Angiopoietins(ANGPT) and their endothelial cell-specific tyrosine kinase receptors TEK are the major regulators of blood vessels angiogenesis under physiological and pathologic conditions. ANGPT1 is essentially involved in maturation, stabilization, and remodeling of blood vessels through inducing TEK autophosphorylation, promoting endothelial cell migration and survival. Instead, ANGPT2 appears to act as a natural antagonist of ANGPT1, it can activate vascular remodeling with the presence of vascular endothelial growth factor(VEGF) or regress frank blood vessels under the absence of VEGF. High expression of angiopoietins and TEK is often detected in tumor tissues. Many studies showed that disrupting the ANGPT/TEK receptor pathway could inhibit the growth of a number of murine tumors and human tumors. Thus, it is possible that inhibitors targeting the ANGPT/TEK pathway will have broad clinical utility to treatment of cancer.
Angiopoietin-1 ; physiology ; Angiopoietin-2 ; physiology ; Angiopoietins ; physiology ; Humans ; Neovascularization, Physiologic ; physiology ; Receptor, TIE-2 ; physiology

Angiopoietin-1 ; chemistry ; physiology ; Angiopoietin-2 ; chemistry ; physiology ; Angiopoietins ; physiology ; Animals ; Cardiovascular Diseases ; therapy ; Embryonic and Fetal Development ; Humans ; Neoplasms ; blood supply ; Receptor, TIE-2 ; chemistry ; physiology ; Signal Transduction

Angiopoietin-1 (Ang1) binds to and activates Tie2 receptor tyrosine kinase. Ang1-Tie2 signal has been proposed to exhibit two opposite roles in the controlling blood vessels. One is vascular stabilization and the other is vascular angiogenesis. There has been no answer to the question as to how Tie2 induces two opposite responses to the same ligand. Our group and Dr. Alitalo's group have demonstrated that trans-associated Tie2 at cell-cell contacts and extracellular matrix (ECM)-anchored Tie2 play distinct roles in the endothelial cells. The complex formation depends on the presence or absence of cell-cell adhesion. Here, we review how Ang1-Tie2 signal regulates vascular maintenance and angiogenesis. We further point to the unanswered questions that must be clarified to extend our knowledge of vascular biology and to progress basic knowledge to the treatment of the diseases in which Ang1-Tie2-mediated signal is central.
Angiopoietin-1/*physiology ; Animals ; Cell Adhesion/physiology ; Cell Movement/physiology ; Endothelial Cells/*physiology ; Endothelium, Vascular/physiology ; Extracellular Matrix/*metabolism ; Humans ; Neovascularization, Physiologic/physiology ; Receptor, TIE-2/*physiology ; Signal Transduction/*physiology

OBJECTIVETo study the effect of dexamethasone on airway morphology and on the expression of angiopoietin-1 (Ang-1) and its tyrosine kinase receptor Tie-2 in the airway of asthmatic rats.

METHODSForty-five Sprague-Dawley rats were randomly divided into control, asthmatic, and dexamethasone-treated asthmatic groups. Asthma was induced by repeated sensitization and challenge with ovalbumin in the latter two groups. The dexamethasone intervention group received an intraperitonea injection of dexamethasone (2 mg/kg) before asthma challenge. Immunohistochemistry was used to measure the expression of Ang-1 and Tie-2 in the airway. Airway thickness was estimated by a computerized digital image analyzer.

RESULTSAirway thickness in the asthmatic group (33.9333+/-8.3791 micro m2/micro m) increased significantly compared with that in the control group (21.1333+/-2.7740 micro m2/micro m) (P<0.01). The dexamethasone intervention group also showed increased thickness of the airway (27.4000 +/- 4.6105 micro m2/micro m) compared with the control group (P<0.01), but the airway thickness in the dexamethasone intervention group was significantly reduced compared with that in the untreated asthmatic group (P<0.01). The expression of Ang-1 (103.9487+/-8.2914 vs 76.0320+/-3.7728; P<0.01) and Tie-2 (99.2307+/-8.1913 vs 75.3153+/-3.7321; P<0.01) in the airway increased significantly in the asthmatic group compared to controls. The expression of Ang-1 and Tie-2 in the airway of the dexamethasone intervention group (90.6180+/-5.2339 and 86.6633+/-3.7321, respectively) was statistically higher than that in the control group (P<0.01) but statistically lower than that in the untreated asthmatic group (P<0.01). Ang-1 and Tie-2 expression in the airway was positively correlated with the thickness of airway (r(Ang)-1=0.719r(Tie)-2=0.746P<0.01). There was also a positive correlation between Ang-1 and Tie-2 expression (r=0.742P<0.01).

CONCLUSIONSThe expression of Ang-1 and Tie-2 in the airway increased in asthmatic rats and was positively correlated with the thickness of the airway. Ang-1 and Tie-2 may participate in the process of airway remodeling in asthma. Dexamethasone can decrease the expression of Ang-1 and Tie-2 in the airway and relieve the changes of airway morphology.

Angiopoietin-1 ; analysis ; physiology ; Animals ; Asthma ; metabolism ; pathology ; Female ; Lung ; chemistry ; pathology ; Rats ; Rats, Sprague-Dawley ; Receptor, TIE-2 ; analysis ; physiology

BACKGROUNDAngiopoietin-1 (Ang-1) is an endothelial-specific growth factor that can promote angiogenesis. Studies demonstrated that Ang-1 can inhibit apoptosis of umbilical endothelial cells, but so far little is known about its effects on apoptosis of microvascular endothelial cells. With the apoptotic model of murine-cerebral-derived microvascular endothelial cells (bEnd.3) induced by serum-free culture, we attempted to clarify the molecular mechanism of bEnd.3 apoptosis, particularly its relation to cytochrome C (Cyt C).

METHODSThe cultured microvascular endothelial cell strain, bEnd.3 cell, was employed. An apoptotic model of bEnd.3 was established by serum-free culture. Flow cytometry after Annexin labeling and PI staining were used to assess the apoptotic effects of Ang-1 on bEnd.3, and the expression of Bax/Bcl-2, caspase 8, caspase 3, and Cyt C were detected with Western blotting and ELISA.

RESULTSThe apoptotic rate of bEnd.3 cells after stimulation with Ang-1 (100 ng/L) in serum-free medium was significantly higher than that in control group. Ang-1 inhibited early-stage apoptosis more than late-stage apoptosis provided by propidium iodide (PI) and AnnexinV double staining. The inhibition of Ang-1 on bEnd.3 cell apoptosis was strengthened with the increase in concentration (0 - 400 ng/ml). Ang-1 could decrease the expression of Bax, caspase3 and 8, and increase that of Bcl-2. The results of ELISA indicated that Ang-1 significantly decreased CytC content in cytoplasm and increase that in mitochondria.

CONCLUSIONSAng-1 could inhibit bEnd.3 apoptosis induced by serum-free medium culture. The apoptosis was associated with decreased Bax expression, increased Bcl-2 expression, which result in Cyt C transferring from mitochondria to cytoplasm, and then caspases activation are reduced and cell apoptosis is suppressed.

Angiopoietin-1 ; pharmacology ; Animals ; Annexin A5 ; analysis ; Apoptosis ; drug effects ; Caspase 3 ; Caspase 8 ; Caspases ; analysis ; Cells, Cultured ; Cytochromes c ; physiology ; Endothelial Cells ; cytology ; drug effects ; Mice ; Microcirculation ; drug effects ; bcl-2-Associated X Protein ; analysis

Men with diabetic erectile dysfunction (ED) respond poorly to the currently available oral phosphodiesterase-5 inhibitors. Therefore, functional therapies for diabetic ED are needed. Stromal vascular fraction (SVF) and the adenovirus-mediated cartilage oligomeric matrix angiopoietin-1 (Ad-COMP-Ang1) gene are known to play critical roles in penile erection. We previously reported that SVF and Ad-COMP-Ang1 have only a short-term effect in restoring erectile function. Further improvements to ED therapy are needed for long-lasting effects. In the present study, we aimed to test if the combination of SVF and Ad-COMP-Ang1 could extend the erection effect in diabetic ED. We found that the combination therapy showed a long-term effect in restoring erectile function through enhanced penile endothelial and neural cell regeneration. Combination therapy with SVF and Ad-COMP-Ang1 notably restored cavernous endothelial cell numbers, pericyte numbers, endothelial cell-cell junctions, decreased cavernous endothelial cell permeability, and promoted neural regeneration for at least 4 weeks in diabetic mice. In summary, this is an initial description of the long-term effect of combination therapy with SVF and Ad-COMP-Ang1 in restoring erectile function through a dual effect on endothelial and neural cell regeneration. Such combination therapy may have therapeutic potential for the treatment of diabetic ED.
Angiopoietin-1/genetics* ; Animals ; Diabetes Mellitus, Experimental/metabolism* ; Endothelium, Vascular/metabolism* ; Erectile Dysfunction/therapy* ; Genetic Therapy/methods* ; Intercellular Junctions/metabolism* ; Male ; Mesenchymal Stem Cell Transplantation ; Mice ; Penile Erection/physiology* ; Permeability

OBJECTIVETo investigate the effects of adenovirus-delivered angiopoietin-1 siRNA (Ad. Ang-1siRNA) on the expression of matrix metalloproteinase-2, 9 (MMP-2, 9) and tissue inhibitor of metallopro-teinase-1 (TIMP-1) in rats with acute lung injury (ALI) induced by phosgene (Psg).

METHODSWe first established a rat model of Psg-induced acute lung injury (ALI). The rats were randomly divided into 6 groups: air control group with exposure to air, air+adenovirus (air+Ad) group with caudal vein injection of 1×10(8) pfu/ml adenovirus 1 h after air exposure, air+Ad/Ang1 group with caudal vein injection of 1×10(8) pfu/ml Ad.Ang-1siRNA 1 h after air exposure, Psg group with exposure to 8.33 mg/L Psg (purity 100%, of the same volume as the inhaled air in the air control group) for 5 min, Psg+Ad group with caudal vein injection of 1×10(8) pfu/ml adenovirus 1 h after exposure to the same dose of Psg, and Psg+Ad/Ang1 group with caudal vein injection of 1×10(8) pfu/ml Ad.Ang-1siRNA 1 h after exposure to the same dose of Psg. Serum, bronchoalveolar lavage fluid (BALF), and lung tissue were collected 36 h after exposure. The protein expression of Ang-1, MMP-2, 9, and TIMP-1 in serum and BALF was determined by double-antibody sandwich ELISA. RT-PCR was used to determine the mRNA levels of Ang-1, MMP-2, 9, and TIMP-1 in lung tissue. The protein expression of MMP-2, 9 and TIMP-1 in lung tissue was determined by Western blot.

RESULTSA rat model of Psg-induced ALI was successfully established. The levels of MMP-2, 9 in serum, BALF, and lung tissue were significantly increased in the Psg group and Psg+Ad/Ang1 group as compared with the control group (P<0.01); no significant change was observed in serum TIMP-1 protein expression (P>0.05); interestingly, TIMP-1 protein expression in BALF and lung tissue was significantly increased (P<0.01). Compared with the Psg group, the Psg+Ad/Ang1 group showed a significant decrease in MMP-2, 9 expression in BALF, serum, and lung tissue (P<0.05), but no significant change in protein expression of TIMP-1 was discovered (P>0.05).

CONCLUSIONAd.Ang-1siRNA has a potential beneficial effect in rats with Psg-induced ALI through inhibition of MMP-2, 9 expression, but has no significant effect on the expression of TIMP-1.

Acute Lung Injury ; chemically induced ; metabolism ; Adenoviridae ; genetics ; Angiopoietin-1 ; physiology ; Animals ; Bronchoalveolar Lavage Fluid ; Chemical Warfare Agents ; toxicity ; Disease Models, Animal ; Lung ; metabolism ; Matrix Metalloproteinase 2 ; genetics ; Matrix Metalloproteinases ; metabolism ; Phosgene ; toxicity ; RNA, Messenger ; genetics ; RNA, Small Interfering ; Rats ; Tissue Inhibitor of Metalloproteinase-1 ; metabolism