Table 1 Comparison of cell invasivity mechanisms in model cell types
From: Invasive cells in animals and plants: searching for LECA machineries in later eukaryotic life
Process or component | Invadopodia | Neurites | Pollen tubes and root hairs |
|---|---|---|---|
Matrix loosening or detachment | Yes (proteases) | Yes (SPARC-like1, reelin) | Yes (xylanases in pollen tubes, secretion of mucilage facilitating movement through soil in root hairs) |
Branched actin network at or close to leading edge or tip | Yes (structural role) | Yes | Yes (delivery of secretory vesicles) |
Actin nucleation mechanism(s) involved | Arp2/3, formins (mDia1-3) | Arp2/3, formins (DAAM) | Formins |
Microtubules required | Yes (for extension) | Partly (for guidance or orientation) | Partly (for orientation) |
RHO class GTPases involved | Cdc42 | Rac1, Cdc42, RhoA (predominantly Rac1) | Rop |
ARF class GTPases involved | Arf6 | Arf6 | Arf1 |
RAB class GTPases involved | Rab8, Rab25, Rab27 | Rab8, Rab17, Rab22 | Rab8/RabE, Rab11/RabA, Rab1/RabD |
Exocyst | Yes (via Cdc42, RhoA and Arp2/3; for MMPs secretion and actin polymerization) | Yes (via RalA and TC10) | Yes (via Rop – maybe indirectly – and Rab; for membrane turnover and cell wall modifications) |
Membrane microdomains as scaffolds for signalling | Cholesterol, sphingolipids | Cholesterol, sphingolipids | Sterols |
PtdIns signalling | Yes (PtdIns(4,5)P2) | Yes (PtdIns(3,4,5)P3, DAG, IP3) | Yes (PtdIns(4,5)P2, PtdIns(3,4,5)P3) |
ROS signalling | Localized production by Nox regulated via Src | Via Nip1/Duoxa1 or NGF, role in differentiation | Localized production by Nox regulated via Ca2+ |