Clin Res Cardiol (2021). 10.1007/s00392-021-01933-9

SHISA3, a novel Wnt-dependent vascular signature in the developing heart

L. Priesmeier1, D. Hartung1, E. Schoger1, F. Raad1, D. Panakova2, L. Zelarayán1

1Institut für Pharmakologie und Toxikologie, Universitätsmedizin Göttingen, Göttingen; 2Max-Delbrück-Centrum für Molekulare Medizin, Berlin;

Myocardial perfusion is a key requisite for homeostasis and this is challenged by insufficient neovascularization upon pathological stress. Understanding the developmental processes and origin of vascular cells will aid to dissect disease mechanisms. We have previously demonstrated that Wnt/β-catenin activation resulted in fetal reprogramming and pathological remodeling in the adult heart. In this context we identified regulation of a novel developmental player, SHISA3, in the adult heart. Next, we aimed to further investigate its role in development. Using transgenic mouse models we showed that modulation of Wnt signaling induced cardiomyocyte de-differentiation accompanied with vascular cell (EC) remodeling and heart dysfunction. Within this transcriptional program, we uncovered a so far uncharacterized cell type expressing SHISA3 in the heart, showing immature vascular cell characteristics. These cells were almost absent in adult ventricles, but were highly expressed in the developing, and stressed adult hearts. Immunofluorescence analysis showed SHISA3 expression in Troponin T (cardiomyocyte)-negative cells in the ventricular and atrial chambers at embryonic day (E)9.5-11.5. At E14.5, SHISA3 pos cells were placed sub-epicardially and at E18.5 they were abundantly expressed in between cardiomyocytes and capillary structures towards ventricular tissue. SHISA3pos cells were progressively lost from postnatal (P) day 1 to adulthood. SHISA3pos cells were periostin (POSTN)-negative but co-expressed actin, aortic smooth muscle (ACTA2) in capillary structures, indicating a more vascular fate. Progressive co-localization of these cells with the early endothelial marker Endomucin (EMCN) was detected from E10.5-E18.5, but was gradually lost postnatally and reappeared upon pathological remodeling. To analyze the contribution of epicardial and sub-epicardial cells to SHISA3pos cells, mouse epicardial explants were cultured. Epicardial derived cells (EPDCs) migrating out of the explants expressed SHISA3 and partially co-localized with ACTA2. EPDCs treated with WNT3A conditional medium showed increased SHISA3pos cells and a concomitant co-localization with ACTA2. Applying SHISA3-morpholinos resulted in early developmental defects and Wnt modulation in zebrafish. To further address SHISA3 in a human context, we observed that SHISA3 was early and transiently expressed during endothelial and vascular smooth muscle cell differentiation and in bioengineered heart muscle (BHM) organoid from human induced pluripotent stem (hiPS) cells. Our results unravel a previously unknown evolutionary conserved SHISA3-expressing cell type and underscore its significance in vascular cell fate development in mouse human and zebrafish, which is controlled by Wnt dynamics. This study also showed that reactivation of SHISA3-expressing cells may be part of the compensatory fetal reprograming upon pathological heart remodeling. Currently, the effect of enzymatically inactive (d)Cas9-mediated doxycycline-controlled activation of SHISA3 is tested in human induced pluripotent stem (hiPS) cells subjected to EC and vascular smooth muscle cell differentiation as well as 3D tissues consisting of hiPS cell-derived cardiomyocytes, ECs and fibroblasts.

https://dgk.org/kongress_programme/ht2021/BS883.htm