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Single Bout Short Duration Fluid Shear Stress Induces Osteogenic Differentiation of MC3T3-E1 Cells via Integrin β1 and BMP2 Signaling Cross-Talk  [PDF]
Zhihui Mai, Zhuli Peng, Sihan Wu, Jinglan Zhang, Lin Chen, Huangyou Liang, Ding Bai, Guangmei Yan, Hong Ai
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061600
Abstract: Fluid shear stress plays an important role in bone osteogenic differentiation. It is traditionally believed that pulsed and continuous stress load is more favorable for fracture recovery and bone homeostasis. However, according to our clinical practice, we notice that one single stress load is also sufficient to trigger osteogenic differentiation. In the present study, we subject osteoblast MC3T3-E1 cells to single bout short duration fluid shear stress by using a parallel plate flow system. The results show that 1 hour of fluid shear stress at 12 dyn/cm2 promotes terminal osteogenic differentiation, including rearrangement of F-actin stress fiber, up-regulation of osteogenic genes expression, elevation of alkaline phosphatase activity, secretion of type I collagen and osteoid nodule formation. Moreover, collaboration of BMP2 and integrin β1 pathways plays a significant role in such differentiation processes. Our findings provide further experimental evidence to support the notion that single bout short duration fluid shear stress can promote osteogenic differentiation.
Forms, Crosstalks, and the Role of Phospholipid Biosynthesis in Autophagy  [PDF]
Leanne Pereira,John Paul Girardi,Marica Bakovic
International Journal of Cell Biology , 2012, DOI: 10.1155/2012/931956
Abstract: Autophagy is a highly conserved cellular process occurring during periods of stress to ensure a cell's survival by recycling cytosolic constituents and making products that can be used in energy generation and other essential processes. Three major forms of autophagy exist according to the specific mechanism through which cytoplasmic material is transported to a lysosome. Chaperone-mediated autophagy is a highly selective form of autophagy that delivers specific proteins for lysosomal degradation. Microautophagy is a less selective form of autophagy that occurs through lysosomal membrane invaginations, forming tubes and directly engulfing cytoplasm. Finally, macroautophagy involves formation of new membrane bilayers (autophagosomes) that engulf cytosolic material and deliver it to lysosomes. This review provides new insights on the crosstalks between different forms of autophagy and the significance of bilayer-forming phospholipid synthesis in autophagosomal membrane formation. 1. Introduction Eukaryotic cells have evolved numerous pathways to improve survival in harsh environments. One such pathway, known as autophagy, specializes in the breakdown of cell components through specific and nonspecific delivering to the lysosome. The products of lysosomal degradation can then be used for the biosynthesis of new proteins and organelles and as an energy source [1]. To date, three forms of autophagy have been identified and characterized. This review will discuss key findings in autophagy research as well as provide new insights on the role of membrane lipids in autophagosome formation. Three major forms of autophagy have been identified in cells: chaperone-mediated autophagy (CMA), microautophagy (MiA), and macroautophagy (MaA). CMA is a selective protein delivering system which uses specific heat shock protein complexes (HSPC) to deliver proteins to the lysosome for degradation [2]. CMA is unique in that it specializes in the sequestration and degradation of a single-protein substrate, whereas both MiA and MaA specialize in bulk sequestration and degradation of cytosolic components. MiA is characterized by the engulfment of cytoplasm (including proteins and organelles) by membrane invagination of lysosome and/or endosome in mammals, or vacuole in yeast [3]. Finally, MaA is distinguished by the formation of a specialized double-membrane vesicle termed the autophagosome, which forms around the material to be digested (organelles/proteins). Once the autophagosome is formed, it fuses with a lysosome forming an autolysosome [4]. Though similar in their means of
Epigenetic switch for Igf2
Cathy Holding
Genome Biology , 2004, DOI: 10.1186/gb-spotlight-20040728-01
Abstract: Wolf Reik's group in the Laboratory of Developmental Genetics and Imprinting at the Babraham Institute, Cambridge, UK, felt "under pressure" to test and prove their prediction of a year ago that the differentially methylated regions (DMRs) in Igf2 and H19 come into physical contact and interact to allow the intervening DNA to loop out, Reik told us.The authors tested the prediction with two different strategies. In the first, Reik's team used yeast Gal4 insertion technology to show that in maternal chromosomes, Gal4 links up with the H19 DMR and the DMR1 of Igf2, while on the paternal chromosome it links up with the H19 DMR and the DMR2 of Igf2. Secondly, chromosome capture conformation confirmed the identity of sequences held in close physical contact in the crosslinked loops.But their interpretation of the data is not necessarily correct, according to Rolf Ohlsson at the Evolutionary Biology Centre at Uppsala University, Sweden. He commented that although Reik involves this higher-order chromatin conformation in his model, "we don't know - it could very well be that the H19 DMR interacting with [Igf2] DMR1 is implementing two other tasks: one is to delay replication timing and the other is to maintain methylation-free DMR1." The model looks fine on paper, but in three dimensions could be more problematic, Ohlsson said.Michael P. Kladde, from the faculty of genetics at Texas A&M University, agreed. "For the maternal allele, it says to me that if everything can loop, what's to keep the H19 enhancer from looping back and hitting the Igf2 promoter?" But Kladde told us he thought there might be a suggestion that the chromatin is packaged up into a very tight loop so that even if the H19 enhancer does contact the Igf2 promoter, it would not be able to load the transcription machinery and fire it.As another group trying to determine how the H19 gene is repressed and silenced on the paternal allele, the authors of an accompanying paper show that the two parental-specific
Low-Intensity Pulsed Ultrasound Stimulation Facilitates Osteogenic Differentiation of Human Periodontal Ligament Cells  [PDF]
Bo Hu, Yuanyuan Zhang, Jie Zhou, Jing Li, Feng Deng, Zhibiao Wang, Jinlin Song
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095168
Abstract: Human periodontal ligament cells (hPDLCs) possess stem cell properties, which play a key role in periodontal regeneration. Physical stimulation at appropriate intensities such as low-intensity pulsed ultrasound (LIPUS) enhances cell proliferation and osteogenic differentiation of mesechymal stem cells. However, the impacts of LIPUS on osteogenic differentiation of hPDLCs in vitro and its molecular mechanism are unknown. This study was undertaken to investigate the effects of LIPUS on osteogenic differentiation of hPDLCs. HPDLCs were isolated from premolars of adolescents for orthodontic reasons, and exposed to LIPUS at different intensities to determine an optimal LIPUS treatment dosage. Dynamic changes of alkaline phosphatase (ALP) activities in the cultured cells and supernatants, and osteocalcin production in the supernatants after treatment were analyzed. Runx2 and integrin β1 mRNA levels were assessed by reverse transcription polymerase chain reaction analysis after LIPUS stimulation. Blocking antibody against integrinβ1 was used to assess the effects of integrinβ1 inhibitor on LIPUS-induced ALP activity, osteocalcin production as well as calcium deposition. Our data showed that LIPUS at the intensity of 90 mW/cm2 with 20 min/day was more effective. The ALP activities in lysates and supernatants of LIPUS-treated cells started to increase at days 3 and 7, respectively, and peaked at day 11. LIPUS treatment significantly augmented the production of osteocalcin after day 5. LIPUS caused a significant increase in the mRNA expression of Runx2 and integrin β1, while a significant decline when the integrinβ1 inhibitor was used. Moreover, ALP activity, osteocalcin production as well as calcium nodules of cells treated with both daily LIPUS stimulation and integrinβ1 antibody were less than those in the LIPUS-treated group. In conclusion, LIPUS promotes osteogenic differentiation of hPDLCs, which is associated with upregulation of Runx2 and integrin β1, which may thus provide therapeutic benefits in periodontal tissue regeneration.
Osteogenic Sarcoma of Lower Jaw.  [PDF]
Des Raj Bhagat, Anayat Lone, Subash Bhardwaj, Aniece Choudhary.
JK Science : Journal of Medical Education & Research , 2004,
Abstract: A rare case of osteogenic sarcoma affecting the lower jaw is presented. Osteogenic sarcoma ofthe jaw is a very rare tumor of the head and neck comprising less than 0.5% of all malignanttumors of head and neck. Pertinent literature is reviewed to emphasize the various treatmentmodalities and histopathological features for diagnosis of this rare tumour.
IGF2 expression in blood is not associated with its imprinting status in healthy pregnant Chinese women
Gao Ru-Fei,Liu Xue-Qing,Wang Ying-Xiong,Chen Xue-Mei
Biological Research , 2012,
Abstract: Loss of Imprinting (LOI) of IGF2 and over-expressed IGF2 are associated with tumorigenesis. Our previous epidemiological study found a relatively high frequency of IGF2 LOI in healthy mid-gestation pregnant women. The aim of this study is to determine whether the expression of IGF2 is associated with its imprinting status in healthy Chinese pregnant women. The IGF2 imprinting status of 300 pregnant women was analyzed. 20 cases of IGF2 LOI and 20 cases of IGF2 retention of imprinting (ROI) were selected randomly for IGF2 expression analysis. The expression pattern of IGF2 between the group with IGF2 ROI and group with IGF2 LOI in healthy Chinese pregnant women was evaluated by real time PCR and western blot. The result showed no significant differences between IGF2 ROI and LOI groups in mRNA and protein levels. These results imply that IGF2 imprinting status has no obvious impact on its expression. There may be some unknown important factors other than imprinting status driving IGF2 expression.
Controlling Osteogenic Stem Cell Differentiation via Soft Bioinspired Hydrogels  [PDF]
Amit K. Jha, Wesley M. Jackson, Kevin E. Healy
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098640
Abstract: Osteogenic differentiation of human mesenchymal stem cells (hMSCs) is guided by various physical and biochemical factors. Among these factors, modulus (i.e., rigidiy) of the ECM has gained significant attention as a physical osteoinductive signal that can contribute to endochondral ossification of a cartilaginous skeletal template. However, MSCs also participate in intramembranous bone formation, which occurs de novo from within or on a more compliant tissue environment. To further understand the role of the matrix interactions in this process, we evaluated osteogenic differentiation of hMSCs cultured on low moduli (102, 390 or 970 Pa) poly(N-isopropylacrylamide) (p(NIPAAm)) based semi-interpenetrating networks (sIPN) modified with the integrin engaging peptide bsp-RGD(15) (0, 105 or 210 μM). Cell adhesion, proliferation, and osteogenic differentiation of hMSCs, as measured by alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), bone sialoprotein-2 (iBSP), and osteocalcien (OCN) protein expression, was highest on substrates with the highest modulus and peptide concentrations. However, within this range of substrate stiffness, many osteogenic cellular functions were enhanced by increasing either the modulus or the peptide density. These findings suggest that within a compliant and low modulus substrate, a high affinity adhesive ligand serves as a substitute for a rigid matrix to foster osteogenic differentiation.
Primary osteogenic sarcoma of the breast
Temidayo O Ogundiran, Samuel A Ademola, Odunayo M Oluwatosin, Effiong E Akang, Clement A Adebamowo
World Journal of Surgical Oncology , 2006, DOI: 10.1186/1477-7819-4-90
Abstract: A 40 year-old Nigerian woman was clinically diagnosed to have carcinoma of the left breast. The histology report of core-needle biopsy of the mass showed a malignant neoplasm comprising islands of chondroblastic and osteoblastic stromal cells. This report changed the diagnosis from carcinoma to osteogenic sarcoma of the breast. She had a left modified radical mastectomy, however there was significant post surgery skin deficit. A latissimus dorsi musculocutaneous flap was used to cover the anterior chest wall defect. Sections from the mastectomy specimen confirmed the diagnosis of osteogenic sarcoma. She died six months after mastectomy.A diagnosis of osteogenic sarcoma of the breast was made based on histology report and after excluding an osteogenic sarcoma arising from underlying ribs and sternum. This is the second documented case of primary osteogenic sarcoma of the breast coming from NigeriaBreast cancer is the commonest cancer that afflicts females worldwide. In Cancer Statistics 2005, breast cancer remains the leading cancer among American women with an estimate of 32% excluding skin cancers [1]. Of all the cancers of the breast, carcinoma forms the bulk while breast sarcomas are negligible [2,3]. Extra-skeletal osteosarcoma has been documented in many tissues of the body including the thyroid gland, kidney, bladder, colon, heart, testis, penis, gall bladder and the cerebellum [4-10]. When it occurs in the breast, it originates either from normal breast tissue de novo, or as metaplastic differentiation of a primary benign or malignant breast lesion. Osteogenic sarcomas of the breast either arising primarily in the breast or as secondary deposits from primary bone sarcomas occur in very rare cases.Almost every previous reference to this entity in literature is in form of single case reports. In almost all cases, the patients had been diagnosed clinically as having breast carcinoma and the correct tissue diagnosis was established by histology [11,12]. The large
Adhesion to Vitronectin and Collagen I Promotes Osteogenic Differentiation of Human Mesenchymal Stem Cells
Roman M. Salasznyk,William A. Williams,Adele Boskey,Anna Batorsky,George E. Plopper
Journal of Biomedicine and Biotechnology , 2004, DOI: 10.1155/s1110724304306017
Abstract: The mechanisms controlling human mesenchymal stem cells (hMSC) differentiation are not entirely understood. We hypothesized that the contact with extracellular matrix (ECM) proteins normally found in bone marrow would promote osteogenic differentiation of hMSC in vitro. To test this hypothesis, we cultured hMSC on purified ECM proteins in the presence or absence of soluble osteogenic supplements, and assayed for the presence of well-established differentiation markers (production of mineralized matrix, osteopontin, osteocalcin, collagen I, and alkaline phosphatase expression) over a 16-day time course. We found that hMSC adhere to ECM proteins with varying affinity (fibronectin > collagen I ≥ collagen IV ≥ vitronectin > laminin-1) and through distinct integrin receptors. Importantly, the greatest osteogenic differentiation occurred in cells plated on vitronectin and collagen I and almost no differentiation took place on fibronectin or uncoated plates. We conclude that the contact with vitronectin and collagen I promotes the osteogenic differentiation of hMSC, and that ECM contact alone may be sufficient to induce differentiation in these cells.
Adhesion to Vitronectin and Collagen I Promotes Osteogenic Differentiation of Human Mesenchymal Stem Cells  [cached]
Salasznyk Roman M.,Williams William A.,Boskey Adele,Batorsky Anna
Journal of Biomedicine and Biotechnology , 2004,
Abstract: The mechanisms controlling human mesenchymal stem cells (hMSC) differentiation are not entirely understood. We hypothesized that the contact with extracellular matrix (ECM) proteins normally found in bone marrow would promote osteogenic differentiation of hMSC in vitro. To test this hypothesis, we cultured hMSC on purified ECM proteins in the presence or absence of soluble osteogenic supplements, and assayed for the presence of well-established differentiation markers (production of mineralized matrix, osteopontin, osteocalcin, collagen I, and alkaline phosphatase expression) over a 16-day time course. We found that hMSC adhere to ECM proteins with varying affinity (fibronectin > collagen I ≥ collagen IV ≥ vitronectin > laminin-1) and through distinct integrin receptors. Importantly, the greatest osteogenic differentiation occurred in cells plated on vitronectin and collagen I and almost no differentiation took place on fibronectin or uncoated plates. We conclude that the contact with vitronectin and collagen I promotes the osteogenic differentiation of hMSC, and that ECM contact alone may be sufficient to induce differentiation in these cells.
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