Published January 1, 2016 | Version v1
Journal article Open

Loss-of-Function Mutations in ELMO2 Cause Intraosseous Vascular Malformation by Impeding RAC1 Signaling

Creators

  • 1. Hacettepe Univ, Fac Med, Gene Mapping Lab, Dept Med Genet, TR-06100 Ankara, Turkey
  • 2. ASTAR, Human Genet & Embryol Lab, Inst Med Biol, Singapore 138648, Singapore
  • 3. Hacettepe Univ, Fac Med, Dept Plast & Reconstruct Surg, TR-06100 Ankara, Turkey
  • 4. Hacettepe Univ, Dept Pathol, Fac Med, TR-06100 Ankara, Turkey
  • 5. Acibadem Univ, Fac Med, Dept Plast & Reconstruct Surg, TR-34457 Istanbul, Turkey
  • 6. TUBITAK, BILGEM, Adv Genom & Bioinformat Res Ctr IGBAM, TR-41400 Kocaeli, Turkey
  • 7. Univ Utah, Dept Pediat, Div Med Genet, Salt Lake City, UT 84108 USA
  • 8. Matern Children Hosp, Dept Pediat, Mecca 24341, Saudi Arabia
  • 9. TUBITAK Marmara Res Ctr, Genet Engn & Biotechnol Inst, TR-41400 Kocaeli, Turkey
  • 10. Koc Univ, Fac Med, Dept Pathol, TR-34450 Istanbul, Turkey
  • 11. Univ Manchester, Fac Biol Med & Hlth, Oxford Rd, Manchester M13 9PT, Lancs, England

Description

Vascular malformations are non-neoplastic expansions of blood vessels that arise due to errors during angiogenesis. They are a heterogeneous group of sporadic or inherited vascular disorders characterized by localized lesions of arteriovenous, capillary, or lymphatic origin. Vascular malformations that occur inside bone tissue are rare. Herein, we report loss-of-function mutations in ELMO2 (which translates extracellular signals into cellular movements) that are causative for autosomal-recessive intraosseous vascular malformation (VMOS) in five different families. Individuals with VMOS suffer from life-threatening progressive expansion of the jaw, craniofacial, and other intramembranous bones caused by malformed blood vessels that lack a mature vascular smooth muscle layer. Analysis of primary fibroblasts from an affected individual showed that absence of ELMO2 correlated with a significant downregulation of binding partner DOCK1, resulting in deficient RAC1-dependent cell migration. Unexpectedly, elmo2-knockout zebrafish appeared phenotypically normal, suggesting that there might be human-specific ELMO2 requirements in bone vasculature homeostasis or genetic compensation by related genes. Comparative phylogenetic analysis indicated that elmo2 originated upon the appearance of intramembranous bones and the jaw in ancestral vertebrates, implying that elmo2 might have been involved in the evolution of these novel traits. The present findings highlight the necessity of ELMO2 for maintaining vascular integrity, specifically in intramembranous bones.

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