Development of pharyngeal pouches endoderm-derived glands Thymus: from organogenesis to involution

Transcription

1 Development of pharyngeal pouches endoderm-derived glands Thymus: from organogenesis to involution Unidade de Organogénese (IHBD-FMUL/IMM) Rita Zilhão ENCONTRO FCUL, 4 February, 2013

2 Faculdade de Medicina de Lisboa Instituto de Histologia e Biologia do Desenvolvimento Instituto de Medicina Molecular U. Organogénese Hélia Neves Rita Zilhão Marta Figueiredo Carlota Lucena Ana sofia Santos Joana Clara Silva André Travessa Adriano Carvalho Vitor Proa U. Biologia Hematopoiética António Cidadão Isabel Alcobia Pedro Moreira

3 Pharyngeal pouches (PP) endoderm-derived glands Thymus: differentiation of T lymphocytes; Parathyroid glands: production of parathyroid hormone (PTH) and control of the calcium amount in blood and bones; C-cells: production of calcitonin (a subtype of thyroid cells). (PA) Thymus 3 rd PP, E11.5 (mouse); 3 rd and 4 th PP, E4 (chicken)

4 Endoderm Ectoderm Thymus organogenesis Early phase Thymocyte-independent Late phase Thymocyte-dependent Adult thymus PA1 PA2 PA3 PA4 3 rd PP 4 th PP Foxn1 TEC LPC ctec Mesenchymal-epithelial interactions Epithelial-LPC interactions mtec (AIRE) E4.5 Function: Production of mature T-Lymphocytes Isolated 3/4PP endoderm

5 The role Notch signaling in thymus organogenesis Notch signaling pathway is important for cell-cell communication, involving gene regulation mechanisms that control several aspects of organogenesis (cell fates, cell numbers and cell position). MAML Modulation of Notch signals: Notch1, 2 ] Intracellular domain of Notch (ICN) Hairy1 Hes5.1 Hes6.1 ICN: Gain-of-function DNMAML: Loss-of-function (Maillard et al. 2004) Delta1, 3, 4 Serrate1, Jagged 21, 2

6 Thymus organogenesis The avian model Easy access to and manipulation of chicken embryos from incubated eggs Isolation of embryonic tissues (microdissection) Tissue cultures: Heterospecific (quail-chick) association of tissues to study epithelialmesenchymal interactions during development Organotypic system: explanted tissues grown and organ formation in corioallantoic membrane (CAM) of chick embryos Genetic modification of embryonic tissues using a system of vectors In vivo modulation of genetic pathways during avian development using growthfactors soaked-beads

7 Thymus organogenesis Vector system Tol2-mediated gene transfer + tetracycline-dependent conditional expression Sato et al. 2007

8 Thymus development In vitro /in vivo assays 1. Isolation of 3/4PP endoderm System of vectors: genetic modification of isolated tissues ICN ou DNMAML 2. Endoderm electroporation (Quail E3) 3. Isolation somatopleural mesenchyme 3. Organotypic culture (Chicken E2.5) 48h 4. Graft into CAM C. D. 10 days + doxy ce8 5. Explant development in CAM QCPN

9 Thymus organogenesis Modulation of Notch signaling in thymic epithelium development Development of TECs in quail E2,5 E3 E4 E5-5.5 E7 Thymocyte-independent Thymocyte-dependent Foxn1 expression Aire expression Modulation of Notch signaling in vivo assay Analysis of Foxn1 expression and thymus development Analysis of thymic epithelium colonization by LPCs Dox Dox Analysis of Aire expression and thymic compartments formation Dox

10 Thymus involution Human model Normal conditions Rapidly declines in function to <5% of its maximal capacity after puberty In healthy individuals this level of residual thymic function is often sufficient With age there is a marked increase in susceptibility to infections and diseases (ex. autoimune disesases).

11 Thymus involution Human model The three events associated with age-related thymic involution 1. A reduction in numbers and intrinsic defects in hematopoietic stem cells (HSCs) 2. Loss of thymic epithelial cells (TECs) and deterioration of stromal microenvironment 3. Extrinsic circulating factors affecting the aged microenvironment, e.g. alterations in hormones/growth factors/cytokines Future studies Modifications of thymic epithelial cells along the first years of life (Descriptive approach) Gene expression study of thymic epithelial cells Correlation expressions patterns in TECs/thymic age Role of notch signaling in thymic epithelium homeostasis (Functional approach) Modulation of Notch signaling in thymic epithelial cells Recreating thymic environment

12 Projects 2012/ / /11 The role of Notch signaling in thymic and parathyroid glands organogenesis (Joana Silva, mbmg) Bioinformatics approach on the evolution of genes related with the origin of the thymus (Bruno Costa, mbbc) Hox-code in thymus identity (Ana Sofia Santos, mbed) Role of Notch signalling on the differentiation of early lymphoid progenitors cells: a view throughout the development of the embryonic chicken thymus (Pedro Moreira, mgmb, FCT/UNL) Avaliação morfológica e molecular da junção córtico-medular do timo humano, ao longo dos primeiros anos de vida: implicações na involução tímica (André Travessa, GAPIC) The role of Notch-signaling in avian thymus and parathyroid glands development (Marta Figueiredo, Doutoramento/FMUL) Embryonic thymic epithelium differentiation in chicken: Study of molecular signals involved in lymhoid progenitor cells colonization (Carlota Lucena, mbmg) Role of Notch signaling in the differentiation of endocrine C-cells during embryogenesis (Rita Zilhão, ½ sabática, DBV/FCUL) (Programa PESSOA , Proc ) The role of Notch signaling in thymic epithelium development (Marta Figueiredo, mbed)