Royal Jelly Enhances the Ability of Myoblast C2C12 Cells to Differentiate into Multilineage Cells.

Royal jelly (RJ) is recognized as beneficial to mammalian health. Multilineage differentiation potential is an important property of mesenchymal stem cells (MSCs). C2C12 cells have an innate ability to differentiate into myogenic cells. Like MSCs, C2C12 cells can also differentiate into osteoblast- and adipocyte-lineage cells. We recently reported that RJ enhances the myogenic differentiation of C2C12 cells. However, the effect of RJ on osteoblast or adipocyte differentiation is still unknown. Here in this study, we have examined the effect of RJ on the osteoblast and adipocyte differentiation of C2C12 cells. Protease-treated RJ was used to reduce the adverse effects caused by RJ supplementation. To induce osteoblast or adipocyte differentiation, cells were treated with bone morphogenetic proteins (BMP) or peroxisome proliferator-activated receptor γ (PPARγ) agonist, respectively. RNA-seq was used to analyze the effect of RJ on gene expression. We found that RJ stimulates osteoblast and adipocyte differentiation. RJ regulated 279 genes. RJ treatment upregulated glutathione-related genes. Glutathione, the most abundant antioxidative factor in cells, has been shown to promote osteoblast differentiation in MSC and MSC-like cells. Therefore, RJ may promote osteogenesis, at least in part, through the antioxidant effects of glutathione. RJ enhances the differentiation ability of C2C12 cells into multiple lineages, including myoblasts, osteoblasts, and adipocytes.

Bonding Pretreatment of Aesthetic Dental CAD-CAM Materials through Surface Etching with a Mixed Aqueous Solution of Ammonium Fluoride and Ammonium Hydrogen Sulfate.

Hydrofluoric acid (HF) is commonly used as an etchant for the pretreatment of dental computer-aided design/computer-aided manufacturing (CAD-CAM) materials, such as glass-ceramics and resin composites. Despite its effectiveness, the harmful and hazardous nature of HF has raised significant safety concerns. In contrast, ammonium fluoride (AF) is known for its relatively low toxicity but has limited etching capability. This study explored the potential of ammonium hydrogen sulfate (AHS), a low-toxicity and weak acid, to enhance the etching ability of aqueous AF solutions for the bonding pretreatment of CAD-CAM materials. This study investigated five types of aesthetic CAD-CAM materials: lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, resin composites, and zirconia. Seven experimental etchants were prepared by varying the amount of AHS added to aqueous AF solutions, with each etchant used to etch the surfaces of the respective CAD-CAM materials. The treated surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. Additionally, the shear bond strength (SBS) of the CAD-CAM materials treated with a luting agent (resin cement) was evaluated. The results indicated that the AF1/AHS3 (weight ratio AF:AHS = 1:3) etchant had the most substantial etching effect on the surfaces of silica-containing materials (lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, and resin composites) but not on zirconia. The SBS of the materials treated with the AF1/AHS3 etchant was comparable to that of the commercial HF etchant. Hence, an AF/AHS mixed solution could effectively etch silica-containing CAD-CAM materials, thereby enhancing their bonding capabilities.

Ser252Trp mutation in fibroblast growth factor receptor 2 promotes branching morphogenesis in mouse salivary glands.

OBJECTIVES: The purpose of this study was to perform morphological and immunohistochemical (IHC) analysis of the submandibular glands (SMGs) in early development in Apert syndrome model mice (Ap mice). METHODS: ACTB-Cre homozygous mice were mated with fibroblast growth factor receptor 2 (Fgfr2+/Neo-S252W) mice; ACTB-Cre heterozygous mice (ACTB-Cre mice) at embryonic day (E) 13.5 served as the control group, and Fgfr2+/S252W mice (Ap mice) served as the experimental group. Hematoxylin and eosin (H&E) staining was performed on SMGs; Total SMG area and epithelial area were determined, and the epithelial occupancy ratio was calculated. Immunostaining was performed to assess the localization of FGF signaling-related proteins. Next, bromodeoxyuridine (BrdU)-positive cells were evaluated to assess cell proliferation. Finally, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was performed to assess apoptosis in SMGs. RESULTS: The epithelial occupancy ratio was significantly higher in SMGs of Ap mice compared with that in SMGs of controls. FGF7 and bone morphogenetic protein 4 (BMP4) exhibited different localizations in SMGs of Ap mice compared with SMGs of controls. Cell proliferation was higher in SMGs of Ap mice compared with that of controls; however, apoptosis did not different significantly between the two groups. CONCLUSION: Our results suggest that enhanced FGF signaling conferred by missense mutations in FGFR2 promotes branching morphogenesis in SMGs of Ap mice.

The Mechanism of Interleukin 33-Induced Stimulation of Interleukin 6 in MLO-Y4 Cells.

The differentiation and function of osteocytes are controlled by surrounding cells and mechanical stress; however, the detailed mechanisms are unknown. Recent findings suggest that IL-33 is highly expressed in periodontal tissues in orthodontic tooth movement. The present study aimed to elucidate the effect of IL-33 on the expression of regulatory factors for bone remodeling and their molecular mechanisms in the osteocyte-like cell line MLO-Y4. MLO-Y4 cells were treated with IL-33, and the activation of intracellular signaling molecules and transcriptional factors was determined using Western blot analysis and chromatin immunoprecipitation assay. IL-33 treatment enhanced the expression of IL-6 in MLO-Y4 cells, which was suppressed by the knockdown of the IL-33 receptor ST2L. Additionally, IL-33 treatment induced activation of NF-κB, JNK/AP-1, and p38 MAPK signaling pathways in MLO-Y4 cells. Moreover, pretreatment with specific inhibitors of NF-κB, p38 MAPK, and JNK/AP-1 attenuated the IL-33-induced expression of IL-6. Furthermore, chromatin immunoprecipitation indicated that IL-33 increased c-Jun recruitment to the IL-6 promoter. Overall, these results suggest that IL-33 induces IL-6 expression and regulates osteocyte function via activation of the NF-κB, JNK/AP-1, and p38 MAPK pathways through interaction with ST2L receptors on the plasma membrane.

PIEZO1 promotes ATP release from periodontal ligament cells following compression force.

OBJECTIVES: Orthodontic mechanical force on the periodontal ligament induces extracellular adenosine triphosphate (ATP) release. However, mechanosensitive molecules have not been confirmed functionally in periodontal ligament cells. In the present study, we examined the roles of mechanosensitive PIEZO channels in the mechanically stimulated release of ATP in human periodontal ligament fibroblasts (HPdLFs). MATERIALS AND METHODS: To examine PIEZO expression in HPdLFs, we performed reverse transcription-quantitative polymerase chain reaction, fluorescent immunostaining, and Ca2+ imaging. ATP concentrations were measured in culture medium after applications of the PIEZO1 agonist Yoda1 and compression force in a newly developed in vitro weight-loaded cell model (IVWLC) using balance weights and a 48-well plate. The mechanosensitive channel inhibitor GsMTx4 and the ATP-releasing route inhibitors clodronic acid, meclofenamic acid, and probenecid were used. To suppress PIEZO1 expression, short interference RNA (siRNA) treatment of the PIEZO1 gene was performed. RESULTS: PIEZO1 mRNA was expressed more abundantly than PIEZO2 mRNA in HPdLFs. HPdLF cell bodies were immunoreactive to anti-PIEZO1 antibody. Yoda1 increased intracellular Ca2+ and extracellular ATP concentrations in a dose-dependent manner. ATP release was inhibited by GsMTx4 and inhibitors of ATP release routes. In the IVWLC, HPdLFs released ATP in response to compression force but not in response to hypoxic stimulation that was simultaneously applied to cells. Mechanically stimulated ATP release was inhibited by GsMTx4, inhibitors of ATP-releasing routes and siRNA treatment of PIEZO1. CONCLUSIONS: PIEZO1 on the cell membranes of HPdLFs is activated by compression force and then induces ATP release via intracellular Ca2+-dependent exocytosis and ATP-permeable channels.

Ascl1-expressing cell differentiation in initially developed taste buds and taste organoids.

Mammalian taste bud cells are composed of several distinct cell types and differentiated from surrounding tongue epithelial cells. However, the detailed mechanisms underlying their differentiation have yet to be elucidated. In the present study, we examined an Ascl1-expressing cell lineage using circumvallate papillae (CVP) of newborn mice and taste organoids (three-dimensional self-organized tissue cultures), which allow studying the differentiation of taste bud cells in fine detail ex vivo. Using lineage-tracing analysis, we observed that Ascl1 lineage cells expressed type II and III taste cell markers both CVP of newborn mice and taste organoids. However, the coexpression rate in type II cells was lower than that in type III cells. Furthermore, we found that the generation of the cells which express type II and III cell markers was suppressed in taste organoids lacking Ascl1-expressing cells. These findings suggest that Ascl1-expressing precursor cells can differentiate into both type III and a subset of type II taste cells.

Msx1 is essential for proper rostral tip formation of the mouse mandible.

The right and left mandibular processes derived from the first branchial arch grow toward the midline and fuse to create the rostral tip region of the mandible during mandibular development. Severe and mild cases of failure in this process results in rare median cleft of the lower lip and cleft chin, respectively. The detailed molecular mechanisms of mandibular tip formation are unknown. We hypothesize that the Msx1 gene is involved in mandibular tip development, because Msx1 has a central role in other craniofacial morphogenesis processes, such as teeth and the secondary palate development. Normal Msx1 expression was observed in the rostral end of the developing mandible; however, a reduced expression of Msx1 was observed in the soft tissue of the mandibular tip than in the lower incisor bud region. The rostral tip of the right and left mandibular processes was unfused in both control and Msx1-null (Msx1-/-) mice at embryonic day (E) 12.5; however, a complete fusion of these processes was observed at E13.5 in the control. The fused processes exhibited a conical shape in the control, whereas the same region remained bifurcated in Msx1-/-. This phenotype occurred with 100% penetrance and was not restored at subsequent stages of development. Furthermore, Meckel's cartilage in addition to the outline surface soft tissues was also unfused and bifurcated in Msx1-/- from E14.5 onward. The expression of phosho-Smad1/5, which is a mediator of bone morphogenetic protein (Bmp) signaling, was downregulated in the mandibular tip of Msx1-/- at E12.5 and E13.5, probably due to the downregulated Bmp4 expression in the neighboring lower incisor bud. Cell proliferation was significantly reduced in the midline region of the mandibular tip in Msx1-/- at the same developmental stages in which downregulation of pSmad was observed. Our results indicate that Msx1 is indispensable for proper mandibular tip development.

Case report: Long-term management of occlusion after surgical-orthodontic treatment for a patient with drug-induced open bite developed after the onset of schizophrenia.

Background: Schizophrenia is a major mental disorder, with an estimated incidence of 1%. Since they are sensitive to sensory changes, orthodontic treatment to move teeth should be avoided as aggressively as possible in these patients because of strong concerns about the possibility of causing adverse psychological effects, thus there are few reports on orthodontic treatment for schizophrenia patients. We report a case of severe open bite caused by medication after the onset of schizophrenia, even though the patient's occlusion had been stable for a long time after surgical orthodontic treatment. Medication control and the use of a minimally invasive orthodontic appliance improved the occlusion without adversely affecting the patient's mental health. Case: A 22-year-old woman presented to the clinic with a chief complaint of an anterior open bite. Intraoral findings showed an overbite (vertical overlap of the incisor teeth) of -3.0 mm and an overjet (horizontal overlap of the incisor teeth) of -0.5 mm. The preoperative orthodontic treatment included bilateral extraction of the maxillary first premolars. Subsequently, orthognathic surgery was performed to achieve a harmonized skeletal relationship and occlusion. Occlusion was stable for 3 years after surgery. However, 10 years after surgery, the patient returned to the clinic complaining of an anterior open bite (overbite = -4.0 mm). Six years prior to the return, the patient was diagnosed with schizophrenia. We thought that ignoring the patient's strong desire to treat her open bite might also cause psychological problems; therefore, in addition to medication control, we treated her using a minimally invasive removable orthodontic appliance (retainer with tongue crib). Her anterior open bite improved (overbite, +1.0 mm) to within the normal range. Conclusion: In this case, medication control was thought to be essential to improve her drug-induced open bite. However, minimally invasive orthodontic treatment, such as the use of a removable appliance, might be helpful in promoting her mental stability as well as for improving occlusion. Careful support is required to obtain information about the patient's mental state and medications through close cooperation with psychiatrists.

Fibrillin-1 regulates periostin expression during maintenance of periodontal homeostasis.

Background/purpose: Human periodontal ligament consists of elastic system fibers, mainly fibrillin-1 (FBN1). Periostin (POSTN) maintains periodontal homeostasis. A previous study showed that the expression of Postn in periodontal ligament cells was decreased in mice underexpressing Fbn1. However, the relationship between FBN1 and POSTN is not fully understood in the context of mechanical stress. FBN1 contributes to transforming growth factor ß1 (TGF-ß1) activation; TGF-ß1 upregulates the expression of POSTN in human periodontal ligament cells. This study examined whether FBN1 contributed to the maintenance of periodontal homeostasis in cultured human periodontal ligament cells. Materials and methods: Human periodontal ligament fibroblasts (HPDLFs) were exposed to mechanical force via centrifugation. The expression of POSTN was examined by quantitative reverse transcription polymerase chain reaction. The phosphorylation of Smad2 in the TGF-ß/Smad signaling pathway was monitored by western blotting. Results: The expression levels of FBN1 and POSTN were not significantly decreased by centrifugation. However, the expression of POSTN after centrifugation significantly decreased upon knockdown of FBN1. The phosphorylation of Smad2 after centrifugation was decreased, regardless of FBN1 knockdown. Supplementation with 0.1 ng/ml recombinant human TGF-ß1 rescued POSTN expression after centrifugation in HPDLFs upon knockdown of FBN1. Conclusion: FBN1 regulates the expression of POSTN to maintain periodontal homeostasis via TGF-ß/Smad signaling during centrifugation.

Factors Regulating or Regulated by Myogenic Regulatory Factors in Skeletal Muscle Stem Cells.

MyoD, Myf5, myogenin, and MRF4 (also known as Myf6 or herculin) are myogenic regulatory factors (MRFs). MRFs are regarded as master transcription factors that are upregulated during myogenesis and influence stem cells to differentiate into myogenic lineage cells. In this review, we summarize MRFs, their regulatory factors, such as TLE3, NF-κB, and MRF target genes, including non-myogenic genes such as taste receptors. Understanding the function of MRFs and the physiology or pathology of satellite cells will contribute to the development of cell therapy and drug discovery for muscle-related diseases.

Applicability of neutral electrolyzed water for cleaning contaminated fixed orthodontic appliances.

INTRODUCTION: We investigated whether water jet washing with neutral electrolyzed water (NW) can be an easy and safe self-performed cleaning method for oral environments of fixed orthodontic appliance-wearing patients. In line with this, we examined the bactericidal effects and dissolution behaviors of metal elements released from appliances. METHODS: A metal or resin bracket ligated with a metal wire and metal bracket adhered to an apatite-pellet were used as specimens. The bacteria and plaque removal effects of the 30 seconds of NW (30, 100 ppm) jet washing for contaminated specimens were examined via an agar-plate method and the observation of the residual plaque, comparing with other treatments (brushing and flow washing), those treatments with tap water (TW), and flow washings with commercial mouthwashes, Listerine Total Care + (LS) and ConCool F (CC). The amounts of metal released from metal specimens during the 1-week immersion in NW were analyzed and compared with those in TW, LS, and CC. RESULTS: NW jet washing produced larger decreases of surviving bacteria than the treatments with TW and CC (P <0.05) and equal or larger decreases than the treatment with LS (P <0.05). NW jet washing yielded the highest plaque removal level. The amounts of nickel and chromium released from metal specimens after the 1-week immersion in NW (30 ppm) were less than or equal to those with LS. CONCLUSIONS: NW jet washing could be applicable for cleaning fixed orthodontic appliances because of its higher bactericidal effects than the treatments with commercial mouthwashes, inducing no or a slight metal release in actual usage time.

Mechanisms involved in suppression of osteoclast supportive activity by transforming growth factor-ß1 via the ubiquitin-proteasome system.

Orthodontic treatment requires the regulation of bone remodeling in both compression and tension sides. Transforming growth factor-ß1 (TGF-ß1) is an important coupling factor for bone remodeling. However, the mechanism underlying the TGF-ß1-mediated regulation of the osteoclast-supporting activity of osteoblasts and stromal cells remain unclear. The current study investigated the effect of TGF-ß1 on receptor activator of nuclear factor kappa-B ligand (RANKL) expression in stromal cells induced by 1α,25(OH)2D3 (D3) and dexamethasone (Dex). TGF-ß1 downregulated the expression of RANKL induced by D3 and Dex in mouse bone marrow stromal lineage, ST2 cells. Co-culture system revealed that TGF-ß1 suppressed osteoclast differentiation from bone marrow cell induced by D3 and Dex-activated ST2 cells. The inhibitory effect of TGF-ß1 on RANKL expression was recovered by inhibiting the interaction between TGF-ß1 and the TGF-ß type I/activin receptor or by downregulating of smad2/3 expression. Interestingly, TGF-ß1 degraded the retinoid X receptor (RXR)-α protein which forms a complex with vitamin D receptor (VDR) and regulates transcriptional activity of RANKL without affecting nuclear translocation of VDR and phosphorylation of signal transducer and activator of transcription3 (STAT3). The degradation of RXR-α protein by TGF-ß1 was recovered by a ubiquitin-proteasome inhibitor. We also observed that poly-ubiquitination of RXR-α protein was induced by TGF-ß1 treatment. These results indicated that TGF-ß1 downregulates RANKL expression and the osteoclast-supporting activity of osteoblasts/stromal cells induced by D3 and Dex through the degradation of the RXR-α protein mediated by ubiquitin-proteasome system.

Tumor necrosis factor alpha regulates myogenesis to inhibit differentiation and promote proliferation in satellite cells.

TNF-α and NF-κB signaling is involved in the wasting of skeletal muscle in various conditions, in addition to cancer cachexia. TNF-α and NF-κB signaling promotes the expression level of muscle RING finger protein 1, a ubiquitin ligase, causing muscle degradation. Several studies have indicated that of TNF-α and NF-κB signaling suppresses muscle differentiation by reducing the levels of MyoD protein. On the other hand, TNF-α and NF-κB is required for myoblast proliferation. Thus, the role of TNF-α and NF-κB signaling in the process of myogenesis and regeneration of skeletal muscle is not completely elucidated. Here, we reported that TNF-α reduced the width of single fibers of skeletal muscle in an organ culture model. TNF-α and p65 repressed the transactivation of MyoD and suppressed myoblast differentiation. In addition, TNF-α increased the number of satellite cells, and NF-κB signaling was promoted at the proliferation stage during skeletal muscle regeneration in vivo. TNF-α and NF-κB signaling regulate myogenesis to inhibit differentiation and promote proliferation in satellite cells.

Natural Compounds Attenuate Denervation-Induced Skeletal Muscle Atrophy.

The weight of skeletal muscle accounts for approximately 40% of the whole weight in a healthy individual, and the normal metabolism and motor function of the muscle are indispensable for healthy life. In addition, the skeletal muscle of the maxillofacial region plays an important role not only in eating and swallowing, but also in communication, such as facial expressions and conversations. In recent years, skeletal muscle atrophy has received worldwide attention as a serious health problem. However, the mechanism of skeletal muscle atrophy that has been clarified at present is insufficient, and a therapeutic method against skeletal muscle atrophy has not been established. This review provides views on the importance of skeletal muscle in the maxillofacial region and explains the differences between skeletal muscles in the maxillofacial region and other regions. We summarize the findings to change in gene expression in muscle remodeling and emphasize the advantages and disadvantages of denervation-induced skeletal muscle atrophy model. Finally, we discuss the newly discovered beneficial effects of natural compounds on skeletal muscle atrophy.

Protein phosphatase 1 regulatory subunit 18 suppresses the transcriptional activity of NFATc1 via regulation of c-fos.

The transcription factor NFATc1 and its binding partner AP-1 (a complex containing c-fos and c-Jun) play a central role in osteoclast differentiation. NFATc1 and AP-1 promote the expression of target genes such as Acp5, Ctsk and also auto-regulate NFATc1 expression as well. We previously reported that protein phosphatase 1 regulatory subunit 18 (PPP1r18) is a negative regulator of osteoclast bone resorption by inhibiting cell attachment to bone matrix. We also reported that PPP1r18 potentially regulates NFATc1 expression during osteoclast differentiation. To further explore this, in this study we have examined the effect of PPP1r18 on NFATc1 expression and activity by overexpressing PPP1r18 during the early stage of osteoclast differentiation. We found that PPP1r18 suppressed NFATc1 expression through inhibition of the transcriptional activity of NFATc1. Since PPP1r18 does not regulate NFATc1 directly, we next explored the involvement of AP-1. Our data showed that c-fos phosphorylation and nuclear localization were reduced by PPP1r18 overexpression. Further experiments showed that overexpression of c-fos together with PPP1r18 rescued NFATc1 expression and transcriptional activity. Moreover, c-fos activity inhibition by PPP1r18 was canceled by mutation of the phosphatase binding site of PPP1r18. Taken together, PPP1r18-regulated phosphatase activity targets c-fos phosphorylation and suppresses subsequent NFATc1 expression and activity.

A Ser252Trp substitution in mouse FGFR2 results in hyperplasia of embryonic salivary gland parenchyma.

OBJECTIVES: Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene are responsible for several severe forms of craniosynostotic disorders, such as Apert and Crouzon syndromes. Patients with craniosynostotic disorders caused by a mutation in Fgfr2 present with several clinical symptoms, including hypersalivation. Here we used a transgenic mouse model of Apert syndrome (Fgfr2+/S252W mice) to evaluate the morphology of the submandibular glands at embryonic day 15.5 (E15.5), the time point reported to mark the start of lumen formation. METHODS: Fgfr2+/S252W mice were generated by crossing ACTB-Cre+/+ and Fgfr2+/Neo-S252W mice. After measuring body weight, the submandibular glands were collected at E15.5. H&E staining, immunostaining, and RT-qPCR were performed to investigate the development of the submandibular gland. RESULTS: The number of ducts and acini in Fgfr2+/S252W mice was significantly higher than in control littermates; however, lumen formation was not affected. The mRNA expression of Fgf1, Fgfr1, Mmp2, Bmp4, Bmp7, Dusp6, and Etv5 in Fgfr2+/S252W mice was significantly higher compared to control littermates. Immunoreactivity for FGF3, FGF1, BMP4, and F4/80 was detected in the parenchyma of Fgfr2+/S252W mice. The area of apoptotic cells stained with TUNEL in Fgfr2+/S252W mice was significantly larger than that of the control littermates. CONCLUSIONS: These results suggested that increased FGFR1 signaling and apoptosis in the submandibular glands of Fgfr2+/S252W mice occurred at E15.5, leading to parenchymal hyperplasia. This study demonstrated that a Ser252Trp substitution in mouse FGFR2 resulted in hyperplasia of the submandibular gland parenchyma during development.

Identification of OPN3 as associated with non-syndromic oligodontia in a Japanese population.

Tooth agenesis is one of the most frequent congenital abnormalities found in the maxillofacial region. Oligodontia, a severe form of tooth agenesis, occurs as an isolated anomaly or as a syndromic feature. We performed whole exome sequencing analyses to identify causative mutation in a Japanese family with three affected individuals with non-syndromic oligodontia. After variant filtering procedures and validation by Sanger sequencing, we identified one missense mutation (c.668 C > T, p.Gly223Asp) in OPN3 at 1q43, encoding a photosensitive G-protein-coupled receptor (GPCR) expressed in various tissues including brain, liver, and adipose. This mutation was predicted to be pathogenic in silico and was not found in the public databases. We further examined 48 genetically unrelated cases by targeted sequencing of the OPN3 gene region and found one additional missense variant in this gene (c.768 C > T, p.Met256Ile) that was also predicted to be pathogenic. Localization of OPN3 protein by immunohistochemical analysis using mouse embryo revealed its specific expression in the tooth gems from bud to bell stages and their surrounding tissues. These results indicated that OPN3 was involved in non-syndromic oligodontia, which has made an anchoring point for clinical application including DNA diagnostics.

Mash1-expressing cells may be relevant to type III cells and a subset of PLCß2-positive cell differentiation in adult mouse taste buds.

Mammalian taste bud cells have a limited lifespan and differentiate into type I, II, and III cells from basal cells (type IV cells) (postmitotic precursor cells). However, little is known regarding the cell lineage within taste buds. In this study, we investigated the cell fate of Mash1-positive precursor cells utilizing the Cre-loxP system to explore the differentiation of taste bud cells. We found that Mash1-expressing cells in Ascl1CreERT2::CAG-floxed tdTomato mice differentiated into taste bud cells that expressed aromatic L-amino acid decarboxylase (AADC) and carbonic anhydrase IV (CA4) (type III cell markers), but did not differentiate into most of gustducin (type II cell marker)-positive cells. Additionally, we found that Mash1-expressing cells could differentiate into phospholipase C ß2 (PLCß2)-positive cells, which have a shorter lifespan compared with AADC- and CA4-positive cells. These results suggest that Mash1-positive precursor cells could differentiate into type III cells, but not into most of type II cells, in the taste buds.

Daily Oral Administration of Protease-Treated Royal Jelly Protects Against Denervation-Induced Skeletal Muscle Atrophy.

Honeybees produce royal jelly (RJ) from their cephalic glands. Royal jelly is a source of nutrition for the queen honey bee throughout its lifespan and is also involved in fertility and longevity. Royal jelly has long been considered beneficial to human health. We recently observed that RJ delayed impairment of motor function during aging, affecting muscle fiber size. However, how RJ affects skeletal muscle metabolism and the functional component of RJ is as of yet unidentified. We demonstrate that feeding mice with RJ daily prevents a decrease in myofiber size following denervation without affecting total muscle weight. RJ did not affect atrophy-related genes but stimulated the expression of myogenesis-related genes, including IGF-1 and IGF receptor. Trans-10-hydroxy-2-decenoic acid (10H2DA) and 10-hydroxydecanoic acid (10HDAA), two major fatty acids contained in RJ. After ingestion, 10H2DA and 10HDAA are metabolized into 2-decenedioic acid (2DA) and sebacic acid (SA) respectively. We found that 10H2DA, 10HDAA, 2DA, and SA all regulated myogenesis of C2C12 cells, murine myoblast cells. These novel findings may be useful for potential preventative and therapeutic applications for muscle atrophy disease included in Sarcopenia, an age-related decline in skeletal muscle mass and strength.