• International Journal of Oral Biology
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• v.30 no.1
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• pp.9-15
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• 2005

Recently, we reported that high extracellular calcium increased receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) expression via p44/42 mitogen-activated protein kinase (p44/42 MAPK) activation in mouse osteoblasts. However, the mechanism for p44/42 MAPK activation by high extracellular calcium is unclear. In this study, we examined the role of intracellular calcium increase in high extracellular calcium-induced RANKL induction and p44/42 MAPK activation. Primary cultured mouse calvarial osteoblasts were used. RANKL expression was highly induced by 10 mM calcium treatment. Ionomycin, a calcium ionophore, also increased RANKL expression and activated p44/42 MAPK. U0126, an inhibitor of MEK1/2, an upstream activator of p44/42 MAPK, blocked the RANKL induction by both high extracellular calcium and ionomycin. High extracellular calcium increased the phosphorylation of proline-rich tyrosine kinase 2 (Pyk2), one of the known upstream regulators of p44/42 MAPK activation. Bisindolylmaleimide, an inhibitor of protein kinase C, did not block RANKL induction and p44/42 MAPK activation induced by high extracellular calcium. 2-Aminoethoxydiphenyl borate, an inhibitor of inositol 1,4,5-trisphosphate (IP3) receptor, blocked the RANKL induction by high extracellular calcium. It also partially suppressed the activation of Pyk2 and p44/42 MAPK. Cyclosporin A, an inhibitor of calcineurin, also inhibited high calcium-induced RANKL expression in dose dependent manner. However, cyclosporin A did not affect the activation of Pyk2 and p44/42 MAPK by high extracellular calcium treatment. These results suggest that 1) the increase in intracellular calcium via IP3-mediated calcium release is necessary for RANKL induction by high extracellular calcium treatment, 2) Pyk2 activation, but not protein kinase C, following the increase in intracellular calcium might be involved in p44/42 MAPK activation, and 3) calcineurin-NFAT activation by the increase in intracellular calcium is involved in RANKL induction by high extracellular calcium treatment.

• Clinical and Experimental Pediatrics
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• v.54 no.8
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• pp.317-321
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• 2011

Children who suffer from steroid-resistant nephrotic syndrome (SRNS) require aggressive treatment to achieve remission. When intravenous high-dose methylprednisolone fails, calcineurin inhibitors, such as cyclosporine and tacrolimus, are used as the first line of treatment. A significant number of patients with SRNS progress to end-stage renal disease if remission is not achieved. For these children, renal replacement therapy can also be problematic; peritoneal dialysis may be accompanied by significant protein loss through the peritoneal membrane, and kidney allograft transplantation may be complicated by recurrence of SRNS. Plasmapheresis and rituximab were initially used for treatment of recurrent SRNS after transplantation; these are now under consideration as rescue therapies for refractory SRNS. Although the prognosis of SRNS is complicated and unfavorable, intensive treatment in the early stages of the disease may achieve remission in more than half of the patients. Therefore, timely referral of pediatric SRNS patients to pediatric nephrology specialists for histological and genetic diagnosis and treatment is highly recommended.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.6
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• pp.353-361
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• 2005

The interaction of cyclosporine A (CsA), an immunosuppressant, with rat brain Kv1.5 (Kv1.5) channels, which were stably expressed in Chinese hamster ovary cells, was investigated using the whole-cell patch-clamp technique. CsA reversibly blocked Kv1.5 currents at +50 mV in a reversible concentrationdependent manner with an apparent $IC_{50}$ of 1.0μM. Other calcineurin inhibitors (cypermethrin, autoinhibitory peptide) had no effect on Kv1.5 and did not prevent the inhibitory effect of CsA. Fast application of CsA led to a rapid and reversible block of Kv1.5, and the onset time constants of the CsA-induced block were decreased in a concentration-dependent manner. The CsA-induced block of Kv1.5 channels was voltage-dependent, with a steep increase over the voltage range of channel opening. However, the block exhibited voltage independence over the voltage range in which channels were fully activated. The rate constants for association and dissociation of CsA were $7.0{\mu}M{-1}s^{-1}$ and $8.1s^{-1}$, respectively. CsA slowed the deactivation time course, resulting in a tail crossover phenomenon. Block of Kv1.5 by CsA was use-dependent. CsA also blocked Kv1.3 currents at +50 mV in a reversible concentration-dependent manner with an apparent $IC_{50}$ of $1.1{\mu}M$. The same effects of CsA on Kv1.3 were also observed in excised inside-out patches when applied to the internal surface of the membrane. The present results suggest that CsA acts directly on Kv1.5 currents as an open-channel blocker, independently of the effects of CsA on calcineurin activity.

• Childhood Kidney Diseases
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• v.12 no.2
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• pp.133-142
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• 2008

For solid organ transplant, ABO blood type of donor and recipient should be compatible in principle. Recent improvement of immunosuppressant made HLA typing not so important while no-mismatch transplant still shows the longest graft survival. PRA(panel reactive antibody) test is to screen and identify recipients with HLA sensitization. When solid organ transplant is scheduled, cross-match test of donor cell and recipient serum should be performed and positive result of cross-match prohibits transplantation. Donor specific antibody(DSA) test can predict the severity of recipient immune reaction against donor organ. Today's mainstay of allograft immunosuppressant regimen is triple therapy of steroid, calcineurin inhibitor(cyclosporine, tacrolimus), azathioprine or mycophenolate mofetil(MMF). Antibody induction using Thymoglobulin or anti-IL-2 receptor antibody(basiliximab or daclizumab) is frequently practiced as well.

• Journal of Ginseng Research
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• v.45 no.6
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• pp.683-694
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• 2021

Background: Ginsenoside Rg1 (Rg1) has been well documented to be effective against various cardiovascular disease. The aim of this study is to evaluate the effect of Rg1 on mechanical stress-induced cardiac injury and its possible mechanism with a focus on the calcium sensing receptor (CaSR) signaling pathway. Methods: Mechanical stress was implemented on rats through abdominal aortic constriction (AAC) procedure and on cardiomyocytes and cardiac fibroblasts by mechanical stretching with Bioflex Collagen I plates. The effects of Rg1 on cell hypertrophy, fibrosis, cardiac function, [Ca²⁺]_i, and the expression of CaSR and calcineurin (CaN) were assayed both on rat and cellular level. Results: Rg1 alleviated cardiac hypertrophy and fibrosis, and improved cardiac decompensation induced by AAC in rat myocardial tissue and cultured cardiomyocytes and cardiac fibroblasts. Importantly, Rg1 treatment inhibited CaSR expression and increase of [Ca²⁺]_i, which similar to the CaSR inhibitor NPS2143. In addition, Rg1 treatment inhibited CaN and TGF-b1 pathways activation. Mechanistic analysis showed that the CaSR agonist GdCl₃ could not further increase the [Ca²⁺]_i and CaN pathway related protein expression induced by mechanical stretching in cultured cardiomyocytes. CsA, an inhibitor of CaN, inhibited cardiac hypertrophy, cardiac fibrosis, [Ca²⁺]_i and CaN signaling but had no effect on CaSR expression. Conclusion: The activation of CaN pathway and the increase of [Ca²⁺]_i mediated by CaSR are involved in cardiac hypertrophy and fibrosis, that may be the target of cardioprotection of Rg1 against myocardial injury.

• Food Science and Biotechnology
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• v.17 no.3
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• pp.598-602
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• 2008

Concentrated catfish Silurus asotus bile (SAB) containing high amounts of ursodeoxycholic acid (UDCA) and taurocholic acid may have immunosuppressive properties. To investigate the putative immunosuppressive properties of SAB, the anti-proliferation and suppression of early T cell activation markers, and the inhibition of cytokines induced by T cells in response to anti-CD3 mAb activation in mouse splenocytes were examined. The suppression of these activation repertoires are the main properties of calcineurin inhibitors. It was found that SAB effectively suppressed the activation of T cells, and cytokines from T cell activation, at levels similar to cyclosporine A, a calcineurin inhibitor. Although the mechanism in which suppression occurs is not clear, we speculate that SAB from Silurus asotus, which has been known to switch their intake habits to zoophagy during an early adult stage, may explain the suppressive effect of SAB as a result of high amounts of functional UDCA in bile. Our results suggest that the treatment or intake of SAB, either in therapy or as a food supplement, may act as an adjuvant therapy for the prevention of transplant rejection, although further investigation is required before this treatment can be applied clinically.

• Mycobiology
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• v.43 no.2
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• pp.150-156
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• 2015

2',4'-Dihydroxychalcone (2',4'-DHC) was identified from a heat shock protein 90 (Hsp90)-targeting library as a compound with Hsp90 inhibitory and antifungal effects. In the presence of 2',4'-DHC ($8{\mu}g/mL$), radial growth of Aspergillus fumigatus was inhibited 20% compared to the control, and green pigmentation was completely blocked. The expression of the conidiation-associated genes abaA, brlA, and wetA was significantly decreased (approximately 3- to 5-fold) by treatment with 2',4'-DHC. The expression of calcineurin signaling components, cnaA and crzA, was also significantly reduced. The inhibitory effects of 2',4'-DHC on metabolic activity and mycelial growth were significantly enhanced by combination treatment with itraconazole and caspofungin. Docking studies indicated that 2',4'-DHC bind to the ATPase domain of Hsp90. These results suggest that 2',4'-DHC act as an Hsp90-calcinurin pathway inhibitor.

• Journal of dental hygiene science
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• v.15 no.4
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• pp.488-494
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• 2015

A recent report showed that nuclear factor of activated T cell (NFATc) 1 is a member of the NFAT family and is strictly implicated osteoblast differentiation and bone formation. Furthermore, the precise expression and function of NFATc1 in periodontal tissue remains unclear. Therefore, the purpose of this study was to investigate the function of NFATc1 in osteoblastic differentiation, and the underlying mechanism regulating periodontal regeneration in human periodontal ligament cells (hPDLCs). NFATc1 messenger RNA (mRNA) and protein levels were accessed by reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay, respectively. Cell proliferation determined using MTT assay. Differentiation was evaluated by alkaline phosphatase activity and formation of calcium nodule with alizarin red S staining. The mRNA expression of osteoblastic differentiation related genes were examined by RT-PCR. Marked upregulation of NFATc1 mRNA and protein was observed in cells grown in osteogenic medium (OS). NFATc1 transactivation was detected in hPDLCs that had been incubated in OS for 14 days. Treatment with $10{\mu}M$ cyclosporine A (CsA), a known calcineurin inhibitor, reduced the proliferation of hPDLCs, while $5{\mu}M$ CsA had no effect. Inhibition of the calcineurin/NFATc1 pathway by CsA, attenuated OS-induced osteoblastic differentiation in hPDLCs. In summary, this study demonstrates for the first time that NFATc1 plays a key role in osteoblastic differentiation of hPDLCs and activation of NFATc1 could provide a novel mechanism for periodontal bone regeneration.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.5
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• pp.291-297
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• 2011

The effect of cyclosporin A (CsA), an immunosuppressant, on human ether-a-go-go-related gene (HERG) channel as it is expressed in human embryonic kidney cells was studied using a whole-cell, patch-clamp technique. CsA inhibited the HERG channel in a concentration-dependent manner, with an $IC_{50}$ value and a Hill coefficient of $3.17{\mu}m$ and 0.89, respectively. Pretreatment with cypermethrine, a calcineurin inhibitor, had no effect on the CsA-induced inhibition of the HERG channel. The CsA-induced inhibition of HERG channels was voltage-dependent, with a steep increase over the voltage range of the channel opening. However, the inhibition exhibited voltage independence over the voltage range of fully activated channels. CsA blocked the HERG channels predominantly in the open and inactivated states rather than in the closed state. Results of the present study suggest that CsA acts directly on the HERG channel as an open-channel blocker, and it acts independently of its effect on calcineurin activity.

• Journal of Microbiology and Biotechnology
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• v.28 no.10
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• pp.1716-1722
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• 2018

Immunosuppressive drugs are used to make the body less likely to reject transplanted organs or to treat autoimmune diseases. In this study, five immunosuppressive drugs including two glucocorticoids (dexamethasone and prednisolone), one calcineurin inhibitor (cyclosporin A), one non-steroid anti-inflammatory drug (aspirin), and one antimetabolite (methotrexate) were tested for their effects on viral proliferation using feline foamy virus (FFV). The five drugs had different cytotoxic effects on the Crandell-Ress feline kidney (CRFK) cells, the natural host cell of FFV. Dexamethasone-pretreated CRFK cells were susceptible to FFV infection, but pretreatment with prednisolone, cyclosporin A, aspirin, and methotrexate showed obvious inhibitory effects on FFV proliferation, by reducing viral production to 29.8-83.8% of that of an untreated control. These results were supported by western blot, which detected viral Gag structural protein in the infected cell lysate. As our results showed a correlation between immunosuppressive drugs and susceptibility to viral infections, it is proposed that immune-compromised individuals who are using immune-suppressive drugs may be especially vulnerable to viral infection originated from pets.