Biology Developmental Genetics Lecture #6 - Tube Formation I

Tube Formation is critical to forming: 1.Lung 2.Kidney 3.Mammary gland 4.Blood vessels 5.Fly trachea 6.C. elegans excretory system (1 cell!) From Nelson, 2003

There are three types of tubes: 1.Multicellular 2.Unicellular, with autocellular junction 3.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, red b-catenin = basolateral, green 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 Rac for proper orientation of polarity +dnRAC +Laminin

MDCK in collagen starts with a polarized cyst Gp135 = apical, red b-catenin = basolateral, green From Pollack et al, 98; Zegers et al, 03

Upon addition of HGF, some cells form 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

As the lumen begins to reform in the extension, 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 Proteins During 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 important For lumen formation in MDCK cells From Lubarsky and Krasnow, 03

Tube formation requires and stabilizes apical- basolateral polarity From Bryant and Mostov, 08

Tube formation requires and stabilizes apical- basolateral polarity

MDCK tubulogenesis can be divided into stages with different molecular requirements Requires ERK activation Requires MMP activity From O’Brienet al, 04

MDCK tubulogenesis p-EMT requires ERK activation Nuclei=blue Actin = red From O’Brien et al, 04

MDCK tubulogenesis redifferentiation Requires MMP activity Nuclei=blue Actin = red From O’Brien et al, 04