Field Hypothesis on the Self-regulation of Gene Expression

The mechanism of the self-regulation of gene expression in living cells is generally explained by considering complicated networks of key-lock relationships, and in fact there is a large body of evidence on a hugenumber of key-lock relationships. However, in the present article we stress that with the network hypothesis alone it is impossible to fully explain the mechanism of self-regulation in life. Recently, it has been established that individual giant DNA molecules, larger than several tens of kilo base pairs, undergo a large discrete transition in their higher-order structure. It has become clear that nonspecific weak interactions with various chemicals, suchas polyamines, small salts, ATP and RNA, cause on/off switching in the higher-order structure of DNA. Thus, the field parameters of the cellular environment should play important roles in the mechanism of self-regulation, in addition to networks of key and locks. This conformational transition induced by field parameters may be related to rigid on/off regulation, whereas key-lock relationships may be involved in a more flexible control of gene expression.     

Inhibition of Cell Proliferation and Migration by miR-509-3p That Targets CDK2, Rac1, and PIK3C2A

CDK2 is a key regulator of cell cycle progression. In this study, we screened for miRNAs targeting CDK2 using a luciferase-3′-untranslated region reporter assay. Among 11 hit miRNAs, miR-509-3p reduced CDK2 protein levels and significantly inhibited cancer cell growth. Microarray, Western blotting, and luciferase reporter analyses revealed additional targets of miR-509-3p, including Rac1 and PIK3C2A. Overexpression of miR-509-3p induced G1 cell-cycle arrest and inhibited colony formation and migration. RNAi experiments indicated that the growth-inhibitory effects of miR-509-3p may occur through down-regulation of CDK2, Rac1, and PIK3C2A. Targeting of multiple growth regulatory genes by miR-509-3p may contribute to effective anti-cancer therapy.     

Bone marrow-derived mesenchymal stem cells repair severe acute pancreatitis by secreting miR-181a-5p to target PTEN/Akt/TGF-β1 signaling

BackgroundSevere acute pancreatitis (SAP) is associated with high morbidity and mortality. Bone marrow mesenchymal stem cells (BMSCs) have shown obvious protective effect on SAP. However, little is known about the underlying mechanism. The objective of this study is to unravel the role and regulatory mechanism of miR-181a-5p in BMSCs-mediated pancreatic repair.MethodsBMSCs were isolated from Sprague-Dawley rats and characterized by flow cytometry and Oil Red O staining. Sodium taurocholate- and caerulein-induced models were used as SAP models in vivo and in vitro, respectively. Pancreatic injury were evaluated by H&E and histopathological analysis, as well as by measuring levels of amylase, lipase and cytokines. qRT-PCR and western blotting were performed to detect the level of miR-181a-5p and the protein levels of PTEN/Akt, respectively. ELISA was conducted to detect the levels of TNF-α, IL-1β, IL-6, angiopoietin, IL-4, IL-10 and TGF-β1. The apoptotic rate of AR42 J cells was quantitated by concurrent staining with Annexin-V-FITC and PI.ResultsBMSCs significantly attenuated pancreatic injury in SAP rats by reducing inflammatory infiltration and necrosis, and this effect was abolished by CXCR4 agonist AMD3100. ADM3100 exhibited more severe pancreatic injury and decreased miR-181a-5p levels in the pancreas and serum compared to SAP group. Overexpression of miR-181a-5p in BMSCs (BMSCs-miR-181a-5p) markedly potentiated the protective effect of BMSCs by reducing histological damage and levels of amylase and lipase. Moreover, BMSCs-miR-181a-5p dramatically reduced levels of angiopoietin, TNF-α, IL-1β and IL-6, but induced the levels of IL-4 and IL-10. In caerulein-treated AR42 J cells, co-culturing of BMSCs-miR-181a-5p alleviated caerulein-induced increase of amylase and lipase, and apoptosis via PTEN/Akt/TGF-β1 signaling.ConclusionBMSCs alleviate SAP and reduce inflammatory responses and apoptosis by secreting miR-181a-5p to target PTEN/Akt/TGF-β1 signaling. Hence, BMSCs-miR-181a-5p could serve as potential therapeutic target for SAP.     

Control of Orienting Movements and Locomotion by Projection-Defined Subsets of Brainstem V2a Neurons

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Long noncoding RNA PTENP1 affects the recovery of spinal cord injury by regulating the expression of miR-19b and miR-21

Exosomes derived from differentiated P12 cells and MSCs were proved to suppress apoptosis of neuron cells, and phosphatase and tensin homolog pseudogene 1 (PTENP1) was reported to inhibit cell proliferation. In this study, we aimed to investigate the role of PTENP1 in the process of post-spinal cord injury (SCI) recovery, so as to evaluate the therapeutic effects of exosomes derived from MSCs transfected with PTENP1 short hairpin RNA (shRNA), as a type of novel biomarkers in the treatment of SCI. Electron microscopy was used to observe the morphology of different exosomes. Real-time polymerase chain reaction and western blot, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, flow cytometry, Nissl staining, immunohistochemistry assay, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay were conducted to investigate and validate the underlying molecular signaling pathway. PTENP1-shRNA downregulated PTENP1 and PTEN while upregulating miR-21 and miR-19b. PTENP1-shRNA also accelerated cell apoptosis and reduced cell viability. In addition, PTENP1 reduced the miR-21 and miR-19b expression by directly targeting miR-21 and miR-19b. Meanwhile, both miR-21 and miR-19b reduced the expression of PTEN by directly targeting the 3′-untranslated region of PTEN. Furthermore, PTEN level and apoptosis index of neuron cells was the highest in the SCI group, while the treatment with exosomes+PTENP1-shRNA reduced the PTEN expression to a level similar to that in the sham group. Finally, PTENP1 inhibited miR-21 and miR-19b expression but upregulated PTEN expression. The upregulation of miR-21/miR-19b also suppressed the apoptosis of neuron cells by downregulating the PTEN expression. PTENP1 is involved in the recovery of SCI by regulating the expression of miR-19b and miR-21, and exosomes from PTENP1-shRNA-transfected cells may be used as a novel biomarker in SCI treatment.     

Is GPR146 really the receptor for proinsulin C-peptide?

Proinsulin C-peptide has previously been proposed to interact with a G-protein coupled receptor (GPCR), specifically the orphan receptor GPR146. To investigate the potential of C-peptide in treating complications of diabetes, such as kidney damage, it is necessary to understand its mode of action. We used CHO-K1 cells expressing human GPR146 to study human and murine C-peptide in dynamic mass redistribution and GPCR β-arrestin assays, as well as with fluorescence confocal microscopy. Neither assay revealed any significant intracellular response to C-peptide at concentrations of up to 33 µM. We observed no internalisation of C-peptide by fluorescence microscopy. Our results do not support GPR146 as the receptor for C-peptide, but suggest that further investigations of the mode of action of C-peptide should be undertaken.