Project description:To study the role of Nox2 in ethanol toxicity on the bone growth plate chondrocytes, we generated Nox2 conditional knockout mice (CKO), in which the catalytic subunit of Nox2, Cybb, is deleted in chondrocytes using a Cre-lox system, where Cre is expressed from the Col2a1 promoter. CKO mice and floxed control mice were fed an ethanol-containing Lieber De-Carli-based diet or pair-fed a control diet for 8 weeks starting at 5-6 weeks of age. As both the Nox2 genotype and ethanol diminished the number of chondrocytes in the growth plates, we conducted an RNA-Seq analysis of the growth-plate containing regions of the femurs.
Project description:Obesity is linked to an increased risk of atrial fibrillation (AF) via increased oxidative stress. While NADPH oxidase II (NOX2), a major source of oxidative stress and reactive oxygen species (ROS) in the heart predisposes to AF, the underlying mechanisms remain unclear. Here, we studied NOX2-mediated ROS production in obesity-mediated AF using Nox2-knock-out (KO) mice and mature human induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCMs). Diet-induced obesity (DIO) mice and hiPSC-aCMs treated with palmitic acid (PA) were infused with a NOX blocker (apocynin) and a NOX2-specific inhibitor, respectively. We showed that NOX2 inhibition normalized atrial action potential duration and abrogated obesity-mediated ion channel remodeling with reduced AF burden. Unbiased transcriptomics analysis revealed that NOX2 mediates atrial remodeling in obesity-mediated AF in DIO mice, PA-treated hiPSC-aCMs, and human atrial tissue from obese individuals by upregulation of paired-like homeodomain transcription factor 2 (PITX2). Furthermore, hiPSC-aCMs treated with hydrogen peroxide, a NOX2 surrogate, displayed increased PITX2 expression, establishing a mechanistic link between increased NOX2-mediated ROS production and modulation of PITX2. Our findings offer insights into possible mechanisms through which obesity triggers AF and support NOX2 inhibition as a potential novel prophylactic or adjunctive therapy for patients with obesity-mediated AF.
Project description:Here we show a multifunctional protein, Hnrnpk, is essential for preventing excessive apoptosis and premature differentiation of growth plate chondrocytes. These datas were the RNA-seq of E18.5 growth plate chondrocytes with or without Hnrnpk.
Project description:The aim of the current study was to identify molecular markers for articular cartilage that can be used for the quality control of tissue engineered cartilage. Therefore a genom-wide expression analysis was performed using RNA isolated from articular and growth plate cartilage, both extracted from the knee joints of minipigs. Keywords: Native material or primary cells isolated from articular cartilage and growth plate cartilage
Project description:Lipids play a crucial role in signalling and metabolism, regulating the development and maintenance of the skeleton. Membrane lipids have been hypothesised to act as intermediates upstream of orphan phosphatase 1 (PHOSPHO1), a major contributor to phosphate generation required for bone mineralisation. Here, we spatially resolve the lipid atlas of the healthy mouse knee and demonstrate the effects of PHOSPHO1 ablation on the growth plate lipidome. Lipids spanning 17 subclasses were mapped across the knee joints of healthy juvenile and adult mice using matrix-assisted laser desorption ionisation imaging mass spectrometry (MALDI-IMS), with annotation supported by shotgun lipidomics. Multivariate analysis identified 96 and 80 lipid ions with differential abundances across joint tissues in juvenile and adult mice respectively. In both ages, marrow was enriched in phospholipid platelet activating factors (PAFs) and related metabolites, cortical bone had a low lipid content, while lysophospholipids were strikingly enriched in the growth plate, an active site of mineralisation and PHOSPHO1 activity. Spatially-resolved profiling of PHOSPHO1-knockout (KO) mice across the resting, proliferating, and hypertrophic growth plate zones revealed 272, 306, and 296 significantly upregulated, and 155, 220 and 190 significantly downregulated features, respectively, relative to wild type (WT) controls. Of note, phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, lysophosphatidylethanolamine and phosphatidylethanolamine derived lipid ions were upregulated in PHOSPHO1-KO versus WT. Our imaging pipeline has established a spatially-resolved lipid signature of joint tissues and has demonstrated that PHOSPHO1 ablation significantly alters the growth plate lipidome, highlighting an essential role of the PHOSPHO1-mediated membrane phospholipid metabolism in lipid and bone homeostasis.
Project description:Bones at different anatomical locations vary dramatically in size. The mechanisms responsible for these size differences are poorly understood. Bone elongation occurs at the growth plates and advances rapidly in early life but then progressively slows due to a developmental program termed growth plate senescence. This developmental program includes declines in cell proliferation and hypertrophy, depletion of cells in all growth plate zones, and extensive underlying changes in the expression of growth-regulating genes. Here we use RNA-Seq to compare changes of gene expression with age in the longer bone (tibia, 1- vs 4-wk) with the difference of gene expression between long and short bones (tibia vs phalanx) at 1wk. We found that the developmental program of growth plate senescence is more advanced in the shorter bone and this differential senescence (or aging) underlies the disparities in bone length.
Project description:The growth plate is histomorphologically classified into four zones {resting zone (RZ), proliferating zone (PZ), maturing zone (MZ) and hypertrophic zone (HZ)}. Gene expression profile analyses of 4 zones were performed using microarrays.
Project description:Growth plate chondrocytes were isolated from the distal metacarpus of young dairy cattle (all under 10 mo of age), the chondrocytes were released from the extracellular matrix by digestion with Collagenase P for 4 hours, and the various zones of the growth plate were separated by density centrifugation. The least-dense Hypertrophic Zone (HZ) cells were compared to the most-dense Reserve Zone (RZ) cells. 6 pairs of HZ vs RZ were compared by microarray.