KIF22 regulates mitosis and proliferation of chondrocyte cells.

Point mutations in KIF22 have been linked to spondyloepimetaphyseal dysplasia with joint laxity, type 2 (SEMDJL2). Skeletal features of SEMDJL2 include short stature and joint laxity. Mechanisms underlying these limb abnormalities are unknown. Here in this manuscript, we have investigated the function of KIF22 in chondrocytes. Quantitative PCR and immunostaining revealed that Kif22 was highly expressed in proliferating-zone growth-plate chondrocytes. Kif22 knockdown resulted in defective mitotic spindle formation and reduced cell proliferation. Forced expression of SEMDJL-associated mutant Kif22 constructs likewise induced abnormal mitotic spindle morphology and reduced proliferation. Mice expressing a KIF22 truncation mutant had shorter growth plates and shorter tibial bones compared to wild-type mice. These results suggest that KIF22 regulates mitotic spindle formation in proliferating chondrocytes thereby linking the stunted longitudinal bone growth observed in SEMDJL2 to failures of chondrocyte division.

Recent advances in the treatment of oral ulcerative mucositis from clinical and basic perspectives.

BACKGROUND: Oral ulcerative mucositis (OUM) is common in patients with cancer, particularly in those undergoing chemoradiation therapy. The effective management of OUM is crucial for continuous cancer care and patient well-being. Recent studies have advanced our understanding of the causes, leading to clinical trials toward novel treatments. This review focuses on the contemporary therapeutic landscape, and provides the latest insights into the mechanisms of mucosal healing and pain. HIGHLIGHTS: Management strategies for oral ulcerative mucositis in patients with cancer include maintaining good oral hygiene, reducing mucosal irritation against radiation, and using various topical analgesic treatments, including herbal medicines. However, the current management practices have limitations that necessitate the development of more efficacious and novel treatments. Molecular research on transient receptor potential (TRP) channels in the oral mucosa is crucial for understanding the mechanisms of wound healing and pain in patients with OUM. Targeting TRP subfamily V member 3 (V3) and TRPV4 can enhance wound healing through re-epithelialization. The suppression of TRPV1, TRPA1, and TRPV4 may be effective in alleviating OUM-induced pain. CONCLUSION: Research advancements have improved our understanding and potentially led to novel treatments that offer symptomatic relief. This progress highlights the importance of collaborations between clinical researchers and scientists in the development of innovative therapies.

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.

Hepcidin expression in the trigeminal ganglion and the oral mucosa in an oral ulcerative mucositis rat model.

Severe intraoral pain induces difficulty in eating and speaking, leading to a decline in the quality of life. However, the molecular mechanisms underlying intraoral pain remain unclear. Here, we investigated gene modulation in the trigeminal ganglion and intraoral pain-related behavior in a rat model of acetic acid-induced oral ulcerative mucositis. Oral ulceration was observed on day 2 after acetic acid treatment to the oral mucosa of male Wistar rats, causing spontaneous pain and mechanical allodynia. Deoxyribonucleic acid microarray analysis of trigeminal ganglion tissue indicated that Hamp (a hepcidin gene that regulates cellular iron transport) was the most upregulated gene. In the oral ulcerative mucositis model, the upregulation of Hamp was also induced in the ulcer region but not in the liver, with no increase in hepcidin levels in the plasma and saliva, indicating that hepcidin was produced locally in the ulcer region in the model. Systemic antibiotic pretreatment did not increase the mRNA levels of Hamp in the trigeminal ganglion and ulcer regions. Hepcidin injection into the oral mucosa enhanced neuronal excitability in response to noxious mechanical stimulation of the oral mucosa in trigeminal spinal subnucleus interpolaris/caudalis neurons. These results imply that oral ulcerative mucositis induces oral mucosal pain because of infectious inflammation of the ulcerative area and potentiates Hamp, which represents anti-bacterial and anti-peptidase gene expression in the ulcer region and trigeminal ganglion. The regulation of cellular iron transport by hepcidin is likely involved in oral ulcerative mucositis-induced pain.

p130Cas is required for androgen-dependent postnatal development regulation of submandibular glands.

Salivary glands develop through epithelial-mesenchymal interactions and are formed through repeated branching. The Crk-associated substrate protein (p130Cas) serves as an adapter that forms a complex with various proteins via integrin and growth factor signaling, with important regulatory roles in several essential cellular processes. We found that p130Cas is expressed in ductal epithelial cells of the submandibular gland (SMG). We generated epithelial tissue-specific p130Cas-deficient (p130CasΔepi-) mice and aimed to investigate the physiological role of p130Cas in the postnatal development of salivary glands. Histological analysis showed immature development of granular convoluted tubules (GCT) of the SMG in male p130CasΔepi- mice. Immunofluorescence staining showed that nuclear-localized androgen receptors (AR) were specifically decreased in GCT cells in p130CasΔepi- mice. Furthermore, epidermal growth factor-positive secretory granules contained in GCT cells were significantly reduced in p130CasΔepi- mice with downregulated AR signaling. GCTs lacking p130Cas showed reduced numbers and size of secretory granules, disrupted subcellular localization of the cis-Golgi matrix protein GM130, and sparse endoplasmic reticulum membranes in GCT cells. These results suggest that p130Cas plays a crucial role in androgen-dependent GCT development accompanied with ER-Golgi network formation in SMG by regulating the AR signaling.

Effect of cisplatin on oral ulcer-induced nociception in rats.

OBJECTIVE: The aim of this study is to investigate effects of cisplatin preadministration on oral ulcerative mucositis-induced nociception by using an experimental model of rats. DESIGN: After two rounds of cisplatin administration, oral ulcers developed with topical acetic acid treatment in rats. Spontaneous mouth rubbing behavior was observed as spontaneous nociceptive behavior in a plastic cage. Head-withdrawal behavior was observed as mechanical allodynia by using von Frey test in the oral mucosa of conscious rats. Bacterial invasion and inflammatory cell infiltration into oral ulcerative region and systemic leukocyte phagocytic activity were assessed. RESULTS: Following cisplatin preadministration, oral ulcerative mucositis-induced spontaneous nociceptive behavior was not observed in the model. The preadministration enhanced leukocyte phagocytic activity, leading to reduce bacterial invasion and inflammatory cell infiltration in the oral ulcerative region. In contrast, oral ulcerative mucositis-induced mechanical allodynia was induced. The exaggerated mechanical allodynia in the oral ulcerative region was largely inhibited by topical treatment with the antioxidative drug, ɑ-lipoic acid, or the blocker of N-formyl peptide receptor 1, N-t-butoxycarbonyl-methionyl-leucyl-phenylalanine. CONCLUSIONS: These results suggest that cisplatin preadministration suppresses spontaneous nociception in oral ulcerative region, due to antiinflammatory effects by enhancement of leukocyte phagocytic activity, but exaggerates mechanical allodynia due to oxidative stress with N-formyl peptide receptor 1 activation. The suppression of spontaneous nociception is one of the advantages of cisplatin treatment for head and neck cancer patients although the exaggerated allodynia is a serious symptom.

Deletion of epithelial cell-specific p130Cas impairs the maturation stage of amelogenesis.

Amelogenesis consists of secretory, transition, maturation, and post-maturation stages, and the morphological changes of ameloblasts at each stage are closely related to their function. p130 Crk-associated substrate (Cas) is a scaffold protein that modulates essential cellular processes, including cell adhesion, cytoskeletal changes, and polarization. The expression of p130Cas was observed from the secretory stage to the maturation stage in ameloblasts. Epithelial cell-specific p130Cas-deficient (p130CasΔepi-) mice exhibited enamel hypomineralization with chalk-like white mandibular incisors in young mice and attrition in aged mouse molars. A micro-computed tomography analysis and Vickers micro-hardness testing showed thinner enamel, lower enamel mineral density and hardness in p130CasΔepi- mice in comparison to p130Casflox/flox mice. Scanning electron microscopy, and an energy dispersive X-ray spectroscopy analysis indicated the disturbance of the enamel rod structure and lower Ca and P contents in p130CasΔepi- mice, respectively. The disorganized arrangement of ameloblasts, especially in the maturation stage, was observed in p130CasΔepi- mice. Furthermore, expression levels of enamel matrix proteins, such as amelogenin and ameloblastin in the secretory stage, and functional markers, such as alkaline phosphatase and iron accumulation, and Na+/Ca2++K+-exchanger in the maturation stage were reduced in p130CasΔepi- mice. These findings suggest that p130Cas plays important roles in amelogenesis (197 words).

Cisplatin induces TRPA1-mediated mechanical allodynia in the oral mucosa.

OBJECTIVE: Cisplatin, a platinum-based anticancer drug, produces reactive oxygen species (ROS) in many cell types and induces mechanical allodynia in the hands and/or feet (chemotherapy-induced painful neuropathy: CIPN). In this study, we examined the possibility of inducing neuropathy in the oral region using oral keratinocytes and rats. METHODS: Human oral keratinocytes (HOKs) were used to evaluate ROS generation after cisplatin application by a ROS-reactive fluorescent assay. In rats, after cisplatin administrations (two times), the trigeminal ganglion (TG) was investigated by electron microscopy and quantitative RT-PCR. Using our proprietary assay system, oral pain-related behaviors were observed in cisplatin-treated rats. RESULTS: In rats, cisplatin administration reduced food intake and body weight. In electron microscopic analysis, glycogen granules in the TG were depleted following administration, although organelles were intact. In HOK cells, cisplatin significantly increased ROS generation with cell death, similar to glycolysis inhibitors. Cisplatin administration did not show any effects on Trpa1 mRNA levels in the TG. However, the same procedure induced hypersensitivity to mechanical stimulation and the TRPA1 agonist allyl isothiocyanate in the oral mucosa. Mechanical hypersensitivity was inhibited by the antioxidative drug α-lipoic acid and the TRPA1 antagonist HC-030031, similar to that of the hind paw. CONCLUSION: The present findings suggest that cisplatin induces TRPA1-mediated CIPN due to ROS generation in the oral region. This study will provide a better understanding of persistent oral pain in cancer patients.

Analgesic Mechanisms of Steroid Ointment against Oral Ulcerative Mucositis in a Rat Model.

Despite the long history of use of steroid ointments for oral mucositis, the analgesic mechanism has not been fully elucidated. In this study, we examined the effects of triamcinolone acetonide (Tmc) on oral ulcerative mucositis-induced pain in conscious rats by our proprietary assay system. Based on evaluations of the physical properties and retention periods in the oral mucosa of human volunteers and rats, we selected TRAFUL® ointment as a long-lasting base. In oral ulcerative mucositis model rats, TRAFUL® with Tmc suppressed cyclooxygenase-dependent inflammatory responses with upregulations of glucocorticoid receptor-induced anti-inflammatory genes and inhibited spontaneous nociceptive behavior. When an ointment with a shorter residual period was used, the effects of Tmc were not elicited or were induced to a lesser extent. Importantly, TRAFUL® with Tmc also improved oral ulcerative mucositis-induced mechanical allodynia, which has been reported to be independent of cyclooxygenase. Ca2+ imaging in dissociated trigeminal ganglion neurons showed that long-term preincubation with Tmc inhibited the hypertonic stimulation-induced Ca2+ response. These results suggest that the representative steroid Tmc suppresses oral ulcerative mucositis-induced pain by general anti-inflammatory actions and inhibits mechanical sensitivity in peripheral nerves. For drug delivery, long-lasting ointments such as TRAFUL® are needed to sufficiently induce the therapeutic effects.

NF-κB Signaling Regulates Physiological and Pathological Chondrogenesis.

The nuclear factor-κB (NF-κB) is a transcription factor that regulates the expression of genes that control cell proliferation and apoptosis, as well as genes that respond to inflammation and immune responses. There are two means of NF-κB activation: the classical pathway, which involves the degradation of the inhibitor of κBα (IκBα), and the alternative pathway, which involves the NF-κB-inducing kinase (NIK, also known as MAP3K14). The mouse growth plate consists of the resting zone, proliferative zone, prehypertrophic zone, and hypertrophic zone. The p65 (RelA), which plays a central role in the classical pathway, is expressed throughout the cartilage layer, from the resting zone to the hypertrophic zone. Inhibiting the classical NF-κB signaling pathway blocks growth hormone (GH) or insulin-like growth factor (IGF-1) signaling, suppresses cell proliferation, and suppresses bone morphogenetic protein 2 (BMP2) expression, thereby promoting apoptosis. Since the production of autoantibodies and inflammatory cytokines, such as tumor necrosis factor-α (TNFα), interleukin (IL)-1ß, IL-6, and IL-17, are regulated by the classical pathways and are increased in rheumatoid arthritis (RA), NF-κB inhibitors are used to suppress inflammation and joint destruction in RA models. In osteoarthritis (OA) models, the strength of NF-κB-activation is found to regulate the facilitation or suppression of OA. On the other hand, RelB is involved in the alternative pathway, and is expressed in the periarticular zone during the embryonic period of development. The alternative pathway is involved in the generation of chondrocytes in the proliferative zone during physiological conditions, and in the development of RA and OA during pathological conditions. Thus, NF-κB is an important molecule that controls normal development and the pathological destruction of cartilage.

Transducin-like enhancer of split 3 regulates proliferation of melanoma cells via histone deacetylase activity.

Melanoma, one of the most aggressive neoplasms, is characterized by rapid cell proliferation. Transducin-like Enhancer of Split (TLE) is an important regulator of cell proliferation via Histone deacetylase (HDAC) recruitment. Given that HDAC activity is associated with melanoma progression, we examined the relationship between TLE3, a TLE family member, and melanoma. TLE3 expression was increased during the progression of human patient melanoma (p < 0.05). Overexpression of Tle3 in B16 murine melanoma cells led to an increase in cell proliferation (p < 0.01) as well as the number of cyclinD1-positive cells. in vivo injection of mice with B16 cells overexpressing Tle3 resulted in larger tumor formation than in mice injected with control cells (p < 0.05). In contrast, siRNA-mediated knockdown of Tle3 in B16 cells or TLE3 in HMV-II human melanoma cells decreased proliferation (p < 0.01). Treatment of B16 cells with trichostatin A (2.5 µM), a class I and II HDAC inhibitor, prevented the effect s of Tle3 on proliferation. In conclusion, these data indicate that Tle3 is required, at least in part, for proliferation in the B16 mouse melanoma model.

A peptide that blocks the interaction of NF-κB p65 subunit with Smad4 enhances BMP2-induced osteogenesis.

Bone morphogenetic protein (BMP) potentiates bone formation through the Smad signaling pathway in vitro and in vivo. The transcription factor nuclear factor κB (NF-κB) suppresses BMP-induced osteoblast differentiation. Recently, we identified that the transactivation (TA) 2 domain of p65, a main subunit of NF-κB, interacts with the mad homology (MH) 1 domain of Smad4 to inhibit BMP signaling. Therefore, we further attempted to identify the interacting regions of these two molecules at the amino acid level. We identified a region that we term the Smad4-binding domain (SBD), an amino-terminal region of TA2 that associates with the MH1 domain of Smad4. Cell-permeable SBD peptide blocked the association of p65 with Smad4 and enhanced BMP2-induced osteoblast differentiation and mineralization without affecting the phosphorylation of Smad1/5 or the activation of NF-κB signaling. SBD peptide enhanced the binding of the BMP2-inudced phosphorylated Smad1/5 on the promoter region of inhibitor of DNA binding 1 (Id-1) compared with control peptide. Although SBD peptide did not affect BMP2-induced chondrogenesis during ectopic bone formation, the peptide enhanced BMP2-induced ectopic bone formation in subcortical bone. Thus, the SBD peptide is useful for enabling BMP2-induced bone regeneration without inhibiting NF-κB activity.

The Actin-Binding Protein PPP1r18 Regulates Maturation, Actin Organization, and Bone Resorption Activity of Osteoclasts.

Osteoclasts resorb bone by attaching on the bone matrix and forming a sealing zone. In Src-deficient mice, osteoclasts cannot form the actin ring, a characteristic actin structure that seals the resorbed area, and resorb hardly any bone as a result. However, the molecular mechanism underlying the role of Src in the regulation and organization of the actin ring is still unclear. We identified an actin-regulatory protein, protein phosphatase 1 regulatory subunit 18 (PPP1r18), as an Src-binding protein in an Src-, Yes-, and Fyn-deficient fibroblast (SYF) cell line overexpressing a constitutively active form of Src. PPP1r18 was localized in the nucleus and actin ring. PPP1r18 overexpression in osteoclasts inhibited terminal differentiation, actin ring formation, and bone-resorbing activity. A mutation of the protein phosphatase 1 (PP1)-binding domain of PPP1r18 rescued these phenotypes. In contrast, PPP1r18 knockdown promoted terminal differentiation and actin ring formation. In summary, we showed that PPP1r18 likely plays a role in podosome organization and bone resorption.

The enamel knot-like structure is eternally maintained in the apical bud of postnatal mouse incisors.

OBJECTIVES: The boundary where inner and outer enamel epithelia meet is referred to as the cervical loop (CL) in molar tooth germs. In contrast, rodent incisors are continuously growing: the labial side of the teeth is covered with enamel (crown-analog), and the lingual side is covered with cementum (root-analog). These results in the appearance of CL in the frontal sections apart from the apical end. However, many researchers have used the term "labial CL" to indicate the apical end of incisors. DESIGN: This study investigated the gene expression patterns for the enamel knot signaling center in tooth morphogenesis to clarify the difference between "labial CL" and molar CL. We examined the three-dimensional expression patterns of markers for the enamel knot including fibroblast growth factor 4 (Fgf4), sonic hedgehog (Shh), Msx2, and P21 in frontal sections of murine mandibular incisors. RESULTS: Serial frontal sections from the apical end of the postnatal incisor clearly demonstrated the existence of enamel knot-like structures composed of supra-inner enamel epithelium and stellate reticulum in the "labial CL". This structure includes the expression of all examined markers for enamel knots such as Fgf4, Shh, Msx2, and P21. CONCLUSIONS: The molar tooth germ-like structure is maintained indefinitely in the "labial CL". Therefore, the "labial CL" is not equivalent to the molar CL. The existence of an EK-like structure in the apical end of incisors implies that the usage of "labial CL" may be inappropriate for indicating this region. The "apical bud" could be used as an alternative term.

The distinct distributions of immunocompetent cells in rat dentin pulp after pulpotomy.

Pulpotomy involves the removal of the coronal portion of pulp, including the diseased tissue, with the intent of maintaining the vitality of the remaining pulpal tissue via a therapeutic dressing. Once odontoblasts suffer injuries, the differentiation of mesenchymal cells is induced from the precursor cell population in the dental pulp, and these cells are recruited to the injured site to differentiate into odontoblasts. However, the involvement of immunocompetent cells during pulpal regeneration remains unclear. Thus, the purpose of this study was to investigate the properties of macrophages that infiltrated wound healing sites in rats between 1 and 28 days after pulpotomy (dap). During the inflammatory phase, ED1(+) (CD68(+) ) macrophages significantly increased throughout root pulp, especially apical to the demarcation zone, and this population persisted until 3 dap before decreasing gradually until 28 dap. OX6(+) macrophages expressing class II MHC also increased in the apical pulp at 1 dap and declined thereafter. However, OX6(+) cells appeared prior to dentin bridge formation at 3 dap and appeared again apical to the dentin bridge during the healing stage at 14 dap. The shift from ED1(+) cells in the inflammation phase to OX6(+) cells during dentin bridge formation might contribute to wound healing.

The novel IκB kinase ß inhibitor IMD-0560 prevents bone invasion by oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) cells display significantly augmented nuclear factor-κB (NF-κB) activity, and inhibiting this activity suppresses malignant tumor characteristics. Thus, we evaluated the effect of IMD-0560, a novel inhibitor of IκB kinase (IKK) ß that is under assessment in a clinical trial of rheumatoid arthritis, on bone invasion by the mouse OSCC cell line SCCVII. We examined the inhibitory effects of IMD-0560 on NF-κB activity and tumor invasion using human OSCC cell lines and SCCVII cells in vitro. Using a mouse model of jaw bone invasion by SCCVII cells, we assessed the inhibitory effect of IMD-0560 on jaw bone invasion, tumor growth, and matrix degradation in vivo. IMD-0560 suppressed the nuclear translocation of NF-κB and the degradation of IκBα in OSCC cells. IMD-0560 also inhibited invasion by suppressing matrix metalloproteinase-9 (MMP-9) production in OSCC cells. IMD-0560 protected against zygoma and mandible destruction by SCCVII cells, reduced the number of osteoclasts by inhibiting receptor activator of NF-κB ligand (RANKL) expression in osteoblastic cells and SCCVII cells, increased SCCVII cell death and suppressed cell proliferation and MMP-9 production in SCCVII cells. Based on these results, IMD-0560 may represent a new therapeutic agent for bone invasion by OSCC cells.

Inhibition of BMP2-induced bone formation by the p65 subunit of NF-κB via an interaction with Smad4.

Bone morphogenic proteins (BMPs) stimulate bone formation in vivo and osteoblast differentiation in vitro via a Smad signaling pathway. Recent findings revealed that the activation of nuclear factor-κB (NF-κB) inhibits BMP-induced osteoblast differentiation. Here, we show that NF-κB inhibits BMP signaling by directly targeting the Smad pathway. A selective inhibitor of the classic NF-κB pathway, BAY11-770682, enhanced BMP2-induced ectopic bone formation in vivo. In mouse embryonic fibroblasts (MEFs) prepared from mice deficient in p65, the main subunit of NF-κB, BMP2, induced osteoblastic differentiation via the Smad complex to a greater extent than that in wild-type MEFs. In p65(-/-) MEFs, the BMP2-activated Smad complex bound much more stably to the target element than that in wild-type MEFs without affecting the phosphorylation levels of Smad1/5/8. Overexpression of p65 inhibited BMP2 activity by decreasing the DNA binding of the Smad complex. The C-terminal region, including the TA2 domain, of p65 was essential for inhibiting the BMP-Smad pathway. The C-terminal TA2 domain of p65 associated with the MH1 domain of Smad4 but not Smad1. Taken together, our results suggest that p65 inhibits BMP signaling by blocking the DNA binding of the Smad complex via an interaction with Smad4. Our study also suggests that targeting the association between p65 and Smad4 may help to promote bone regeneration in the treatment of bone diseases.