| Model . | Chemoattractant . | Leader/ follower . | Rac activation at leader cell . | Traction substrate . | Cadherin subtype . | CIL/contact- dependent polarity . | Gradient of chemoattractant . |
|---|---|---|---|---|---|---|---|
| Border cell | PVF/EGF (1–4) Gurken(2) | Yes (5) Dynamically rearranged (5,6) | Yes (7–10) | E-cadherin (7,11) | E-cadherin (7,11) | Yes Observations of contact-dependent cell polarity (5) Active suppression of internal protrusions (12) and Rac1 polarization (7) | Not yet elucidated PVF-1 protein is expressed in the oocyte (2), and Krn and Spi mRNAs are also detected in the oocyte (3) |
| Lateral line | CXCL12/SDF-1 (13–15) | Yes (14) Dynamic rearrangements not yet elucidated | Not yet elucidated | Not yet elucidated | E-cadherin (16) N-cadherin (17) | Yes Observations of contact-dependent cell polarity (14,18) | Yes Self-generated SDF-1 gradient (13) Moving source of FGF: anterior lateral line (19) |
| Branching morphogenesis | Drosophila Trachea: Branchless (20–22) Mouse retina: VEGF (23) | Yes Specified by Btl/VEGF signaling levels (22–25), dynamic rearrangements may occur (26–29) | Yes Drosophila trachea (24,30) Mouse retina: not yet elucidated | Mouse retina: FN ECM (31) | Drosophila trachea: E-cadherin (32,33) Mouse retina: VE-cadherin (29) | Yes Observations of contact-dependent cell polarity and Rac1 polarization (24) | Yes Drosophila trachea: O-sulfotransferases sulfateless and sugarless genetically interact with branchless (34), although gradient not yet elucidated Mouse hindbrain: VEGF isoforms binding to ECM create a gradient of VEGF protein (35) |
| Neural crest | CXCL12/SDF-1 (36–39) VEGF (55) | Yes (40,41) Dynamically rearranged (42) | Yes (36,41,43,44) | Fibronectin ECM (45–47) | N-cadherin (36, 37,41,42) | Yes Mediated by N-cadherin and Wnt/PCP (36,37,40) Rac1 polarization and suppression of protrusions at internal contacts (36,40,41) | Yes Moving source of SDF-1: epibranchial placodes (37) VEGF gradient suggested (55) |
| Mesendoderm | PDGF (48–50) | No All cells in the collective form oriented unipolar protrusions (48,51) | Yes Rac required for protrusion formation in zebrafish (52) | Xenopus: FN ECM (51,53) Zebrafish: E-cadherin (52,54) | E-cadherin (52,54), C-cadherin (56) | Yes Mediated by E-cadherin and Wnt/PCP via Rac1 (52) Tension-dependent polarization mediated by C-cadherin (56) | Not yet elucidated. PDGF mRNA expressed in roof plate but protein localization not yet investigated (49,50) |
| Model . | Chemoattractant . | Leader/ follower . | Rac activation at leader cell . | Traction substrate . | Cadherin subtype . | CIL/contact- dependent polarity . | Gradient of chemoattractant . |
|---|---|---|---|---|---|---|---|
| Border cell | PVF/EGF (1–4) Gurken(2) | Yes (5) Dynamically rearranged (5,6) | Yes (7–10) | E-cadherin (7,11) | E-cadherin (7,11) | Yes Observations of contact-dependent cell polarity (5) Active suppression of internal protrusions (12) and Rac1 polarization (7) | Not yet elucidated PVF-1 protein is expressed in the oocyte (2), and Krn and Spi mRNAs are also detected in the oocyte (3) |
| Lateral line | CXCL12/SDF-1 (13–15) | Yes (14) Dynamic rearrangements not yet elucidated | Not yet elucidated | Not yet elucidated | E-cadherin (16) N-cadherin (17) | Yes Observations of contact-dependent cell polarity (14,18) | Yes Self-generated SDF-1 gradient (13) Moving source of FGF: anterior lateral line (19) |
| Branching morphogenesis | Drosophila Trachea: Branchless (20–22) Mouse retina: VEGF (23) | Yes Specified by Btl/VEGF signaling levels (22–25), dynamic rearrangements may occur (26–29) | Yes Drosophila trachea (24,30) Mouse retina: not yet elucidated | Mouse retina: FN ECM (31) | Drosophila trachea: E-cadherin (32,33) Mouse retina: VE-cadherin (29) | Yes Observations of contact-dependent cell polarity and Rac1 polarization (24) | Yes Drosophila trachea: O-sulfotransferases sulfateless and sugarless genetically interact with branchless (34), although gradient not yet elucidated Mouse hindbrain: VEGF isoforms binding to ECM create a gradient of VEGF protein (35) |
| Neural crest | CXCL12/SDF-1 (36–39) VEGF (55) | Yes (40,41) Dynamically rearranged (42) | Yes (36,41,43,44) | Fibronectin ECM (45–47) | N-cadherin (36, 37,41,42) | Yes Mediated by N-cadherin and Wnt/PCP (36,37,40) Rac1 polarization and suppression of protrusions at internal contacts (36,40,41) | Yes Moving source of SDF-1: epibranchial placodes (37) VEGF gradient suggested (55) |
| Mesendoderm | PDGF (48–50) | No All cells in the collective form oriented unipolar protrusions (48,51) | Yes Rac required for protrusion formation in zebrafish (52) | Xenopus: FN ECM (51,53) Zebrafish: E-cadherin (52,54) | E-cadherin (52,54), C-cadherin (56) | Yes Mediated by E-cadherin and Wnt/PCP via Rac1 (52) Tension-dependent polarization mediated by C-cadherin (56) | Not yet elucidated. PDGF mRNA expressed in roof plate but protein localization not yet investigated (49,50) |
(1) Duchek and Rørth, 2001; (2) Duchek et al., 2001; (3) McDonald et al., 2006; (4) McDonald et al., 2003; (5) Prasad and Montell, 2007; (6) Bianco et al., 2007; (7) Cai et al., 2014; (8) Ramel et al., 2013; (9) Wang et al., 2010; (10) Fernández-Espartero et al., 2013; (11) Niewiadomska et al., 1999; (12) Lucas et al., 2013; (13) Donà et al., 2013; (14) Haas and Gilmour, 2006; (15) Valentin et al., 2007; (16) Matsuda and Chitnis, 2010; (17) Revenu et al., 2014; (18) Lecaudey et al., 2008; (19) Dalle Nogare et al., 2014; (20) Sutherland et al., 1996; (21) Klämbt et al., 1992; (22) Ghabrial and Krasnow, 2006; (23) Gerhardt et al., 2003; (24) Lebreton and Casanova, 2014; (25) Hellström et al., 2007; (26) Arima et al., 2011; (27) Jakobsson et al., 2010; (28) Caussinus et al., 2008; (29) Bentley et al., 2014; (30) Chihara et al., 2003; (31) Stenzel et al., 2011b; (32) Cela and Llimargas, 2006; (33) Shaye et al., 2008; (34) Lin et al., 1999; (35) Ruhrberg et al., 2002; (36) Theveneau et al., 2010; (37) Theveneau et al., 2013; (38) Belmadani et al., 2005; (39) Olesnicky Killian et al., 2009; (40) Carmona-Fontaine et al., 2008; (41) Scarpa et al., 2015; (42) Kuriyama et al., 2014; (43) Carmona-Fontaine et al., 2011; (44) Moore et al., 2013; (45) Alfandari et al., 2003; (46) Kil et al., 1996; (47) Lallier et al., 1992; (48) Montero et al., 2003; (49) Damm and Winklbauer, 2011; (50) Nagel et al., 2004; (51) Davidson et al., 2002; (52) Dumortier et al., 2012; (53) Boucaut and Darribere, 1983; (54) Montero et al., 2005; (55) McLennan and Kulesa, 2010; (56) Weber et al., 2012.