C-type natriuretic peptide-induced PKA activation promotes endochondral bone formation in hypertrophic chondrocytes

Longitudinal bone growth is achieved by a tightly controlled process termed endochondral bone formation. C-type natriuretic peptide (CNP) stimulates endochondral bone formation through binding to its specific receptor, guanylyl cyclase (GC)-B. However, CNP/GC-B signaling dynamics in different stages of endochondral bone formation have not been fully clarified, especially in terms of the interaction between the cyclic guanine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) pathways. Here, we demonstrated that CNP activates the cAMP/protein kinase A (PKA) pathway and that this activation contributed to the elongation of the hypertrophic zone in the growth plate. Cells of the chondrogenic line ATDC5 were transfected with Förster resonance energy transfer (FRET)–based cGMP and PKA biosensors. Dual-FRET imaging revealed that CNP increased intracellular cGMP levels and PKA activities in chondrocytes. Further, CNP-induced PKA activation was enhanced following differentiation of ATDC5 cells. Live imaging of the fetal growth plate of transgenic mice, expressing a FRET biosensor for PKA, PKAchu mice, showed that CNP predominantly activates the PKA in the hypertrophic chondrocytes. Additionally, histological analysis of the growth plate of PKAchu mice demonstrated that CNP increased the length of the growth plate, but coadministration of a PKA inhibitor, H89, inhibited the growth-promoting effect of CNP only in the hypertrophic zone. In summary, we revealed that CNP-induced cGMP elevation activated the cAMP/PKA pathway, and clarified that this PKA activation contributed to the bone growth–promoting effect of CNP in hypertrophic chondrocytes. These results provide insights regarding the cross-talk between cGMP and cAMP signaling in endochondral bone formation and in the physiological role of the CNP/GC-B system

C-type Natriuretic Peptide–induced PKA Activation Promotes Endochondral Bone Formation in Hypertrophic Chondrocytes

Longitudinal bone growth is achieved by a tightly controlled process termed endochondral bone formation. C-type natriuretic peptide (CNP) stimulates endochondral bone formation through binding to its specific receptor, guanylyl cyclase (GC)-B. However, CNP/GC-B signaling dynamics in different stages of endochondral bone formation have not been fully clarified, especially in terms of the interaction between the cyclic guanine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) pathways. Here, we demonstrated that CNP activates the cAMP/protein kinase A (PKA) pathway and that this activation contributed to the elongation of the hypertrophic zone in the growth plate. Cells of the chondrogenic line ATDC5 were transfected with Förster resonance energy transfer (FRET)–based cGMP and PKA biosensors. Dual-FRET imaging revealed that CNP increased intracellular cGMP levels and PKA activities in chondrocytes. Further, CNP-induced PKA activation was enhanced following differentiation of ATDC5 cells. Live imaging of the fetal growth plate of transgenic mice, expressing a FRET biosensor for PKA, PKAchu mice, showed that CNP predominantly activates the PKA in the hypertrophic chondrocytes. Additionally, histological analysis of the growth plate of PKAchu mice demonstrated that CNP increased the length of the growth plate, but coadministration of a PKA inhibitor, H89, inhibited the growth-promoting effect of CNP only in the hypertrophic zone. In summary, we revealed that CNP-induced cGMP elevation activated the cAMP/PKA pathway, and clarified that this PKA activation contributed to the bone growth–promoting effect of CNP in hypertrophic chondrocytes. These results provide insights regarding the cross-talk between cGMP and cAMP signaling in endochondral bone formation and in the physiological role of the CNP/GC-B system

Clinical Practice Changes After Post-Market Safety Reports on Desmopressin Orally Disintegrating Tablet in Japan: A Single-Center Retrospective Study

Background: Desmopressin orally disintegrating tablet (ODT) was approved in March 2012 in Japan; the post-market safety reports, which warned about adequate initial dose of desmopressin ODT, were published in 2014. However, it is unclear how the warning affected physician and patient behavior. Methods: We performed a retrospective single-center study to compare the clinical situation of Japanese central diabetes insipidus patients before and after the report. Results: Thirty-four patients before October 2014 and 16 patients after November 2014 switched from intranasal desmopressin to desmopressin ODT. The mean follow-up period after the switch to desmopressin ODT was 38 ± 3 months. Patients switching after November 2014 tended to have lower ratios of oral to nasal desmopressin dose at switching and 3 months after the switch (at switching; P = 0.20, 3 months; P = 0.42, respectively), and higher ratios from 6 to 12 months than before October 2014 (6 months; P = 0.93, 9 months; P = 0.52, 12 months; P = 0.80, respectively). Relative doses per initial desmopressin ODT at 9 and 12 months were significantly higher in patients switching after November 2014 than in patients switching before October 2014 (9 months; P = 0.02, 12 months; P = 0.04, respectively). Moreover, logistic regression analysis revealed that the incidence of hyponatremia was dependent on the ratio of nasal to oral desmopressin dose (P = 0.02). In addition, in four out of six patients who had serum sodium level reduced below 130 mEq/L, hyponatremia occurred within 1 month after the switch. Conclusions: A more gradual dose titration after the safety reports was performed, which involved the long-term safety of desmopressin ODT use. Vigilance of hyponatremia in early phase of desmopressin ODT use should be noted

Osteocrin ameliorates adriamycin nephropathy via p38 mitogen-activated protein kinase inhibition

Natriuretic peptides exert multiple effects by binding to natriuretic peptide receptors (NPRs). Osteocrin (OSTN) binds with high affinity to NPR-C, a clearance receptor for natriuretic peptides, and inhibits degradation of natriuretic peptides and consequently enhances guanylyl cyclase-A (GC-A/NPR1) signaling. However, the roles of OSTN in the kidney have not been well clarified. Adriamycin (ADR) nephropathy in wild-type mice showed albuminuria, glomerular basement membrane changes, increased podocyte injuries, infiltration of macrophages, and p38 mitogen-activated protein kinase (MAPK) activation. All these phenotypes were improved in OSTN- transgenic (Tg) mice and NPR3 knockout (KO) mice, with no further improvement in OSTN-Tg/NPR3 KO double mutant mice, indicating that OSTN works through NPR3. On the contrary, OSTN KO mice increased urinary albumin levels, and pharmacological blockade of p38 MAPK in OSTN KO mice ameliorated ADR nephropathy. In vitro, combination treatment with ANP and OSTN, or FR167653, p38 MAPK inhibitor, reduced Ccl2 and Des mRNA expression in murine podocytes (MPC5). OSTN increased intracellular cyclic guanosine monophosphate (cGMP) in MPC5 through GC-A. We have elucidated that circulating OSTN improves ADR nephropathy by enhancing GC-A signaling and consequently suppressing p38 MAPK activation. These results suggest that OSTN could be a promising therapeutic agent for podocyte injury

High-absorption curcumin reduces BNP in hypertensive heart disease

Aims Hypertension is a strong risk factor for heart failure with preserved ejection fraction. Curcumin has p300-specific histone acetyltransferase inhibitory activity, suppresses cardiomyocyte hypertrophy and fibrosis, and significantly reduces myocardial brain natriuretic peptide (BNP) expression without altering blood pressure in a rat model of hypertensive heart disease. This double-blind, placebo-controlled, randomized study, for the first time, aimed to examine the efficacy of a high-absorption curcumin for the prevention of hypertensive heart disease in humans. Methods and results Patients exhibiting initial signs of hypertensive heart disease with left ventricular ejection fraction ≥60% and stable blood pressure <140/90 mmHg orally took a double-blinded capsule (either a 90 mg curcumin capsule or placebo) twice daily for 24 weeks. The primary endpoint was per cent changes in left ventricular diastolic function (E/E′) from baseline to 6 months after administration. The secondary endpoint was the per cent change in plasma BNP levels. The E/E′ ratio per cent change from baseline to 6 months after administration was similar between the placebo (n = 69) and the curcumin (n = 73) groups. The per cent change in plasma BNP levels was significantly lower in the curcumin group than in the placebo group. In patients <65 years, BNP per cent changes were significantly lower in the curcumin group than in the placebo group, but similar between groups in ≥65 years (<65 vs. ≥65 years: P for interaction = 0.011). Conclusions A high-absorption curcumin agent did not affect the E/E′ ratio, rather it significantly inhibited the increase in plasma BNP levels in patients with initial signs of hypertensive heart disease

Gingival bleeding and pocket depth among smokers and the related changes after short-term smoking cessation

Background: Smoking is associated with the deteriorating health of the gingiva and periodontium. The long-term beneficial effects of smoking cessation on oral health are well known. However, the effects of short-term smoking cessation on gingival bleeding and periodontal pocket depth are unknown. The purpose of the present study was to determine the effects of short-term smoking cessation on gingival bleeding and periodontal pocket depth. Methods: Dentate smokers with a mean age of 56.9 ± 14.4 years at an outpatient smoking cessation clinic participated in this study. A professional dentist checked the periodontal pocket depth and gingival bleeding. Patients visited the smoking cessation clinic on their first visit and 2, 4, 8, and 12 weeks (three months). The gingival assessment was re-performed in those who succeeded in smoking cessation 3 months after the baseline. Results: The baseline data of 83 patients showed that an increase in pocket depth was associated with increasing age and the amount of smoking. A significant increase in gingival bleeding (p = .031) and increase in pocket depth (p = .046) were observed 3 months after the baseline in patients who successfully quit smoking (n = 14). Conclusion: Short-term smoking cessation increased periodontal pocket depth and gingival bleeding. These findings may reflect healing processes that occur in the healthy gingiva. Implications: Study findings will be useful to advise patients during smoking cessation programs. Dentists can inform patients that an initial increase in gingival bleeding and pocket depth could be associated with smoking cessation. Such advice will prevent patients from any apprehension that may cause them to recommence smoking

ナトリウム利尿ペプチドファミリーの内軟骨性骨化調節作用-C型ナトリウム利尿ペプチド(CNP)/B型グアニル酸シクラーゼ(GC-B)系の意義

本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・課程博士博士(医学)甲第7759号医博第2112号新制||医||713(附属図書館)UT51-99-G353京都大学大学院医学研究科内科系専攻(主査)教授 中西 重忠, 教授 中村 孝志, 教授 中尾 一和学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Physiological and Pathophysiological Effects of C-Type Natriuretic Peptide on the Heart

C-type natriuretic peptide (CNP) is the third member of the natriuretic peptide family. Unlike other members, i.e., atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), which are cardiac hormones secreted from the atrium and ventricle of the heart, respectively, CNP is regarded as an autocrine/paracrine regulator with broad expression in the body. Because of its low expression levels compared to ANP and BNP, early studies failed to show its existence and role in the heart. However, recent studies have revealed the physiological and pathophysiological importance of CNP in the heart; in concert with the distribution of its specific natriuretic peptide receptor-B (NPR-B), CNP has come to be regarded as the major heart-protective natriuretic peptide in the failed heart. NPR-B generates intracellular cyclic guanosine 3&prime;,5&prime;-monophosphate (cGMP) upon CNP binding, followed by various molecular effects including the activation of cGMP-dependent protein kinases, which generates diverse cytoprotective actions in cardiomyocytes, as well as in cardiac fibroblasts. CNP exerts negative inotropic and positive lusitropic responses in both normal and failing heart models. Furthermore, osteocrin, the intrinsic and specific ligand for the clearance receptor for natriuretic peptides, can augment the effects of CNP and may supply a novel therapeutic strategy for cardiac protection

Voriconazole-induced periostitis in a patient with overlap syndromes.

A 52-year-old woman with overlap syndrome and interstitial pneumonia underwent immunosuppressive therapy and she was suspected to suffer from pulmonary aspergillosis. Oral voriconazole was initiated, and a rapid elevation of alkaline phosphatase (ALP) occurred after 4 weeks. After 2 months, the patient presented diffuse pain in bilateral skeletal regions, and bone scintigraphy revealed bilateral multiple areas of increased radiotracer uptake. We suspected the skeletal involvement as voriconazole-induced periostitis. Actually, the plasma fluoride level was increased. Voriconazole was replaced with itraconazole, and after 3 weeks, the patient stopped complaining of bone pain concomitant with the decrease in ALP. Voriconazole-induced periostitis is a rare condition but had previously been reported in solid organ or patients with bone marrow transplant who received a long-term voriconazole therapy. Our present case is distinctive of previous ones, because it occurred in a patient with connective tissue disease which had its rapid progression