| 1. |
- Xie, Meng, et al.
(författare)
-
Secondary ossification center induces and protects growth plate structure
- 2020
-
Ingår i: eLIFE. - : ELIFE SCIENCES PUBLICATIONS LTD. - 2050-084X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Growth plate and articular cartilage constitute a single anatomical entity early in development but later separate into two distinct structures by the secondary ossification center (SOC). The reason for such separation remains unknown. We found that evolutionarily SOC appears in animals conquering the land - amniotes. Analysis of the ossification pattern in mammals with specialized extremities (whales, bats, jerboa) revealed that SOC development correlates with the extent of mechanical loads. Mathematical modeling revealed that SOC reduces mechanical stress within the growth plate. Functional experiments revealed the high vulnerability of hypertrophic chondrocytes to mechanical stress and showed that SOC protects these cells from apoptosis caused by extensive loading. Atomic force microscopy showed that hypertrophic chondrocytes are the least mechanically stiff cells within the growth plate. Altogether, these findings suggest that SOC has evolved to protect the hypertrophic chondrocytes from the high mechanical stress encountered in the terrestrial environment.
|
|
| 2. |
- Chen, Yin Huai, et al.
(författare)
-
Absence of GP130 cytokine receptor signaling causes extended Stüve-Wiedemann syndrome
- 2020
-
Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 217:3
-
Tidskriftsartikel (refereegranskat)abstract
- The gene IL6ST encodes GP130, the common signal transducer of the IL-6 cytokine family consisting of 10 cytokines. Previous studies have identified cytokine-selective IL6ST defects that preserve LIF signaling. We describe three unrelated families with at least five affected individuals who presented with lethal Stüve-Wiedemann-like syndrome characterized by skeletal dysplasia and neonatal lung dysfunction with additional features such as congenital thrombocytopenia, eczematoid dermatitis, renal abnormalities, and defective acute-phase response. We identified essential loss-of-function variants in IL6ST (a homozygous nonsense variant and a homozygous intronic splice variant with exon skipping). Functional tests showed absent cellular responses to GP130-dependent cytokines including IL-6, IL-11, IL-27, oncostatin M (OSM), and leukemia inhibitory factor (LIF). Genetic reconstitution of GP130 by lentiviral transduction in patient-derived cells reversed the signaling defect. This study identifies a new genetic syndrome caused by the complete lack of signaling of a whole family of GP130-dependent cytokines in humans and highlights the importance of the LIF signaling pathway in pre- and perinatal development.
|
|
| 3. |
- Kaucka, Marketa, et al.
(författare)
-
Oriented clonal cell dynamics enables accurate growth and shaping of vertebrate cartilage
- 2017
-
Ingår i: eLIFE. - : Elife Sciences Publications LTD. - 2050-084X. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Cartilaginous structures are at the core of embryo growth and shaping before the bone forms. Here we report a novel principle of vertebrate cartilage growth that is based on introducing transversally-oriented clones into pre-existing cartilage. This mechanism of growth uncouples the lateral expansion of curved cartilaginous sheets from the control of cartilage thickness, a process which might be the evolutionary mechanism underlying adaptations of facial shape. In rod-shaped cartilage structures (Meckel, ribs and skeletal elements in developing limbs), the transverse integration of clonal columns determines the well-defined diameter and resulting rod-like morphology. We were able to alter cartilage shape by experimentally manipulating clonal geometries. Using in silico modeling, we discovered that anisotropic proliferation might explain cartilage bending and groove formation at the macro-scale.
|
|
| 4. |
- Mehrbani Azar, Yashar, Dr, et al.
(författare)
-
Recovery from radiation-induced damage to growth plates involves functional compensation
- 2022
-
Ingår i: Bone Reports. - : Elsevier. - 2352-1872. ; 16:Suppl.
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Children receiving radiotherapy during cancer treatment are highly susceptible to side-effects including short stature, irregular body proportions and spinal curvature. One reason radiotherapy impairs bone growth is that radiation directly damages cells that are responsible for bone elongation: growth plate chondrocytes.Purpose: After irradiation, bone growth can continue to a limited extent, but the underlying mechanisms of this recovery process are poorly understood. We aimed to characterize the effects of radiation on the growth plate and reveal the cellular recovery processes.Methods: The left proximal tibia of one month-old mice was irradiated(x-ray) dorso-ventrally. The effects of radiation were characterized by measuring bone lengths and conducting immunofluorescence. Recovery was analyzed using clonal genetic tracing, imaged with confocal microscopy.Results: We first conducted an irradiation-dose-response study up to 15Gy. In our model, a single dose of 10Gy focal irradiation (with biological effective dose of 38.57Gy, equivalent to 12 fractions of 2Gy) was the lowest dose that significantly reduced bone length, fourteen days after irradiation (irradiated tibia were 96.3% the length of the contralateral control, n=5, p= 0.0036). We then used clonal genetic tracing with Col2CreERT:R26R-Confetti mice to visualize the clonal recovery one month after irradiation, and made two inter-connected observations: (i) radiation dose-dependently prevented chondrocytes from further dividing, thus reducing the number of clonal-columns (Fig.1, arrowheads), (ii) some chondrocytes dose-dependently produced an increased number of columns (Fig.1, asterisk); of the clones that did produce columns, individual clones produced a mean of 4.85 columns in the irradiated side versus 2.08 columns in the contralateral control (p<0.0001, unpaired t-test, n= minimum of 17 clones pooled from 4 mice).Conclusion: After radiation-induced damage, some growth plate chondrocytes can functionally compensate for the damaged cells and produce more than twice the expected number of columns.Ethical permission: All experiments were approved by the Swedish board of agriculture.
|
|
| 5. |
- Mirzazadeh, Reza, et al.
(författare)
-
Spatially resolved transcriptomic profiling of degraded and challenging fresh frozen samples
- 2023
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Spatially resolved transcriptomics has enabled precise genome-wide mRNA expression profiling within tissue sections. The performance of methods targeting the polyA tails of mRNA relies on the availability of specimens with high RNA quality. Moreover, the high cost of currently available spatial resolved transcriptomics assays requires a careful sample screening process to increase the chance of obtaining high-quality data. Indeed, the upfront analysis of RNA quality can show considerable variability due to sample handling, storage, and/or intrinsic factors. We present RNA-Rescue Spatial Transcriptomics (RRST), a workflow designed to improve mRNA recovery from fresh frozen specimens with moderate to low RNA quality. First, we provide a benchmark of RRST against the standard Visium spatial gene expression protocol on high RNA quality samples represented by mouse brain and prostate cancer samples. Then, we test the RRST protocol on tissue sections collected from five challenging tissue types, including human lung, colon, small intestine, pediatric brain tumor, and mouse bone/cartilage. In total, we analyze 52 tissue sections and demonstrate that RRST is a versatile, powerful, and reproducible protocol for fresh frozen specimens of different qualities and origins.
|
|
| 6. |
- Vuppalapati, Karuna K, et al.
(författare)
-
Targeted Deletion of Autophagy Genes Atg5 or Atg7 in the Chondrocytes Promotes Caspase-Dependent Cell Death and Leads to Mild Growth Retardation.
- 2015
-
Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - : Wiley. - 1523-4681. ; 30:12, s. 2249-2261
-
Tidskriftsartikel (refereegranskat)abstract
- Longitudinal bone growth takes place in epiphyseal growth plates located in the ends of long bones. The growth plate consists of chondrocytes traversing from the undifferentiated (resting zone) to the terminally differentiated (hypertrophic zone) stage. Autophagy is an intracellular catabolic process of lysosome-dependent recycling of intracellular organelles and protein complexes. Autophagy is activated during nutritionally depleted or hypoxic conditions in order to facilitate cell survival. Chondrocytes in the middle of the growth plate are hypoxic and nutritionally depleted owing to the avascular nature of the growth plate. Accordingly, autophagy may facilitate their survival. To explore the role of autophagy in chondrocyte survival and constitutional bone growth, we generated mice with cartilage-specific ablation of either Atg5 (Atg5cKO) or Atg7 (Atg7cKO) by crossing Atg5 or Atg7 floxed mice with cartilage-specific collagen type 2 promoter-driven Cre. Both Atg5cKO and Atg7cKO mice showed growth retardation associated with enhanced chondrocyte cell death and decreased cell proliferation. Similarly, inhibition of autophagy by Bafilomycin A1 (Baf) or 3-methyladenine (3MA) promoted cell death in cultured slices of human growth plate tissue. To delineate the underlying mechanisms we employed ex vivo cultures of mouse metatarsal bones and RCJ3.IC5.18 rat chondrogenic cell line. Baf or 3MA impaired metatarsal bone growth associated with processing of caspase-3 and massive cell death. Similarly, treatment of RCJ3.IC5.18 chondrogenic cells by Baf also showed massive cell death and caspase-3 cleavage. This was associated with activation of caspase-9 and cytochrome C release. Altogether, our data suggest that autophagy is important for chondrocyte survival, and inhibition of this process leads to stunted growth and caspase-dependent death of chondrocytes. © 2015 American Society for Bone and Mineral Research.
|
|
| 7. |
- Xie, Meng, et al.
(författare)
-
The level of protein in the maternal murine diet modulates the facial appearance of the offspring via mTORC1 signaling.
- 2024
-
Ingår i: Nature communications. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The development of craniofacial skeletal structures is fascinatingly complex and elucidation of the underlying mechanisms will not only provide novel scientific insights, but also help develop more effective clinical approaches to the treatment and/or prevention of the numerous congenital craniofacial malformations. To this end, we performed a genome-wide analysis of RNA transcription from non-coding regulatory elements by CAGE-sequencing of the facial mesenchyme of human embryos and cross-checked the active enhancers thus identified against genes, identified by GWAS for the normal range human facial appearance. Among the identified active cis-enhancers, several belonged to the components of the PI3/AKT/mTORC1/autophagy pathway. To assess the functional role of this pathway, we manipulated it both genetically and pharmacologically in mice and zebrafish. These experiments revealed that mTORC1 signaling modulates craniofacial shaping at the stage of skeletal mesenchymal condensations, with subsequent fine-tuning during clonal intercalation. This ability of mTORC1 pathway to modulate facial shaping, along with its evolutionary conservation and ability to sense external stimuli, in particular dietary amino acids, indicate that the mTORC1 pathway may play a role in facial phenotypic plasticity. Indeed, the level of protein in the diet of pregnant female mice influenced the activity of mTORC1 in fetal craniofacial structures and altered the size of skeletogenic clones, thus exerting an impact on the local geometry and craniofacial shaping. Overall, our findings indicate that the mTORC1 signaling pathway is involved in the effect of environmental conditions on the shaping of craniofacial structures.
|
|
