Cell signalling pathways underlying induced pluripotent stem cell reprogramming

Induced pluripotent stem(i PS) cells, somatic cells reprogrammed to the pluripotent state by forced expression of defined factors, represent a uniquely valuable resource for research and regenerative medicine. However, this methodology remains inefficient due to incomplete mechanistic understanding of the reprogramming process. In recent years, various groups have endeavoured to interrogate the cell signalling that governs the reprogramming process, including LIF/STAT3, BMP, PI3 K, FGF2, Wnt, TGFβ and MAPK pathways, with the aim of increasing our understanding and identifying new mechanisms of improving safety, reproducibility and efficiency. This has led to a unified model of reprogramming that consists of 3 stages: initiation, maturation and stabilisation. Initiation of reprogramming occurs in almost all cells that receive the reprogramming transgenes; most commonly Oct4, Sox2, Klf4 and c Myc, and involves a phenotypic mesenchymal-to-epithelial transition. The initiation stage is also characterised by increased proliferation and a metabolic switch from oxidative phosphorylation to glycolysis. The maturation stage is considered the major bottleneck within the process, resulting in very few "stabilisation competent" cells progressing to the final stabilisation phase. To reach this stage in both mouse and human cells, pre-i PS cells must activate endogenous expression of the core circuitry of pluripotency, comprising Oct4, Sox2, and Nanog, and thus reach a state of transgene independence. By the stabilisation stage, i PS cells generally use the same signalling networks that govern pluripotency in embryonic stem cells. These pathways differ between mouse and human cells although recent work has demonstrated that this is context dependent. As i PS cell generation technologies move forward, tools are being developed to interrogate the process in more detail, thus allowing a greater understanding of this intriguing biological phenomenon.

Regulation of microRNAs in cell signaling pathways-mediated vascular remodeling

Vascular remodeling,which can be found in atherosclerosis,restenosis after angioplasty,hypertension,and some other frequent and serious chronic diseases.Smooth muscle cell(SMC)phenotype change,which has been described as converting from a contractile state into a synthetic phenotype,is a crucial event during vascular remodeling.Recently,micro RNAs(mi RNAs)a kind of small non-coding RNA molecules,has been proven to target critical genes of cell signaling pathways to regulate SMC phenotypic change.By searching the Pub Med,Embase,reviews,and reference listsof relevant papers,we systematically carried out a review of the literature to provide an overview of the mi RNAs and their target genes in cell signaling pathways,focus inthe pathways involving in SMC phenotype change.To be specific,mi RNAs that regulate genes involved in the MAPK signaling pathways(such as:mi R-155,mi R-92a,mi R-424/503,mi R-133,mi R-181b,mi R-31,mi R-1298,mi R-132,mi R-200c and mi R-483-3p),mi RNAs target genes involved in the TGF-βsignaling pathways(including mi R-24,mi R-17/92 cluster,mi R-599,mi R-21 and mi R-143/145),mi RNAs target the genes involved in the AMPK signaling pathways including mi R-144/451 and mi R-195,mi RNAs target the genes involved in the PI3K-Akt signaling pathways(including mi R-138,mi R-34c,mi R-223,mi R-761,mi R-10a,mi R-146a),mi R-199a-5ptargets the genes involved in the Wnt signaling pathways mi RNAs(mi R-221/222,mi R-15b,mi R-24/29a,mi R-224)involved in the PDGF signaling pathways and some mi RNAs(mi R-638,mi R-328,mi R-365,mi R-663,mi R-29b,mi R-130,mi R-142-5p,mi R-424/322)which regulate SMC phenotype change by other corresponding targets were in detailed discussed in our review.Exploring the regulation of miR NAs in key cellsignaling pathways-mediatedvascular remodeling wil have momentous impact on identifying novel therapeutic targets for its associated disease.

Lysophospholipids in retinal axon guidance: roles and cell signaling

Nerve regeneration in the central nervous system（CNS）has become a holy grail of biomedical research.To understand nerve growth that would be required for efficient regeneration,many scientists have turned to developing systems where nerve growth is abundant and normal neural connections are established.One aspect of this neural development,which would also be important in nerve regeneration,

Research Progress of miRNA Regulating Cell Signaling Pathways Related to Hepatocarcinogenesis

Hepatocellular carcinoma(HCC)is one of the most common malignant tumors in clinical practice.The pathogenesis of HCC is still unclear.Currently,the clinical treatment of HCC is poorly targeted and the therapeutic effect is poor.MicroRNAs(miRNAs)are closely related to the occurrence of HCC,and they are mainly involved in the occurrence and development of HCC through binding to target genes or acting on related signaling pathways.In recent years,studies have shown that miRNA can be used as a potential biomarker for diagnosis and prognosis of HCC.In addition,studies have also shown that miRNA plays a tumorsuppressing or tumor-promoting role in the process of HCC by regulating the biological processes of tumor cell proliferation,migration,invasion and metastasis.In this paper,the recent studies on miRNA signaling pathways related to the occurrence and development of HCC were reviewed,with a view to providing ideas for the clinical diagnosis and treatment of HCC.

Epigenetic disruption of cell signaling in nasopharyngeal carcinoma

Nasopharyngeal carcinoma(NPC) is a malignancy with remarkable ethnic and geographic distribution in southern China and Southeast Asia.Alternative to genetic changes,aberrant epigenetic events disrupt multiple genes involved in cell signaling pathways through DNA methylation of promoter CpG islands and/or histone modifications.These epigenetic alterations grant cell growth advantage and contribute to the initiation and progression of NPC.In this review,we summarize the epigenetic deregulation of cell signaling in NPC tumorigenesis and highlight the importance of identifying epigenetic cell signaling regulators in NPC research.Developing pharmacologic strategies to reverse the epigenetic-silencing of cell signaling regulators might thus be useful to NPC prevention and therapy.

Early monitoring values of oncogenic signalling molecules for hepatocellular carcinoma

The prevention and early diagnosis of liver cancer remains a global medical challenge.During the malignant transformation of hepatocytes,a variety of oncogenic cellular signalling molecules,such as novel high mobility group-Box 3,angiopoietin-2,Golgi protein 73,glypican-3,Wnt3a(a signalling molecule in the Wnt/β-catenin pathway),and secretory clusterin,can be expressed and secreted into the blood.These signalling molecules are derived from different signalling pathways and may not only participate in the malignant transformation of hepatocytes but also become early diagnostic indicators of hepatocarcinogenesis or specific targeted molecules for hepatocellular carcinoma therapy.This article reviews recent progress in the study of several signalling molecules as sensitive biomarkers for monitoring hepatocarcinogenesis.

MIR-448 Regulates MAGEA6/AMPK Signaling Pathway in Hepatocellular Carcinoma Tumor Stem Cells

Objective: To explore the role of miR-448 in regulating MAGEA6/AMPK signaling pathway in the biological study of hepatocellular carcinoma (HCC) tumor stem cells. Methods: Using the database, the hepatocellular carcinoma related expression chips were obtained and the regulatory mirnas of candidate genes were predicted, and the predicted results were analyzed. The effects of miR-448 and MAGEA6 on the pellet formation rate and clone formation rate of hepatocellular carcinoma stem cells were detected by immunofluorescence identification of stem cell markers and light microscope counting method. The effects of miR-448 and MAGEA6 on migration and invasion of hepatocellular carcinoma stem cells were detected by scratch and Transwell assay. Dual luciferase reporter assay to verify whether miR-448 targets MAGEA6. The expression and influence of miR-448 on MAGEA6 and AMPK pathway were detected by qRT-PCR and Western blot. Results: It was found that miR-448 may directly regulate the expression of MAGEA6. Overexpression of miR-448 inhibited the characteristics, proliferation, migration, and invasion of hepatocellular carcinoma stem cells in vitro, as well as the ability of xenograft tumor formation in vivo. However, inhibition of miR-448 showed opposite results. In addition, miR-448 directly targets MAGEA6 and regulates AMPK signaling. Silencing MAGEA6 and adding AMPK activator further verified that miR-448 activated AMPK signaling pathway by targeting MAGEA6, thus affecting characteristics, proliferation, migration and invasion of hepatoma stem cells. Conclusions: Our results reveal that miR-448 activates AMPK signaling pathway by targeting MAGEA6, thereby affecting characteristics, proliferation, migration and invasion of hepatoma stem cells. It is suggested that overexpression of miR-448 may be a new therapeutic strategy for hepatocellular carcinoma.

JAK/STAT signaling regulates tissue outgrowth and male germline stem cell fate in Drosophila

In multicellular organisms, biological activities are regulated by cell signaling. The various signal transduction path- ways regulate cell fate, proliferation, migration, and polarity. Miscoordination of the communicative signals will lead to disasters like cancer and other fatal diseases. The JAK/STAT signal transduction pathway is one of the pathways, which was first identified in vertebrates and is highly conserved throughout evolution. Studying the JAK/STAT signal transduc- tion pathway in Drosophila provides an excellent opportunity to understand the molecular mechanism of the cell regu- lation during development and tumor formation. In this review, we discuss the general overview of JAK/STAT signaling in Drosophila with respect to its functions in the eye development and stem cell fate determination.

Osteogenesis stimulation by copper-containing 316L stainless steel via activation of akt cell signaling pathway and Runx2 upregulation

As a metallic orthopedic implant,316L stainless steel(316L SS)is used extensively for its good resistance to corrosion and mechanical properties.However,it takes a long time to achieve osseointegration between 316L SS and adjacent tissues due to its bio-inert characteristic.Hence,the aim is to improve the bio-adaption of 316L SS.A good approach is to add elements to materials to improve their osteogenic capabilities by the appropriate release of ions.Hence copper-containing 316L stainless steel(316L-Cu SS)was investigated in this work,where Cu is an essential trace element that can stimulates osteogenesis.It was found that 316L-Cu SS was bio-safe and did not affect the proliferation of co-cultured osteoblasts in comparison with 316L SS.It increased cell apoptosis on day 1 but inhibited it on day 3,which cooperates with new bone formation processes.Osteoblasts extend themselves more quickly and in a better manner on the surface of 316L-Cu SS,wheneven more pseudopodia are present.Furthermore,the gene expression of alkaline phosphatase,collagen I and runt-related transcription factor 2(Runx2)in osteoblasts cultured with 316L-Cu SS was significantly enhanced.Runx2 protein expression increased,and osteogenesis was stimulated by 316L-Cu SS via an Akt cell signaling pathway.In conclusion,316L-Cu SS stimulates osteogenesis through activation of the Akt cell signaling pathway and the upregulation of Runx2.Thus,316L-Cu SS is a promising material that may be used in surgical implants to stimulate osteogenesis.

Mitogen activated protein kinase signaling pathways participate in the active principle region of Buyang Huanwu decoction-induced differentiation of bone marrow mesenchymal stem cells

Our preliminary studies confirmed that an active principle region of Buyang Huanwu decoction, comprising alkaloid, polysaccharide, aglycon, glucoside and volatile oil, can induce bone marrow mesenchymal stem cell differentiation into neurons. Mitogen-activated protein kinase signaling was identified as one of the key pathways underlying this differentiation process. The present study shows phosphorylated extracellular signal-regulated protein kinase and phosphorylated p38 protein expression was increased after differentiation. Cellular signaling pathway blocking agents, PD98059 and SB203580, inhibited extracellular signal-regulated protein kinase and p38 in mitogen-activated protein kinase signaling pathways respectively, mRNA and protein expression of the neuronal marker, neuron specific enolase, and neural stem cell marker, nestin, were decreased in bone marrow mesenchymal stem cells after treatment with the active principle region of Buyang Huanwu decoction. Experimental findings indicate that, extracellular signal-regulated protein kinase and p38 in mitogen-activated protein kinase signaling pathways participate in bone marrow mesenchymal stem cell differentiation into neuron-like cells, induced by the active principle region of Buyang Huanwu decoction.

Cell signaling leads the way

Cells in plants, like in animals, constantly communicate with one another to coordinate their cellular activities in response to surrounding environmental conditions. Higher plants are multicellular organisms. A plant is originated from a single fertilized egg, which eventually develops into an intact individual with all necessary tissues and organs. Cell-to-cell communication is therefore especially critical throughout its life span, from embryo development, to tissue and organ formation, and finally to flowering and senescence, in addition.

Role of cell adhesion signal molecules in hepatocellular carcinoma cell apoptosis

AIM： Cell adhesion molecules and their signal molecules play a very important role in carcinogenesis. The aim of this study is to elucidate the role of these molecules and the signal molecules of integrins and E-cadherins, such as （focal adhesion kinase） FAK, （integrin linked kinase） ILK, and β-catenin in hepatocellular carcinoma cell apoptosis. METHODS： We first synthesized the small molecular compound, S-（1,2-dichlorovinyl）-L-cysteine （DCVC）, and identified it, by element analysis and ^1H NMR. To establish the apoptosis model of the SMMC-7721 hepatocellular carcinoma cell, we treated cells with DCVC in EBSS for different concentrations or for various length times in the presence of 20 μmol/L N,N-cliphenyl-p-phenylenediamine, which blocks necrotic cell death and identified this model by flow cytometry and DNA ladder. Then we studied the changes of FAK, ILK, β-catenin, and PKB in this apoptotic model by Western blot. RESULTS： We found that the loss or decrease of cell adhesion signal molecules is an important reason in apoptosis of SMMC-7721 hepatocellular carcinoma cell and the apoptosis of SMMC-7721 cell was preceded by the loss or decrease of FAK, ILK, PKB, and β-catenin or the damage of cell-matrix and cell-cell adhesion. CONCLUSION： Our results suggested that the decrease of adhesion signal molecules, FAK, ILK, PKB, and β-catenin, could induce hepatocellular carcinoma cell apoptosis.

Niclosamide,an old antihelminthic agent,demonstrates antitumor activity by blocking multiple signaling pathways of cancer stem cells

Niclosamide,an oral antihelminthic drug,has been used to treat tapeworm infection for about 50 years.Niclosamide is also used as a molluscicide for water treatment in schistosomiasis control programs.Recently,several groups have independently discovered that niclosamide is also active against cancer cells,but its precise mechanism of antitumor action is not fully understood.Evidence supports that niclosamide targets multiple signaling pathways (NF-κB,Wnt/β-catenin,Notch,ROS,mTORC1,and Stat3),most of which are closely involved with cancer stem cells.The exciting advances in elucidating the antitumor activity and the molecular targets of this drug will be discussed.A method for synthesizing a phosphate pro-drug of niclosamide is provided.Given its potential antitumor activity,clinical trials for niclosamide and its derivatives are warranted for cancer treatment.

B cell receptor signaling pathway involved in benign lymphoepithelial lesions of the lacrimal gland

AIM：To detect the expression of B cell receptor signaling pathway（BCRSP） in lacrimal gland benign lymphoepithelial lesions（LGBLEL）.METHODS：Gene microarray was used to compare whole-genome expression in lacrimal gland tissues from LGBLEL patients to tissues from orbital cavernous hemangioma（control tissues）. Expression of BCRSP was confirmed by polymerase chain reaction（PCR） and immunohistochemistry. RESULTS：The expression of 22 genes of the BCRSP increased significantly in LGBLEL patients. PCR analysis showed that CD22, CR2, and BTK were all highly expressed in LGBLEL tissues. Immunohistochemical analysis showed that CR2 protein was present in LGBLEL, but CD22 and BTK proteins were negative. CR2, CD22, and BTK were not observed in the orbital cavernous hemangiomas with either PCR or immunohistochemistry. CONCLUSION：BCRSP might be involved in the pathogenesis of LGBLEL.

Neural differentiation from embryonic stem cells in vitro : An overview of the signaling pathways

Neurons derived from embryonic stem cells(ESCs) have gained great merit in both basic research and regenerative medicine. Here we review and summarize the signaling pathways that have been reported to be involved in the neuronal differentiation of ESCs,particularly those associated with in vitro differentiation. The inducers and pathways explored include retinoic acid, Wnt/b-catenin, transforming growth factor/bone morphogenetic protein, Notch, fibroblast growth factor, cytokine, Hedgehog, c-Jun N-terminal kinase/mitogen-activated protein kinase and others. Some other miscellaneous molecular factors that have been reported in the literature are also summarized and discussed. These include calcium, calcium receptor, calcineurin, estrogen receptor, Hox protein, ceramide, glycosaminioglycan, ginsenoside Rg1, opioids, two pore channel 2, nitric oxide, chemically defined medium, cellcell interactions, and physical stimuli. The interaction or crosstalk between these signaling pathways and factors will be explored. Elucidating these signals in detail should make a significant contribution to future progress in stem cell biology and allow, for example, better comparisons to be made between differentiation in vivo and in vitro. Of equal importance, a comprehensive understanding of the pathways that are involved in the development of neurons from ESCs in vitro will also accelerate their application as part of translational medicine.

Influence on Cellular Signal Transduction Pathway in Dairy Cow Mammary Gland Epithelial Cells by Galactopoietic Compound Isolated from Vaccariae segetalis

The galactopoietic mechanism of Vaccaria segetalis is still unknown. Understanding dibutyl phthalate （DBP） separated from Vaccaria segetalis on the expression of lactation signal transduction genes of mammary gland epithelial cells, including prlr, erα, akt1, socs2, pparγ and elf5, will be helpful to reveal the molecular mechanism. Western blot and qRT- PCR were used to study the change of prlr, erα, akt, socs2, pparγ, and elf5 expression at mRNA and protein level. Co- localization expression of prolactin receptor （PRLR） and estrogen receptor α （ERα） was observed by immunofluorescence; the expression changes of miRNAs （21, 125b, 143, and 195） and the secretion of β-casein and lactose were detected by qRT-PCR and RP-HPLC. The results showed that Vaccaria segetalis active compound had similar fuctions as estrogen and/or prolactin （PRL） in dairy cow mammary gland epithelial cells （DCMECs）, increased the expressions of prlr, erα, akt1, and elf5 genes, while repressed pparγ expressions. DBP promoted socs2 mRNA expression, but its protein expressions were repressed. Furthermore, both DBP and PRL could repress the expressions of miRNA-125b, miRNA-143 and miRNA- 195 in DCMECs. DBP could repress the expression of miRNA-21, while the influence of PRL on miRNA-21 was not certain. DBP could promote the lactation ability of DCMECs by regulating the ER and PRLR cellular signal transduction pathway.

Exogenous p27KIP1 expression induces anti-tumour effects and inhibits the EGFR/PI3K/Akt signalling pathway in PC3 cells

p27 is a cyclin-dependent kinase inhibitor that regulates the progression of cells from G1 to S phase of the cell cycle. Loss of p27 has been associated with disease progression and with an unfavourable outcome in prostate cancer. In this study, we investigated whether exogenous p27 expression in the human androgen-independent prostate cancer PC3 cell line had any effect on cell growth, and we studied the molecular mechanisms involved. p27 expression was restored in PC3 cells by plasmid delivery. Cell proliferation and apoptosis were assessed in PC3 cells transfected with p27. We also investigated the effects of p27 on the epidermal growth factor receptor （EGFR）/ phosphatidylinositol 3-kinase （PI3K）/Akt signalling pathway in PC3 cells. By restoring p27 expression in PC3 cells, we observed that p27 reduced proliferation and induced arrest in G0/G1 phase. Moreover, p27-transfected PC3 cells underwent apoptosis, as shown by flow cytometric analysis and western blotting analysis of Bcl-2, Bax, Bad, caspase-3 and poly（ADP-ribose）polymerase expression. Furthermore, the p27-induced anti-tumour action corre- lated with inhibition of the EGFR/PI3K/Akt signalling pathway, as confirmed by western blotting analysis and densitometry of EGFR, PI3K （p85）, Akt and p-Akts473 expression. Our results suggest that exogenous expression of p27 inhibits the proliferation of PC3 cells through induction of G1 arrest and apoptosis, and this process correlates with inhibition of the EGFR/PI3K/Akt signalling pathway.

Signaling involved in stem cell reprogramming and differentiation

Stem cell differentiation is regulated by multiple signaling events. Recent technical advances have reve-aled that differentiated cells can be reprogrammed into stem cells. The signals involved in stem cell pro-gramming are of major interest in stem cell research. The signaling mechanisms involved in regulating stem cell reprogramming and differentiation are the subject of intense study in the field of life sciences. In this review,the molecular interactions and signaling pathways related to stem cell differentiation are discussed.

Memory stem T cells generated by Wnt signaling from blood of human renal clear cell carcinoma patients

Objective: Memory stem T cells(Tscm) have attracted attention because of their enhanced self-renewal, multipotent capacity, and anti-tumor capacities. However, little is known about Tscm in patients with renal clear cell carcinoma(RCC) and the role of Wnt signaling in these cells. We evaluated Tscm from RCC patients concerning their activation of Wnt signaling in vitro and explored the mechanism of preferential survival.Methods: Flow cytometry identified surface markers and cytokines produced from accumulated Tscm in the presence of the glycogen synthase kinase beta inhibitor TWS119. Apoptosis was evaluated after induction using tumor necrosis factor-alpha.Immunofluorescence and Western blot analyses were used to investigate the activation of the nuclear factor-kappa B(NF-КB)pathway.Results: RCC patients had a similar percentage of CD4^+ and CD8^+ Tscm as healthy donors. Activation of Wnt signaling by TWS119 resulted in the accumulation of Tscm in activated T cells, but reversal of differentiated T cells to Tscm was not achieved.Preferential survival of Tscm was associated with increased anti-apoptotic ability mediated downstream of the NF-КB activation pathway.Conclusions: The finding that Tscm can accumulate by Wnt signaling in vitro in blood from RCC patients will help in devising new cancer therapy strategies of Tscm-based adoptive immunotherapy, such as dendritic cell-stimulated Tscm, and T cell receptor or chimeric antigen receptor-engineered Tscm.

Differentially expressed genes and signalling pathways are involved in mouse osteoblast-like MC3T3-E1 cells exposed to 17-β estradiol

Oestrogen is essential for maintaining bone mass, and it has been demonstrated to induce osteoblast proliferation and bone formation.In this study, complementary DNA（cDNA） microarrays were used to identify and study the expression of novel genes that may be involved in MC3T3-E1 cells’ response to 17-b estradiol. MC3T3-E1 cells were inoculated in minimum essential media alpha（a-MEM）cell culture supplemented with 17-b estradiol at different concentrations and for different time periods. MC3T3-E1 cells treated with1028mol？L2117-b estradiol for 5 days exhibited the highest proliferation and alkaline phosphatase（ALP） activity; thus, this group was chosen for microarray analysis. The harvested RNA was used for microarray hybridisation and subsequent real-time reverse transcription polymerase chain reaction（RT-PCR） to validate the expression levels for selected genes. The microarray results were analysed using both functional and pathway analysis. In this study, microarray analysis detected 5 403 differentially expressed genes,of which 1 996 genes were upregulated and 3 407 genes were downregulated, 1 553 different functional classifications were identified by gene ontology（GO） analysis and 53 different pathways were involved based on pathway analysis. Among the differentially expressed genes, a portion not previously reported to be associated with the osteoblast response to oestrogen was identified. These findings clearly demonstrate that the expression of genes related to osteoblast proliferation, cell differentiation, collagens and transforming growth factor beta（TGF-b）-related cytokines increases, while the expression of genes related to apoptosis and osteoclast differentiation decreases, following the exposure of MC3T3-E1 cells to a-MEM supplemented with 17-b estradiol. Microarray analysis with functional gene classification is critical for a complete understanding of complementary intracellular processes. This microarray analysis provides large-scale gene expression data that require further confirmatory studies.