1 / 21

Stem cell types , their maintenance and homeostasis

Manifestation of Novel Social Challenges of the European Union in the Teaching Material of Medical Biotechnology Master’s P rogrammes at the University of Pécs and at the University of Debrecen Identification number : TÁMOP-4.1.2-08/1/A-2009-0011.

lynna
Download Presentation

Stem cell types , their maintenance and homeostasis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Manifestation of Novel Social Challenges of the European Unionin the Teaching Material ofMedical Biotechnology Master’s Programmesat theUniversity of Pécs and at the University of Debrecen Identificationnumber: TÁMOP-4.1.2-08/1/A-2009-0011

  2. Manifestation of Novel Social Challenges of the European Unionin the Teaching Material ofMedical Biotechnology Master’s Programmesat theUniversity of Pécs and at the University of Debrecen Identification number: TÁMOP-4.1.2-08/1/A-2009-0011 Dr. PéterBalogh and Dr. Péter Engelmann Transdifferentiation and regenerative medicine – Lecture 2 Stemcelltypes, theirmaintenance and homeostasis

  3. Sources and types of stem cells: different origins and developmental spectra • ES: • Embryonic stem cells from theICM (inner cell mass) • Primordial Germ Cells (PGCs) →Embryonic Germ (EG) cells • iPS:non-embryonic somatic cells developed by the introduction of specific key transcription factors: Oct4, Sox2, c-myc, Klf4 • MSC: mesenchymal stem cells present in bone marrow, adipose tissue, umbilical cord blood, amniotic fluid, placenta, dental pulp, tendons, synovial membrane and skeletal muscle, capable of self-renewal and differentiation in vitro into a variety of cells of the mesenchymal lineages such asosteoblasts,chondrocytes, adipocytes and myoblasts

  4. Sources of embryonicstemcells(ESCs) Morula Early blastocyst Late blastocyst Eggcylinderstage Oct3/4 Nanog Innercellmass (ICM) Primitive ectoderm Epiblast Germcelllineage Somatic cell lineages Ectoderm Mesoderm Endoderm Blastocystcavity Visceral endoderm Proamniotic cavity Primitive endoderm Parietal endoderm Gata6 Trophectoderm Extraembryonic ectoderm Cdx2

  5. Stem cell sources in the mouse embryo • Preimplantation embryo: inner cell mass (ICM) of the blastocyst (early blastocyst stage). • Late blastocyst stage: formation of epiblast • Postimplantation embryo: formation of primitiveectoderm with restricted pluripotency→ the germ cell lineage and somatic lineages of the embryo.

  6. Characteristics of ES cells • Derivation from the preimplantation or periimplantation embryo • Prolonged undifferentiated proliferation, • Stable developmental potential to form derivatives of all three embryonic germ layers even after prolonged culture • EC cells: teratocarcinoma-derived pluripotentembryonal carcinoma cells generating cells of all three germ layers Cartilage (mesodermal) Epidermis (ectodermal) Intestinalglands (endodermal)

  7. Cell membrane markers for ESCs PSA-NCAM Glc Gal Lewis X Man CD34 Tra 1-60 (KSPG) GlcNAc NG2 and 473HD (CSPG) GalNAc SSEA-4 GlcA SSEA-3 IdoA Xyl Fuc Sia

  8. Structure of glycoantigenscharacteristicfor ES cells • SSEA-3 and SSEA-4: 5–6 monosaccharidesattachedto a ceramidelipidtail, formingthegloboseriesglycosphingolipids GL-5 and GL-7, theirexpression is reducedupondifferentiation. • The TRA (tumor rejectionantigens) TRA-1–60 and TRA-1–81keratansulfatedproteoglycan (KSPG) epitopes , probablyassociatedwithpodocalyxin, a heavilysialylatedmembrane protein structurallysimilarto CD34.

  9. Characteristics of CD-defined antigens for ES cells • CD34:HSC/endothelial shared antigen expressed hemopoietic stem cells/progenitors • CD133:Five transmembrane domain cell-surface glycoprotein, expressed by neural stem cells

  10. Main regulatory mechanisms of stem cells – external and internal effects • External • Interactions with the matrix proteins, soluble factors and othercell types in stem cell niches, direct interactions with ECM proteins, complex signaling feedback from adjacent ESC niche cells (stromal/differentiated). • Internal • TF network regulating pluripotency or differentiation

  11. Stemcellnichesinvariousorgans Germarium of theovary The apex of thetestis The subventricularzone(SVZ) of thebrain Innersheath cell BL SSC Neuroblast Spermatogonia BV BL Capcell Astrocyte SSC GSC BL Terminal filament Hubcells Egg chamber Transit- amplifying Meiosis Gonialblast GSC Cystoblast Cystcell Spermatocytes Ependymal cells Follicle cells 16-cell cyst Lateralventricle The bonemarrow The crypt of an intestinalvillus The bulge of thehairfollicle Hairshaft Enteroendocrinecells Stromalcell Villus Muscle BL Gobletcells Multipotent SC Bonemarrow Sebaceous gland HSC BL Bulge SC Myeloid Lymphoid Crypt Transitamplifying Stemcells Osteoblast Matrix Hair bulb Dermal papilla Panethcells

  12. Stem cell environment – examples for stem cell niche • Germanium region of the ovary and the apex of the testis (germ-line stem cell and somatic stem cell) • Subventricular zone in the brain (neural stem cell) • Bulge of hair follicle (epithelial stem cell) • Crypt of intestinal villi (endodermal stem cell) • Bone marrow (hemopoietic stem cell)

  13. Multiple interactions involved in stem cell homeostasis Nanog Oct4 Tcf3 Oct4 Nanog Tbx3 Tcf3 Tle1 Fzd5 Jarid2 Phc1 N-myc Dppa5 Rif1 Trp53bp1 RNA binding protein Telomere associated Tumor suppressor ESC regulators Wntsignaling Epigenetic regulators Sox2 Nanog Sall4 LRH1 Oct4 GCNF Tcf3 Oct4 Oct4 Pluripotency Differentation

  14. Antagonistic regulatory circuits between differentiation and pluripotency • ESC/iPS regulation – hierarchic transcription factors • Wnt signaling • Epigenetic regulators • RNA binding • Telomere associated effectors • Tumor suppression • Cell cycle regulation

  15. mRNA regulation of stem cell gene expression Sox2 Oct4 Nanog Other factors mRNAs miRNAs AAAAA AAAAA AAAAA AAAAA Alternatively spliced mRNAs Antisense transcripts AAAAA AAAAA Other RNAs? siRNAs? Intergenic transcripts Intergenic spliced mRNAs

  16. TF regulation forself-renewal/differentiation • Oct3/4, Nanog, Sox2, Stat3: maintenance of proliferation • Cdx2: Inhibitory cross-interaction with Oct3/4

  17. Reprogramming: Induction of pluripotency in iPS cells Oct3/4 Klf4 Sox2 Transcription factors Target genes c-Myc Epigenetic modifiers

  18. Reprogramming: Lineage shift in differentiated cells • Reprogramming of B-cell lineage into macrophages – role of C/EBPa • Induction of neuronal commitment from fibroblasts – Ascl1, Brn2 and Mytl1

  19. Sequential maturation and regeneration of pluripotency Ectoderm progenitor Pluripotent cell Neuronal progenitor Pluripotent cell Mature neuron Endoderm Mesoderm Ectoderm Pluripotent cell

  20. Differentiation-associated commitment and reversibility • Differentiationis coupled with • commitment and loss of pluripotency/transdifferentiation capacity BETWEEN lineages • Requirement for continuous stimulation for promoting specification WITHIN a lineage. • Reversal: Introduction of iPS-associated multilineage differentiation is associated with LOWERING of pleiotropic induction requirement and ELEVATION of differentiation signal threshold

  21. Summary • Depending on their origin and developmental spectra, stem cells are quite heterogeneous, where their homeostasis is determined by their (a) endogenous programming with various levels of regulating gene expression and (b) external factors, including cytokines and adhesion proteins binding to extacellular matrix an other cell comprising the stem cell niche. • Stem cell commitment and differentiationare not irreversible, as differentiated cell can be modulated to regain multipotency.

More Related