SATB2: A versatile transcriptional regulator of craniofacial and skeleton development, neurogenesis and tumorigenesis, and its applications in regenerative medicine

SATB2 Loss Is a Sensitive Biomarker for Dysplasia in Inflammatory Bowel Disease

Loss of SATB2 expression has emerged as a promising biomarker for dysplasia in inflammatory bowel disease (IBD), but its sensitivity and specificity remain unclear. We retrospectively evaluated immunohistochemical (IHC) staining of SATB2 and p53 in colorectal biopsies from 37 IBD patients (25 men and 12 women; median age: 48 years) with suspected dysplasia. The cohort included 26 ulcerative colitis (70%) and 11 Crohn's disease (30%). Fourteen patients (38%) developed IBD-associated invasive carcinoma, and 18 (49%) had persistent dysplasia on follow-up. Histologic review identified 80 lesions initially diagnosed as negative (16%), indefinite (39%), low-grade (36%), and high-grade (9%) dysplasia. IHC revealed aberrant p53 in 35 lesions (44%) and SATB2 loss in 42 lesions (53%), with 19 (24%) showing both abnormalities. Reappraisal of diagnoses combining histology and IHC reclassified lesions into indefinite (20%), low-grade (63%), and high-grade (17%) dysplasia. Lesions with SATB2 loss alone were more frequently of lower grade (P = .003). Dysplasia types included 15 conventional dysplasia (19%) and 65 nonconventional dysplasia (81%). The rates of p53 abnormality, SATB2 loss, and their combination were similar in nonconventional dysplasia (45%, 55%, and 75%, respectively) and conventional dysplasia (40%, 47%, and 67%, respectively) and comparable between cancer patients (50%, 56%, and 74%, respectively) and noncancer patients (39%, 50%, and 72%, respectively). Missed dysplasias in cancer patients were all nonconventional, and lesions with p53 abnormality more likely progressed to cancer (P = .002). In conclusion, SATB2 loss is a sensitive marker for IBD-associated dysplasia. Combined use of SATB2 and p53 IHC improves dysplasia detection and reduces false-negative diagnosis, supporting its application into routine diagnostic practice.

Astragaloside IV inhibits nasopharyngeal carcinoma progression by suppressing the SATB2/Wnt signaling axis

Astragaloside IV (AS-IV), a major bioactive component of Astragalus membranaceus, exhibits anti-cancer and anti-inflammatory properties. However, its precise role in nasopharyngeal carcinoma (NPC) remains unclear. This study investigated the effects of AS-IV on NPC progression and its relationship with Special AT-rich binding protein-2 (SATB2), a diagnostic marker for NPC. AS-IV treatment reduced NPC cell viability in a dose-dependent manner, as assessed by CCK-8 assays. Functional experiments, including transwell, immunofluorescence, and flow cytometry assays, demonstrated that AS-IV inhibited cell migration, invasion, and autophagy while promoting apoptosis. Western blot analysis showed that SATB2 expression was significantly elevated in NPC cells, particularly in C666-1 and HK-1 cells. Overexpression of SATB2 partially reversed AS-IV's inhibitory effects on NPC progression. Further analysis revealed that AS-IV suppressed the Wnt signaling pathway by downregulating SATB2 expression, while SATB2 overexpression restored Wnt pathway activation. This effect was reversed upon treatment with the Wnt pathway inhibitor DKK-1. In vivo, AS-IV administration inhibited tumor growth in a nude mouse subcutaneous xenograft model, reduced Ki-67 positivity, and lowered LC3B expression, indicating decreased proliferation and autophagy. However, these effects were diminished upon SATB2 overexpression. These findings suggest that AS-IV exerts anti-tumor effects in NPC by downregulating SATB2 and suppressing Wnt pathway activation, highlighting its potential as a therapeutic agent for NPC.

Highlights

Astragaloside IV (AS-IV) reduces nasopharyngeal carcinoma (NPC) cell vitality, suppresses cell migration, invasion and autophagy, and fosters apoptosis.SATB2 exhibits notably high levels in NPC cells.Overexpression of SATB2 counteracts the inhibition of NPC malignant progression by AS-IV.AS-IV impedes NPC progression by decreasing SATB2 and thereby hindering the Wnt pathway.AS-IV deters NPC tumor growth in nude mice.

Reduced Expression of SATB2 in Colorectal Cancer and Its Association with Demographic and Clinicopathological Parameters

Special AT-rich sequence-binding protein 2 (SATB2), as a nuclear matrix-associated protein and transcription factor engaged in chromatin remodeling and the regulation of gene expression, plays an important role in growth and development processes. SATB2 has been shown to have tissue-specific expression, also related to some cancers, including colorectal cancer (CRC). The aim of this study was to compare SATB2 gene expression in tumor and matched non-involved colorectal tissues obtained from CRC patients, and to investigate its association with clinicopathological and demographic parameters, as well as patients' overall survival. SATB2 mRNA levels in the tested tissues were assessed by quantitative polymerase chain reaction, while SATB2 protein expression was determined by immunohistochemistry. We found that the average levels of both SATB2 mRNA and protein were significantly lower in tumor specimens than in matched non-involved colon tissues. Moreover, SATB2 immunoreactivity was associated with patients' sex, tumor localization, and grade of differentiation. Lower immunoreactivity of SATB2 protein was noted in high-grade tumors, in women, and in tumors located in the cecum, ascending, and transverse colon. However, the results of the present study did not show an association between SATB2 expression levels and patients' overall survival. Our findings indicate the involvement of impaired SATB2 expression, significantly reduced in high-grading tumors, in the pathogenesis of CRC, while its sex- and localization-specificity should be further elucidated.

SATB2 promotes radiation resistance of esophageal squamous cell carcinoma by regulating epithelial-to-mesenchymal transition via the Wnt/β-catenin pathway

Purpose

Radioresistance remains a predominant factor contributing to local recurrence in esophageal squamous cell carcinoma (ESCC). SATB2, as a transcriptional co-gene, may affect the radioresistance of cancer cells. Consequently, this study aims to elucidate the mechanism by which SATB2 modulates radiotherapy resistance in esophageal cancer.

Methods

We identified highly expressed genes associated with radioresistance in ESCC using the MSigDB database and conducted survival correlation analysis. A radioresistant esophageal squamous cell carcinoma cell line (KYSE150R) was established using the gradient dose method, and RT-qPCR was used to detect the expression of SATB2 in KYSE150 and KYSE150R cells. CCK-8, Transwell, colony formation assay, and cell scratching were performed to determine and evaluate cell proliferation, cell migration, and cell invasion. Furthermore, the expression levels of mRNA and protein were correlated using WB and RT-qPCR. Mitochondrial membrane potential and apoptosis detection kits were used to evaluate the level of apoptosis. Finally, a mouse subcutaneous xenograft tumor model was employed to elucidate the role of SATB2 on the radiotherapy resistance of ESCC in vivo.

Results

Bioinformatics analysis indicated that SATB2 is linked to increased drug resistance in esophageal cancer. The results demonstrated that suppression of SATB2 decelerates cell proliferation and migration, accelerates apoptosis, inhibits the GSK-3β (Ser9) phosphorylation, and reduces β-catenin and target gene C-myc. The addition of the Wnt/β-catenin signaling pathway agonist (CHIR-99021) reversed these effects. Xenograft studies in mice revealed that knockdown of SATB2 reduced ESCC radioresistance.

Conclusion

We concluded that SATB2 may dysregulate the Wnt/β-catenin pathway, thereby facilitating EMT progression and conferring radioresistance.

CDX2 and SATB2 loss are associated with myeloid cell infiltration and poor survival in colorectal cancer

BACKGROUND

Caudal-type homeobox 2 (CDX2) and special AT-rich sequence-binding protein 2 (SATB2) are transcription factors playing important roles in intestinal homeostasis and participating in the regulation of intestinal inflammation. In colorectal cancer (CRC), reduced expression levels of CDX2 and SATB2 have been associated with poor differentiation and worse survival. However, their prognostic significance still needs further clarification, and the associations between CDX2 and SATB2 and immune cell infiltration into the CRC microenvironment are largely unknown.

METHODS

We analyzed CDX2 and SATB2 expression in two large cohorts of stages I-IV CRC patients (N = 2302) and analyzed their associations with clinicopathologic parameters, the density of local immune cells (determined with three multiplex immunohistochemistry panels and conventional immunohistochemistry), and survival.

RESULTS

In mismatch repair-proficient tumors, reduced CDX2 and SATB2 expression were associated with higher densities of immature monocytic cells, macrophages, and M2-like macrophages. Low expression of CDX2 was associated with shorter cancer-specific survival independent of conventional prognostic parameters in both cohorts. In the larger cohort, adjusted hazard ratio (HR) for negative (vs. high) CDX2 expression was 3.62 (95% CI 2.08-6.31, ptrend < 0.0001), and adjusted HR for negative (vs. high) SATB2 level was 1.61 (95% CI 0.97-2.67, ptrend = 0.002).

CONCLUSION

This study indicates that reduced CDX2 and SATB2 expression levels are associated with myeloid cell infiltration in the CRC microenvironment and represent markers for poor outcome. These findings highlight the potential of CDX2 and SATB2 as biomarkers for classifying CRC patients and support their role in regulating the tumor microenvironment.

Molecular Regulation of Palatogenesis and Clefting: An Integrative Analysis of Genetic, Epigenetic Networks, and Environmental Interactions

Palatogenesis is a complex developmental process requiring temporospatially coordinated cellular and molecular events. The following review focuses on genetic, epigenetic, and environmental aspects directing palatal formation and their implication in orofacial clefting genesis. Essential for palatal shelf development and elevation (TGF-β, BMP, FGF, and WNT), the subsequent processes of fusion (SHH) and proliferation, migration, differentiation, and apoptosis of neural crest-derived cells are controlled through signaling pathways. Interruptions to these processes may result in the birth defect cleft lip and/or palate (CL/P), which happens in approximately 1 in every 700 live births worldwide. Recent progress has emphasized epigenetic regulations via the class of non-coding RNAs with microRNAs based on critically important biological processes, such as proliferation, apoptosis, and epithelial-mesenchymal transition. These environmental risks (maternal smoking, alcohol, retinoic acid, and folate deficiency) interact with genetic and epigenetic factors during palatogenesis, while teratogens like dexamethasone and TCDD inhibit palatal fusion. In orofacial cleft, genetic, epigenetic, and environmental impact on the complex epidemiology. This is an extensive review, offering current perspectives on gene-environment interactions, as well as non-coding RNAs, in palatogenesis and emphasizing open questions regarding these interactions in palatal development.

Histological features indicate the risk of progression of patients with Barrett's esophagus

Our understanding of predictors of progression in Barrett's esophagus (BE) remains incomplete. To address this gap, we evaluated histological features and biomarkers that could predict dysplastic/neoplastic progression in patients with BE. We conducted a retrospective study to identify eligible BE patients and classified the cases into two groups: cases with BE progression (n = 10; progressing to high-grade dysplasia or carcinoma within five years of initial diagnosis) and cases without BE progression (n = 52; without progression to high-grade dysplasia or carcinoma within five years). Morphological features were evaluated on tissue slides for the initial diagnosis of Barrett's esophagus. Biomarkers including TP53, p16, HER2, β-Catenin, c-MYC, Ki67 and SATB2,were assessed by immunohistochemistry. The results of this study revealed that histologic features, including glandular irregularity and Paneth cell metaplasia (PCM), exhibited significant predictive potential for the progression of Barrett's esophagus to high-grade dysplasia or carcinoma within five years. Additionally, the immunohistochemical biomarkers assessed in our study were not associated with progression in Barrett's esophagus. These findings indicate the potential role of morphological features in assessing the risk of progression for patients with BE at the initial diagnosis. By integrating these insights into clinical practice, we may be able to optimize surveillance strategies for patients with this condition, ultimately improving patient outcomes.

FOXG1 interaction with SATB2 promotes autophagy to alleviate neuroinflammation and mechanical abnormal pain in rats with lumbar disc herniation

BACKGROUND

Most patients with lumbar disc herniation can be relieved or cured by surgical or non-surgical treatment; however, postoperative persistent radiculopathy is common. This study demonstrates the regulation of autophagy by the FOXG1/SATB2 axis in lumbar disc herniation (LDH).

METHODS

Rat dorsal root neurons were induced with TNF-α in vitro. Sprague Dawley (SD) rats were used to construct the LDH rat model, which was treated with L. paracasei S16 or oe-FOXG1. Paw withdrawal threshold or latency assay (PWT/L) was performed. Peripheral blood samples were collected and analysed using ELISA and miRNAseq. RT-qPCR was used to analyse the expression of FOXG1, LC3B, Beclin1, p62, and SATB2. TUNEL staining and flow cytometry were used to analyse apoptosis. The expression of Cyclin D1, PCNA, Ki67, FOXG1, SATB2, and autophagy proteins was measured using western blotting.

RESULTS

TNF-α induced low expression of FOXG1 and SATB2 in dorsal root ganglion (DRG) neurons of rats. TNF-α induced an increase in p62 protein and a decrease in LC3II/I and Beclin-1 proteins in neurons, which were blocked by oe-FOXG1. oe-FOXG1 suppressed inflammation and apoptosis in TNF-α-induced DRG neurons and LDH rats and promoted the expression of Cyclin D1, PCNA, and Ki67. Many miRNAs were increased in the peripheral blood of LDH rats, but decreased after L. paracasei S16 intervention. L. paracasei S16 affects miR-31a-5p and SATB2 expression. Dual luciferase reporter gene assay confirmed that miR-31a-5p bound to SATB2. Co-IP analysis confirmed the interaction between FOXG1 and SATB2. Silencing of SATB2 inhibited the beneficial effects of oe-FOXG1 in TNF-α-induced dorsal root ganglion neurons. Animal experiments further demonstrated that oe-FOXG1 improved LDH disease characteristics by downregulating PWT, PWL, inflammation, and apoptosis levels and upregulating SATB2-autophagy levels.

CONCLUSIONS

MiR-31a-5p/SATB2 is involved in the treatment of L. paracasei S16 in LDH rats. Overexpression of FOXG1 promotes autophagy through SATB2 to improve LDH levels This provides a new approach for the treatment of LDH.

Individuals with SATB2-associated syndrome have impaired vitamin and energy metabolism pathways

Special AT-rich sequence-binding protein 2 (SATB2) is a master regulator of gene expression. Mutations of the SATB2 gene results in the SATB2-associated syndrome (SAS), a genetic disorder characterized by neurodevelopmental disabilities and autism-related phenotype. The importance of plasma as an indicator of SAS phenotypes is unknown. We aim to investigate if pathogenic variants in SATB2 are associated with alteration to relevant pathways in the plasma of SAS patients and identify key differentially regulated proteins which may serve as biomarkers to improve diagnostic and future pharmacological approaches. We used well-validated proteomic technologies to determine the proteomic profile of plasma from SAS patients compared to healthy control subjects. Bioinformatical analysis was performed to identify significant proteins and functionally enriched pathways. We identified differentially expressed proteins in the plasma of SAS patients that are significantly involved in metabolism-related pathways. Energy metabolism, glucose metabolism and vitamin metabolism pathways are significantly enriched in SAS patients as compared to healthy controls. Our study linked SATB2 mutations to the impairment of plasma proteins involved in different metabolic pathways in SAS patients.

Establishment and characterization of a rat model of scalp-cranial composite defect for multilayered tissue engineering

Composite cranial defects have individual functional and aesthetic ramifications, as well as societal burden, while posing significant challenges for reconstructive surgeons. Single-stage composite reconstruction of these deformities entail complex surgeries that bear many short- and long-term risks and complications. Current research on composite scalp-cranial defects is sparse and one-dimensional, often focusing solely on bone or skin. Thus, there is an unmet need for a simple, clinically relevant composite defect model in rodents, where there is a challenge in averting healing of the skin component via secondary intention. By utilizing a customizable (3D-printed) wound obturator, the scalp wound can be rendered non-healing for a long period (more than 6 weeks), with the cranial defect patent. The wound obturator shows minimal biotoxicity and will not cause severe endocranium-granulation adhesion. This composite defect model effectively slowed the scalp healing process and preserved the cranial defect, embodying the characteristics of a "chronic composite defect". In parallel, an autologous reconstruction model was established as the positive control. This positive control exhibited reproducible healing of the skin within 3 weeks with variable degrees of osseointegration, consistent with clinical practice. Both models provide a stable platform for subsequent research not only for composite tissue engineering and scaffold design but also for mechanistic studies of composite tissue healing.

Cell signaling and transcriptional regulation of osteoblast lineage commitment, differentiation, bone formation, and homeostasis

The initiation of osteogenesis primarily occurs as mesenchymal stem cells undergo differentiation into osteoblasts. This differentiation process plays a crucial role in bone formation and homeostasis and is regulated by two intricate processes: cell signal transduction and transcriptional gene expression. Various essential cell signaling pathways, including Wnt, BMP, TGF-β, Hedgehog, PTH, FGF, Ephrin, Notch, Hippo, and Piezo1/2, play a critical role in facilitating osteoblast differentiation, bone formation, and bone homeostasis. Key transcriptional factors in this differentiation process include Runx2, Cbfβ, Runx1, Osterix, ATF4, SATB2, and TAZ/YAP. Furthermore, a diverse array of epigenetic factors also plays critical roles in osteoblast differentiation, bone formation, and homeostasis at the transcriptional level. This review provides an overview of the latest developments and current comprehension concerning the pathways of cell signaling, regulation of hormones, and transcriptional regulation of genes involved in the commitment and differentiation of osteoblast lineage, as well as in bone formation and maintenance of homeostasis. The paper also reviews epigenetic regulation of osteoblast differentiation via mechanisms, such as histone and DNA modifications. Additionally, we summarize the latest developments in osteoblast biology spurred by recent advancements in various modern technologies and bioinformatics. By synthesizing these insights into a comprehensive understanding of osteoblast differentiation, this review provides further clarification of the mechanisms underlying osteoblast lineage commitment, differentiation, and bone formation, and highlights potential new therapeutic applications for the treatment of bone diseases.

From compartments to loops: understanding the unique chromatin organization in neuronal cells

The three-dimensional organization of the genome plays a central role in the regulation of cellular functions, particularly in the human brain. This review explores the intricacies of chromatin organization, highlighting the distinct structural patterns observed between neuronal and non-neuronal brain cells. We integrate findings from recent studies to elucidate the characteristics of various levels of chromatin organization, from differential compartmentalization and topologically associating domains (TADs) to chromatin loop formation. By defining the unique chromatin landscapes of neuronal and non-neuronal brain cells, these distinct structures contribute to the regulation of gene expression specific to each cell type. In particular, we discuss potential functional implications of unique neuronal chromatin organization characteristics, such as weaker compartmentalization, neuron-specific TAD boundaries enriched with active histone marks, and an increased number of chromatin loops. Additionally, we explore the role of Polycomb group (PcG) proteins in shaping cell-type-specific chromatin patterns. This review further emphasizes the impact of variations in chromatin architecture between neuronal and non-neuronal cells on brain development and the onset of neurological disorders. It highlights the need for further research to elucidate the details of chromatin organization in the human brain in order to unravel the complexities of brain function and the genetic mechanisms underlying neurological disorders. This research will help bridge a significant gap in our comprehension of the interplay between chromatin structure and cell functions.

Adipose-derived mesenchymal stem cells (MSCs) are a superior cell source for bone tissue engineering

Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors, osteoinductive biofactors and biocompatible scaffold materials. Mesenchymal stem cells (MSCs) represent the most promising seed cells for bone tissue engineering. As multipotent stem cells that can self-renew and differentiate into multiple lineages including bone and fat, MSCs can be isolated from numerous tissues and exhibit varied differentiation potential. To identify an optimal progenitor cell source for bone tissue engineering, we analyzed the proliferative activity and osteogenic potential of four commonly-used mouse MSC sources, including immortalized mouse embryonic fibroblasts (iMEF), immortalized mouse bone marrow stromal stem cells (imBMSC), immortalized mouse calvarial mesenchymal progenitors (iCAL), and immortalized mouse adipose-derived mesenchymal stem cells (iMAD). We found that iMAD exhibited highest osteogenic and adipogenic capabilities upon BMP9 stimulation in vitro, whereas iMAD and iCAL exhibited highest osteogenic capability in BMP9-induced ectopic osteogenesis and critical-sized calvarial defect repair. Transcriptomic analysis revealed that, while each MSC line regulated a distinct set of target genes upon BMP9 stimulation, all MSC lines underwent osteogenic differentiation by regulating osteogenesis-related signaling including Wnt, TGF-β, PI3K/AKT, MAPK, Hippo and JAK-STAT pathways. Collectively, our results demonstrate that adipose-derived MSCs represent optimal progenitor sources for cell-based bone tissue engineering.

SATB2, CKAE1/AE3, and synaptophysin as a sensitive immunohistochemical panel for the detection of lymph node metastases of Merkel cell carcinoma

Histopathological evaluation of lymph nodes in Merkel cell carcinoma has become crucial in progression estimation and treatment modification. This study was undertaken to determine the most sensitive immunohistochemical panel for detecting MCC nodal metastases. We included 56 patients with 102 metastatic MCC lymph nodes, which were tested with seven antibodies: cytokeratin (CKAE1/AE3), CK20, chromogranin A, synaptophysin, INSM1, SATB2, and neurofilament (NF). Tissue microarrays (TMA) composed of 2-mm tissue cores from each nodal metastasis were constructed. A semiquantitative 5-tier scoring system (0%, < 25%, 25-74%, 75-99%, 100% positive MCC cells with moderate to strong reactivity) was implemented. In the statistical assessment, we included Merkel cell polyomavirus (MCPyV) status and expression heterogeneity between lymph nodes from one patient. A cumulative percentage of moderate to strong expression ≥ 75% of tumoral cells was observed for single cell markers as follows: 91/102 (89.2%) SATB2, 85/102 (83%) CKAE1/AE3, 80/102 (78.4%) synaptophysin, 75/102 (75.5%) INSM1, 68/102 (66.7%) chromogranin A, 60/102 cases (58.8%) CK20, and 0/102 (0%) NF. Three markers presented a complete lack of immunoreactivity: 8/102 (7.8%) CK20, 7/102 (6.9%) chromogranin A, and 6/102 (5.9%) NF. All markers showed expression heterogeneity in lymph nodes from one patient; however, the most homogenous was INSM1. The probability of detecting nodal MCC metastases was the highest while using SATB2 as a first-line marker (89.2%) with subsequential adding CKAE1/AE3 (99%); these results were independent of MCPyV status. Synaptophysin showed a superior significance in confirming the neuroendocrine origin of metastatic cells. This comprehensive analysis allows us to recommend simultaneous evaluation of SATB2, CKAE1/AE3, and synaptophysin in the routine pathologic MCC lymph node protocol.

Identification of multiple transcription factor genes potentially involved in the development of electrosensory versus mechanosensory lateral line organs

In electroreceptive jawed vertebrates, embryonic lateral line placodes give rise to electrosensory ampullary organs as well as mechanosensory neuromasts. Previous reports of shared gene expression suggest that conserved mechanisms underlie electroreceptor and mechanosensory hair cell development and that electroreceptors evolved as a transcriptionally related "sister cell type" to hair cells. We previously identified only one transcription factor gene, Neurod4, as ampullary organ-restricted in the developing lateral line system of a chondrostean ray-finned fish, the Mississippi paddlefish (Polyodon spathula). The other 16 transcription factor genes we previously validated in paddlefish were expressed in both ampullary organs and neuromasts. Here, we used our published lateral line organ-enriched gene-set (arising from differential bulk RNA-seq in late-larval paddlefish), together with a candidate gene approach, to identify 25 transcription factor genes expressed in the developing lateral line system of a more experimentally tractable chondrostean, the sterlet (Acipenser ruthenus, a small sturgeon), and/or that of paddlefish. Thirteen are expressed in both ampullary organs and neuromasts, consistent with conservation of molecular mechanisms. Seven are electrosensory-restricted on the head (Irx5, Irx3, Insm1, Sp5, Satb2, Mafa and Rorc), and five are the first-reported mechanosensory-restricted transcription factor genes (Foxg1, Sox8, Isl1, Hmx2 and Rorb). However, as previously reported, Sox8 is expressed in ampullary organs as well as neuromasts in a catshark (Scyliorhinus canicula), suggesting the existence of lineage-specific differences between cartilaginous and ray-finned fishes. Overall, our results support the hypothesis that ampullary organs and neuromasts develop via largely conserved transcriptional mechanisms, and identify multiple transcription factors potentially involved in the formation of electrosensory versus mechanosensory lateral line organs.

Transcription Factor SATB2 Regulates Skeletal Muscle Cell Proliferation and Migration via HDAC4 in Pigs

Skeletal muscle development remarkably affects meat production and growth rate, regulated by complex regulatory mechanisms in pigs. Specific AT sequence-binding protein 2 (SATB2) is a classic transcription factor and chromatin organizer, which holds a profound effect in the regulation of chromatin remodeling. However, the regulation role of SATB2 concerning skeletal muscle cell fate through chromatin remodeling in pigs remains largely unknown. Here, we observed that SATB2 was expressed higher in the lean-type compared to the obese-type pigs, which also enriched the pathways of skeletal muscle development, chromatin organization, and histone modification. Functionally, knockdown SATB2 led to decreases in the proliferation and migration markers at the mRNA and protein expression levels, respectively, while overexpression SATB2 had the opposite effects. Further, we found histone deacetylase 4 (HDAC4) was a key downstream target gene of SATB2 related to chromatin remodeling. The binding relationship between SATB2 and HDAC4 was confirmed by a dual-luciferase reporter system and ChIP-qPCR analysis. Besides, we revealed that HDAC4 promoted the skeletal muscle cell proliferation and migration at the mRNA and protein expression levels, respectively. In conclusion, our study indicates that transcription factor SATB2 binding to HDAC4 positively contributes to skeletal muscle cell proliferation and migration, which might mediate the chromatin remodeling to influence myogenesis in pigs. This study develops a novel insight into understanding the molecular regulatory mechanism of myogenesis, and provides a promising gene for genetic breeding in pigs.

Progress of epigenetic modification of SATB2 gene in the pathogenesis of non-syndromic cleft lip and palate

Non-syndromic Cleft Lip and Palate (NSCLP) is one of the most common congenital craniofacial malformations. However, there is no enough knowledge about its mechanism, even through many relevant studies verify that cleft lip and palate is caused by interactions between environmental and genetic factors. SATB2 gene is one of the most common candidate genes of NSCLP, and the development of epigenetics provides a new direction on pathogenesis of cleft lip and palate. This review summarizes SATB2 gene in the pathogenesis of non-syndromic cleft lip and palate, expecting to provide strategies to prevent and treat cleft and palate in the future.

Special at-rich sequence-binding protein 2 and its role in healing of the experimental mandible bone tissue defect filling with a synthetic bone graft material and electrical stimulation impact

OBJECTIVE

Aim: The purpose of the study was to identify the role of SATB2 in healing of the experimental mandible bone tissue defect filling with a synthetic bone graft material and electrical stimulation impact.

PATIENTS AND METHODS

Materials and Methods: An experiment was carried out on 48 mature male rats of the WAG population, which were divided into 4 groups. Each group included 12 experimental animals. Group 1 included rats that were modeled with a perforated defect of the lower jaw body. Group 2 included animals that were modeled with a perforated defect similar to group 1. In animals, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect. The negative electrode connected to the negative pole of the battery was in contact with the bone defect. The battery and electrode were insulated with plastic heat shrink material. Group 3 included rats that were modeled with a perforated defect similar to previous groups, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). Group 4 included animals that were modeled with a perforated defect similar to groups 1-3, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). The simulation of electrical stimulation was the same as in group 2. The material for the morphological study was a fragment of the body of the lower jaw from the zone of the perforated defect. Immunohistochemical study was performed using rabbit anti-human SATB2 monoclonal antibody.

RESULTS

Results: In the regenerate filling the defect in the bone tissue of the lower jaw of rats, there was an increase in SATB2 expression under conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation. The most pronounced expression of SATB2 was observed under conditions of simultaneous filling the defect with a synthetic bone graft material and electrical stimulation; minimally expressed - in conditions of filling the defect with a synthetic bone graft material; moderately expressed - under conditions of electrical stimulation. In the regenerate, in cases of all treatment methods, SATB2 was expressed by immune cells, fibroblastic differon cells, osteoblasts, and in case of electrical stimulation, also by adipocytes, vascular pericytes and endothelial cells, epidermis.

CONCLUSION

Conclusions: The activation of SATB2 expression identified by the authors is one of the mechanisms for stimulating reparative osteogenesis under the conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation.

A. Epigenetic regulation of craniofacial development and disease

BACKGROUND

The formation of the craniofacial complex relies on proper neural crest development. The gene regulatory networks (GRNs) and signaling pathways orchestrating this process have been extensively studied. These GRNs and signaling cascades are tightly regulated as alterations to any stage of neural crest development can lead to common congenital birth defects, including multiple syndromes affecting facial morphology as well as nonsyndromic facial defects, such as cleft lip with or without cleft palate. Epigenetic factors add a hierarchy to the regulation of transcriptional networks and influence the spatiotemporal activation or repression of specific gene regulatory cascades; however less is known about their exact mechanisms in controlling precise gene regulation.

AIMS

In this review, we discuss the role of epigenetic factors during neural crest development, specifically during craniofacial development and how compromised activities of these regulators contribute to congenital defects that affect the craniofacial complex.

Dorsoventral Arrangement of Lateral Hypothalamus Populations in the Mouse Hypothalamus: a Prosomeric Genoarchitectonic Analysis

The lateral hypothalamus (LH) has a heterogeneous cytoarchitectonic organization that has not been elucidated in detail. In this work, we analyzed within the framework of the prosomeric model the differential expression pattern of 59 molecular markers along the ventrodorsal dimension of the medial forebrain bundle in the mouse, considering basal and alar plate subregions of the LH. We found five basal (LH1-LH5) and four alar (LH6-LH9) molecularly distinct sectors of the LH with neuronal cell groups that correlate in topography with previously postulated alar and basal hypothalamic progenitor domains. Most peptidergic populations were restricted to one of these LH sectors though some may have dispersed into a neighboring sector. For instance, histaminergic Hdc-positive neurons were mostly contained within the basal LH3, Nts (neurotensin)- and Tac2 (tachykinin 2)-expressing cells lie strictly within LH4, Hcrt (hypocretin/orexin)-positive and Pmch (pro-melanin-concentrating hormone)-positive neurons appeared within separate LH5 subdivisions, Pnoc (prepronociceptin)-expressing cells were mainly restricted to LH6, and Sst (somatostatin)-positive cells were identified within the LH7 sector. The alar LH9 sector, a component of the Foxg1-positive telencephalo-opto-hypothalamic border region, selectively contained Satb2-expressing cells. Published studies of rodent LH subdivisions have not described the observed pattern. Our genoarchitectonic map should aid in systematic approaches to elucidate LH connectivity and function.

Psammomatoid Ossifying Fibroma Is Defined by SATB2 Rearrangement

Psammomatoid ossifying fibroma (PsOF), also known as juvenile PsOF, is a benign fibro-osseous neoplasm predominantly affecting the extragnathic bones, particularly the frontal and ethmoid bones, with a preference for adolescents and young adults. The clinical and morphologic features of PsOF may overlap with those of other fibro-osseous lesions, and additional molecular markers would help increase diagnostic accuracy. Because identical chromosomal breakpoints at bands Xq26 and 2q33 have been described in 3 cases of PsOF located in the orbita, we aimed to identify the exact genes involved in these chromosomal breakpoints and determine their frequency in PsOF using transcriptome sequencing and fluorescence in situ hybridization (FISH). We performed whole RNA transcriptome sequencing on frozen tissue in 2 PsOF index cases and identified a fusion transcript involving SATB2, located on chromosome 2q33.1, and AL513487.1, located on chromosome Xq26, in one of the cases. The fusion was validated using reverse transcription (RT)-PCR and SATB2 FISH. The fusion lead to a truncated protein product losing most of the functional domains. Subsequently, we analyzed an additional 24 juvenile PsOFs, 8 juvenile trabecular ossifying fibromas (JTOFs), and 11 cemento-ossifying fibromas (COFs) for SATB2 using FISH and found evidence of SATB2 gene rearrangements in 58% (7 of 12) of the evaluable PsOF cases but not in any of the evaluable JTOF (n = 7) and COF (n = 7) cases. A combination of SATB2 immunofluorescence and a 2-color SATB2 FISH in our index case revealed that most tumor cells harboring the rearrangement lacked SATB2 expression. Using immunohistochemistry, 65% of PsOF, 100% of JTOF, and 100% of COF cases showed moderate or strong staining for SATB2. In these cases, we observed a mosaic pattern of expression with >25% of the spindle cells in between the bone matrix, with osteoblasts and osteocytes being positive for SATB2. Interestingly, 35% (8 of 23) of PsOFs, in contrast to JTOFs and COFs, showed SATB2 expression in <5% of cells. To our knowledge, this is the first report that shows the involvement of SATB2 in the development of a neoplastic lesion. In this study, we have showed that SATB2 rearrangement is a recurrent molecular alteration that appears to be highly specific for PsOF. Our findings support that PsOF is not only morphologically and clinically but also genetically distinct from JTOF and COF.

Transcription Factor Expression in Sinonasal Neuroendocrine Neoplasms and Olfactory Neuroblastoma (ONB): Hyams' Grades 1-3 ONBs Expand the Spectrum of SATB2 and GATA3-Positive Neoplasms

Sinonasal neuroendocrine neoplasms (SN-NENs) are rare and mostly include neuroendocrine carcinoma (NEC), whereas neuroendocrine tumor (NET) is exceptional in this site. Olfactory neuroblastoma (ONB) is a malignant neuroectodermal neoplasm arising in the nasal cavity. Albeit crucial for correct patients' management, the distinction of high grade ONB from NEC is challenging and requires additional diagnostic markers. The transcription factor SATB2 has been recently introduced in routine diagnostics as an immunohistochemical marker of distal intestine differentiation. No specific data are available about SATB2 and GATA3 expression in SN-NENs. GATA3, SATB2, and, for comparison, CDX2 expression were investigated in a series of epithelial and non-epithelial SN-NENs. We collected 26 cases of ONB and 7 cases of epithelial SN-NENs diagnosed and treated in our Institution. ONBs were graded according to Hyams' system and epithelial NENs were reclassified into 5 NECs, 1 MiNEN, and 1 amphicrine carcinoma. Immunohistochemistry was performed using standard automated protocols. Hyams' grades 1-3 ONBs stained diffusely and intensely for SATB2, whereas grade 4 ONBs and NECs were globally negative. The non-neuroendocrine component of MiNEN and the amphicrine carcinoma were strongly positive. GATA3 was heterogeneously and unpredictably expressed in Hyams' grades 1-3 ONBs, whereas grade 4 ONBs and NECs were completely negative. CDX2 was negative in all cases. Our study identifies, for the first time, SATB2 and GATA3 expression as features of Hyams' grades 1-3 ONBs, expands the spectrum of SATB2 and GATA3-positive neoplasms, and suggests that Hyams' grade 4 ONBs are not only clinically but also biologically different from low graded ONBs.

OUHP: an optimized universal hairpin primer system for cost-effective and high-throughput RT-qPCR-based quantification of microRNA (miRNA) expression

MicroRNAs (miRNAs or miRs) are single-stranded, ∼22-nucleotide noncoding RNAs that regulate many cellular processes. While numerous miRNA quantification technologies are available, a recent analysis of 12 commercial platforms revealed high variations in reproducibility, sensitivity, accuracy, specificity and concordance within and/or between platforms. Here, we developed a universal hairpin primer (UHP) system that negates the use of miRNA-specific hairpin primers (MsHPs) for quantitative reverse transcription PCR (RT-qPCR)-based miRNA quantification. Specifically, we analyzed four UHPs that share the same hairpin structure but are anchored with two, three, four and six degenerate nucleotides at 3'-ends (namely UHP2, UHP3, UHP4 and UHP6), and found that the four UHPs yielded robust RT products and quantified miRNAs with high efficiency. UHP-based RT-qPCR miRNA quantification was not affected by long transcripts. By analyzing 14 miRNAs, we demonstrated that UHP4 closely mimicked MsHPs in miRNA quantification. Fine-tuning experiments identified an optimized UHP (OUHP) mix with a molar composition of UHP2:UHP4:UHP6 = 8:1:1, which closely recapitulated MsHPs in miRNA quantification. Using synthetic LET7 isomiRs, we demonstrated that the OUHP-based qPCR system exhibited high specificity and sensitivity. Collectively, our results demonstrate that the OUHP system can serve as a reliable and cost-effective surrogate of MsHPs for RT-qPCR-based miRNA quantification for basic research and precision medicine.

Special AT-rich sequence-binding protein 2 (Satb2) synergizes with Bmp9 and is essential for osteo/odontogenic differentiation of mouse incisor mesenchymal stem cells

OBJECTIVES

Mouse incisor mesenchymal stem cells (MSCs) have self-renewal ability and osteo/odontogenic differentiation potential. However, the mechanism controlling the continuous self-renewal and osteo/odontogenic differentiation of mouse incisor MSCs remains unclear. Special AT-rich sequence-binding protein 2 (SATB2) positively regulates craniofacial patterning, bone development and regeneration, whereas SATB2 deletion or mutation leads to craniomaxillofacial dysplasia and delayed tooth and root development, similar to bone morphogenetic protein (BMP) loss-of-function phenotypes. However, the detailed mechanism underlying the SATB2 role in odontogenic MSCs is poorly understood. The aim of this study was to investigate whether SATB2 can regulate self-renewal and osteo/odontogenic differentiation of odontogenic MSCs.

MATERIALS AND METHODS

Satb2 expression was detected in the rapidly renewing mouse incisor mesenchyme by immunofluorescence staining, quantitative RT-PCR and Western blot analysis. Ad-Satb2 and Ad-siSatb2 were constructed to evaluate the effect of Satb2 on odontogenic MSCs self-renewal and osteo/odontogenic differentiation properties and the potential role of Satb2 with the osteogenic factor bone morphogenetic protein 9 (Bmp9) in vitro and in vivo.

RESULTS

Satb2 was found to be expressed in mesenchymal cells and pre-odontoblasts/odontoblasts. We further discovered that Satb2 effectively enhances mouse incisor MSCs self-renewal. Satb2 acted synergistically with the potent osteogenic factor Bmp9 in inducing osteo/odontogenic differentiation of mouse incisor MSCs in vitro and in vivo.

CONCLUSIONS

Satb2 promotes self-renewal and osteo/odontogenic differentiation of mouse incisor MSCs. Thus, Satb2 can cooperate with Bmp9 as a new efficacious bio-factor for osteogenic regeneration and tooth engineering.