• Studies of human embryonic stem cells (hESCs) commonly describe the nonfunctional p53-p21 axis of the G1/S checkpoint pathway with subsequent relevance for cell cycle regulation and the DNA damage response (DDR). (wikipedia.org)
  • However, the mechanisms by which Akt signaling regulates stem cell behavior in the complexity of the whole body are poorly understood. (biomedcentral.com)
  • Planarians are flatworms with large populations of stem cells capable of dividing to support adult tissue renewal and regeneration. (biomedcentral.com)
  • Our findings abrogating Smed-Akt with RNA-interference in the planarian Schmidtea mediterranea led to a gradual decrease in stem cell (neoblasts) numbers. (biomedcentral.com)
  • Nonetheless, there is limited understanding of how Akt signaling controls the response of stem cells during cellular turnover and tissue injury in the complexity of the whole organism. (biomedcentral.com)
  • This paucity is likely due to the ubiquitous nature of this signaling pathway and the difficulty of analyzing stem cells in their natural environment during physiological cell turnover and regeneration in conventional animal models [ 15 - 17 ]. (biomedcentral.com)
  • This organism is well known for its stem cell-based regenerative capability. (biomedcentral.com)
  • Planarians contain an abundant and accessible population of somatic adult stem cells called neoblasts [ 18 - 21 ]. (biomedcentral.com)
  • Unidirectional regeneration in the basal chordate Ciona intestinalis involves the proliferation of adult stem cells residing in the branchial sac vasculature and the migration of progenitor cells to the site of distal injury. (biomedcentral.com)
  • However, after the Ciona body is bisected, regeneration occurs in the proximal but not in the distal fragments, even if the latter include a part of the branchial sac with stem cells. (biomedcentral.com)
  • The upregulation of HSP70 chaperone genes was verified and their expression confirmed in BS vasculature cells previously identified as stem and progenitor cells. (biomedcentral.com)
  • This study demonstrates the importance of a stress response for stem cell activation and regeneration in a basal chordate, which may have implications for understanding the limited regenerative activities in other animals, including vertebrates. (biomedcentral.com)
  • After amputation, granular hemocytes infiltrate the blastema of regenerating cephalic tentacles of the freshwater snail Pomacea canaliculata. (unimore.it)
  • Histological studies focusing on the early cephalic tentacle regeneration in P. canaliculata, have demonstrated that wound closure and blastema formation took place within 24 h post amputation (hpa). (unimore.it)
  • However, in response to amputation, levels of cell death were decreased and failed to localize near the injury site. (biomedcentral.com)
  • Interestingly, the neoblast mitotic response was increased around the amputation area but the regenerative blastema failed to form. (biomedcentral.com)
  • Advances in tissue engineering technology have led to the production of novel human skin equivalents and organoids that reproduce cell-cell interactions with tissue-scale tensional homeostasis, and enable us to evaluate skin tissue morphology, functionality, drug response and wound healing. (mdpi.com)
  • The protein kinase Akt also known as PKB, regulates multiple cellular functions including proliferation, survival, and growth during embryonic development and adult tissue homeostasis [ 1 - 5 ]. (biomedcentral.com)
  • p53 plays a role in regulation or progression through the cell cycle, apoptosis, and genomic stability by means of several mechanisms: It can activate DNA repair proteins when DNA has sustained damage. (wikipedia.org)
  • In this cell type, p53 activates numerous microRNAs (like miR-302a, miR-302b, miR-302c, and miR-302d) that directly inhibit the p21 expression in hESCs. (wikipedia.org)
  • p53, also known as Tumor protein P53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. (wikipedia.org)
  • In mammals, Akt is ubiquitously expressed and is associated with regulation of cellular proliferation, metabolism, cell growth and cell death. (biomedcentral.com)
  • The neoblasts are the only dividing cells in planarians and constantly proliferate to repair tissues and support systemic cellular turnover [ 21 ]. (biomedcentral.com)
  • Functional disruption of Smed-Akt alters the balance between cell proliferation and cell death leading to systemic impairment of adult tissue renewal. (biomedcentral.com)
  • This study defined the role of Smed-Akt in abnormal cell proliferation triggered by the abrogation of the phosphatase PTEN, an upstream component of the Akt signaling pathway, which is highly mutated in human cancers. (biomedcentral.com)
  • A mutant p53 will no longer bind DNA in an effective way, and, as a consequence, the p21 protein will not be available to act as the "stop signal" for cell division. (wikipedia.org)
  • The p21 protein binds directly to cyclin-CDK complexes that drive forward the cell cycle and inhibits their kinase activity, thereby causing cell cycle arrest to allow repair to take place. (wikipedia.org)
  • It can arrest growth by holding the cell cycle at the G1/S regulation point on DNA damage recognition-if it holds the cell here for long enough, the DNA repair proteins will have time to fix the damage and the cell will be allowed to continue the cell cycle. (wikipedia.org)
  • However, experiments demonstrate that even at this early stage, cells are already polarized in some sense and carry positional information. (medscape.com)
  • Therefore, we propose that damage to and subsequent release of mtDNA elicits a protective signalling response that enhances nDNA repair in cells and tissues, suggesting that mtDNA is a genotoxic stress sentinel. (regenerativemedicine.net)
  • During the fifth week, differentiating mesenchymal cells condense in a proximal-to-distal fashion to form blastemas, which eventually develop into cartilaginous models of, ultimately, the bones of the upper extremity. (medscape.com)
  • Mesenchymal cells derived from the dermomyotome condense within connective tissue (mesenchymal) scaffolds to form 2 common muscle masses. (medscape.com)
  • When p21(WAF1) is complexed with CDK2, the cell cannot continue to the next stage of cell division. (wikipedia.org)
  • Recently, we described that the genome of S. mediterranea contains a single Akt ortholog termed Smed-Akt , which affects cell division and impairs planarian locomotion [ 22 ]. (biomedcentral.com)
  • After the injection of clodronate liposomes, a specific computer-assisted image analysis protocol still evidenced the presence of granular hemocytes in the tentacle blastema. (unimore.it)
  • 2] It is 2-5 cells thick and covers a layer of undifferentiated, proliferating mesenchymal cells 5-15 cells thick. (medscape.com)
  • During the fifth week, differentiating mesenchymal cells condense in a proximal-to-distal fashion to form blastemas, which eventually develop into cartilaginous models of, ultimately, the bones of the upper extremity. (medscape.com)
  • Mesenchymal cells derived from the dermomyotome condense within connective tissue (mesenchymal) scaffolds to form 2 common muscle masses. (medscape.com)
  • Lim-1 is required for the aggregation of the mesenchymal cells of the intermediate mesoderm into the primary nephric ducts. (clinicalgate.com)
  • This marks the transformation of the induced mesenchymal cells into an epithelium-the specialized podocytes , which ultimately surround the vascular endothelium of the glomerulus. (clinicalgate.com)
  • Hence TP53 is classified as a tumor suppressor gene. (wikipedia.org)
  • P21 expression is tightly controlled by the tumor suppressor p53, another regulator of cell division and a known factor in many forms of cancer. (eurekalert.org)
  • Unlike typical mammals, which heal wounds by forming a scar, these mice begin by forming a blastema, a structure associated with rapid cell growth and de-differentiation as seen in amphibians. (eurekalert.org)
  • Results showed that RM cells (RMCs) DNA methylation levels were significantly lower than those of CA, suggesting that DNA demethylation may be involved in antler fast cartilage differentiation. (bvsalud.org)
  • ASCs possess the same biological features as MSCs, including the capacity for self-renewal and multidirectional differentiation, immunomodulatory functions, and the maintenance of stem cell characteristics after multiple passages. (bvsalud.org)
  • The aim was to determine (1) MMPs' action in antler stem cells (ASCs) before and after differentiation into adipo-, osteo-, and chondrocytes and (2) the effect of RA on modifying MMP action in ASCs. (bvsalud.org)
  • The down regulation of p21 promotes the induced pluripotent state in mammalian cells, highlighting a correlation between stem cells, tissue regeneration, and the cell cycle. (eurekalert.org)
  • Antlers are the only fully regenerable mammalian appendages whose annual renewal is initiated by antler stem cells (ASCs), defined as a specialized type of mesenchymal stem cells (MSCs) with embryonic stem cell properties. (bvsalud.org)
  • Studies of human embryonic stem cells (hESCs) commonly describe the nonfunctional p53-p21 axis of the G1/S checkpoint pathway with subsequent relevance for cell cycle regulation and the DNA damage response (DDR). (wikipedia.org)
  • While it is commonly accepted as an aging-related phenomenon, senescence might happen also during the embryonic development with the biological meaning of replacing transient structures or specific cell types with other ones [ 3 - 5 ]. (hindawi.com)
  • Senescence in adult tissues can be classified in two main subcategories, based on the underlying molecular mechanism: replicative (or intrinsic), caused by telomere shortening, and stress-induced, in response to reactive oxygen species (ROS) and/or oncogenes [ 7 - 9 ]. (hindawi.com)
  • According to the Wistar researchers, the loss of p21 causes the cells of these mice to behave more like embryonic stem cells than adult mammalian cells, and their findings provide solid evidence to link tissue regeneration to the control of cell division. (eurekalert.org)
  • Pathologies, as atherosclerosis, cardiac fibrosis, and cardiomyopathy, are often linked to the failure of cardiovascular tissue cells to reenter the cell cycle, namely, senescence, due to endogenous or exogenous causes. (hindawi.com)
  • As demonstrated by the growing body of literature in the latest years, senescence is an important function involved in the maintenance of tissue homeostasis, as well as the more extensively studied apoptosis. (hindawi.com)
  • Hippo signalling integrates diverse stimuli related to epithelial architecture to regulate tissue growth and cell fate decisions. (sdbonline.org)
  • This review will focus on the cardiovascular pathologies correlated to senescence, the effect of aging on the cardiac endogenous resources of stem cells, and the potential strategies of regenerative medicine to be applied to maintain the heart younger and healthier. (hindawi.com)
  • Medical applications based on ASCs and ASC-derived molecules provide a new source of stem cells and therapeutic modalities for regenerative medicine. (bvsalud.org)
  • The p21 protein binds directly to cyclin-CDK complexes that drive forward the cell cycle and inhibits their kinase activity, thereby causing cell cycle arrest to allow repair to take place. (wikipedia.org)
  • Furthermore, Activated cdc42 kinase interacts with Expanded and induces tyrosine phosphorylation of Expanded on multiple sites. (sdbonline.org)
  • Microvesicles loaded with MCs encoding a thymidine kinase (TK)/nitroreductase (NTR) fusion protein produced prolonged TK-NTR expression in mammary carcinoma cells. (regenerativemedicine.net)
  • During embryonic development and postembryonic life of multicellular organisms, the proportions of overall body and organ size are actively controlled, being increased or decreased in a species-specific manner. (biologists.com)
  • In vivo delivery of TK-NTR and administration of prodrugs led to the effective killing of both targeted cells and surrounding tumor cells via TK-NTR-mediated conversion of co-delivered prodrugs into active cytotoxic agents. (regenerativemedicine.net)
  • In vivo evaluation of the bystander effect in mouse models demonstrated that for effective therapy, at least 1% of tumor cells need to be delivered with TK-NTR-encoding MCs. (regenerativemedicine.net)
  • Metalloproteinases (MMP)s regulate developmental processes, control angiogenesis and wound healing, participate in the formation of immune receptors, and are expressed in stem cells. (bvsalud.org)
  • Khamilia Bedebaeva, M.D., Ph.D., having studied genetic effects following the Chernobyl reactor radiation accident, noticed immediately that these cells were atypical, showing profound differences in cell cycle characteristics and DNA damage. (eurekalert.org)
  • Another 2011 study found that the p53 homozygous (Pro/Pro) genotype was associated with a significantly increased risk for renal cell carcinoma. (wikipedia.org)
  • We demonstrated that MCs can be loaded into shed microvesicles with greater efficiency than their parental plasmid counterparts and that microvesicle-mediated MC delivery led to significantly higher and more prolonged transgene expression in recipient cells than microvesicles loaded with the parental plasmid. (regenerativemedicine.net)
  • Bone morphogenetic protein ( BMP ) signaling in the surrounding mesoderm is also inhibitory to outgrowth of the ureteric bud, but within the metanephrogenic blastema its action is counteracted by the BMP-inhibitory actions of gremlin , which is produced within the blastema itself. (clinicalgate.com)
  • The end of the eighth week marks the end of the embryonic period and the beginning of the fetal period. (medscape.com)
  • p21 (WAF1) binds to the G1-S/CDK (CDK4/CDK6, CDK2, and CDK1) complexes (molecules important for the G1/S transition in the cell cycle) inhibiting their activity. (wikipedia.org)
  • Ptp61F also regulates cell contractility and myosin activation and controls 3D cell shape by reducing cell height and horizontal cell size. (sdbonline.org)
  • We previously demonstrated that microvesicles can functionally deliver plasmid DNA to cells and showed that plasmid size and sequence, in part, determine the delivery efficiency. (regenerativemedicine.net)
  • Snyder found that p21, a cell cycle regulator, was consistently inactive in cells from the MRL mouse ear. (eurekalert.org)
  • In this cell type, p53 activates numerous microRNAs (like miR-302a, miR-302b, miR-302c, and miR-302d) that directly inhibit the p21 expression in hESCs. (wikipedia.org)
  • Additionally, we dissect the effects of aging on the cardiac endogenous and exogenous reservoirs of stem cells. (hindawi.com)
  • Estrogen and progesterone interactive effects in postconfluent MCF-7 cell culture. (edu.au)
  • Pathologically, Ptp61F loss synergizes with Ras(V12) to induce tumorigenesis . (sdbonline.org)