Dysregulation of the Wnt pathway has been extensively studied in multiple diseases, including some angiogenic disorders. Wnt signaling activation is a major stimulator in pathological angiogenesis and thus, Wnt antagonists are believed to have therapeutic potential for neovascular disorders. Actually, some Wnt antagonists have been identified directly from the anti-angiogenic factor family. This review summarizes the recent progress toward understanding of the roles of Wnt pathway antagonists in angiogenic regulation and their mechanism of action, and exploring their therapeutic potential.
Adaptor Proteins, Signal Transducing ; metabolism ; Animals ; Humans ; Neovascularization, Pathologic ; physiopathology ; Repressor Proteins ; metabolism ; Signal Transduction ; physiology ; Wnt Proteins ; antagonists & inhibitors

OBJECTIVETo study the effect of human spastic paraplegia 21 protein (SPG21) on the replication of hepatitis B virus(HBV) and its regulatory mechanism.

METHODSHBV infectious clone pHBV1.3 and its promoter pHBV-Luc were transfected respectively into HepG2 cells with SPG21 of different concentrations, HBsAg and HBeAg in the supernatants were measured by enzyme linked immunosorbent assay (ELISA), expression of HBV core mRNA and protein were detected by RT-PCR and western blot, covalently closed circular DNA(ccc DNA) levels were measured by real-time PCR, and HBV promoter activity was measured by luminometer fluorescence detector.

RESULTSExpression of HBsAg, HBeAg, HBV core protein and cccDNA were upregulated by SPG21 as well as HBV promoter activity in a dose-dependent approach. The activity of HBV promoter increased to 1.63, 3.09 and 4.66 times in HepG2 cells treated with 50mug/ml, 100mug/ml and 200mug/ml SPG21 respectively during 48 hour-treated ( P less than 0.05), as compared to the control group.

CONCLUSIONSSPG21 can enhance the replication of HBV in HepG2 cells.

Adaptor Proteins, Signal Transducing ; metabolism ; Hep G2 Cells ; Hepatitis B virus ; metabolism ; physiology ; Humans ; Transfection ; Virus Replication

While several organs in mammals retain partial regenerative capability following tissue damage, the underlying mechanisms remain unclear. Recently, the Hippo signaling pathway, better known for its function in organ size control, has been shown to play a pivotal role in regulating tissue homeostasis and regeneration. Upon tissue injury, the activity of YAP, the major effector of the Hippo pathway, is transiently induced, which in turn promotes expansion of tissue-resident progenitors and facilitates tissue regeneration. In this review, with a general focus on the Hippo pathway, we will discuss its major components, functions in stem cell biology, involvement in tissue regeneration in different organs, and potential strategies for developing Hippo pathway-targeted regenerative medicines.
Adaptor Proteins, Signal Transducing ; metabolism ; Animals ; Homeostasis ; physiology ; Humans ; Phosphoproteins ; metabolism ; Protein-Serine-Threonine Kinases ; metabolism ; Regeneration ; physiology ; Signal Transduction ; physiology

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These f indings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.
Mesenchymal Stem Cells/physiology* ; Cellular Senescence ; Homeostasis ; Cell Cycle Proteins/metabolism* ; Adaptor Proteins, Signal Transducing/metabolism* ; Mitochondria/metabolism* ; Electron Transport Complex III/metabolism* ; Humans ; Cells, Cultured

OBJECTIVETo investigate function of the Lim-only protein(LMO2) in hemangioblast generated from murine embryonic stem cells differentiation to hematopoietic cells.

METHODSThe hemangioblast-specific expression vector with lmo2 or green fluorescence protein gene was constructed, respectively. The murine embryonic stem cells were transfected by the hemangioblast-specific expression vectors. The neomycin-resistance ES cell clones were obtained after having been screened by G418. The cell clones were spontaneously differentiated into embryo bodies(EB) containing hemangioblast.Expression of the hematopoietic genes was investigated by real-time reverse transcription-ploymerase chain reaction during EB differentiation.For the EB cells, blast-cloning forming cells analysis and blood-colony forming unit analysis were then performed, respectively. The numbers of the blasts were counted during hematopoietic differentiation.

RESULTSThe hemangioblast-specific expression vector with lmo2 or green fluorescence protein was transfected into ES cells.The neomycin-resistance ES cells generated EBs from 2.5 days to 10 days.Real time reverse transcription-ploymerase chain reaction analysis indicated that overexpression of lmo2 increased the expression of hematopoietic genes(gata1, tal1, Β-h1, and Β-major globin) during EB formation.Blast-cloning forming cells analysis showed that the numbers of the blasts generated by ES/lmo2 was 2-or 3-fold than those in the controls.The total numbers of the blood-colony forming unit or the numbers of the erythrocyte colony-forming unit generated by ES/lmo2 were 2.5 times or 3 times, respectively, when compared with the controls.

CONCLUSIONLMO2 enhances the proliferation and differentiation of hemangioblasts.

Adaptor Proteins, Signal Transducing ; physiology ; Animals ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Embryonic Stem Cells ; cytology ; Hematopoietic Stem Cells ; cytology ; metabolism ; LIM Domain Proteins ; physiology ; Mice

LMO4 is a novel member of the LIM-only (LMO) subfamily of LIM domain-containing transcription factors, so named because they are composed almost entirely of two tandem LIM domains. This subgroup of LIM proteins has 4 members: LMO-1, LMO-2, LMO-3 and LMO-4. They all play important roles in the normal mammalian development, functioning as an important regulator of cell proliferation. LMO4 is highly expressed in the epithelial compartments at locations of active epithelial-mesenchymal interactions, and can interact with some signaling pathways involved in epithelial-mesenchymal signaling. Thus the disregulation of LMO4 expression may be involved in tumorigenesis. In this paper, we will at first expound LMO4 in detail, based on which the possible mechanisms for its interaction with TGF-β signaling and the roles of this cross-talk between them in the vital process of cell will be introduced. All of those will add to our understanding of tumorigenesis and contribute to the search of new targets for the treatment of cancer.
Adaptor Proteins, Signal Transducing ; Epithelial-Mesenchymal Transition ; Homeodomain Proteins ; metabolism ; physiology ; Humans ; LIM Domain Proteins ; Neoplasms ; metabolism ; pathology ; Signal Transduction ; Transcription Factors ; metabolism ; physiology ; Transforming Growth Factor beta ; metabolism

To study the cellular changes and the potential role of CD2-associated protein (CD2AP) in podocyte differentiation, conditionally immortalized murine podocyte cell line was cultured in RPMI 1640 medium under permissive condition at 33 °C. After transfection with CD2AP small interfering RNA (siRNA) the cells were shifted to non-permissive condition at 37 °C. Simultaneously, untransfected cells were taken as differentiation control. The podocyte proliferation rate was determined by MTT method. The expressions of CD2AP, WT1, synaptopodin and nephrin mRNAs were examined by RT-PCR. CD2AP, WT1 and nephrin protein expressions were examined by Western blot. The distribution of CD2AP, nephrin, F-actin and tubulin in differentiated and undifferentiated podocytes was detected by laser scanning confocal microscopy. The results showed: (1) CD2AP, WT1 and nephrin were stably expressed in differentiated and undifferentiated podocytes while synaptopodin was only expressed in differentiated podocytes. (2) CD2AP and nephrin mRNA and protein expressions were up-regulated during podocyte differentiation (P<0.05). (3) CD2AP and tubulin were distributed in the cytoplasm and perinulcear region in undifferentiated podocytes, and F-actin was predominantly localized to a cortical belt and paralleled to the cell axis. Under differentiation condition, CD2AP distribution profile was presented as peripheral accumulation, tubulin took on fascicular style and F-actin extended into foot processes in podocytes. CD2AP colocalized with nephrin and F-actin in undifferentiated podocytes. (4) After transfection with CD2AP siRNA, the expression of CD2AP was partially inhibited and cell growth was arrested; Synaptopodin, the differentiation podocyte marker, was apparently down-regulated; The differentiation of podocytes was delayed. The results demonstrate that podocyte differentiation is accompanied by cytoskeleton rearrangement and cell morphology change. CD2AP might play an essential role in podocyte differentiation.
Actins ; metabolism ; Adaptor Proteins, Signal Transducing ; physiology ; Animals ; Cell Differentiation ; Cell Line ; Cytoskeletal Proteins ; physiology ; Cytoskeleton ; metabolism ; Membrane Proteins ; metabolism ; Mice ; Microfilament Proteins ; metabolism ; Podocytes ; cytology ; RNA, Small Interfering ; Transfection ; WT1 Proteins ; metabolism

OBJECTIVETo study the role of adaptor protein Dok6 in neurite outgrowth in PC12 cells.

METHODSSeries of fusion clones were constructed by fusing different domains of Dok6 into mutant TrkC/Y516F. These constructs were transiently transfected into PC12 cells separately and the expression levels of fusion proteins were detected by Western blot. Neurite outgrowth in these PC12 cells was tested after stimulation of NT-3.

RESULTSEach fusion clone was stably expressed in PC12 cells. The fusion clones that fused both TrkC/Y516F-Dok6 (PTB+C) and TrkC/Y516F-Dok6C rescued the loss of neurite outgrowth in PC12 cells resulting from the mutation in tyrosine 516, while fusion clones that fused with single TrkC/Y516F-Dok6PTB did not show such effect.

CONCLUSIONDok6 can promote neurite outgrowth induced by NT-3 stimulation through its C-terminal in TrkC-positive PC12 cells.

Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Animals ; Neurites ; drug effects ; physiology ; Neurotrophin 3 ; pharmacology ; PC12 Cells ; Rats ; Receptor, trkC ; metabolism ; Transfection

BACKGROUNDTransient sublethal ischemia is known as ischemic preconditioning, which enables cells and tissues to survive subsequent prolonged lethal ischemic injury. Ischemic preconditioning exerts neuroprotection through phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Cbl-b belongs to the Casitas B-lineage lymphoma (Cbl) family, and it can regulate the cell signal transduction.The roles of ubiquitin ligase Cbl-b and PI3K/Akt pathway and the relationship between them in oxygen-glucose deprivation preconditioning (OGDPC) in PC12 cells were investigated in the present study.

METHODSOxygen and glucose deprivation (OGD) model in PC12 cells was used in the present study. The 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, nuclear staining with Hoechst 33258, and Western blotting were applied to explore the roles of Cbl-b and PI3K/Akt pathway and the relationship between them in OGDPC in PC12 cells.

RESULTSCell viability was significantly changed by OGD and OGDPC. OGD significantly decreased cell viability compared with the control group (P < 0.05), and preconditioning could rescue this damage was demonstrated by the increase of cell viability (P < 0.05). The expression of Cbl-b was significantly increased after OGD treatment. However, the activation of Akt and GSK3β was greatly inhibited. Preconditioning could inhibit the increase of Cbl-b caused by OGD and increase the activation of Akt and GSK3β. LY294002, a specific inhibitor of PI3K, could effectively inhibit the increase of Akt and GSK3β after preconditioning treatment. It partly inhibited the decrease of Cbl-b expression after preconditioning treatment.

CONCLUSIONUbiquitin ligase Cbl-b and PI3K/Akt pathway are differently involved in OGDPC in PC12 cells.

Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Animals ; Cell Survival ; Glucose ; deficiency ; Ischemic Preconditioning ; Oxygen ; metabolism ; PC12 Cells ; Phosphatidylinositol 3-Kinase ; genetics ; metabolism ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; Proto-Oncogene Proteins c-cbl ; genetics ; metabolism ; Rats ; Signal Transduction ; physiology

BACKGROUNDCD44v6 plays an important role in invasion and metastasis of tumor, Livin has anti-apoptotic effects. The present study aimed to explore the expression and clinical significance of CD44v6 and Livin in gastric cancer tissue.

METHODSStreptavidin-peroxidase linked immunohistochemical method was used to determine the expression of CD44v6 and Livin in gastric cancer tissue and adjacent normal gastric tissues from 59 patients with histopathologically confirmed gastric cancer, and in gastric tissue specimens of 15 patients with gastric polyps, and 15 patients with chronic non-atrophic gastritis. The chi-square test was used for comparison of the relevant factors, Spearman's rank correlation test was applied for relationship among positive expression of the proteins.

RESULTSThe expresion of CD44v6 was positive in 64.4% of the gastric cancer patients; 5.1%, 0 and 13.3% in specimens of normal tissues adjacent to the cancer tissues, in gastric tissue specimens of patients with gastric polyps, and patients with chronic non-atrophic gastritis, respectively. The expression of Livin was positive in 52.5% of the gastric cancer tissues, 6.8%, 0 and 6.7% in the adjacent normal gastric tissue, specimens of patients with gastric polyps and chronic non-atrophic gastritis, respectively. The expression of CD44v6 was significantly correlated with the depth of invasion, the degree of differentiation, and lymphnode metastasis of gastric cancer (P < 0.05). The positive expression rate of Livin protein was also significantly correlated with degree of differentiation of gastric cancer cells and metastasis to lymphnodes (P < 0.05), but not correlated with the depth of invasion and pathological types (P > 0.05). The expression of CD44v6 and Livin in the gastric cancer tissue was positively correlated (r(s) = 0.286, P = 0.028).

CONCLUSIONSThe increased expression of CD44v6 and Livin in gastric cancer tissue may be closely related with development and progression of gastric cancer. CD44v6 and Livin may be new biological markers of gastric cancer.

Adaptor Proteins, Signal Transducing ; analysis ; physiology ; Aged ; Female ; Humans ; Hyaluronan Receptors ; analysis ; physiology ; Immunohistochemistry ; Inhibitor of Apoptosis Proteins ; analysis ; physiology ; Male ; Middle Aged ; Neoplasm Proteins ; analysis ; physiology ; Stomach Neoplasms ; chemistry ; metabolism ; pathology