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) ↓