Loss of cerebral cavernous malformation 3 ( Ccm3 ) in neuroglia leads to CCM and vascular pathology

Abstract

Communication between neural cells and the vasculature is integral to the proper development and later function of the central nervous system. A mechanistic understanding of the interactions between components of the neurovascular unit has implications for various disorders, including cerebral cavernous malformations (CCMs) in which focal vascular lesions form throughout the central nervous system. Loss of function mutations in three genes with proven endothelial cell autonomous roles, CCM1/krev1 interaction trapped gene 1, CCM2, and CCM3/programmed cell death 10, cause familial CCM. By using neural specific conditional mouse mutants, we show that Ccm3 has both neural cell autonomous and nonautonomous functions. Gfap-or Emx1-Cre-mediated Ccm3 neural deletion leads to increased proliferation, increased survival, and activation of astrocytes through cell autonomous mechanisms involving activated Akt signaling. In addition, loss of neural CCM3 results in a vascular phenotype characterized by diffusely dilated and simplified cerebral vasculature along with formation of multiple vascular lesions that closely resemble human cavernomas through cell nonautonomous mechanisms. RNA sequencing of the vascular lesions shows abundant expression of molecules involved in cytoskeletal remodeling, including protein kinase A and Rho-GTPase signaling. Our findings implicate neural cells in the pathogenesis of CCMs, showing the importance of this pathway in neural/vascular interactions within the neurovascular unit. cerebrovascular disease | activated astrocytes | animal models

Cerebral cavernous malformation proteins at a glance

“…PDCD10 also appears to induce VEGFR2 endocytosis after VEGF stimulation and is required for the relocation of MST4 to the cell periphery after oxidative stress, where it phosphorylates and activates ERM proteins, thereby promoting cell survival (Fidalgo et al, 2012). Conversely, PDCD10 expression has been linked to cell death Lin et al, 2010;Zhu et al, 2010) and loss of PCDC10 has been reported to increase survival and proliferation, possibly through reduced Notch signaling, enhanced VEGF signaling, or increased ERK activity (Louvi et al, 2011;You et al, 2013;Zhu et al, 2010). How these conflicting observations can be reconciled remains to be determined.…”

Ccm3, a gene associated with cerebral cavernous malformations, is required for neuronal migration

“…Loss of CCM3 in neural progenitors has cell-autonomous (astrocyte activation) and non-autonomous effects (diffusely dilated cerebrovasculature and lesion formation) in postnatal brain . CCM3 downregulation in cell lines and primary astrocytes enhances proliferation and cell survival Louvi et al, 2011). For an overview of current models of CCM protein function, see Draheim et al (Draheim et al, 2014).…”

Ccm3, a gene associated with cerebral cavernous malformations, is required for neuronal migration

“…animals Louvi et al, 2011) with Emx1-Cre (Gorski et al, 2002) and hGfap-Cre (Zhuo et al, 2001;Malatesta et al, 2003) mice to target neural progenitors and their progeny, respectively, in dorsal telencephalon at E9.5, or broadly in the CNS starting at E13.5. Loss of CCM3 expression in the conditional mutant animals was confirmed by in situ hybridization, immunostaining and western blotting (supplementary material Fig.…”