TM9SF4 is a novel regulator in lineage commitment of bone marrow mesenchymal stem cells to either osteoblasts or adipocytes

Comparative analysis of the expression patterns of TM9SF family members in mice

Transmembrane 9 superfamily proteins (TM9SFs) define a highly conserved protein family, each member of which is characterized by a variable extracellular domain and presumably nine transmembrane domains. Although previous studies have delineated the potential cytological roles of TM9SFs like autophagy and secretory pathway, their functions during development are largely unknown. To establish the basis for dissecting the functions of TM9SFs in vivo, we employed the open-source database, structure prediction, immunofluorescence and Western blot to describe the gene and protein expression patterns of TM9SFs in human and mouse. While TM9SFs are ubiquitously and homogeneously expressed in all tissues in human with RNA sequencing and proteomics analysis, we found that all mice Tm9sf proteins are preferentially expressed in lung except Tm9sf1 which is enriched in brain although they all distributed in various tissues we examined. In addition, we further explored their expression patterns in the mice central nervous system (CNS) and its extension tissue retina. Interestingly, we could show that Tm9sf1is developmentally up-regulated in brain. In addition, we also detected all Tm9sf proteins are located in neurons and microglia instead of astrocytes. Importantly, Tm9sf3 is localized in the nuclei which is distinct from the other members that are dominantly targeted to the plasma membrane/cytoplasm as expected. Finally, we also found that Tm9sf family members are broadly expressed in the layers of INL, OPL, and GCL of retina and likely targeted to the plasma membrane of retinal cells. Thus, our data provided a comprehensive overview of TM9SFs expression patterns, illustrating their ubiquitous roles in different organs, implying the possible roles of Tm9sf2/3/4 in lung functions and Tm9sf1 in neurodevelopment, and highlighting a unique cell biological functions of TM9SF3 in neuronal and microglia.

The quantitative parameters derived from IDEAL-IQ in the lumbar vertebrae of healthy children: a pilot study of bone development

Background

Early childhood bone development affects that of bone disease in adolescence and adulthood. Many diseases can affect the cancellous bone or bone marrow. Therefore, it is of great significance to quantify the bone development of healthy children. The evaluation methods of bone development include bone age (BA) assessment and dual-energy X-ray bone mineral densitometry (DXA), both of which have strong subjectivity. The present study was conducted to improve our understanding of the bone development of healthy children using the quantitative parameters derived from iterative decomposition of water and fat with echo asymmetry and least squares estimation quantification (IDEAL-IQ) sequence.

Methods

Our study enrolled healthy children between January 2022 to December 2022 consecutively in Children's Hospital of Shanxi. The inclusion criteria were as follows: (I) age ≤18 years; (II) no contraindications (surgical and interventional devices for ferromagnetic materials, cardiac implantable electronic devices, cochlear implants, insulin pumps, dental implants containing metal or alloy) to magnetic resonance imaging (MRI) scan. The exclusion criteria were as follows: (I) previous malignant disease, (II) previous chemoradiotherapy, (III) previous spine surgery, (IV) previous or acute vertebral compression fracture, (V) artifacts present in images. Participants underwent MRI scans using IDEAL-IQ sequence in the lumbar vertebrae. The IDEAL-IQ parameters [proton density fat fraction (PDFF), 1/T2* (R2*)] were obtained. The factor analysis of variance was applied to compare the differences of PDFF and R2* in different lumbar vertebral groups. The Kruskal-Wallis H test or Mann-Whitney U test was applied to compare the differences of quantitative data among different gender or age groups. Spearman correlation analysis was applied to study the relationship among the age, PDFF, and R2*.

Results

A total of 145 participants (76 males, 69 females) were evaluated. There were no significant differences in PDFF and R2* of different lumbar vertebrae (PPDFF=0.338, PR2*=0.868). The average age was 36 [13-72] months. They were assigned into 4 groups (0-11, 12-35, 36-71, and 72-144 months). As the age increased, the average PDFF and R2* both increased significantly (rPDFF=0.659, rR2*=0.359, P<0.001). There were significant statistical differences in PDFF and R2* between the 4 age groups (ZPDFF=46.651, ZR2*=27.537, P<0.001). Moreover, the PDFF was also positively correlated with R2* (r=0.576, P<0.001). No association was found between the gender and PDFF, R2* (PPDFF=0.949, PR2*=0.177).

Conclusions

The quantitative parameters derived from IDEAL-IQ in the lumbar vertebrae of healthy children will improve our understanding of bone development and provide a basis for further exploring the diseases that affect children's bone development.

Urine-derived stem cells-extracellular vesicles ameliorate diabetic osteoporosis through HDAC4/HIF-1α/VEGFA axis by delivering microRNA-26a-5p

Critical roles of stem cell-extracellular vesicles (EVs) in the management of osteoporosis have been documented. Here, this study was designed to enlarge the research of the specific effects and underlying mechanism of urine-derived stem cells-EVs (USCs-EVs) on osteoporosis in diabetes rats. Firstly, miR-26a-5p and histone deacetylase 4 (HDAC4) expression in USCs of rats after diabetic osteoporosis (DOP) modeling induced by streptozotocin injection was determined, followed by study of their interaction. Then, USCs-EVs were co-cultured with osteogenic precursor cells, the effects of miRNA-26a-5p (miR-26a-5p) on osteoblasts, osteoclasts, bone mineralization deposition rate were evaluated. Meanwhile, the effect of USCs-EVs carrying miR-26a-5p on DOP rats was assessed. Elevated miR-26a-5p was seen in USCs-EVs which limited HDAC4 expression. Moreover, USCs-EVs delivered miR-26a-5p to osteogenic precursor cells, thereby promoting their differentiation, enhancing the activity of osteoblasts, and inhibiting the activity of osteoclasts, thereby preventing DOP through the activation of hypoxia inducible factor 1 subunit alpha (HIF-1α)/vascular endothelial growth factor A (VEGFA) pathway by repressing HDAC4. In a word, USCs-EVs-miR-26a-5p is a promising therapy for DOP by activating HIF-1α/VEGFA pathway through HDAC4 inhibition. 1. USCs-EVs-miR-26a-5p targeted HDAC4 and limited HDAC4 expression. 2. miR-26a-5p was delivered by USCs-EVs into osteoblast precursor cells. 3. USCs-EVs-miR-26a-5p promoted the differentiation of osteoblast precursor cells into osteoblasts. 4. miR-26a-5p delivered by USCs-EVs could inhibit HDAC4. 5. USCs-EVs-miR-26a-5p could prevent the pathogenesis of DOP via HIF-1α/VEGFA aix.

Trehalose improves palmitic acid-induced apoptosis of osteoblasts by regulating SIRT3-medicated autophagy via the AMPK/mTOR/ULK1 pathway

Accumulation of lipid substances decreased the activity of osteoblasts. Trehalose is a typical stress metabolite to form a protective membrane on cell surface which has been demonstrated to regulate lipid metabolism. This activity of Trehalose indicates the potential effect of osteoporosis treatment. Our study aimed to determine the therapeutic effect of Trehalose in high fat-induced osteoporosis. We used palmitic acid (PA) to mimic the state of high fat and observed the apoptosis ratio of osteoblasts increased. After adding Trehalose, the apoptosis ratio decreased obviously. Autophagy is a regulatory means involved in the process of apoptosis. We detected the autophagy protein and found that the expression of Beclin-1, Atg5, and LC3 II increased, and p62 decreased after Trehalose treatment. When adding an autophagy inhibitor (3-MA), the expression of Beclin-1, Atg5, and LC3 II decreased, and p62 increased. These results indicated autophagy was an important factor involved in the preventive effect of Trehalose in PA-induced apoptosis. SIRT3 is a mitochondrial gene that can inhibit apoptosis, which has been reported to promote autophagy. We used SIRT3-siRNA to silence the expression of SIRT3 and found the effect of Trehalose was counteracted. The apoptosis ratio increased and the expression of Beclin-1, Atg5, and LC3 II decreased, p62 increased. Additionally, we also fed the mice with a high-fat diet (HFD) and intragastrical Trehalose. The results showed that Trehalose could inhibit the bone mass loss with HFD. Our study revealed the effect and mechanism of Trehalose in the treatment of osteoporosis.

Neuroprotective Effects of TRPM7 Deletion in Parvalbumin GABAergic vs. Glutamatergic Neurons following Ischemia

Oxidative stress induced by brain ischemia upregulates transient receptor potential melastatin-like-7 (TRPM7) expression and currents, which could contribute to neurotoxicity and cell death. Accordingly, suppression of TRPM7 reduces neuronal death, tissue damage and motor deficits. However, the neuroprotective effects of TRPM7 suppression in different cell types have not been investigated. Here, we found that induction of ischemia resulted in loss of parvalbumin (PV) gamma-aminobutyric acid (GABAergic) neurons more than Ca²⁺/calmodulin-kinase II (CaMKII) glutamatergic neurons in the mouse cortex. Furthermore, brain ischemia increased TRPM7 expression in PV neurons more than that in CaMKII neurons. We generated two lines of conditional knockout mice of TRPM7 in GABAergic PV neurons (PV-TRPM7^−/−) and in glutamatergic neurons (CaMKII-TRPM7^−/−). Following exposure to brain ischemia, we found that deleting TRPM7 reduced the infarct volume in both lines of transgenic mice. However, the volume in PV-TRPM7^−/− mice was more significantly lower than that in the control group. Neuronal survival of both GABAergic and glutamatergic neurons was increased in PV-TRPM7^−/− mice; meanwhile, only glutamatergic neurons were protected in CaMKII-TRPM7^−/−. At the behavioral level, only PV-TRPM7^−/− mice exhibited significant reductions in neurological and motor deficits. Inflammatory mediators such as GFAP, Iba1 and TNF-α were suppressed in PV-TRPM7^−/− more than in CaMKII-TRPM7^−/−. Mechanistically, p53 and cleaved caspase-3 were reduced in both groups, but the reduction in PV-TRPM7^−/− mice was more than that in CaMKII-TRPM7^−/− following ischemia. Upstream from these signaling molecules, the Akt anti-oxidative stress signaling was activated only in PV-TRPM7^−/− mice. Therefore, deleting TRPM7 in GABAergic PV neurons might have stronger neuroprotective effects against ischemia pathologies than doing so in glutamatergic neurons.