RASA1-driven cellular export of collagen IV is required for the development of lymphovenous and venous valves in mice

Development. 2020 Dec 7;147(23):dev192351. doi: 10.1242/dev.192351.


RASA1, a negative regulator of Ras-MAPK signaling, is essential for the development and maintenance of lymphatic vessel valves. However, whether RASA1 is required for the development and maintenance of lymphovenous valves (LVV) and venous valves (VV) is unknown. In this study, we show that induced disruption of Rasa1 in mouse embryos did not affect initial specification of LVV or central VV, but did affect their continued development. Similarly, a switch to expression of a catalytically inactive form of RASA1 resulted in impaired LVV and VV development. Blocked development of LVV was associated with accumulation of the basement membrane protein, collagen IV, in LVV-forming endothelial cells (EC), and could be partially or completely rescued by MAPK inhibitors and drugs that promote collagen IV folding. Disruption of Rasa1 in adult mice resulted in venous hypertension and impaired VV function that was associated with loss of EC from VV leaflets. In conclusion, RASA1 functions as a negative regulator of Ras signaling in EC that is necessary for EC export of collagen IV, thus permitting the development of LVV and the development and maintenance of VV.

Keywords: Lymphovenous valves; Signal transduction; Vascular biology; Venous valves.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Basement Membrane / growth & development
  • Basement Membrane / metabolism
  • Collagen Type IV / genetics
  • Embryo, Mammalian
  • Embryonic Development / genetics*
  • Endothelial Cells / cytology
  • Lymphatic Vessels / metabolism
  • Mice
  • Organogenesis / genetics*
  • Venous Valves / growth & development*
  • Venous Valves / metabolism
  • p120 GTPase Activating Protein / genetics*


  • Collagen Type IV
  • RASA1 protein, mouse
  • p120 GTPase Activating Protein