Adeno-Associated Virus-Mediated RNAi against Mutant Alleles Attenuates Abnormal Calvarial Phenotypes in an Apert Syndrome Mouse Model

An Hsp70 promoter-based mouse for heat shock-induced gene modulation

Physical therapy is extensively employed in clinical settings. Nevertheless, the absence of suitable animal models has resulted in an incomplete understanding of the in vivo mechanisms and cellular distribution that respond to physical stimuli. The objective of this research was to create a mouse model capable of indicating the cells affected by physical stimuli. In this study, we successfully established a mouse line based on the heat shock protein 70 (Hsp70) promoter, wherein the expression of CreERT2 can be induced by physical stimuli. Following stimulation of the mouse tail, ear, or cultured calvarias with heat shock (generated by heating, ultrasound, or laser), a distinct Cre-mediated excision was observed in cells stimulated by these physical factors with minimal occurrence of leaky reporter expression. The application of heat shock to Hsp70-CreERT2; FGFR2-P253R double transgenic mice or Hsp70-CreERT2 mice infected with AAV-BMP4 at calvarias induced the activation of Cre-dependent mutant FGFR2-P253R or BMP4 respectively, thereby facilitating the premature closure of cranial sutures or the repair of calvarial defects. This novel mouse line holds significant potential for investigating the underlying mechanisms of physical therapy, tissue repair and regeneration, lineage tracing, and targeted modulation of gene expression of cells in local tissue stimulated by physical factor at the interested time points. KEY MESSAGES: In the study, an Hsp70-CreERT2 transgenic mouse was generated for heat shock-induced gene modulation. Heat shock, ultrasound, and laser stimulation effectively activated Cre expression in Hsp70-CreERT2; reporter mice, which leads to deletion of floxed DNA sequence in the tail, ear, and cultured calvaria tissues of mice. Local laser stimuli on cultured calvarias effectively induce Fgfr2-P253R expression in Hsp70-mTmG-Fgfr2-P253R mice and result in accelerated premature closure of cranial suture. Heat shock activated AAV9-FLEX-BMP4 expression and subsequently promoted the repair of calvarial defect of Hsp70-CreERT2; Rosa26-mTmG mice.

Unraveling the Complexity of Apert Syndrome: Genetics, Clinical Insights, and Future Frontiers

Apert syndrome (AS), also known as type I acrocephalosyndactyly, is a rare congenital condition characterized by craniosynostosis resulting from missense mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. This comprehensive review delves into AS, covering its clinical manifestations, genetics, diagnosis, medical management, psychosocial considerations, and future research directions. AS presents with distinct features, including a brachycephalic skull, midface hypoplasia, and limb anomalies such as syndactyly. It follows an autosomal dominant inheritance pattern with mutations in the FGFR2 gene. Prenatal diagnosis is possible through advanced imaging techniques and molecular testing. The multidisciplinary approach to AS management involves surgical interventions, orthodontics, and psychological support. Although no curative treatment exists, early interventions can significantly improve function and aesthetics. The quality of life for AS patients is influenced by psychosocial factors, necessitating comprehensive support for both patients and their families. Future research directions include gene therapy, understanding cellular responses to FGFR2 mutations, and addressing genetic heterogeneity. Collaborative efforts are vital to advancing knowledge about AS and its genetic underpinnings. Overall, this review serves as a valuable resource for healthcare professionals, educators, and researchers, contributing to a deeper understanding of AS and facilitating advancements in diagnosis and treatment.

CRISPR/Cas9-based application for cancer therapy: Challenges and solutions for non-viral delivery

CRISPR/Cas9 genome editing is a promising therapeutic technique, which makes precise and rapid gene editing technology possible on account of its high sensitivity and efficiency. CRISPR/Cas9 system has been proved to able to effectively disrupt and modify genes, which shows great potential for cancer treatment. Current researches proves that virus vectors are capable of effectively delivering the CRISPR/Cas9 system, but immunogenicity and carcinogenicity caused by virus transmission still trigger serious consequences. Therefore, the greatest challenge of CRISPR/Cas9 for cancer therapy lies on how to deliver it to the target tumor site safely and effectively. Non-viral delivery systems with specific targeting, high loading capacity, and low immune toxicity are more suitable than viral vectors, which limited by uncontrollable side effects. Their medical advances and applications have been widely concerned. Herein, we present the molecule mechanism and different construction strategies of CRISPR/Cas9 system for editing genes at the beginning of this research. Subsequently, several common CRISPR/Cas9 non-viral deliveries for cancer treatment are introduced. Lastly, based on the main factors limiting the delivery efficiency of non-viral vectors proposed in the existing researches and literature, we summarize and discuss the main methods to solve these limitations in the existing tumor treatment system, aiming to introduce further optimization and innovation of the CRISPR/Cas9 non-viral delivery system suitable for cancer treatment.

Myeloid-derived growth factor alleviates non-alcoholic fatty liver disease alleviates in a manner involving IKKβ/NF-κB signaling

Whether bone marrow modulates systemic metabolism remains unknown. Our recent study suggested that myeloid-derived growth factor (MYDGF) improves insulin resistance. Here, we found that myeloid cell-specific MYDGF deficiency aggravated hepatic inflammation, lipogenesis, and steatosis, and show that myeloid cell-derived MYDGF restoration alleviated hepatic inflammation, lipogenesis, and steatosis. Additionally, recombinant MYDGF attenuated inflammation, lipogenesis, and fat deposition in primary mouse hepatocytes (PMHs). Importantly, inhibitor kappa B kinase beta/nuclear factor-kappa B (IKKβ/NF-κB) signaling is involved in protection of MYDGF on non-alcoholic fatty liver disease (NAFLD). These data revealed that myeloid cell-derived MYDGF alleviates NAFLD and inflammation in a manner involving IKKβ/NF-κB signaling, and serves as a factor involved in the crosstalk between the liver and bone marrow that regulates liver fat metabolism. Bone marrow functions as an endocrine organ and serves as a potential therapeutic target for metabolic disorders.

CRISPR/Cas9-generated mouse model with humanizing single-base substitution in the Gnao1 for safety studies of RNA therapeutics

The development of personalized medicine for genetic diseases requires preclinical testing in the appropriate animal models. GNAO1 encephalopathy is a severe neurodevelopmental disorder caused by heterozygous de novo mutations in the GNAO1 gene. GNAO1 c.607 G>A is one of the most common pathogenic variants, and the mutant protein Gαo-G203R likely adversely affects neuronal signaling. As an innovative approach, sequence-specific RNA-based therapeutics such as antisense oligonucleotides or effectors of RNA interference are potentially applicable for selective suppression of the mutant GNAO1 transcript. While in vitro validation can be performed in patient-derived cells, a humanized mouse model to rule out the safety of RNA therapeutics is currently lacking. In the present work, we employed CRISPR/Cas9 technology to introduce a single-base substitution into exon 6 of the Gnao1 to replace the murine Gly203-coding triplet (GGG) with the codon used in the human gene (GGA). We verified that genome-editing did not interfere with the Gnao1 mRNA or Gαo protein synthesis and did not alter localization of the protein in the brain structures. The analysis of blastocysts revealed the off-target activity of the CRISPR/Cas9 complexes; however, no modifications of the predicted off-target sites were detected in the founder mouse. Histological staining confirmed the absence of abnormal changes in the brain of genome-edited mice. The created mouse model with the “humanized” fragment of the endogenous Gnao1 is suitable to rule out unintended targeting of the wild-type allele by RNA therapeutics directed at lowering GNAO1 c.607 G>A transcripts.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Insights and future directions of potential genetic therapy for Apert syndrome: A systematic review

Apert syndrome is a genetic disorder characterised by craniosynostosis and structural discrepancy of the craniofacial region as well as the hands and feet. This condition is closely linked with fibroblast growth factor receptor-2 (FGFR2) gene mutations. Gene therapies are progressively being tested in advanced clinical trials, leading to a rise of its potential clinical indications. In recent years, research has made great progress in the gene therapy of craniosynostosis syndromes and several studies have investigated its influences in preventing/diminishing the complications of Apert syndrome. This article reviewed and exhibited different techniques of gene therapy and their influences in Apert syndrome progression. A systematic search was executed using electronic bibliographic databases including PubMed, EMBASE, ScienceDirect, SciFinder and Web of Science for all studies of gene therapy for Apert syndrome. The primary outcomes measurements vary from protein to gene expressions. According to the findings of included studies, we conclude that the gene therapy using FGF in Apert syndrome was critical in the regulation of suture fusion and patency, occurred via alterations in cellular proliferation. The superior outcome could be brought by biological therapies targeting the FGF/FGFR signalling. More studies in molecular genetics in Apert syndrome are recommended. This study reviews the current literature and provides insights to future possibilities of genetic therapy as intervention in Apert syndrome.

Ubiquitin-specific protease 53 promotes osteogenic differentiation of human bone marrow-derived mesenchymal stem cells

The ubiquitin protease pathway plays important role in human bone marrow-derived mesenchymal stem cell (hBMSC) differentiation, including osteogenesis. However, the function of deubiquitinating enzymes in osteogenic differentiation of hBMSCs remains poorly understood. In this study, we aimed to investigate the role of ubiquitin-specific protease 53 (USP53) in the osteogenic differentiation of hBMSCs. Based on re-analysis of the Gene Expression Omnibus database, USP53 was selected as a positive regulator of osteogenic differentiation in hBMSCs. Overexpression of USP53 by lentivirus enhanced osteogenesis in hBMSCs, whereas knockdown of USP53 by lentivirus inhibited osteogenesis in hBMSCs. In addition, USP53 overexpression increased the level of active β-catenin and enhanced the osteogenic differentiation of hBMSCs. This effect was reversed by the Wnt/β-catenin inhibitor DKK1. Mass spectrometry showed that USP53 interacted with F-box only protein 31 (FBXO31) to promote proteasomal degradation of β-catenin. Inhibition of the osteogenic differentiation of hBMSCs by FBXO31 was partially rescued by USP53 overexpression. Animal studies showed that hBMSCs with USP53 overexpression significantly promoted bone regeneration in mice with calvarial defects. These results suggested that USP53 may be a target for gene therapy for bone regeneration.

Characterization of dental pulp stem cells isolated from a patient diagnosed with Crouzon syndrome

Stem cells isolated from patients with rare diseases are important to elucidate their pathogeny and mechanisms to enable regenerative therapy. However, the mechanisms underlying tissue regeneration using patient‐derived dental pulp stem cells (DPSCs) are unclear. In this study, we investigated the levels of mRNA and protein expression related to cellular differentiation of Crouzon syndrome patient‐derived DPSCs (CS‐DPSCs) with a Gly338Arg fibroblast growth factor receptor 2 mutation. Multipotency‐related gene expression levels were equivalent in both healthy donor DPSCs and CS‐DPSCs. CS‐DPSCs showed higher osteocalcin (OCN) expression than healthy donor DPSCs. CS‐DPSCs showed a lower increase in the rate of OCN expression among phorbol 12‐myristate 13‐acetate (PMA)‐treated cells than healthy donor DPSCs compared with untreated control cells. CS‐DPSCs showed a lower phosphorylation rate of p38 and p44/42 in PMA‐treated cells than healthy donor DPSCs compared with untreated control cells. These results demonstrate that CS‐DPSCs have higher OCN expression and lower PMA stimulation‐responsiveness than healthy donor DPSCs.

FGF/FGFR signaling in health and disease

Growing evidences suggest that the fibroblast growth factor/FGF receptor (FGF/FGFR) signaling has crucial roles in a multitude of processes during embryonic development and adult homeostasis by regulating cellular lineage commitment, differentiation, proliferation, and apoptosis of various types of cells. In this review, we provide a comprehensive overview of the current understanding of FGF signaling and its roles in organ development, injury repair, and the pathophysiology of spectrum of diseases, which is a consequence of FGF signaling dysregulation, including cancers and chronic kidney disease (CKD). In this context, the agonists and antagonists for FGF-FGFRs might have therapeutic benefits in multiple systems.

Downregulation of microRNA-16-5p accelerates fracture healing by promoting proliferation and inhibiting apoptosis of osteoblasts in patients with traumatic brain injury

Patients who suffered a traumatic brain injury (TBI) show a faster fracture healing than patients with isolated fractures. Prior studies have suggested that this process may be accelerated through the inhibition of key microRNAs. In this study, we aimed to explore the mechanisms underlying this phenomenon, with a special focus on miR-16-5p, which is markedly decreased in patients with TBI. In vitro, miR-16-5p over-expression significantly inhibited cell proliferation in MC3T3-E1 cells transfected with agomiR-16-5p. Flow cytometry analysis further demonstrated that the overexpression of miR-16-5p induced cell cycle G1/S phase arrest and apoptosis. Moreover, target prediction and luciferase reporter assay demonstrated that miR-16-5p could negatively regulate Bcl-2 and Cyclin-D1 expression. Meanwhile, Bcl-2 and Cyclin-D1 were up-regulated after osteogenic differentiation while the down-regulation of endogenous Bcl-2 and Cyclin-D suppressed the osteogenic differentiation of MC3T3-E1 cells. In vivo, PBS, agomiR-16-5p and antagomiR-16-5p were injected into fracture sites to assess any improvements in fracture healing, which further confirmed the negative effect of miR-16-5p on fracture healing. Together, these results demonstrate miR-16-5p downregulation may accelerate fracture healing by enhancing the proliferation and inhibiting the apoptosis of osteoblasts in patients with both fractures and TBI. These phenomena may be exploited in the treatment of fractures.

Bone-targeting AAV-mediated silencing of Schnurri-3 prevents bone loss in osteoporosis

RNAi-based bone anabolic gene therapy has demonstrated initial success, but many practical challenges are still unmet. Here, we demonstrate that a recombinant adeno-associated virus 9 (rAAV9) is highly effective for transducing osteoblast lineage cells in the bone. The adaptor protein Schnurri-3 (SHN3) is a promising therapeutic target for osteoporosis, as deletion of shn3 prevents bone loss in osteoporotic mice and short-term inhibition of shn3 in adult mice increases bone mass. Accordingly, systemic and direct joint administration of an rAAV9 vector carrying an artificial-microRNA that targets shn3 (rAAV9-amiR-shn3) in mice markedly enhanced bone formation via augmented osteoblast activity. Additionally, systemic delivery of rAAV9-amiR-shn3 in osteoporotic mice counteracted bone loss and enhanced bone mechanical properties. Finally, we rationally designed a capsid that exhibits improved specificity to bone by grafting the bone-targeting peptide motif (AspSerSer)6 onto the AAV9-VP2 capsid protein. Collectively, our results identify a bone-targeting rAAV-mediated gene therapy for osteoporosis.

miRNA-26a-5p Accelerates Healing via Downregulation of PTEN in Fracture Patients with Traumatic Brain Injury

Patients who sustain a traumatic brain injury (TBI) are known to have a significantly quicker fracture healing time than patients with isolated fractures, but the underlying mechanism has yet to be identified. In this study, we found that the upregulation of miRNA-26a-5p induced by TBI correlated with a decrease in phosphatase and tensin homolog (PTEN) in callus formation. In vitro, overexpressing miRNA-26a-5p inhibited PTEN expression and accelerated osteoblast differentiation, whereas silencing of miRNA-26a-5p inhibited osteoblast activity. Reduction of PTEN facilitated osteoblast differentiation via the PI3K/AKT signaling pathway. Through luciferase assays, we found evidence that PTEN is a miRNA-26a-5p target gene that negatively regulates the differentiation of osteoblasts. Moreover, the present study confirmed that preinjection of agomiR-26a-5p leads to increased bone formation. Collectively, these results indicate that miRNA-26a-5p overexpression may be a key factor governing the improved fracture healing observed in TBI patients after the downregulation of PTEN and PI3K/AKT signaling. Upregulation of miRNA-26a-5p may therefore be a promising therapeutic strategy for promoting fracture healing.