Biphasic effects of FGF2 on adipogenesis

Although stem cells from mice deficient of FGF2 have been reported to display enhanced capacity for adipogenesis, the literature using in vitro cell culture system has so far reported conflicting results on the role of FGF2 in adipogenesis. We here demonstrate that FGF2, depending on concentration, can function as either a positive or negative factor of in vitro adipogenesis by regulating activation of the ERK signaling pathway. FGF2 at concentrations lower than 2 ng/ml enhanced in vitro adipogenesis of human adipose-derived stem cells (hASCs). However, FGF2 at concentrations higher than 10 ng/ml was able to suppress adipogenesis by maintaining sustained phosphorylation of ERK and function as a dominant negative adipogenic factor toward BMP ligands. Expression levels of FGF2 in the fat tissues from high fat diet induced obese C57BL/6 mice were lower than those from normal chow diet mice, indicating that expression levels of FGF2 in the fat tissues might be in reverse correlation with the size of fat tissues. Our observation of concentration dependent biphasic effect as well as dominant negative effect of FGF2 on adipogenesis provides a mechanistic basis to understand roles of FGF2 in adipogenesis and development of fat tissues.

216 HORMONAL REGULATION OF CLAUDIN-4 TIGHT JUNCTION MOLECULE IN MOUSE PLACENTA

Tight junctions (TJ) are composed of a branching network of sealing strands. TJ regulate paracellular conductance and ionic selectivity. TJ components include the peripheral protein ZO-1, junctional adhesion molecules (JAM) and the integral proteins such as occludin and claudin. Claudins are a family of proteins that are the most important components in the tight junctions. The established paracellular transport barriers that control transportation of molecules within intercellular space. The present study focused on the expression of claudin, suggesting as major working molecules in the paracellular transport system. To study the regulation and roles of claudin family, we examined expression of mouse placental claudin family. Fifteen pregnant C57/BL6 mice were used in this study and TJ proteins including Claudin-1 to Claudin-24 expressions by real-time RT–PCR and Western blotting. The mice were divided into 3 groups depending on the gestational day (on Days 12, 16, and 20 of gestation).The localization of TJ proteins were examined by immunohistochemistry. After we identified the fluctuation of claudin expression during pregnancy, we assumed that the hormones are one regulator for claudin family. Therefore, we performed an in vivo study with hormone receptor antagonists (ICI 182, 780, and RU-486) for examining hormonal effect on claudin expression in the placenta. Forty-nine mice were divided into 7 groups. The changes of claudin expression were examined with real-time RT-PCR and Western blotting. In the transcription levels, Claudin-1, claudin-2, claudin-4, and Claudin-5 expression levels were relatively high compared to others in the claudin family in all periods of the pregnancy. The claudin-4 expression, which reduces permeability of ions, increased over a period of time. However, caludin-5 expression that is the responsive protein for a decrease in paracellular conductance, were decreased. Claudin-1 and -4 have been known as responsive genes for a decrease in paracellular conductance. On the other hand, claudin 2 and 5 have been known as increasing paracellular conductance. In addition, immunohistochemistry was performed to identify their localization for inferring permeability in placenta. In summary, we analysed the claudin expressions and presented possible important claudins among its family. Furthermore, their localization was also examined in the mouse placenta. In addition, the regulation of critically expressed claudins by pregnancy-associated hormones, E2 and P4, was examined. These results may provide functional and structural roles of claudins and their involvement in the maternal-fetal interaction and in the transportation of placental materials.

218 DISTINCT EXPRESSION OF CALCIUM TRANSPORT CHANNELS, TRPV5, TRPV6, PMCA1, NCKX3, AND CaBP-9k IN THE DUODENUM, KIDNEY, AND PLACENTA DURING PREGNANCY

Preeclampsia is a pregnancy-specific disease characterised by concurrent development of hypertension, proteinuria, and oxidative stress in the placenta. Preeclampsia-like genetic models were also developed by modification of preeclampsia-related genes, such as catechol-O-methyltranferase (COMT). In the current study, we hypothesised that inhibition of COMT alters the expression of calcium transport genes and contributes to induction of a preeclampsia-like condition, and the treatment regimen such as calcium supplementation ameliorates the imbalanced calcium metabolism and preeclamptic symptoms. In this study, we induced COMT inhibition in mice during pregnancy to reproduce physiological conditions associated with preeclampsia. The expression of genes known as hypoxia biomarker, HIF-1a, was highly induced in the placenta of this model. The overexpression of HIF-1a demonstrates that our experimental conditions closely were similar with preeclampsia. We measured the expression of several calcium transporters (TRPV5, TRPV6, PMCA1, and CaBP-9k) in the placenta, duodenum, and kidney after COMT inhibition on gestation day 17.5 (GD 17.5). Twenty-eight mice were divided into 4 groups [Vehicle, calcium, RO41–0960, and RO41–0960 and calcium (2% of calcium carbonate)]. In addition, we evaluated the calcium transporters in the kidney and duodenum of nonpregnant female mice. The placental TRPV5,6, PMCA1, and CaBP-9k were investigated by real-time RT-PCR. All experimental data was presented mean ± standard error of the mean (s.e.m.); P-values were calculated using one-way ANOVA. Placental TRPV5, TRPV6 and PMCA1 expressions were significantly down-regulated by COMT inhibitor (ro41–0960). In addition, the reduced PMCA1 expression in the placenta was reversed by calcium supplementation. Duodenal expressions of TRPV5, TRPV6, and PMCA1 were significantly decreased in the COMT-inhibited mice, and slightly recovered after calcium supplementation. Renal expression of TRPV5, TRPV6, and PMCA1 was also decreased by COMT inhibition, while it was reversed by calcium supplementation to the level of control. Duodenal- and renal calcium transporting genes, TRPV5, TPRV6, PMCA1, and CaBP-9k, were down-regulated by COMT treatment in female mice. Taken together, these results indicate that physiological changes observed in COMT inhibition showed similar symptoms as in preeclampsia, which may be related with disturbance of calcium metabolism during pregnancy.

Regulation of FSHβ induction in LβT2 cells by BMP2 and an Activin A/BMP2 chimera, AB215

Activins and bone morphogenetic proteins (BMPs) share activin type 2 signaling receptors but utilize different type 1 receptors and Smads. We designed AB215, a potent BMP2-like Activin A/BMP2 chimera incorporating the high-affinity type 2 receptor-binding epitope of Activin A. In this study, we compare the signaling properties of AB215 and BMP2 in HEK293T cells and gonadotroph LβT2 cells in which Activin A and BMP2 synergistically induce FSHβ. In HEK293T cells, AB215 is more potent than BMP2 and competitively blocks Activin A signaling, while BMP2 has a partial blocking activity. Activin A signaling is insensitive to BMP pathway antagonism in HEK293T cells but is strongly inhibited by constitutively active (CA) BMP type 1 receptors. By contrast, the potencies of AB215 and BMP2 are indistinguishable in LβT2 cells and although AB215 blocks Activin A signaling, BMP2 has no inhibitory effect. Unlike HEK293T, Activin A signaling is strongly inhibited by BMP pathway antagonism in LβT2 cells but is largely unaffected by CA BMP type 1 receptors. BMP2 increases phospho-Smad3 levels in LβT2 cells, in both the absence and the presence of Activin A treatment, and augments Activin A-induced FSHβ. AB215 has the opposite effect and sharply decreases basal phospho-Smad3 levels and blocks Smad2 phosphorylation and FSHβ induction resulting from Activin A treatment. These findings together demonstrate that while AB215 activates the BMP pathway, it has opposing effects to those of BMP2 on FSHβ induction in LβT2 cells apparently due to its ability to block Activin A signaling.

An activin A/BMP2 chimera, AB204, displays bone-healing properties superior to those of BMP2

Recombinant bone morphogenetic protein 2 (rhBMP2) has been used clinically to treat bone fractures in human patients. However, the high doses of rhBMP2 required for a therapeutic response can cause undesirable side effects. Here, we demonstrate that a novel Activin A/BMP2 (AB2) chimera, AB204, promotes osteogenesis and bone healing much more potently and effectively than rhBMP2. Remarkably, 1 month of AB204 treatment completely heals tibial and calvarial defects of critical size in mice at a concentration 10-fold lower than a dose of rhBMP2 that only partially heals the defect. We determine the structure of AB204 to 2.3 Å that reveals a distinct BMP2-like fold in which the Activin A sequence segments confer insensitivity to the BMP2 antagonist Noggin and an affinity for the Activin/BMP type II receptor ActRII that is 100-fold greater than that of BMP2. The structure also led to our identification of a single Activin A-derived amino acid residue, which, when mutated to the corresponding BMP2 residue, resulted in a significant increase in the affinity of AB204 for its type I receptor BMPRIa and a further enhancement in AB204's osteogenic potency. Together, these findings demonstrate that rationally designed AB2 chimeras can provide BMP2 substitutes with enhanced potency for treating non-union bone fractures.

Impact of vitamin D, bisphosphonate, and combination therapy on bone mineral density in kidney transplant patients

BACKGROUND

Osteoporosis can develop and become aggravated in kidney transplant patients; however, the best preventive options for post-transplantation osteoporosis remain controversial.

METHODS

We retrospectively analyzed cohort of 182 renal transplant recipients of mean age 46.7 ± 12.1 years including 47.3% women. Seventy-three patients received neither vitamin D nor bisphosphonate after transplantation (group 1). The other patients were classified into the following 3 groups: calcium plus vitamin D (group 2; n = 40); bisphosphonate (group 3; n = 18); and both regimens (group 4; n = 51). Bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry at baseline and at 1 year after transplantation.

RESULTS

At 1 year after transplantation, T-scores of the femoral neck and entire femur were significantly decreased in group 1 (-0.23 ± 0.65 [P = .004] and -0.21 ± 0.74 [P = .018], respectively), whereas the lumbar spine was significantly increased in group 4 (0.27 ± 0.79; P = .020). Post hoc analysis demonstrated that the delta T-score was significantly lower in group 1 than in group 4 (P = .009, 0.035, and 0.031 for lumbar spine, femoral neck, and entire femur, respectively). In a multivariate analysis adjusted by age, sex, body mass index, dialysis duration, diabetes, calcineurin inhibitors, estimated glomerular filtration rate, and persistent hyperparathyroidism, both group 2 and group 4 showed protective effects on BMD reduction (odds ratio [OR], 0.165; 95% confidence interval [CI] 0.032-0.845 [P = .031]; and OR, 0.169; 95% CI, 0.045-0.626 [P = .008]; respectively). However, group 3 did not show a protective effect (OR, 0.777; 95% CI, 0.198-3.054; P = .718), because their incidence of persistent hyperparathyroidism after transplantation was significantly higher (50.0%) than the other groups (P < .001). The incidence of bone fractures did not differ among the groups.

CONCLUSIONS

Combination therapy with vitamin D and bisphosphonate was the most effective regimen to improve BMD among kidney recipients.

Effects of xenoestrogens on streptozotocin-induced diabetic mice

In diabetic mellitus, apoptotic or necrotic deaths of pancreatic β-cells lead to insulin deficiency because plasma insulin is synthesized and released from pancreatic β-cells and involved with blood glucose homeostasis. Since estrogen receptors have been related with glucose metabolis, estrogen-like chemicals (xenoestrogens) including bisphenol A (BPA) and octylphenol (OP) alter the endocrine system, and cause adverse health consequences such as obesity and diabetes. In the current study, levels of plasma glucose were evaluated after administration of BPA and OP using biochemical analysis, and were investigated in insulin and insulin synthesis-related genes in the pancreas and liver of streptozotocin (STZ)-induced insulin-deficient mice. Although the STZ-induced insulin-deficient groups showed an increase in blood glucose compared with control groups, the induced blood glucose level dropped to that of baseline after administration of xenoestrogens. When insulin level and mRNA expression of insulin transcriptional regulators (Pdx1, Mafa, and Neurod1) in pancreatic β-cells were decreased in STZ-induced insulin-deficient groups, they were significantly restored by administration of xenoestrogens. The latter observation is also related to NF-κB activation for anti-apoptosis effects in pancreatic β-cells. In addition, we observed a complementary convergence in regulation of gluconeogenesis for determination of blood glucose levels. Therefore, the current study may be particularly important for assessment of xenoestrogens under condition of diabetic mellitus or metabolic disorder.

Effects of newly developed chemotherapy regimens, comorbidities, chemotherapy-related toxicities on the changing patterns of the leading causes of death in elderly patients with colorectal cancer

BACKGROUND

Abundant evidences have shown that newly developed chemotherapy regimens improved 5-year survival rate of colorectal cancer (CRC) patients over the past two decades. However, their impact on risk of death from leading causes among elderly patients is still poorly understood.

PATIENTS AND METHODS

A retrospective cohort study of 69 718 elderly CRC patients with their first primary tumors in 1992-2009, identified from the 12 areas of Surveillance, Epidemiology, and End Results-Medicare linked database with their Medicare claims up to 2010. Multivariate Cox regression models were used to assess the effect of newly developed chemotherapy regimens, comorbidities, and chemotherapy related toxicities on cause-specific death and their temporal patterns among elderly CRC patients.

RESULTS

The leading causes of death among CRC patients were CRC, circulation disorders, and secondary cancers, which accounted for 51.4%, 25%, and 4.6% of all-cause death, respectively. Patients diagnosed in more recent diagnostic time periods were significantly less likely to die of CRC [period 2: 5-year hazard ratio = 0.94, 95% confidence interval (CI) 0.90-0.97; period 3: 0.86, 0.83-0.90], circulation disorders (period 2: 0.94, 0.88-1.00; period 3: 0.80, 0.75-0.87), and more likely to die of secondary cancer (period 3: 1.42, 1.20-1.68) compared with those diagnosed in period 1. Charlson comorbidities index and the selected pre-existing comorbidities were significantly associated with increased 5-year risk of death from all three leading causes. Both hematological and gastric toxicity were associated with reduced risk of death from CRC and circulation disorders. The association between diagnostic time period and risk reduction in death from CRC depended on chemotherapy treatment (P < 0.0001). Subgroup analyses showed that the chemotherapy-dependent significant risk reduction was seen in patients with stage II-III CRC, patients without comorbidities, and patients without toxicities (P < 0.0001 for all).

CONCLUSION

The newly developed chemotherapy regimens were associated with the decreased risk of mortality from CRC.

128 EXPRESSIONS OF MOUSE TIGHT JUNCTION MOLECULES IN PLACENTA – CLAUDINS AND OTHER PARACELLULAR TRANSPORT MOLECULES

Tight junctions (TJ) are composed of a branching network of sealing strands. Tight junctions regulate paracellular conductance and ionic selectivity. The TJ components include the peripheral protein ZO-1, junctional adhesion molecules (JAM), and integral proteins, such as occludin and claudin. Claudins, a family of proteins, are the most important components in TJ. They establish paracellular transport barriers, which control transportation of molecules within intercellular space. The current study focused on expression of claudin, suggesting claudin as a major working molecule in the paracellular transport system. In order to study the mechanisms and roles of the claudin family, the expression levels of claudin family in various organs should be determined. In this study, we examined expression of the mouse placental claudin family. Pregnant C57/BL6 mice (n = 5) were used in this study, and compared with β-actin, expression of TJ proteins, including Claudin-1 to Claudin-24, JAM-a, Zo-1, and occludin, tricellulin, and MarvelD3 was examined. In the transcription levels, Claudin-1 and -4 proteins were predominantly expressed. Claudin-1 and -4 have been known as a responsive gene for a direct decrease in paracellular conductance by selective reduction of the permeability of Na+ ions. On the other hand, Claudin-2, Claudin-3, Claudin-5, Cludin-11, and Claudin-12 showed ~33% expression compared with Claudin-1. Claudin-6 and Claudin-7 showed ~20% relative expression compared to Claudin 1. Claudin-10a and Claudin-16 were not detectable by real-time RT-PCR under our experimental conditions. Other claudin proteins showed low expression. Because the transcriptional levels of TJ genes were expressed variously, protein levels and their localization in the placenta will be further evaluated by immunostaining and Western blot assay. This study will provide data on expression of TJ genes and their localization in the mouse placenta, which may contribute to assuming the roles of these TJ genes regarding maternal-fetal ion transportation in the placenta.

129 UTERINE EXPRESSION OF TRANSIENT RECEPTOR POTENTIAL MELASTATIN 2 CHANNEL AND ITS REGULATION BY SEX STEROID HORMONES

The transient potential receptor (TRP) channels are membrane-binding proteins that are non-selectively permeable for cations, such as Ca2+ and Mg2+, in numerous mammalian cells. The extracellular or intracellular ions play key roles in physiological function, including muscle contraction, cytokine production, insulin release, and apoptosis. Although TRPM channels have been implicated in the brain, bone marrow, and spleen, the presence of TRPM2 has been reported in the endometrium of the uterus. To determine whether expression of the TRPM2 gene in the uterus is due to gonadal steroid hormones or a hormone-independent effect, the uterine TRPM2 gene was monitored in mature rats during the oestrous cycle and in immature rats after treatment with gonadal steroid oestrogen (E2), progesterone (P4) with/without their antagonist, ICI 182,780, and RU486. Dramatic induction of the level of TRPM2 mRNA occurs at proestrus, followed by a drop to baseline levels at metestrus, and its level is restored at diestrus. Furthermore, the immune-reactive TRPM2 is observed in stromal cells of the myometrium and endometrium, and changes during the oestrus cycle. In addition, E2-induced TRPM2 is inhibited by co-treatment with P4. Taken together, these results imply that TRPM2 expression levels in the uterus are regulated by gonadal steroid hormones E2 and P4. Results of this study suggest possible involvement of TRPM2 in reproductive function during the oestrous cycle in female rats.

Designer nodal/BMP2 chimeras mimic nodal signaling, promote chondrogenesis, and reveal a BMP2-like structure

Nodal, a member of the TGF-β superfamily, plays an important role in vertebrate and invertebrate early development. The biochemical study of Nodal and its signaling pathway has been a challenge, mainly because of difficulties in producing the protein in sufficient quantities. We have developed a library of stable, chemically refoldable Nodal/BMP2 chimeric ligands (NB2 library). Three chimeras, named NB250, NB260, and NB264, show Nodal-like signaling properties including dependence on the co-receptor Cripto and activation of the Smad2 pathway. NB250, like Nodal, alters heart looping during the establishment of embryonic left-right asymmetry, and both NB250 and NB260, as well as Nodal, induce chondrogenic differentiation of human adipose-derived stem cells. This Nodal-induced differentiation is shown to be more efficient than BPM2-induced differentiation. Interestingly, the crystal structure of NB250 shows a backbone scaffold similar to that of BMP2. Our results show that these chimeric ligands may have therapeutic implications in cartilage injuries.