Wrong place, wrong time: Runt-related transcription factor 2/SATB2 pathway in bone development and carcinogenesis

The Bone-Vascular Axis: A Key Player in Chronic Kidney Disease Associated Vascular Calcification

Background

The bone-vascular axis plays a key role in the pathogenesis of vascular calcification (VC) in patients with chronic kidney disease (CKD). Understanding and managing the role of the bone-vascular axis in CKD-mineral and bone disorder (CKD-MBD) is critical for preventing and treating associated complications, including osteoporosis, arterial calcification, and cardiovascular diseases. This study aimed to comprehensively summarize the role of bone metabolism markers in uremic VC.

Summary

The skeleton, as an endocrine organ, can regulate systemic metabolic processes by secreting various bioactive substances. These molecules can induce the transdifferentiation of vascular smooth muscle cells, promoting their transition to other functional states, thereby affecting vascular growth and remodeling.

Key Messages

The prevalence of VC in individuals with CKD is notably high. CKD-associated VC is characterized by the widespread accumulation of hydroxyapatite within the arterial media, which occurs as a result of the transformation of smooth muscle cells into osteoblastic smooth muscle cells under the influence of uremic toxins. Osteoblasts and osteoclasts in bone tissue secrete mineral metabolic proteins, which can influence neighboring cells, primarily vascular smooth muscle cells, through paracrine signaling. Both circulating and osteocytic sclerostin can exert a protective effect by inhibiting wingless/integrated (WNT)-induced calcification. The therapeutic goal for CKD-MBD is to reduce production of sclerostin by decreasing the osteogenic transdifferentiation of vascular smooth muscle cells. Calciprotein particles act as a physiological agent for delivering calcium-phosphate the bone and inducing fibroblast growth factor-23 expression in osteoblasts.

Comparison of the effect of different doses of phenylephrine infusion on the prevention of hypotension in the elderly under spinal anaesthesia in orthopaedic surgery

BACKGROUND

Considering the vasopressor drug categories and doses that can be used for elderly patients following hypotension are few, the present trial aimed to compare the effect of different doses of phenylephrine infusion on the prevention of hypotension in elderly patients undergoing orthopaedic lower extremities surgery.

METHODS

This randomised, double-blind prospective clinical trial was conducted by including 60 elderly patients older than 60 years and classified as American Society of Anesthesiology class I and II who were candidates for femur fracture fixation surgery. White and black cards randomly allocated patients to: group A (25µg/kg/h phenylephrine) or group B (35µg/kg/h phenylephrine).

RESULTS

At the T3-T7 time points, group A's systolic and diastolic blood pressure was significantly higher than in group B's (p < 0.05). However, after 27 minutes (T0-T7) of phenylephrine infusion, statistical analysis showed no significant difference between the two groups regarding blood pressure (T8-Tend). The frequency of bradycardia and reactive hypertension in group B were significantly higher than in group A (p = 0.02) and (p = 0.03), respectively. There was no significant difference between the bleeding loss, blood transfusion and crystalloid volume in both groups (p > 0.05).

CONCLUSION

Our trial illustrated that high-dose phenylephrine infusion could not assure haemodynamic stability and may cause some side effects.

The prognostic and biological importance of chromatin regulation-related genes for lung cancer is examined using bioinformatics and experimentally confirmed

BACKGROUND

The pathogenesis and clinical diagnosis of lung adenocarcinoma (LUAD), a malignant illness with substantial morbidity and mortality, are still being investigated. Genes involved in chromatin regulation are crucial in the biological function of LUAD.

METHODS

The prognostic prediction model for LUAD was developed using multivariables and least absolute shrinkage and selection operator (LASSO) regression. It consisted of 10 chromatin regulators. The LUAD has been divided into two groups, high- and low-risk, using a predictive model. The model was shown to be accurate in predicting survival by the nomogram, receiver operating characteristic (ROC) curves, and principal component analysis (PCA). An analysis of differences in immune-cell infiltration, immunologicalfunction, and clinical traits between low- and high-risk populations was conducted. Protein-protein interaction (PPI) networks and Gene Ontology (GO) pathways of differentially expressed genes (DEGs) in the high versus low risk group were also examined to investigate the association between genes and biological pathways. The biological roles of chromatin regulators (CRs) in LUAD were finally estimated using colony formation and cell movement. The important genes' mRNA expression has been measured using real-time polymerase chain reaction (RT-PCR).

RESULTS AND CONCLUSION

Risk score and stage based on the model could be seen as separate prognostic indicators for patients with LUAD. The main signaling pathway difference across various risk groups was in cell cycle. The immunoinfiltration profile of the tumor microenvironment (TME) and individuals with different risk levels were correlated, suggesting that the interaction of immune cells with the tumor led to the creation of a favorable immunosuppressive microenvironment. These discoveries aid in the creation of individualized therapies for LUAD patients.

Exposure to ambient air pollution and osteoarthritis; an animal study

Exposure to air pollution has been associated with many adverse health effects. However, the evidence on the effects on osteoarthritis (OA) is scarce and the potential mechanism is unclear yet. Therefore, this study assessed the effect of exposure to air pollution (gaseous and particulate matter) and OA based on an animal model. We used four groups of female rats, including i) exposure to PMs and gaseous pollutants, ii) exposure only to gaseous pollutants, iii) exposure only to PMs, and iv) control (unexposed) group. The OA biomarkers, i.e., osteocalcin, cartilage oligomeric protein (COMP), and N-Telopeptides of Type I Collagen (NTX-I) and cytokines were measured in the plasma to detect the effect of exposure to ambient air pollution on OA in this animal model. The forced jogging exercises for 1 h and 5 days per week were used to record the physical activities. The median (interquartile range) concentrations of PM_2.5 and PM₁₀ were 35.9 (15.4) and 47.5 (22.5) μg/m³, respectively. The median (interquartile range (IQR)) of PM_2.5, PM₁₀, CO, NO₂, SO₂ and O₃ in the inlet ambient air were 36.9 (16.9), 51.7 (23.6) μg/m³, 16.1 (12.5) ppm, 413.7 (177.1), 334.2 (218.8) and 208.9 (113.1) ppb, respectively. The osteocalcin was significantly lower in PM as well as PM-gaseous exposure groups compared to control. Moreover, expressions of COMP were increased significantly in the PMs and exposure group compared to the control. For the PMs-gaseous exposure group, the COMP expressions were the highest compared to the control group. Similar results were observed for NTX-I. Exposure to PM and gaseous pollutants significantly increased plasma cytokine levels compared to control. Overall, our study showed a significant effect of exposure to PMs and PMs-gaseous exposure with OA in rats. Moreover, we observed a synergistic effect of mixed gaseous-PMs exposure compared to PMs and gaseous pollutants separately.

A novel mutation of SATB2 inhibits odontogenesis of human dental pulp stem cells through Wnt/β-catenin signaling pathway

BACKGROUND

SATB2-associated syndrome (SAS) is a multisystem disorder caused by mutation of human SATB2 gene. Tooth agenesis is one of the most common phenotypes observed in SAS. Our study aimed at identifying novel variant of SATB2 in a patient with SAS, and to investigate the cellular and molecular mechanism of tooth agenesis caused by SATB2 mutation.

METHODS

We applied whole exome sequencing (WES) to identify the novel mutation of SATB2 in a Chinese patient with SAS. Construction and overexpression of wild-type and the mutant vector was performed, followed by functional analysis including flow cytometry assay, fluorescent immunocytochemistry, western blot, quantitative real-time PCR and Alizarin Red S staining to investigate its impact on hDPSCs and the underlying mechanisms.

RESULTS

As a result, we identified a novel frameshift mutation of SATB2 (c. 376_378delinsTT) in a patient with SAS exhibiting tooth agenesis. Human DPSCs transfected with mutant SATB2 showed decreased cell proliferation and odontogenic differentiation capacity compared with hDPSCs transfected with wild-type SATB2 plasmid. Mechanistically, mutant SATB2 failed to translocate into nucleus and distributed in the cytoplasm, failing to activate Wnt/β-catenin signaling pathway, whereas the wild-type SATB2 translocated into the nucleus and upregulated the expression of active β-catenin. When we used Wnt inhibitor XAV939 to treat hDPSCs transfected with wild-type SATB2 plasmid, the increased odontogenic differentiation capacity was attenuated. Furthermore, we found that SATB2 mutation resulted in the upregulation of DKK1 and histone demethylase JHDM1D to inhibit Wnt/β-catenin signaling pathway.

CONCLUSION

We identified a novel frameshift mutation of SATB2 (c.376_378delinsTT, p.Leu126SerfsX6) in a Chinese patient with SATB2-associated syndrome (SAS) exhibiting tooth agenesis. Mechanistically, SATB2 regulated osteo/odontogenesis of human dental pulp stem cells through Wnt/β-catenin signaling pathway by regulating DKK1 and histone demethylase JHDM1D.

Phenotype from SAMD9 Mutation at 7p21.1 Appears Attenuated by Novel Compound Heterozygous Variants at RUNX2 and SALL1

Sterile α motif domain-containing protein 9 (SAMD9) is a regulatory protein centrally involved in cell proliferation and apoptosis. Mapped to 7p21.2, variants in SAMD9 have been reported in <50 pediatric cases worldwide, typically with early lethality. Germline gain-of-function SAMD9 variants are associated with MIRAGE syndrome (myelodysplasia, infection, restricted growth, adrenal hypoplasia, genital anomalies, and enteropathy). Spalt like transcription factor 1 (SALL1) is a zinc finger transcriptional repressor located at 16q12.1 where only two transcript variants in SALL1 are known. RUNX2 (6p21.1) encodes a nuclear protein with a Runt DNA-binding domain critical for osteoblastic differentiation, skeletal morphogenesis, and serves as a scaffold for nucleic acids and regulatory factors involved in skeletal gene expression. RUNX2 and SALL1 are thus both “master regulators” of tissue organization and embryo development. Here, we describe exome sequencing and copy number variants in two previously unknown mutations—R824Q in SAMD9, and Q253H in SALL1. A multiexon 3′ terminal duplication of RUNX2 not previously encountered is also reported. This is the first known phenotype assessment for an intersection of all three variants in a healthy 46,XX adult. Focusing on developmental progress, ultrastructural renal anatomy, and selected reproductive aspects, we describe this unique genotype diagnosed incidentally during coronavirus disease 2019 (COVID-19) illness. Individually, disruption in SAMD9, RUNX2, or SALL1 would be expected to give a bleak prognosis. However, this variant convergence appears to dampen severe pathology perhaps by cross-gene silencing of effects normally deleterious when such changes occur alone.