Expression of the High-affinity Choline Transporter CHT1 in Rat and Human Arteries

Abstract

S U M M A R YThe arterial vascular wall contains a non-neuronal intrinsic cholinergic system. The rate-limiting step in acetylcholine (ACh) synthesis is choline uptake. A high-affinity choline transporter, CHT1, has recently been cloned from neural tissue and has been identified in epithelial cholinergic cells. Here we investigated its presence in rat and human arteries and in primary cell cultures of rat vascular cells (endothelial cells, smooth muscle cells, fibroblasts). CHT1-mRNA was detected in the arterial wall and in all isolated cell types by RT-PCR using five different CHT1-specific primer pairs. Antisera raised against amino acids 29-40 of the rat sequence labeled a single band (50 kD) in Western blots of rat aorta, and an additional higher molecular weight band appeared in the hippocampus. Immunohistochemistry demonstrated CHT1 immunoreactivity in endothelial and smooth muscle cells in situ and in all cultured cell types. A high-affinity [ 3 H]-choline uptake mechanism sharing characteristics with neuronal high-affinity choline uptake, i.e., sensitivity to hemicholinium-3 and dependence on sodium, was demonstrated in rat thoracic aortic segments by microimager autoradiography. Expression of the high-affinity choline transporter CHT1 is a novel component of the intrinsic non-neuronal cholinergic system of the arterial vascular wall, predominantly in the intimal and medial layers.

Intermedin/adrenomedullin-2 is a hypoxia-induced endothelial peptide that stabilizes pulmonary microvascular permeability

“…Pulmonary microvascular endothelial cells (PMEC) were isolated as described by Lips et al (26) with Dynabeads coated with Bandeiraea simplicifolia lectin. HL-1 cells were kindly provided by Dr. W. C. Claycomb (Louisiana State University Health Science Center, New Orleans, LA).…”

Genomic organization, promoter activity, and expression of the human choline transporter-like protein 1

“…ns, Not significant. including neuronal CHT1 is frequently attributed to similar proteolytic processing (28,44).…”

The Cholinergic System Can Be of Unexpected Importance in Osteoarthritis

“…Existence of a non-neuronal cholinergic system has also recently been shown for osteoblast-like cells (En-Nosse et al, 2009) and hepatocytes (Delbro et al, 2011). Of special interest with respect to what will be discussed below, is the fact that inflammatory cells (Kawashima & Fuji, 2004) and fibroblasts (Fisher et al, 1993;Lips et al, 2003) show production of ACh. It should here be remembered that the tenocytes of human tendons in principle have fibroblast-like appearances.…”

“…It is likely that the ACh produced in non-neuronal cells is released directly after synthesis, in contrast to the nerve-related ACh which is released via exocytosis. Cell types for which ACh production has been shown are cells in the airways , the keratinocytes of the skin (Grando et al, 1993(Grando et al, , 2006, cells of the intestinal epithelium (Klapproth et al, 1997;Ratcliffe et al, 1998;Jönsson et al, 2007), cells of the urinary bladder wall (Lips et al, 2007;Yoshida et al, 2008), cells in blood vessel walls Lips et al, 2003) and certain cancer cells (Song et al, 2003(Song et al, , 2008Paleari et al, 2008). A further celltype for which there is evidence of ACh production is the tenocyte of human patellar (Danielson et al, 2006(Danielson et al, , 2007 and Achilles (Bjur et al, 2008) tenocytes.…”