An NKX-COUP-TFII morphogenetic code directs mucosal endothelial addressin expression

Abstract

Immunoglobulin family and carbohydrate vascular addressins encoded by Madcam1 and St6gal1 control lymphocyte homing into intestinal tissues, regulating immunity and inflammation. The addressins are developmentally programmed to decorate endothelial cells lining gut post-capillary and high endothelial venules (HEV), providing a prototypical example of organ- and segment-specific endothelial specialization. We identify conserved NKX-COUP-TFII composite elements (NCCE) in regulatory regions of Madcam1 and St6gal1 that bind intestinal homeodomain protein NKX2-3 cooperatively with venous nuclear receptor COUP-TFII to activate transcription. The Madcam1 element also integrates repressive signals from arterial/capillary Notch effectors. Pan-endothelial COUP-TFII overexpression induces ectopic addressin expression in NKX2-3+ capillaries, while NKX2-3 deficiency abrogates expression by HEV. Phylogenetically conserved NCCE are enriched in genes involved in neuron migration and morphogenesis of the heart, kidney, pancreas and other organs. Our results define an NKX-COUP-TFII morphogenetic code that targets expression of mucosal vascular addressins.

Quantitative Analysis of NKX2-3 Expression in Human Colon: An Immunohistochemical Study

“…35 The endothelial effects of Nkx2-3 in murine PPs HEVs involve the transcriptional action of a composite recognition element in the regulatory regions for Nkx2-3 and COUP-TFII proteins, influencing the expression of MAdCAM-1 addressin and St6Gal1 sulfotransferase enzyme defining the addressin's glycosylation characteristics. 37 While Nkx2-3 is also expressed in hematopoietic stem cells (HSCs) influencing their homeostasis, in mature leukocytes, Nkx2-3 is absent, in agreement with our immunohistochemical observations in human samples. Although the absence of Nkx2-3 in mice causes defective development of PPs and isolated follicles and suppresses dextran sulfate sodium (DSS)-induced colitis, 25,26,29 this deviation is likely be related to disrupted endothelial specification affecting intestinal immunity.…”

Absence of Nkx2-3 induces ectopic lymphatic endothelial differentiation associated with impaired extramedullary stress hematopoiesis in the spleen

“…What can the explanation be for this eventual shift of RP vasculature into putative lymphatic capillaries? In the HEVs of intestinal lymphoid tissue vasculature, Nkx2-3 activates the promoter of MAdCAM-1 addressin through forming a composite element together with DNA-binding orphan nuclear receptor COUP-TFII, a critical transcription factor defining vein identity through suppressing Notch activity ( You et al, 2005 ; Dinh et al, 2022 ). This mechanism relies on the availability of respective binding sites for both Nkx2-3 and COUP-TFII within the MAdCAM-1 promoter region in HEV-programmed venous endothelial cells.…”

Uncovering the heterogeneity of pancreatic endothelial cells using integrative and comparative single cell gene expression analysis

“…NKX2-3 in particular is involved in the development of the spleen and gut (89), both of which arise from the endoderm, which also gives rise to the pancreas. Specifically, NKX2-3 has been shown to be integral for proper vascular specification in these organs (90,91). Primarily, NKX2-3 is involved in regulating the expression of mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) (92).…”

“…NKX2-3 in particular is involved in the development of the spleen and gut( 65 ), both of which arise from the endoderm, which also gives rise to the pancreas. Specifically, NKX2-3 has been shown to be integral for proper vascular specification in these organs( 66–67 ). Primarily, NKX2-3 is involved in regulating the expression of mucosal vascular addressing cell adhesion molecule 1 (MAdCAM-1)( 98 ), a tissue-specific adhesion molecule that facilitates the homing of leukocytes in vascular segments involved in immune surveillance and inflammation, such as the high endothelial venules found in lymph nodes and Peyer’s patches of the small intestine( 68–69 ).…”