Tmem119 is involved in bone anabolic effects of PTH through enhanced osteoblastic bone formation in mice

Roles of Transmembrane Protein 119 in the Effects of Transforming Growth Factor-β on Mouse Bone Cells

Transforming growth factor-β (TGF-β), a local growth factor, is essential for bone remodeling; when administered in bone tissues, it stimulates bone formation. On the other hand, transmembrane protein 119 (Tmem119) is a crucial factor for osteoblastic bone formation related to the TGF-β signaling molecule, Smad3. However, the role of Tmem119 in TGF-β-mediated effects on osteoblasts and osteoclasts remains unclear.The function of Tmem119 in TGF-β-mediated effects was examined for osteoblastic differentiation, bone matrix protein expression, and osteoclast formation in mouse osteoblasts, adipose tissue-derived stromal cells, and bone marrow cells from wild-type and Tmem119-deficient mice. Tmem119 deficiency significantly reversed the TGF-β-induced expressions of type I collagen and matrix-Gla protein (MGP) in mouse osteoblasts but did not affect TGF-β-suppressed alkaline phosphatase activity in mouse adipose tissue-derived stromal cells, even when TGF-β could suppress alkaline phosphatase (ALP) activity in mouse osteoblasts regardless of Tmem119 deficiency. Tmem119 deficiency significantly reduced osteoclast formation and Nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) mRNA levels in mouse bone marrow cells.Tmem119 is involved in regulating type I collagen and MGP expressions and TGF-β-induced osteoclast formation, but does not affect TGF-β-suppressed osteoblastic differentiation in mouse cells.

Roles of Insulin-Like Growth Factor-1 in Muscle Wasting and Osteopenia in Mice with Hyponatremia

Hyponatremia is associated with sarcopenia and osteoporosis in elderly individuals. Skeletal muscle releases myokines, which affect distant organs, including bone. However, the detailed mechanisms by which hyponatremia influences muscle and bone remain unclear. We herein investigated the effects of hyponatremia on muscle, bone, and myokines linking muscle to bone in mice treated with 1-desamino-8-D-arginine vasopressin (dDAVP) or furosemide, which induce hyponatremia. Muscle mass and bone mineral density (BMD) were analyzed 8 weeks after the administration of dDAVP or furosemide. dDAVP significantly reduced grip strength, but did not affect tissue weights of gastrocnemius or soleus muscles of mice. Furosemide significantly decreased muscle mass, tissue weights of gastrocnemius and soleus muscles, and grip strength in mice. dDAVP and furosemide decreased trabecular BMD, trabecular bone volume, and cortical BMD at the femurs. Among myokines linking muscle to bone, hyponatremia reduced expression of insulin-like growth factor (IGF)-1 in gastrocnemius and soleus muscles and serum IGF-1 levels in mice. In simple regression analyses, serum IGF-1 levels were positively related to muscle IGF-1 expression, trabecular bone volume, and cortical BMD in mice. The administration of sodium chloride solution to mice ameliorated the decreases in grip strength, muscle mass, trabecular bone volume, cortical BMD, and the levels of muscle and circulating IGF-1 in furosemide-treated mice. The present study demonstrated that hyponatremia induces muscle and bone loss as well as a decrease in muscle IGF-1 expression in mice. The present findings suggest that IGF-1 might be related to muscle wasting and bone loss induced by hyponatremia in mice.

Dual release scaffolds as a promising strategy for enhancing bone regeneration: an updated review

Advancements in tissue regeneration, particularly bone regeneration is key area of research due to potential of novel therapeutic approaches. Efforts to reduce reliance on autologous and allogeneic bone grafts have led to the development of biomaterials that promote synchronized and controlled bone healing. However, the use of growth factors is limited by their short half-life, slow tissue penetration, large molecular size and potential toxicity. These factors suggest that traditional delivery methods may be inadequate hence, to address these challenges, new strategies are being explored. These novel approaches include the use of bioactive substances within advanced delivery systems that enable precise spatiotemporal control. Dual-release composite scaffolds offer a promising solution by reducing the need for multiple surgical interventions and simplifying the treatment process. These scaffolds allow for sustained and controlled drug release, enhancing bone repair while minimizing the drawbacks of conventional methods. This review explores various dual-drug release systems, discussing their modes of action, types of drugs used and release mechanisms to improve bone regeneration.

Tmem119 deficiency delays bone repair in mice

Tmem119 was identified as a bone anabolic factor in osteoblasts, however the roles of Tmem119 on bone repair have remained unknown. Therefore, we herein investigated the roles of Tmem119 on bone repair by examining the bone repair process after a femoral bone defect using Tmem119-deficient mice. In Tmem119-deficient mice, bone repair after a femoral bone defect was significantly delayed 10 and 14 days after bone injury in female and male mice with 3-dimensional micro-computed tomography analyses, respectively. The number of alkaline phosphatase-positive cells at the damaged sites was significantly decreased 7 days after bone injury in Tmem119-deficient mice, although the number of Osterix-positive cells was not significantly different 4 days after bone injury. The number of tartrate-resistant acid phosphatase-positive multinucleated cells as well as the number and luminal area of CD31-positive vessels at the damaged sites were not significantly different between Tmem119-deficient and wild-type mice. The present study first showed that Tmem119 deficiency delayed bone repair partly through a decrease in the osteoblastic bone formation of differentiated osteoblasts.

TMEM119 (c.G143A, p.S48L) Mutation Is Involved in Primary Failure of Eruption by Attenuating Glycolysis-Mediated Osteogenesis

Primary failure of eruption (PFE) is a rare oral disease with an incidence rate of 0.06%. It is characterized by abnormal eruption mechanisms that disrupt tooth eruption. The underlying pathogenic genetic variant and mechanism of PFE remain largely unknown. The purpose of this study was to explore the role of a novel transmembrane protein 119 (TMEM119) mutation in two PFE patients in a Chinese family. Information collection was performed on the family with a diagnosis of PFE, and blood samples from patients and healthy family members were extracted. Whole-exome sequencing was performed. Bioinformatics analysis revealed that a heterozygous variant in the TMEM119 gene (c.G143A, p.S48L) was a disease-associated mutation in this family. Recombinant pcDNA3.1 plasmid-containing wild-type and mutant TMEM119 expression cassettes were successfully constructed and transfected into MC3T3-E1 cells, respectively. The results of in vitro analysis suggested that the subcellular distribution of the TMEM119 protein was transferred from the cell cytoplasm to the nucleus, and the ability of cells to proliferate and migrate as well as glycolytic and mineralized capacities were reduced after mutation. Furthermore, rescue assays showed that activating transcription factor 4 (ATF4) overexpression rescued the attenuated glycolysis and mineralization ability of cells. Results of in vivo analysis demonstrated that TMEM119 was mainly expressed in the alveolar bone around the mouse molar germs, and the expression level increased with tooth eruption, demonstrated using immunohistochemistry and immunofluorescence. Collectively, the novel TMEM119 mutation is potentially pathogenic in the PFE family by affecting the glucose metabolism and mineralized function of osteoblasts, including interaction with ATF4. Our findings broaden the gene mutation spectrum of PFE and further elucidate the pathogenic mechanism of PFE.