TRIM47 is a crucial regulator of brain endothelial cell functions  

Juliette Vaurs 1 , Claire Peghaire 1 , Valentin Delobel 1 , Romain Boulestreau 1 , Béatrice Jaspard-Vinassa 1 , Carole Proust 1 , Cécile Duplàa 1 , Thierry Couffinhal 1   

1 Biology of cardiovascular disease, University of Bordeaux, Inserm France  

Correspondence: Juliette Vaurs - <This email address is being protected from spambots. You need JavaScript enabled to view it.>  

Cerebral small vessel disease (cSVD) is a leading cause of strokes and a major contributor to vascular  dementia.  Evidence  indicates  that  BBB  dysfunction  may  play  a  significant  role  in vascular  dementia  pathogenesis.  However,  the  molecular  determinants  and  responsible mechanisms  are  still  not  resolved.  Recently,  we  reported,  using  a  human  genome-wide association  study,  an  inverse  correlation  between  the  expression  of  an  ubiquitin  ligase, TRIM47, and extensive cSVD severity. TRIM47 is highly expressed in human and mouse brain endothelial cells (EC), indicative of its putative role at the BBB level.
We demonstrate that TRIM47 knockdown in human brain microvascular EC (HBMEC) impairs BBB properties with an increased permeability, decreased directed migration, and blockage of endothelial sprouting.  TRIM47 loss led to profound alteration in the actin  cytoskeleton organisation assembly via the inhibition of the RhoA/ROCK1/LIMK1 pathway.
By performing RNA-sequencing, we identify that loss of TRIM47 represses NRF2 associated gene expression in HBMEC. NRF2 is an important transcriptional regulator of antioxydant and anti-inflammatory enzymes. It binds to its inhibitor  KEAP1 in the  cytoplasm  under normal conditions. Using proximity labeling (BioID) and co-immunoprecipitation assays, we report an interaction of TRIM47 with KEAP1. Repression of TRIM47 increases KEAP1 level. Finally, we showed that KEAP1 inhibitor treatment restores HBMEC functions impaired by TRIM47 loss. In summary, we report that TRIM47 dysregulation affects EC properties by dysregulating the RhoA/ROCK1 signaling via the NRF2/KEAP1 pathway. It may, per se, reduce stress resistance to EC at the BBB level.