Project description:The progenitors of Drosophila leg tendon are specified among leg disc epithelium during third larval instar. At the end of larval stages and beiginning of pupae formation, tendon cells invaginate and then collectively migrate to form a tube-shaped structure.
Project description:Although the majority of genomic binding sites for the insulator protein CTCF are constitutively occupied, a subset show variable occupancy. Such variable sites provide an opportunity to assess context-specific CTCF functions in gene regulation. Here we have identified a variably occupied CTCF site in the Ultrabithorax (Ubx) gene in Drosophila. This site is occupied in tissues where Ubx is active (third thoracic imaginal leg disc) but is not bound in tissues where the Ubx gene is repressed (first thoracic imaginal leg disc). Comparison of CTCF binding in T1 leg disc vs T3 leg disc in from 3rd instar larva
Project description:Animal limb development relies on the establishment of organizing centers, which govern limb outgrowth and patterning by regulating the spatial and temporal expression of secreted signaling molecules. On a molecular level the establishment of organizing centers occurs via cis regulatory modules (CRMs), also known as transcriptional enhancers, that integrate upstream temporal and spatial inputs. We elucidated the mechanism that governs the establishment of an Epidermal Growth Factor Receptor (EGFR) organizing center (EOC) during leg development in Drosophila melanogaster. We find that EGFR activation occurs by sequential activation of the EGFR ligand Vein (Vn) and the EGFR ligand-processing protease Rhomboid (Rho), each through single CRMs. These CRMs integrate in a distinct manner inputs from the Wingless (Wg) and Decapentaplegic (Dpp) signaling pathways, and from the leg selector transcription factors Distal-less (Dll) and Sp1. Elimination of the vn (vnE) and rho (rhoE) EOC enhancers eliminates the expression of these genes in the center of the leg imaginal discs, respectively. A vnE rhoE double deficiency, but not single deletions, demonstrates an absolute requirement of these CRMs for specifying the most distal, but not more proximal, leg fates. In addition, the cis-regulatory logic of vnE and rhoE transcends the leg EOC developmental program, because genomic regions with similar inputs, based on predicted and genome-wide binding by the transcription factors that establish the EOC, faithfully predicts novel CRMs active in the distal leg. The combinatorial input of Wg, Dpp, Dll and Sp1 at these CRMs reveals a molecular signature for coordinating gene expression in the Drosophila leg that might be analogous to many other multi-cellular systems.
Project description:to gain a better understanding on the genomic mechanisms involved in defective healing in diabetes, we characterized here the gene expression profile and gene-gene interaction network of cultured fibroblasts derived from chronic diabetic leg ulcers comparatively to fibroblast obtained from control donors. Comparative transcriptomic analysis of cultured fibroblasts derived from six diabetic leg ulcers and five control fibroblasts using DNA microarrays and bioinformatics tools for studying gene-gene interaction networks.
Project description:Although the majority of genomic binding sites for the insulator protein CTCF are constitutively occupied, a subset show variable occupancy. Such variable sites provide an opportunity to assess context-specific CTCF functions in gene regulation. Here we have identified a variably occupied CTCF site in the Ultrabithorax (Ubx) gene in Drosophila. This site is occupied in tissues where Ubx is active (third thoracic imaginal leg disc) but is not bound in tissues where the Ubx gene is repressed (first thoracic imaginal leg disc).
Project description:We report the transcriptomic profiling of tendon and fibrocartilage induction by day, examining both the fate dependent and independent modules
Project description:Regenerative medicine approaches utilizing stem cells offer a promising strategy to address tendinopathy, a class of common tendon disorders associated with pain and impaired function. Tendon progenitor cells (TPCs) are important in healing and maintaining tendon tissues. Here we provide a comprehensive single cell transcriptomic profiling of TPCs from three normal and three clinically classified tendinopathy samples in response to mechanical stimuli. Analysis reveals seven distinct TPC subpopulations including subsets that are responsive to the mechanical stress, highly clonogenic, and specialized in cytokine or growth factor expression. The single cell transcriptomic profiling of TPCs and their subsets serves as a foundation for further investigation into the pathology and molecular hallmarks of tendinopathy in mechanical stimulation conditions.
Project description:Our ability to sense and move our bodies relies on proprioceptors, sensory neurons that detect mechanical forces within the body. Proprioceptors are diverse: different subtypes detect different features of joint kinematics, such as position, directional movement, and vibration. However, because they are located within complex and dynamic peripheral tissues, the underlying mechanisms of proprioceptor feature selectivity remain poorly understood. Here, we investigate molecular and biomechanical contributions to proprioceptor diversity in the Drosophila leg. Using single-nucleus RNA sequencing, we found that different proprioceptor subtypes express similar complements of mechanosensory and other ion channels. However, anatomical reconstruction of the proprioceptive organ and connected tendons revealed major biomechanical differences between proprioceptor subtypes. We constructed a computational model of the proprioceptors and tendons, which identified a putative biomechanical mechanism for joint angle selectivity. The model also predicted the existence of a goniotopic map of joint angle among position-tuned proprioceptors, which we confirmed using calcium imaging. Our findings suggest that biomechanical specialization is a key determinant of proprioceptor feature selectivity in Drosophila. More broadly, our discovery of proprioceptive maps in the fly leg reveals common organizational principles between proprioception and other topographically organized sensory systems.