ABSTRACT
In newborn humans, and up to approximately 2 y of age, calvarial bone defects can naturally regenerate. This remarkable regeneration potential is also found in newborn mice and is absent in adult mice. Since previous studies showed that the mouse calvarial sutures are reservoirs of calvarial skeletal stem cells (cSSCs), which are the cells responsible for calvarial bone regeneration, here we hypothesized that the regenerative potential of the newborn mouse calvaria is due to a significant amount of cSSCs present in the newborn expanding sutures. Thus, we tested whether such regenerative potential can be reverse engineered in adult mice by artificially inducing an increase of the cSSCs resident within the adult calvarial sutures. First, we analyzed the cellular composition of the calvarial sutures in newborn and in older mice, up to 14-mo-old mice, showing that the sutures of the younger mice are enriched in cSSCs. Then, we demonstrated that a controlled mechanical expansion of the functionally closed sagittal sutures of adult mice induces a significant increase of the cSSCs. Finally, we showed that if a calvarial critical size bone defect is created simultaneously to the mechanical expansion of the sagittal suture, it fully regenerates without the need for additional therapeutic aids. Using a genetic blockade system, we further demonstrate that this endogenous regeneration is mediated by the canonical Wnt signaling. This study shows that controlled mechanical forces can harness the cSSCs and induce calvarial bone regeneration. Similar harnessing strategies may be used to develop novel and more effective bone regeneration autotherapies.
Subject(s)
Bone Regeneration , Cranial Sutures , Humans , Adult , Mice , Animals , Stem Cells , Cell Proliferation , SuturesABSTRACT
Highly efficient synthesis of monomeric and dimeric thiourea macrocycles with a per-O-benzylated sucrose scaffold is reported. Application of flow synthesis results in exclusive formation of a monomer in 79% yield. Batch synthesis provides two isomeric dimers in 85% yield. Dimers are capable of anion binding via two thiourea groups acting cooperatively.
ABSTRACT
The growing concern over extending the shelf life of food products, coupled with the escalating environmental impact of synthetic plastic waste, has fuelled a quest for bio-based alternatives in packaging research. In response to this pressing need, our study delves into the synthesis of chitosan-based films incorporating a deep eutectic solvents (DES). Choline chloride and diverse hydrogen bond donors were used as plasticizers, we also explored the active properties of DES integrated into the chitosan (Ch) matrix. The Ch-based films with chlorine chloride: citric acid can prevent the mold spotting up to 29 days longer in comparison to bread wrapped in polyethylene films (PE). The obtained Ch/DES films exhibited mechanical properties comparable to conventional PE (e.g., up to tensile strength of 26 MPa and up to 210% in case of elongation at break). This synthesis approach represents a significant stride towards environmentally friendly packaging materials, aligning with the principles of green chemistry.
Subject(s)
Chitosan , Chitosan/chemistry , Plasticizers/chemistry , Deep Eutectic Solvents , Choline/chemistry , Tensile Strength , Solvents/chemistryABSTRACT
BACKGROUND: Piezosurgery is an osteotomy system used in medical and dental surgery. Many studies have proven clinical advantages of piezosurgery in terms of quality of cut, maneuverability, ease of use, and safety. However, few investigations have tested its superiority over the traditional osteotomy systems in terms of dynamics of bone healing. Therefore, the aim of this study was to evaluate the dynamics of bone healing after osteotomies with piezosurgery and to compare them with those associated to traditional bone drilling. METHODS: One hundred and ten rats were divided into two groups with 55 animals each. The animals were anesthetized and the tibiae were surgically exposed to create defects 2 mm in diameter by using piezosurgery (Piezo group) and conventional drilling (Drill group). Animals were sacrificed at 3, 7, 14, 30 and 60 days post-surgery. Bone samples were collected and processed for histological, histomorphometrical, immunohistochemical, and molecular analysis. The histological analysis was performed at all time points (n = 8) whereas the histomorphometrical analysis was performed at 7, 14, 30 and 60 days post-surgery (n = 8). The immunolabeling was performed to detect Vascular Endothelial Growth Factor (VEGF), Caspase-3 (CAS-3), Osteoprotegerin (OPG), Receptor Activator of Nuclear Factor kappa-B Ligand (RANKL), and Osteocalcin (OC) at 3, 7, and 14 days (n = 3). For the molecular analysis, animals were sacrificed at 3, 7 and 14 days, total RNA was collected, and quantification of the expression of 21 genes related to BMP signaling, Wnt signaling, inflammation, osteogenenic and apoptotic pathways was performed by qRT-PCR (n = 5). RESULTS: Histologically and histomorphometrically, bone healing was similar in both groups with the exception of a slightly higher amount of newly formed bone observed at 30 days after piezosurgery (p < 0.05). Immunohistochemical and qRT-PCR analyses didn't detect significant differences in expression of all the proteins and most of the genes tested. CONCLUSIONS: Based on the results of our study we conclude that in a rat tibial bone defect model the bone healing dynamics after piezosurgery are comparable to those observed with conventional drilling.
Subject(s)
Arthroplasty , Bone and Bones/metabolism , Bone and Bones/pathology , Osteotomy , Piezosurgery , Wound Healing , Animals , Biomarkers/metabolism , Bone Regeneration/genetics , Gene Expression Regulation , Immunohistochemistry , Rats , Reverse Transcriptase Polymerase Chain Reaction , Time Factors , Wound Healing/geneticsABSTRACT
Ovarian tumors have an uncommon occurrence in children and adolescent girls compared with adult women. The peak incidence of ovarian tumors is between 15-19 years of age. Malignant ovarian tumors in children and adolescent girls are extremely rare. A case of a 14-year-old girl with ovarian mucinous adenocarcinoma that has probably not been described before in the literature is presented below.
ABSTRACT
Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs, acting by inhibiting the reabsorption of glucose in the kidneys. They turned out to improve cardiovascular and renal outcomes not only in patients with type 2 diabetes but also in nondiabetic patients. At present, they are more and more widely used in patients without diabetes. Since there were concerns that SGLT2 inhibitors may increase fracture risk in diabetes, the aim of the study was to examine the effect of dapagliflozin and canagliflozin on the musculoskeletal system of nondiabetic, healthy rats. The experiments were carried out on mature female rats, divided into the control rats and rats treated with dapagliflozin (1.4 mg/kg p.o.) or canagliflozin (4.2 mg/kg p.o.) for 4 weeks. Serum bone turnover markers, skeletal muscle strength and mass, bone mass, density, histomorphometric parameters and mechanical properties were determined. Administration of the drugs did not affect the skeletal muscle mass and strength. There was no effect on serum bone turnover markers, and bone mass and composition. However, administration of both drugs resulted in disorders of cancellous bone microarchitecture and worsening of bone mechanical properties. In conclusion, both SGLT2 inhibitors unfavorably affected the skeletal system of healthy rats.
Subject(s)
Antiemetics , Diabetes Mellitus, Type 2 , Sodium-Glucose Transporter 2 Inhibitors , Female , Rats , Animals , Sodium-Glucose Transporter 2 , Canagliflozin/pharmacology , Sodium-Glucose Transporter 2 Inhibitors/pharmacology , Sodium-Glucose Transporter 2 Inhibitors/therapeutic use , Diabetes Mellitus, Type 2/chemically induced , Diabetes Mellitus, Type 2/drug therapy , Antiemetics/therapeutic use , Benzhydryl Compounds/pharmacology , Benzhydryl Compounds/therapeutic use , Hypoglycemic Agents/pharmacology , Hypoglycemic Agents/therapeutic use , Glucose/therapeutic use , Biomarkers , Bone and Bones , SodiumABSTRACT
OBJECTIVE: The aim of this investigation was to evaluate the property of bovine lactoferrin (LF) in the generation of delayed type hypersensitivity (DTH) as an oral adjuvant during immunization with ovalbumin (OVA) and BCG. METHODS: LF admixed with OVA or BCG was used for immunization of CBA or C57BL/6 mice when given via oral or subcutaneous routes. Elicited DTH response was measured post immunization. Inhibition studies using mannose or galactose were accomplished by gavage prior to oral administration of antigens. LF was also examined for effects on BCG uptake by bone marrow derived macrophages (BMM). RESULTS: LF at doses of 1.0 mg and 10.0 mg, admixed with OVA (10.0 mg), significantly enhanced the antigen-specific DTH reaction. The stimulatory effects of LF were inhibited by the oral pretreatment of mice with 50.0 mg of mannose but not galactose. LF also enhanced the DTH reaction to orally administered BCG. LF enhanced uptake of BCG by BMM in a dose-dependent manner. CONCLUSION: LF was able to augment development of DTH when orally administered with OVA or BCG antigens. Inhibition studies suggest the involvement of the receptor with an affinity to mannose in mediation of the adjuvant effect. LF augmentation of the DTH response was partially effective when given in advance of oral delivery of the antigen; this effect could also be saturated by mannose. BCG studies provide preliminary evidence for LF in the potential augmentation of oral vaccination to prevent mycobacterial infection. In vitro experiments provide evidence that LF plays a role in modulation of antigen presenting cell activation.
Subject(s)
Adjuvants, Immunologic/administration & dosage , Antigens/administration & dosage , Hypersensitivity, Delayed/pathology , Lactoferrin/administration & dosage , Macrophages/immunology , Mycobacterium bovis/immunology , Ovalbumin/administration & dosage , Administration, Oral , Animals , Antigens/immunology , Hypersensitivity, Delayed/etiology , Lactoferrin/immunology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Ovalbumin/immunologyABSTRACT
Nano- and microemulsions have found various applications in pharmaceutical and medical areas both in research field as well as in applied solutions for drug delivery or diagnostic agents. However, production of stable and bio- / hemocompatible nanoemulsions are still challenging. New group of ionic surfactants have been synthesized with perfluorohexyl- or perfluorooctyl-groups as hydrophobic tail. The CMC and the parametres of the O/W emulsion (the particle size distribution and the zeta-potential) were determined. The influence of the surfactants on in vitro proliferation of human endothelial cell lines HMEC-1, murine fibroblasts L929 and hemolysis were investigated as characteristic for biocompatibility. Three candidates of surfactants were selected for pre-clinical tests on a small animal model (adult Sprague Dawley rats) on the basis of preliminary studies. This allowed to obtain nanoemulsions with narrow droplets size (average droplet diameter 141-147 nm with PDI index 0.059 - 0.065) and showed better stability over time in comparison to the commercially available surfactants. Neither cytotoxic nor hemolytic potential were observed during incubation of obtained fluorosurfactans with model cell lines L929 and HMEC-1 (average cell viability above 85 % after incubation with 1% solutions) and erythrocytes (hemolysis rate below 3.1 % for all 0.5 % solutions). During acute toxicity test on rat model, it was found that all three tested surfactant solutions showed no significant differences in controlled parameters and survival rate with control group (p > 0.05). Presented surfactants are dedicated but not limited to emulsification of organic fluorocompounds.
Subject(s)
Nanoparticles , Animals , Drug Delivery Systems , Emulsions , Mice , Particle Size , Rats , Rats, Sprague-Dawley , Surface-Active AgentsABSTRACT
Parkinson's disease (PD) is a common neurodegenerative disorder impacting cognition, movement, and quality of life in >10 million individuals worldwide. We recently characterized and quantified a skeletal muscle pathology in PD represented by exaggerated type I myofiber grouping presumed to result from denervation-reinnervation processes. Our previous findings indicated that impaired neuromuscular junction integrity may be involved in type I grouping, which is associated with excessive motor unit activation during weight-bearing tasks. In this study, we performed transcriptional profiling to test the hypothesis that type I grouping severity would link to distinct gene expression networks. We generated transcriptome-wide poly(A) RNA-Seq data from skeletal muscle of individuals with PD [n = 12 (9 men, 3 women); 67 ± 2 yr], age- and sex-matched older adults (n = 12; 68 ± 2 yr), and sex-matched young adults (n = 12; 30 ± 1 yr). Differentially expressed genes were evaluated across cohorts. Weighted gene correlation network analysis (WGCNA) was performed to identify gene networks most correlated with indicators of abnormal type I grouping. Among coexpression networks mapping to phenotypes pathologically increased in PD muscle, one network was highly significantly correlated to type I myofiber group size and another to percentage of type I myofibers found in groups. Annotation of coexpressed networks revealed that type I grouping is associated with altered expression of genes involved in neural development, postsynaptic signaling, cell cycle regulation and cell survival, protein and energy metabolism, inflammation/immunity, and posttranscriptional regulation (microRNAs). These transcriptomic findings suggest that skeletal muscle may play an active role in signaling to promote myofiber survival, reinnervation, and remodeling, perhaps to an extreme in PD.NEW & NOTEWORTHY Despite our awareness of the impact of Parkinson's disease (PD) on motor function for over two centuries, limited attention has focused on skeletal muscle. We previously identified type I myofiber grouping, a novel indicator of muscle dysfunction in PD, presumably a result of heightened rates of denervation/reinnervation. Using transcriptional profiling to identify networks associated with this phenotype, we provide insight into potential mechanistic roles of skeletal muscle in signaling to promote its survival in PD.
Subject(s)
Gene Regulatory Networks , Muscle Fibers, Slow-Twitch/pathology , Muscle, Skeletal/pathology , Neuromuscular Junction/physiopathology , Parkinson Disease , Adult , Aged , Female , Humans , Male , Parkinson Disease/genetics , Parkinson Disease/pathology , Quality of Life , RNA-Seq , TranscriptomeABSTRACT
Parkinson's disease (PD) is the most common motor neurodegenerative disease, and neuromuscular function deficits associated with PD contribute to disability. Targeting these symptoms, our laboratory has previously evaluated 16-week high-intensity resistance exercise as rehabilitative training (RT) in individuals with PD. We reported significant improvements in muscle mass, neuromuscular function (strength, power, and motor unit activation), indices of neuromuscular junction integrity, total and motor scores on the unified Parkinson's disease rating scale (UPDRS), and total and sub-scores on the 39-item PD Quality of Life Questionnaire (PDQ-39), supporting the use of RT to reverse symptoms. Our objective was to identify transcriptional networks that may contribute to RT-induced neuromuscular remodeling in PD. We generated transcriptome-wide skeletal muscle RNA-sequencing in 5 participants with PD [4M/1F, 67 ± 2 years, Hoehn and Yahr stages 2 (n = 3) and 3 (n = 2)] before and after 16-week high intensity RT to identify transcriptional networks that may in part underpin RT-induced neuromuscular remodeling in PD. Following RT, 304 genes were significantly upregulated, notably related to remodeling and nervous system/muscle development. Additionally, 402 genes, primarily negative regulators of muscle adaptation, were downregulated. We applied the recently developed Pathway-Level Information ExtractoR (PLIER) method to reveal coordinated gene programs (as latent variables, LVs) that differed in skeletal muscle among young (YA) and old (OA) healthy adults and PD (n = 12 per cohort) at baseline and in PD pre- vs. post-RT. Notably, one LV associated with angiogenesis, axon guidance, and muscle remodeling was significantly lower in PD than YA at baseline and was significantly increased by exercise. A different LV annotated to denervation, autophagy, and apoptosis was increased in both PD and OA relative to YA and was also reduced by 16-week RT in PD. Thus, this analysis identified two novel skeletal muscle transcriptional programs that are dysregulated by PD and aging, respectively. Notably, RT has a normalizing effect on both programs in individuals with PD. These results identify potential molecular transducers of the RT-induced improvements in neuromuscular remodeling and motor function that may aid in optimizing exercise rehabilitation strategies for individuals with PD.
ABSTRACT
Levosimendan is a new inodilator which involves 3 main mechanisms: increases the calcium sensitivity of cardiomyocytes, acts as a vasodilator due to the opening of potassium channels, and has a cardioprotective effect. Levosimendan is mainly used in the treatment of acute decompensated heart failure (class IIb recommendation according to the European Society of Cardiology guidelines). However, numerous clinical trials indicate the validity of repeated infusions of levosimendan in patients with stable heart failure as a bridge therapy to heart transplantation, and in patients with accompanying right ventricular heart failure and pulmonary hypertension. Due to the complex mechanism of action, including the cardioprotective and anti- -aggregating effect, the use of levosimendan may be particularly beneficial in acute coronary syndromes, preventing the occurrence of acute heart failure. There are data indicating that levosimendan administered prior to cardiac surgery may improve outcomes in patients with severely impaired left ventricular function. The multidirectional mechanism of action also affects other organs and systems. The positive effect of levosimendan in the treatment of cardiorenal and cardiohepatic syndromes has been shown. It has a safe and predictable profile of action, does not induce tolerance, and shows no adverse effects affecting patients survival or prognosis. However, with inconclusive results of previous studies, there is aneed for awell-designed multicenter randomized placebo-controlled study, including an adequately large group of outpatients with chronic advanced systolic heart failure.
Subject(s)
Heart Failure , Pyridazines , Cardiotonic Agents/therapeutic use , Expert Testimony , Heart Failure/drug therapy , Humans , Hydrazones/therapeutic use , Poland , Pyridazines/therapeutic use , SimendanABSTRACT
Previous studies have shown that post-natal skeletal stem cells expressing Paired-related homeobox 1 (PRX1 or PRRX1) are present in the periosteum of long bones where they contribute to post-natal bone development and regeneration. Our group also identified post-natal PRX1 expressing cells (pnPRX1+ cells) in mouse calvarial synarthroses (sutures) and showed that these cells are required for calvarial bone regeneration. Since calvarial synarthroses are similar to dentoalveolar gomphosis (periodontium) and since there is no information available on the presence or function of pnPRX1+ cells in the periodontium, the present study aimed at identifying and characterizing pnPRX1+ cells within the mouse periodontium and assess their contribution to periodontal development and regeneration. Here we demonstrated that pnPRX1+ cells are present within the periodontal ligament (PDL) of the mouse molars and of the continuously regenerating mouse incisor. By means of diphtheria toxin (DTA)-mediated conditional ablation of pnPRX1+ cells, we show that pnPRX1+ cells contribute to post-natal periodontal development of the molars and the incisor, as ablation of pnPRX1+ cells in 3-days old mice resulted in a significant enlargement of the PDL space after 18 days. The contribution of pnPRX1+ cells to periodontal regeneration was assessed by developing a novel non-critical size periodontal defect model. Outcomes showed that DTA-mediated post-natal ablation of pnPRX1+ cells results in lack of regeneration in periodontal non-critical size defects in the regeneration competent mouse incisors. Importantly, gene expression analysis of these cells shows a profile typical of quiescent cells, while gene expression analysis of human samples of periodontal stem cells (PDLSC) confirmed that Prx1 is highly expressed in human periodontium. In conclusion, pnPRX1+ cells are present within the continuously regenerating PDL of the mouse incisor, and at such location they contribute to post-natal periodontal development and regeneration. Since this study further reports the presence of PRX1 expressing cells within human periodontal ligament, we suggest that studying the mouse periodontal pnPRX1+ cells may provide significant information for the development of novel and more effective periodontal regenerative therapies in humans.
ABSTRACT
Bmp2 is known to play an essential role in the initiation of fracture healing via periosteal activation. Specifically, activation and subsequent differentiation of periosteal progenitor cells requires Bmp2 signaling for activation of the osteo-chondrogenic pathway. Here, we explored the interactive transcriptional gene-gene interplays between Bmp2 and 150 known candidate genes during fracture repair. We constructed the interactive Bmp2 signaling pathways in vivo, by comparing gene expression levels prior and 24â¯h post femur fracture, in presence (wild type) and in absence of Bmp2 (Bmp2c/c;Prx1::cre limb-specific conditional knockout). Twenty-six differentially expressed genes (pre- vs. post-fracture), which demonstrated high correlations within each experimental condition, were used to construct the co-expression networks. Topological dynamic shifts across different co-expression networks characterized the 26 differentially expressed genes as non-redundant focal linking hubs, redundant connecting hubs, periphery genes, or non-existent. Top-ranked up- or down-regulated genes were identified and discussed. Protein-protein interactions in public databases support our findings. Thus, the co-expression networks from this study can be used for future experimental hypotheses.
Subject(s)
Bone Morphogenetic Protein 2/metabolism , Extremities/physiology , Fracture Healing/genetics , Gene Regulatory Networks , Animals , Gene Expression Profiling , Gene Expression Regulation , Mice, Inbred C57BL , Mice, Knockout , Molecular Sequence Annotation , Organ SpecificityABSTRACT
Histomorphometry and Micro-CT are commonly used to assess bone remodeling and bone microarchitecture. These approaches typically require separate cohorts of animals to analyze 3D morphological changes and involve time-consuming immunohistochemistry preparation. Intravital Microscopy (IVM) in combination with mouse genetics may represent an attractive option to obtain bone architectural measurements while performing longitudinal monitoring of dynamic cellular processes in vivo. In this study we utilized two-photon, multicolor fluorescence IVM together with a lineage tracing reporter mouse model to image skeletal stem cells (SSCs) in their calvarial suture niche and analyze their differentiation fate after stimulation with an agonist of the canonical Wnt pathway (recombinant Wnt3a). Our in vivo histomorphometry analyses of bone formation, suture volume, and cellular dynamics showed that recombinant Wnt3a induces new bone formation, differentiation and incorporation of SSCs progeny into newly forming bone. IVM technology can therefore provide additional dynamic 3D information to the traditional static 2D histomorphometry.
Subject(s)
Bone and Bones/cytology , Cell Differentiation , Imaging, Three-Dimensional , Microscopy, Fluorescence, Multiphoton , Stem Cells/cytology , Animals , MiceABSTRACT
INTRODUCTION: Lactoferrin, an 80-kDa basic N-glycoprotein, has been identified as a potent immune modulator. When used experimentally as an adjuvant in mice, lactoferrin can boost the efficacy of the BCG vaccine to increase delayed type hypersensitive responses and to limit subsequent pathology upon infection with virulent mycobacterium. These studies outline preliminary findings to examine the multiple mechanisms of action of lactoferrin on antigen-presenting cells which would enhance vaccination and bridge the innate and adaptive responses. MATERIAL/METHODS: Bone marrow-derived macrophages (BMMs) and human and murine cells lines were infected with BCG in the presence or absence of bovine lactoferrin. The cells were examined for changes in uptake of BCG post infection and increases in the surface expressions of Class I or Class II molecules by flow cytometric analysis. Infected cultures were collected to examine cytokine production by ELISA. RESULTS: Lactoferrin was found to significantly increase the uptake of BCG organisms during infection of BMMs and human monocyte cell lines. Lactoferrin added to BCG-infected BMMs demonstrated significantly increased surface expression of Class II (I-Ab), but no change in Class I (H-2kb) molecules. In addition, BCG-infected cells incubated in the presence of lactoferrin demonstrated a significant increase in relative IL-12 to IL-10 ratios in a dose-dependent manner. CONCLUSIONS: Overall, lactoferrin was able to alter BCG-infected antigen-presenting cells (APCs) in vitroin a manner consistent with the induction of responses required for successful presentation of antigen to the adaptive arm of the immune response, which would lead to the generation of strong T-helper 1 type immunity.
Subject(s)
BCG Vaccine/immunology , Lactoferrin/immunology , Macrophages/immunology , Mycobacterium tuberculosis/immunology , Animals , BCG Vaccine/pharmacology , Cells, Cultured , Cytokines/metabolism , Enzyme-Linked Immunosorbent Assay , Humans , Lactoferrin/pharmacology , Lymphocyte Activation/immunology , Macrophages/drug effectsABSTRACT
A high-yielding, one-pot simultaneous synthesis and full characterization of two regioisomeric C2-symmetrical macrocycles 3a and 3b from triphosgene and readily available hexa-O-benzyl-6,6'-diaminosucrose 1 is reported. The efficient macrocyclization (90% overall yield, â¼1:1 ratio of 3a vs 3b) is attributed to favorable steric constraints and to a templation by a chloride anion. 1H NMR titration studies and theoretical predictions revealed that both receptors show similar affinity for acetate and benzoate anions and enhanced preference for chloride over H2PO4-.
ABSTRACT
Post-natal skeletal stem cells expressing PRX1 (pnPRX1+) have been identified in the calvaria and in the axial skeleton. Here we characterize the location and functional capacity of the calvarial pnPRX1+ cells. We found that pnPRX1+ reside exclusively in the calvarial suture niche and decrease in number with age. They are distinct from preosteoblasts and osteoblasts of the sutures, respond to WNT signaling in vitro and in vivo by differentiating into osteoblasts, and, upon heterotopic transplantation, are able to regenerate bone. Diphtheria toxin A (DTA)-mediated lineage ablation of pnPRX1+ cells and suturectomy perturb regeneration of calvarial bone defects and confirm that pnPRX1+ cells of the sutures are required for bone regeneration. Orthotopic transplantation of sutures with traceable pnPRX1+ cells into wild-type animals shows that pnPRX1+ cells of the suture contribute to calvarial bone defect regeneration. DTA-mediated lineage ablation of pnPRX1+ does not, however, interfere with calvarial development.
Subject(s)
Bone Regeneration , Homeodomain Proteins/metabolism , Skull/cytology , Skull/physiology , Stem Cells/cytology , Aging , Animals , Gene Deletion , Homeodomain Proteins/analysis , Homeodomain Proteins/genetics , Male , Mice, Transgenic , Skull/growth & development , Skull/ultrastructure , Stem Cells/metabolism , Wnt Signaling PathwayABSTRACT
During Xenopus oogenesis, the message transport organizer (METRO) pathway delivers germinal granules and localized RNAs to the vegetal cortex of the oocyte via the mitochondrial cloud (Balbiani body). According to the traditional model, the mitochondrial cloud is thought to break up at the onset of vitellogenesis and the germinal granules and METRO-localized RNAs are transported within the mitochondrial cloud fragments to the vegetal cortex of the oocyte. We used light and electron microscopy in situ hybridization and three-dimensional reconstruction to show that germinal granules and METRO-localized RNAs are delivered to the oocyte cortex before the onset of mitochondrial cloud fragmentation and that the delivery involves accumulation of localized RNAs and aggregation of germinal granules at the vegetal tip of the mitochondrial cloud and subsequent internal expansion of the mitochondrial cloud between its animal (nuclear) and vegetal tips, which drives the germinal granules and METRO-localized RNAs toward the vegetal cortex. Thus the fragmentation of the cloud that occurs later in oogenesis is irrelevant to the movement of METRO-localized RNAs and germinal granules. On the basis of these findings, we propose here a revised model of germinal granule and localized RNAs delivery to the oocyte vegetal cortex via the METRO pathway.