Stress responsive miR-23a attenuates skeletal muscle atrophy by targeting MAFbx /atrogin-1

Muscle atrophy occurs in many pathological states and results primarily from accelerated protein degradation by the ubiquitin-proteasome pathway. We used dexamethasone to induce muscle wasting and investigated the role of a microRNA (miRNA) in the control of muscle-specific E3 ubiquitin ligase MAFbx/atrogin-1. Here we show that miR-23a suppresses MAFbx/atrogin-1 translation by binding to 3'UTR of the mRNA. Furthermore, ectopic expression of miR-23a is sufficient to protect myocytes from atrophy in vitro and in vivo in response to dexamethasone treatment, and heat stress-induced miR-23a protects muscle from dexamethasone-induced muscle atrophy. Our surprising discovery of the physiological role of miR-23a in preventing the atrophy program should lay the basis not only for further understanding of the mechanisms of muscle wasting in diverse diseases, but also for developing novel therapies for these debilitating conditions

Mesenchymal progenitor cell markers in human articular cartilage: normal distribution and changes in osteoarthritis

INTRODUCTION: Recent findings suggest that articular cartilage contains mesenchymal progenitor cells. The aim of this study was to examine the distribution of stem cell markers (Notch-1, Stro-1 and VCAM-1) and of molecules that modulate progenitor differentiation (Notch-1 and Sox9) in normal adult human articular cartilage and in osteoarthritis (OA) cartilage. METHODS: Expression of the markers was analyzed by immunohistochemistry (IHC) and flow cytometry. Hoechst 33342 dye was used to identify and sort the cartilage side population (SP). Multilineage differentiation assays including chondrogenesis, osteogenesis and adipogenesis were performed on SP and non-SP (NSP) cells. RESULTS: A surprisingly high number (>45%) of cells were positive for Notch-1, Stro-1 and VCAM-1 throughout normal cartilage. Expression of these markers was higher in the superficial zone (SZ) of normal cartilage as compared to the middle zone (MZ) and deep zone (DZ). Non-fibrillated OA cartilage SZ showed reduced Notch-1 and Sox9 staining frequency, while Notch-1, Stro-1 and VCAM-1 positive cells were increased in the MZ. Most cells in OA clusters were positive for each molecule tested. The frequency of SP cells in cartilage was 0.14 +/- 0.05% and no difference was found between normal and OA. SP cells displayed chondrogenic and osteogenic but not adipogenic differentiation potential. CONCLUSIONS: These results show a surprisingly high number of cells that express putative progenitor cell markers in human cartilage. In contrast, the percentage of SP cells is much lower and within the range of expected stem cell frequency. Thus, markers such as Notch-1, Stro-1 or VCAM-1 may not be useful to identify progenitors in cartilage. Instead, their increased expression in OA cartilage implicates involvement in the abnormal cell activation and differentiation process characteristic of OA

通気量と塩分勾配がオニオコゼ仔稚魚の生残と成長に与える影響

We examined the effects of a flow field in the rearing tank exhibited by different aeration rate and salinity gradient on the larviculture of the devil stinger Inimicus japonicus. Two different rearing experiments using 1 kl rearing tanks were conducted from hatching (day 0) to settlement. In the Experiment 1, fish were reared until day 21 in 5 different aeration rates (0-1200 ml/min). There was a significant and positive relationship between survival andaeration rate, and fish survival became stable at an aeration rate of more than 300 ml/min. In Experiment 2, the salinity gradient in a rearing tank was formed by pumping brackish water (22 ppt) from the surface and seawater (34 ppt) from the bottom at the same time. Control rearing tanks (34 ppt) were aerated at 300 ml/min and fish were reared until day 23. Growth and development was synchronized in the salinity gradient tanks with little standard deviation, although average survival at settlement in the salinity gradient tank (47.3 %) was lower than the aeration tank (68.2 %). The optimal aeration rate for devil stinger larviculture is stronger than 300 ml/min and introducing a salinity gradient can be a novel approach for enhancing performance of the fish.異なる通気量と塩分勾配がオニオコゼ仔魚飼育に与える影響を調べた。容量1klの円形水槽で2つの飼育実験を孵化仔魚（0日齢）より着底まで実施した。実験1では5つの異なる通気量（0-1200 ml/min）で21日齢までの飼育を行った。その結果，最終日の生残と通気量の間に有意な正の相関が検出され，300ml/min以上の通気量で生残が安定した。実験2では飼育水槽に水面から22pptの汽水，底面から34pptの海水をそれぞれ連続注入することで塩分勾配を形成させ，対照に34ppt海水に300ml/minの通気を施す水槽を設け，23日齢まで飼育した。その結果，塩分勾配水槽で飼育した魚の成長と着底が同調したが，飼育終了時の生残（47.3 %）は対照のそれ（68.2 %）より低い傾向があった。1kl規模でのオニオコゼの仔魚飼育には300ml/min以上の強い通気による水流が必要であることが明らかになり，さらに塩分勾配の飼育水槽への導入により種苗生産に新たな可能性を見いだした

Feasibility of administration of calcitonin gene-related peptide receptor antagonist on attenuation of pain and progression in osteoarthritis

Abstract Suppressing inflammation and abnormal subchondral bone turnover is essential for reducing osteoarthritis (OA) progression and pain relief. This study focused on calcitonin gene-related peptide (CGRP), which is involved in inflammation and bone metabolism, and investigated whether a CGRP receptor antagonist (rimegepant) could suppress OA progression and relieve pain in two OA models. C57BL/6 mice (10-week-old) underwent surgical destabilization of the medial meniscus, and Rimegepant (1.0 mg/kg/100 μL) or phosphate-buffered saline (100 μL) was administered weekly intraperitoneally after OA surgery and evaluated at 4, 8, and 12 weeks. In the senescence-accelerated mice (SAM)-prone 8 (SAMP8), rimegepant was administered weekly before and after subchondral bone sclerosis and sacrificed at 9 and 23 weeks, respectively. Behavioral assessment and immunohistochemical staining (CGRP) of the dorsal root ganglion (DRG) were conducted to assess pain. In DMM mice, synovitis, cartilage degeneration, and osteosclerosis were significantly suppressed in the rimegepant group. In SAMP8, synovitis, cartilage degeneration, and osteosclerosis were significantly suppressed by rimegepant at 9 weeks; however, not at 23 weeks. Behavioral assessment shows the traveled distance and the number of standings in the rimegepant group were significantly longer and higher. In addition, CGRP expression of the DRG was significantly lower in the rimegepant group at 8 and 12 weeks of DMM and 9 weeks of SAMP8 treatment. No adverse effects were observed in either of the mouse models. Inhibition of CGRP signaling has the potential to be a therapeutic target to prevent OA progression and suppress pain through the attenuation of subchondral bone sclerosis and synovitis

Tissue neogenesis and STRO-1 expression in immature and mature articular cartilage

This study determined the potential for neotissue formation and the role of STRO-1+ cells in immature versus mature articular cartilage. Cartilage explants from immature and mature bovine knee joints were cultured for up to 12 weeks and stained with safranin-O, for type II collagen and STRO-1. Bovine chondrocyte pellet cultures and murine knee joints at the age of 2 weeks and 3 months, and surgically injured cartilage, were analyzed for changes in STRO-1 expression patterns. Results show that immature explants contained more STRO-1+ cells than mature explants. After 8 weeks in culture, immature explants showed STRO-1+ cell proliferation and newly formed tissue, which contained glycosaminoglycan and type II collagen. Mature cartilage explants showed only minimal cell expansion and neotissue formation. Pellet cultures with chondrocytes from immature cartilage showed increased glycosaminoglycan synthesis and STRO-1+ staining, as compared to pellets with mature chondrocytes. The frequency of STRO-1+ cells in murine knee joints significantly declined with joint maturation. Following surgical injury, immature explants had higher potential for tissue repair than mature explants. In conclusion, these findings suggest that the high percentage of STRO-1+ cells in immature cartilage changes with joint maturation. STRO-1+ cells have the potential to form new cartilage spontaneously and after tissue injury. (c) 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res

通気量と塩分勾配がオニオコゼ仔稚魚の生残と成長に与える影響

We examined the effects of a flow field in the rearing tank exhibited by different aeration rate and salinity gradient on the larviculture of the devil stinger Inimicus japonicus. Two different rearing experiments using 1 kl rearing tanks were conducted from hatching (day 0) to settlement. In the Experiment 1, fish were reared until day 21 in 5 different aeration rates (0-1200 ml/min). There was a significant and positive relationship between survival and aeration rate, and fish survival became stable at an aeration rate of more than 300 ml/min. In Experiment 2, the salinity gradient in a rearing tank was formed by pumping brackish water (22 ppt) from the surface and seawater (34 ppt) from the bottom at the same time. Control rearing tanks (34 ppt) were aerated at 300 ml/min and fish were reared until day 23. Growth and development was synchronized in the salinity gradient tanks with little standard deviation, although average survival at settlement in the salinity gradient tank (47.3 %) was lower than the aeration tank (68.2 %). The optimal aeration rate for devil stinger larviculture is stronger than 300 ml/min and introducing a salinity gradient can be a novel approach for enhancing performance of the fish.異なる通気量と塩分勾配がオニオコゼ仔魚飼育に与える影響を調べた。容量1klの円形水槽で2つの飼育実験を孵化仔魚（0日齢）より着底まで実施した。実験1では5つの異なる通気量（0-1200 ml/min）で21日齢までの飼育を行った。その結果，最終日の生残と通気量の間に有意な正の相関が検出され，300ml/min以上の通気量で生残が安定した。実験2では飼育水槽に水面から22pptの汽水，底面から34pptの海水をそれぞれ連続注入することで塩分勾配を形成させ，対照に34ppt海水に300ml/minの通気を施す水槽を設け，23日齢まで飼育した。その結果，塩分勾配水槽で飼育した魚の成長と着底が同調したが，飼育終了時の生残（47.3 %）は対照のそれ（68.2 %）より低い傾向があった。1kl規模でのオニオコゼの仔魚飼育には300ml/min以上の強い通気による水流が必要であることが明らかになり，さらに塩分勾配の飼育水槽への導入により種苗生産に新たな可能性を見いだした