Effect of insulin resistance on whole blood mRNA and microRNA expression affecting bone turnover

Type 2 diabetic mellitus related osteoporosis: focusing on ferroptosis

With the aging global population, type 2 diabetes mellitus (T2DM) and osteoporosis(OP) are becoming increasingly prevalent. Diabetic osteoporosis (DOP) is a metabolic bone disorder characterized by abnormal bone tissue structure and reduced bone strength in patients with diabetes. Studies have revealed a close association among diabetes, increased fracture risk, and disturbances in iron metabolism. This review explores the concept of ferroptosis, a non-apoptotic cell death process dependent on intracellular iron, focusing on its role in DOP. Iron-dependent lipid peroxidation, particularly impacting pancreatic β-cells, osteoblasts (OBs) and osteoclasts (OCs), contributes to DOP. The intricate interplay between iron dysregulation, which comprises deficiency and overload, and DOP has been discussed, emphasizing how excessive iron accumulation triggers ferroptosis in DOP. This concise overview highlights the need to understand the complex relationship between T2DM and OP, particularly ferroptosis. This review aimed to elucidate the pathogenesis of ferroptosis in DOP and provide a prospective for future research targeting interventions in the field of ferroptosis.

miRDM-rfGA: Genetic algorithm-based identification of a miRNA set for detecting type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) affects approximately 451 million adults globally. In this study, we identified the optimal combination of marker candidates for detecting T2DM using miRNA-Seq data from 95 samples including T2DM and healthy individuals.

METHODS

We utilized the genetic algorithm (GA) in the discovery of an optimal miRNA biomarker set. We discovered miRNA subsets consisting of three miRNAs for detecting T2DM by random forest-based GA (miRDM-rfGA) as a feature selection algorithm and created six GA parameter settings and three settings using traditional feature selection methods (F-test and Lasso). We then evaluated the prediction performance to detect T2DM in the miRNA subsets derived from each setting.

RESULTS

The miRNA subset in setting 5 using miRDM-rfGA performed the best in detecting T2DM (mean AUROC = 0.92). Target mRNA identification and functional enrichment analysis of the best miRNA subset (hsa-miR-125b-5p, hsa-miR-7-5p, and hsa-let-7b-5p) validated that this combination was involved in T2DM. We also confirmed that the targeted genes were negatively correlated with the clinical variables related to T2DM in the BxD mouse genetic reference population database.

CONCLUSIONS

Using GA in miRNA-Seq data, we identified the optimal miRNA biomarker set for T2DM detection. GA can be a useful tool for biomarker discovery and drug-target identification.

A Review on the Crosstalk between Insulin and Wnt/β-Catenin Signalling for Bone Health

A positive association between insulin resistance and osteoporosis has been widely established. However, crosstalk between the signalling molecules in insulin and Wingless (Wnt)/beta-(β-)catenin transduction cascades orchestrating bone homeostasis remains not well understood. The current review aims to collate the existing evidence, reporting (a) the expression of insulin signalling molecules involved in bone-related disorders and (b) the expression of Wnt/β-catenin signalling molecules involved in governing insulin homeostasis. The downstream effector molecule, glycogen synthase kinase-3 beta (GSK3β), has been identified to be a point of convergence linking the two signal transduction networks. This review highlights that GSK3β may be a drug target in the development of novel anabolic agents and the potential use of GSK3β inhibitors to treat bone-related disorders.

The role of wnt signaling in diabetes-induced osteoporosis

Osteoporosis, a chronic complication of diabetes mellitus, is characterized by a reduction in bone mass, destruction of bone microarchitecture, decreased bone strength, and increased bone fragility. Because of its insidious onset, osteoporosis renders patients highly susceptible to pathological fractures, leading to increased disability and mortality rates. However, the specific pathogenesis of osteoporosis induced by chronic hyperglycemia has not yet been fully elucidated. But it is currently known that the disruption of Wnt signaling triggered by chronic hyperglycemia is involved in the pathogenesis of diabetic osteoporosis. There are two main types of Wnt signaling pathways, the canonical Wnt signaling pathway (β-catenin-dependent) and the non-canonical Wnt signaling pathway (non-β-catenin-dependent), both of which play an important role in regulating the balance between bone formation and bone resorption. Therefore, this review systematically describes the effects of abnormal Wnt pathway signaling on bone homeostasis under hyperglycemia, hoping to reveal the relationship between Wnt signaling and diabetic osteoporosis to further improve understanding of this disease.

Transcriptome-wide association study for postpartum depression implicates altered B-cell activation and insulin resistance

Postpartum depression (PPD) affects 1 in 7 women and has negative mental health consequences for both mother and child. However, the precise biological mechanisms behind the disorder are unknown. Therefore, we performed the largest transcriptome-wide association study (TWAS) for PPD (482 cases, 859 controls) to date using RNA-sequencing in whole blood and deconvoluted cell types. No transcriptional changes were observed in whole blood. B-cells showed a majority of transcriptome-wide significant results (891 transcripts representing 789 genes) with pathway analyses implicating altered B-cell activation and insulin resistance. Integration of other data types revealed cell type-specific DNA methylation loci and disease-associated eQTLs (deQTLs), but not hormones/neuropeptides (estradiol, progesterone, oxytocin, BDNF), serve as regulators for part of the transcriptional differences between cases and controls. Further, deQTLs were enriched for several brain region-specific eQTLs, but no overlap with MDD risk loci was observed. Altogether, our results constitute a convergence of evidence for pathways most affected in PPD with data across different biological mechanisms.

The Exosomes Containing LINC00461 Originated from Multiple Myeloma Inhibit the Osteoblast Differentiation of Bone Mesenchymal Stem Cells via Sponging miR-324-3p

Multiple myeloma is one of the hematological malignancies and inhibited osteoblast differentiation of bone marrow mesenchymal stem cells (BM-MSCs) which has been proved as a major complication of the patients with multiple myeloma. However, the pathomechanism of symptom remains unclear. Besides, several studies have indicated that LINC00461 plays an important role in the progression of multiple tumors. Hence, this study attempted to reveal the role of LINC00461 in the osteoblast differentiation of MSCs. In this study, the expression level of LINC00461 in the exosomes of multiple myeloma cells was measured, and BM-MSCs were cultured with the exosomes to observe the change of cellular phenotype. Moreover, downstream target of LINC00461 was searched and verified with dual-luciferase reporter assay, and the activation of the Wnt/β-catenin pathway was also observed by Western blot. The results showed that the isolated BMSCs exhibited special biomarkers of MSCs. LINC00461 was significantly upregulated in the exosomes originated multiple myeloma cells, and increased LINC00461 significantly impeded the osteoblast differentiation of MSCs. Moreover, LINC00461 could significantly suppress the activation of the Wnt/β-catenin pathway in MSCs. In conclusion, this study suggested that LINC00461 in exosomes of multiple myeloma could reduce the activity of the Wnt/β-catenin pathway to inhibit the osteoblast differentiation of BM-MSCs via targeting miR-324-3p.

Adulthood blood levels of hsa-miR-29b-3p associate with preterm birth and adult metabolic and cognitive health

Preterm birth (PTB) is associated with increased risk of type 2 diabetes and neurocognitive impairment later in life. We analyzed for the first time the associations of PTB with blood miRNA levels in adulthood. We also investigated the relationship of PTB associated miRNAs and adulthood phenotypes previously linked with premature birth. Blood MicroRNA profiling, genome-wide gene expression analysis, computer-based cognitive testing battery (CANTAB) and serum NMR metabolomics were performed for Young Finns Study subjects (aged 34-49 years, full-term n = 682, preterm n = 84). Preterm birth (vs. full-term) was associated with adulthood levels of hsa-miR-29b-3p in a fully adjusted regression model (p = 1.90 × 10^-4, FDR = 0.046). The levels of hsa-miR-29b-3p were down-regulated in subjects with PTB with appropriate birthweight for gestational age (p = 0.002, fold change [FC] = - 1.20) and specifically in PTB subjects with small birthweight for gestational age (p = 0.095, FC = - 1.39) in comparison to individuals born full term. Hsa-miR-29b-3p levels correlated with the expressions of its target-mRNAs BCL11A and CS and the gene set analysis results indicated a target-mRNA driven association between hsa-miR-29b-3p levels and Alzheimer's disease, Parkinson's disease, Insulin signaling and Regulation of Actin Cytoskeleton pathway expression. The level of hsa-miR-29b-3p was directly associated with visual processing and sustained attention in CANTAB test and inversely associated with serum levels of VLDL subclass component and triglyceride levels. In conlcusion, adult blood levels of hsa-miR-29b-3p were lower in subjects born preterm. Hsa-miR-29b-3p associated with cognitive function and may be linked with adulthood morbidities in subjects born preterm, possibly through regulation of gene sets related to neurodegenerative diseases and insulin signaling as well as VLDL and triglyceride metabolism.

Bone Autophagy: A Potential Way of Exercise-Mediated Meg3/P62/Runx2 Pathway to Regulate Bone Formation in T2DM Mice

BACKGROUND

Meg3 has been shown to attenuate T2DM bone autophagy by activating p62 to inhibit bone formation. However, whether exercise can reverse this process to promote T2DM bone formation and its mechanism remains unknown.

METHODS

A T2DM mouse model was established by a high-fat diet and STZ injection, and the mice were trained with 8-week HIIT and downhill running exercise. Micro-CT was used to scan the bone microstructure. Bone morphology was observed by HE staining, and the osteoblast (OB) activity in bones was observed by AKP staining. Calcium ion and phosphorus concentration in serum was detected by ELISA; RT-PCR was used to detect the mRNA level, and Western blot was used to detect the protein level of related indexes in Meg3/p62/Runx2 pathway.

RESULTS

The inhibition of bone autophagy, in the bones of T2DM mice, resulted in the degradation of the bone tissue morphology and structure, with the increase of the expressions of Meg3, PI3K, Akt, mTOR, p62 and NF-κB. However, 8-week HIIT and downhill running could reverse this process, especially downhill running, manifested with the up-regulation of miR-16 mRNA level, along with Beclin-1, LC3 II and Runx2 mRNA and protein level.

CONCLUSION

T2DM leads to pathology in model mice. Eight-week HIIT and downhill running exercise can inhibit Meg3, activate autophagy of osteoblasts and promote bone formation in T2DM mice.

Bone health and hyperglycemia in pediatric populations

The impact of prediabetes and diabetes on skeletal health in the context of increased risk of fragility fractures in adults has been studied recently. However, the prevalence of diabetes, overweight, and obesity have also increased in younger subjects. Current data concerning bone metabolism based on assessment of markers for bone turnover and of bone quality in diabetes patients in diverse age groups appears to be inconsistent. This review synthesizes the current data on the assessment of bone turnover based on the use of circulating bone markers recommended by international organizations; the effects of age, gender, and other factors on the interpretation of the data; and the effects of type 1 and type 2 diabetes as well as hyperglycemia on bone quality and turnover with particular emphasis on the pediatric population. Early intervention in the pediatric population is necessary to prevent the progression of metabolic disturbances that accompany prediabetes and diabetes in the context of common low vitamin D status that may interfere with bone growth.

Dual Effects of Lipid Metabolism on Osteoblast Function

The skeleton is a dynamic and metabolically active organ with the capacity to influence whole body metabolism. This newly recognized function has propagated interest in the connection between bone health and metabolic dysfunction. Osteoblasts, the specialized mesenchymal cells responsible for the production of bone matrix and mineralization, rely on multiple fuel sources. The utilization of glucose by osteoblasts has long been a focus of research, however, lipids and their derivatives, are increasingly recognized as a vital energy source. Osteoblasts possess the necessary receptors and catabolic enzymes for internalization and utilization of circulating lipids. Disruption of these processes can impair osteoblast function, resulting in skeletal deficits while simultaneously altering whole body lipid homeostasis. This article provides an overview of the metabolism of postprandial and stored lipids and the osteoblast's ability to acquire and utilize these molecules. We focus on the requirement for fatty acid oxidation and the pathways regulating this function as well as the negative impact of dyslipidemia on the osteoblast and skeletal health. These findings provide key insights into the nuances of lipid metabolism in influencing skeletal homeostasis which are critical to appreciate the extent of the osteoblast's role in metabolic homeostasis.