Biology 624 - Developmental Genetics

Biology 624 - Developmental Genetics

Lecture #6 - Tube Formation I

Tube Formation is critical to forming:

1.Lung2.Kidney3.Mammary gland4.Blood vessels5.Fly trachea6.C. elegans excretory system (1 cell!)

From Nelson, 2003

There are three types of tubes:

1.Multicellular2.Unicellular, with autocellular

junction3.Unicellular, seamless

From Lubarsky and Krasnow, 2003

Processes of Tubulogenesis

From Lubarsky and Krasnow, 2003

Processes of Tubulogenesis

From Lubarsky and Krasnow, 2003

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

Genetic Programs involved in Tube Formation

From Nelson, 2003

MDCK Cells in Collagen Gels

- HGF +HGF

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

MDCK in collagen starts with a polarized cyst

Gp135 = apical, redb-catenin = basolateral, green

From Pollack et al, 98; Zegers et al, 03

Upon addition of HGF, some cellsform an extension outward on their

basolateral side

Gp135, apicalE-cadherin, basolateral

From Pollack et al, 98

The extended cell divides, and cells in the extension express E-cadherin

but not gp135

E-cadherin, basolateral

Gp135, apical

From Pollack et al, 98

From Pollack et al, 98From Pollack et al, 98

As the lumen begins to reform in theextension, gp135 is re-expressed

on the new apical surface

E-cadherin, basolateral

Gp135, apical

From Pollack et al, 98

As lumen formation continues, cells re-establish basolateral expression of

E-cadherin

E-cadherin, basolateral

Gp135, apical

Model derived from this study:

1.Stimulation of migration is the first step in tubulogenesis

2.Apical/basal polarity is transiently lost and then restored

3.Discontinuous lumens form in tubules

4.Cell-cell contacts are retained throughout the process

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

Apical membrane biogenesis is importantFor lumen formation in MDCK cells

From Lubarsky and Krasnow, 03

Tube formation requires and stabilizes apical-basolateral polarity

From Bryant and Mostov, 08

From Bryant and Mostov, 08

Tube formation requires and stabilizes apical-basolateral polarity

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