F-box only protein 9 is an E3 ubiquitin ligase of PPARγ

Peroxisome proliferator-activated receptor gamma (PPARγ) is a critical regulator of carbohydrate and lipid metabolism, adipocyte differentiation and inflammatory response. Post-translational modification of PPARγ and its degradation involve several pathways, including the ubiquitin–proteasome system. Here, we identified F-box only protein 9 (FBXO9) as an E3 ubiquitin ligase of PPARγ. We screened interacting partners of PPARγ using immunoprecipitation and mass spectrometric analysis and identified FBXO9 as an E3 ubiquitin ligase of PPARγ. FBXO9 directly interacted with PPARγ through the activation function-1 domain and ligand-binding domain. FBXO9 decreased the protein stability of PPARγ through induction of ubiquitination. We found that the F-box motif of FBXO9 was required for its ubiquitination function. The activity of PPARγ was significantly decreased by FBXO9 overexpression. Furthermore, FBXO9 overexpression in 3T3-L1 adipocytes resulted in decreased levels of endogenous PPARγ and suppression of adipogenesis. These results suggest that FBXO9 is an important enzyme that regulates the stability and activity of PPARγ through ubiquitination.

Murine Sca1+Lin- bone marrow contains an endodermal precursor population that differentiates into hepatocytes

The direct differentiation of hepatocytes from bone marrow cells remains controversial. Several mechanisms, including transdifferentiation and cell fusion, have been proposed for this phenomenon, although direct visualization of the process and the underlying mechanisms have not been reported. In this study, we established an efficient in vitro culture method for differentiation of functioning hepatocytes from murine lineage-negative bone marrow cells. These cells reduced liver damage and incorporated into hepatic parenchyma in two independent hepatic injury models. Our simple and efficient in vitro protocol for endodermal precursor cell survival and expansion enabled us to identify these cells as existing in Sca1+ subpopulations of lineage-negative bone marrow cells. The endodermal precursor cells followed a sequential developmental pathway that included endodermal cells and hepatocyte precursor cells, which indicates that lineage-negative bone marrow cells contain more diverse multipotent stem cells than considered previously. The presence of equivalent endodermal precursor populations in human bone marrow would facilitate the development of these cells into an effective treatment modality for chronic liver diseases.

Effect of Hyperkalemia and Hemolysis Caused by Hyperacute Rejection on Cardiac Function in Pig to Human Ex Vivo Xenogeneic Cardiac Perfusion Model

BACKGROUND AND OBJECTIVES: Hyperacute rejection (HAR) is a major obstacle to successful xenotransplantation of vascularized organs. This study was conducted to observe the effect of hemolysis of perfused human whole blood on pig heart function, and determine the major risk factors for preservation of xenoperfused cardiac function using ex-vivo pig to human xenogeneic cardiac perfusion model. MATERIALS AND METHODS: Harvested pig hearts were perfused with normal human whole blood (group 1), two different types of pre-treated human whole blood (group 2: immunoglobulins were depleted by plasmapheresis, group 3: pre-treated with plasmapheresis, GAS914, cobra venom factor (CVF) and steroid), and normal porcine whole blood as control (group 4) for 3 hours. RESULTS: Duration of heart beat was significantly prolonged in group 2 and group 3. Histological examination showed widespread HAR features but was gradually delayed in groups 2 and 3 compared to group 1. The absolute levels of serum creatine kinase-MB and Troponin I increased gradually, and was lower in group 3. Serum hemoglobin levels were rapidly increased in groups 3 and 4, compared to group 1. Extracellular potassium level increased sharply from the beginning of blood perfusion in groups 1, 2 and 3, compared to group 4. CONCLUSION: Pretreatment of human whole blood, including immunoglobulin depletion, CVF and steroid reduced and delayed the destruction of pig myocardium by HAR. However, the increased extracellular potassium levels in groups 1, 2 and 3 reflected that these treatments could not prohibit myocardial injury by HAR.

Mechanism of Humoral and Cellular Immune Modulation Provided by Porcine Sertoli Cells

The understanding of main mechanisms that determine the ability of immune privilege related to Sertoli cells (SCs) will provide clues for promoting a local tolerogenic environment. In this study, we evaluated the property of humoral and cellular immune response modulation provided by porcine SCs. Porcine SCs were resistant to human antibody and complement-mediated formation of the membrane attack complex (38.41+/-2.77% vs. 55.02+/-5.44%, p=0.027) and cell lysis (42.95+/-1.75% vs. 87.99 +/-2.25%, p<0.001) compared to immortalized aortic endothelial cells, suggesting that porcine SCs are able to escape cellular lysis associated with complement activation by producing one or more immunoprotective factors that may be capable of inhibiting membrane attack complex formation. On the other hand, porcine SCs and their culture supernatant suppressed the up-regulation of CD40 expression (p<0.05) on DCs in the presence of LPS stimulation. These novel findings, as we know, suggest that immune modulatory effects of porcine SCs in the presence of other antigen can be obtained from the first step of antigen presentation. These might open optimistic perspectives for the use of porcine SCs in tolerance induction eliminating the need for chronic immunosuppressive drugs.

The Role of GADD45beta in Acute Myocardial Injury / 대한흉부외과학회지

BACKGROUND: A critical shortage of donor organs has necessitated an investigation of new strategies to increase the availability of additional organs available for human transplantation. We investigated the amount of apoptosis and expression of GADD45beta in two groups, a GADD45beta-transfected group and untransfected group. MATERIAL AND METHOD: The experimental groups consist of a control group (normal H9C2 cell line) and GADD45beta-transfected group. After injury of the each group, we evaluated the expression of GADD45beta and the level of apoptosis in each group. RESULT: There was a significant increase in the expression of GADD45beta in the GADD45beta-transfected group at 1 hour, 2 hours, and 3 hours after stimuli as compared with the control group. The amount of cardiac myoblast cell line apoptosis was significantly lower in the GADD45beta-transfected group as compared with the control group. The concentration of annexin in the GADD45beta-transfected group was significantly lower than that of the control group after cell injury. CONCLUSION: Transfection of a rat myoblast cell line with the GADD45beta gene results in decreased susceptibility to cell injury of human serum.

Role of Complement Regulatory Proteins in the Survival of Murine Allo-transplanted Sertoli Cells

Sertoli cells (SC) are known to contain immunoprotective properties, which allow them to survive as allografts without the use of immunosuppressive drugs. Experiments were designed to determine which factors are related to prolonged survival of allogeneic SC. Balb/c derived Sertoli (TM4) and colon cancer (CT-26) cell lines were implanted beneath the kidney capsule of non-immunosuppressed C57BL/6 mice and compared their survival as allografts. Compared to TM4 graft, which survived more than 7 days after transplantation, CT-26 showed massive infiltration of polymorphonuclear cells, necrosis and enlargement of draining lymph nodes. Cultured cell lines showed no differences in their expression patterns of FasL, TGF beta1, clusterin and two complement regulatory proteins (CRP, i.e., membrane cofactor protein, MCP; decay accelerating factor, DAF), but protectin (CD59), another member of CRP was expressed only on TM4. These results suggest that CD59 and unknown factors may contribute to the prolonged survival of SC in non-immunoprivileged sites.

Effect of Antibody Titer on Xenograft Survival in Pig-To-Dog Heterotopic Cardiac Xenotransplantation: Opening of Xenotransplantation Era / 대한흉부외과학회지

BACKGROUND: Xenotransplantation in discordant species results in immediate and irreversible hyperacute rejection due to natural antibodies, IgM. With this, antibody depletion is one option to reduce hyperacute rejection, we investigated the effect of PCPP (postcentrifugal plasmapheresis) on the depletion of natural antibodies and the effect of antibody titer on xenograft survival. MATERIAL ANDMETHOD: Outbred swines (n=4) weighing 10~20 kg were used as donors and mongrel dogs (n=4) weighing 25~30 kg were used as recipients. Recipient canines underwent plasmapheresis (COBE TPE Laboratories, Lakewood. CO, USA). Pre-transplantation PCPP was performed on day - 2 and day 0. There were three groups (Group 0: no PCPP, Group 1: 1 pla sma-volume (PV) at day 2 and 2 PV at day 0, Group 2: 2 PV at day - 2 and 2 PV at day 0). A swine heart was heterotopically transplanted into a recipient's abdominal infrarenal aorta and inferior vena cava. Mean percent depletion of total IgM and IgG in plasma of the recipients was calculated. Serum albumin, elecctrolyte, complement activity and coagualtion factors were measured. Histopathologic examination of heart specimens was performed. RESULT: Mean percent depletion of IgM and IgG were 95.7+/-1.2%, 80.5+/-2.4% in the group 2 at the end of PCPP. The percent depletion of serum albumin concentration was decreased from 2.8 to 1.4 g/dL in the group 1 and 3.0 to 1.5 g/dL in the group 2. Complement hemolytic activity was decreased in group 1 and 2, but returned to normal level within 24 hours. Complement hemolytic activity was reduced to 10% of pre-PCPP level in group 2. Serum fibrinogen decreased to 20% or less and was recovered within 24 hours in group 2. Antithrombin III decreased but less than fibrinogen. PT and aPTT were sometimes but not always prolonged during plasmapheresis. After plasmapheresis, PT and aPTT were prolonged beyond the measurable level. D-dimer was not found during PCPP, but appeared and maintained from 10 minutes after transplantation. Graft survival time was 5 min in group 0, and it was 90+/-0 min in the group 2. Histopathologic changes were more typically characterized by edema, hemorrhages, thrombosis in all groups at the end of experiment. CONCLUSION: PCPP effectively removed immuoglobulins and reduced the titer of natural antibodies, as a result, significantly prololonged swine heart xenograft survival.

A Short-Term Study of the Effects of UDCA on Gingival Inflammation in the Beagle Dog / 대한치주과학회지

Ursodeoxycholic acid(UDCA) is a hydrophilic gall bladder acid and has been used as a effective drug for liver disease related to immunity. This drug inhibits secretions of IL-2, IL-4, and IFN- ? from T-cells and production of immunoglobulin from B-cells. Also it has been reported that UDCA inhibits production of IL-1 related to the progression of periodontal disease and activation of collagenases. The purpose of the present study was to elucidate the effects of UDCA on inhibition of periodontal disease progression using clinical, microbiological and histometrical parameters. Twelve pure bred, 16 month-old-beagle dogs were used in the study. After ligature-induced periodontal diseases were formed, experimental drugs were applied twice a day and then the results of clinical, microbiological, and histometrical parameters were measured at baselie(initiation of experiment), 4weeks and 8weeks. The gel with UDCA(concentration 0.5%, 5% 3 dogs in each) was applied to experimental group, chlorhexidine to positive control group(3dogs) and the gel without UDCA(base) to negative control group. After induction of general anesthesia, the maxillary 2nd, 3rd premolars and 1st molar and the mandibular 2nd, 3rd-4th premolars and 1st molar were ligated in one side selected randomly and were not ligated in the opposite side. The plaque index(PI), gingival index(GI), pocket depth(PD) and gingival crevicular fluid(GCF) volum were measured clinically. The PI and GI were measured at 3 buccal points of all experimental teeth and the GCF was measured only at the 3rd premolar in the maxilla and the 4th premolar in the mandible. In the microbiological study, the samples extracted from the 3rd premolar of the maxilla and the 4th premolar of the mandible at the center of buccal surface were analyzed aerobics, anaerobics and Streptococcus colony forming units. After clinical and microbiological examination at 8weeks, the dogs were sacrificed by carotid artery perfusion. The samples were fixed and sectioned including interproximal area, and the distance from cementoenamel junction(CEJ) to alveolar crest was measured, The results were that PI, GI and PD increased until 4 weeks and decreased at 8 weeks in three groups but the differences between all the groups were not significant. The 0.5% UDCA in non-ligated group showed remarkable decrease of GCF. The experimental group applied 5% UDCA decreased the number of aerobics and anaerobics. The distance from CEJ to alveolar crest was greater in the negative control group on both ligated and non-ligated sides, but the differences were not significant stastically.