purpose

Phosphatidylinositol 3-kinase (PI3K) plays an important role in tumorigenesis by cross-talking with several signaling pathways. p55PIK is a unique regulatory subunit of PI3K and contains an extra 24-residue N-terminal domain (N24). This study aimed to explore the interaction of p55PIK with p53 and the role of p55PIK in regulating p53-dependent apoptosis in cancer cells.

Materials and Methods

The expression of p55PIK was detected in cancer cells, and the interaction of p55PIK with p53 was examined by immunoprecipitation and pull-down assay. The expression of p53-dependent apoptosis-related genes was detected by PCR.

Results

N24 domain of p55PIK interacted with DNA-specific binding domain (DBD) of p53. The increase or decrease of p55PIK expression led to the change of the expression of p53 and p53-regulated genes in cancer cells. Moreover, N24 peptide led to the change of the expression of p53-regulated genes. Moreover, a membrane-permeable N24 peptide enhanced p53-dependent apoptosis induced by methyl methanesulfonate.

Conclusion

Our results reveal a novel mechanism that regulates p53-dependent apoptosis in cancer cells via p55PIK-p53 interaction.

MicroRNA-432 targeting E2F3 and P55PIK inhibits myogenesis through PI3K/AKT/mTOR signaling pathway

Skeletal muscle is the dominant executant in locomotion and regulator in energy metabolism. Embryonic myogenesis and postnatal muscle growth are controlled by a cascade of transcription factors and epigenetic regulatory mechanisms. MicroRNAs (miRNAs), a family of non-coding RNA of 22 nucleotides in length, post-transcriptionally regulates expression of mRNA by pairing the seed sequence to 3' UTR of target mRNA. Increasing evidence has demonstrated that miRNAs are important regulators in diverse myogenic processes. The profiling of miRNA expression revealed that miR-432 is more enriched in the longissimus dorsi of 35-day-old piglets than that of adult pigs. Our gain of function study showed that miR-432 can negatively regulate both myoblast proliferation and differentiation. Mechanically, we found that miR-432 is able to down-regulate E2F transcription factor 3 (E2F3) to inactivate the expression of cell cycle and myogenic genes. We also identified that phosphatidylinositol 3-kinase regulatory subunit (P55PIK) is another target gene of miR-432 in muscle cells. downregulation of P55PIK by miR-432 leads to inhibition of P55PIK-mediated PI3K/AKT/mTOR signaling pathway during differentiation. The blocking effect of miR-432 on this pathway can be rescued by insulin treatment. Taken together, our findings identified microRNA-432 as a potent inhibitor of myogenesis which functions by targeting E2F3 and P55PIK in muscle cells.