MDCK tubulogenesis can be divided into stageswith different molecular requirements
RequiresERK activation
RequiresMMP activity
From O’Brienet al, 04
MDCK tubulogenesis p-EMT requires ERKactivation
Nuclei=blueActin = red From O’Brien et al, 04
MDCK tubulogenesis redifferentiation Requires MMP activity
Nuclei=blueActin = red
From O’Brien et al, 04
Cellular Processes involved in Tube Formation
1. Cell-cell adhesion
2. Cell migration
3. Cell shape changes
4. Lumen formation
5. Cell division
6. Cell death
Trachea Formation in Drosophila
MDCK in collagen forms a polarized cyst - how?
Gp135 = apical, redb-catenin = basolateral, green
From Zegers et al, 03
From Zegers et al, 03
Drive for three surfaces model - epithelial cells try to establish apical, lateral, and basal domains
+dnRAC
From Zegers et al, 03
MDCK cyst formation requires Racfor proper orientation of polarity
+dnRAC+Laminin
Differential Regulation of Junctional ProteinsDuring Tubulogenesis (same paper)
1. Adherens junctions (E-cadherin) move around, and new ones are made
2. ZO-1, a tight junction protein, is between apical and basolateral domains, and during extension is at cell-cell contact points
3. Desmosome components dpI/II are in large intracellular pools during tubulogenesis
Steps in Tracheal Branching Morphogenesis
Ghabrial A, Krasnow M
Model of the FGF signaling Pathway in the Control of Cell Migration in Drosophila.
Bnl: BranchlessBtl: BreathlessDof: Downstream of FGF, StumpsCsw: Corkscrew(phosphatase)HSPG: heparan sulfate proteoglycan
Petit V, Affolter M
Steps of Tracheal Tube Formation
• Tracheal sac formation Specification of tracheal cells (tracheal placodes) Invagination of the tracheal placode
• General branch outgrowth via FGF signaling• Branch-specific outgrowth is controlled by regional signals and branch
identity genes Branch identity dentermination DB migration requires Dpp signaling GB migration requires slit-robo signaling Tube elongation through cell intercalation
• Determination and differentiation of distinct cell types (fusion cell, terminal cell) Fusion process Terminal branching
Dysfusion is Required for Fusion Process
btl-gal4, UAS-actin-GFP btl-gal4, UAS-actin-GFP ; dys
Wild-type dys mutant
Dysfusion Regulates Downstream Targets with Various Functions
• Shotgun and CG13196 (cell adhesion)↑• members only (protein trafficking) ↑• CG15252 (unknown function) ↑• Trachealess (tracheal migration) ↓