Identification of brush cells in the alimentary and respiratory system by antibodies to villin and fimbrin

Abstract

Brush cells represent a population of epithelial cells with unknown function, which are scattered throughout the epithelial lining of both the respiratory system and the alimentary system. These cells are reliably distinguished from other epithelial cells only at the ultrastructural level by the presence of an apical tuft of stiff microvilli and extremely long microvillar rootlets that may project down to the perinuclear space. In the present study we show that brush cells can be identified in tissue sections even at the light microscopic level by immunostaining with antibodies against villin and fimbrin, two proteins that crosslink actin filaments to form bundles. In brush cells, villin and fimbrin are not only present in the actin filament core bundles of apical microvilli and their long rootlets but, in addition, both proteins are also associated with microvilli extending from the basolateral cell surface of the brush cells. Basolateral immunostaining specific for villin and fimbrin does not occur in any other epithelial cell type of the respiratory and alimentary tract. Thus immunostaining with antibodies against both proteins allows unequivocal identification of individual brush cells even in sectional planes that do not contain the brightly stained apical tuft of microvilli and their long rootlets.

Taste receptor-like cells in the rat gut identified by expression of alpha-gustducin.

“…§1734 solely to indicate this fact. against a-gustducin and the actin filament-bundling protein villin, a marker molecule for brush cells (10,12), identified these cells as brush cells (Fig. 1 D and E).…”

“…Binding of taste molecules to these receptors is thought to induce GTP binding to a-gustducin that, like other G,-proteins, stimulates second messenger systems involved in signal transduction. The lumenal cell pole of both brush cells (4,5,6,12) and taste receptor cells (11) contains numerous microvilli that are the most likely site for chemoreception. In support of this notion, we found that the lumenal cell pole of both cell types was the most strongly immunolabeled portion.…”

Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

“…Such cell populations express T2Rs, gustducin, PLCβ2, and TrpM5 as well as other markers of taste cells. Despite this similarity in molecular expression, these diverse cells in different organ systems are not identical despite their sometimes being lumped together under the term "brush cells" (35). For example, the gustducin-positive cells that we have studied in the nasal cavity are heavily innervated by polymodal nociceptors (1) (Fig.…”

Bitter triggers acetylcholine release from polymodal urethral chemosensory cells and bladder reflexes

“…Likely owing due to their anatomic restriction to the portal of entry into the urogenital tract (i.e., the urethra and glandular ducts opening into it), these chemosensory cells have escaped detection in previous searches for urogenital brush cells that focused on more centrally located organs, including the kidney, uterus, and prostate gland, before the sentinel function of solitary chemosensory cells had been proposed (14). Coexpression patterns of various components of the taste transduction cascade and ChAT-eGFP suggest the presence of more than one chemosensory cell type in the urethra, including a cholinergic type using PLCβ2 and TRPM5, proteins essential for oropharyngeal bitter and umami perception (27), for downstream signaling.…”

“…2D and Table S2) and at the ultrastructural level exhibit a tuft of apical microvilli and additional basolateral microvilli (Fig. 2 F and G), the defining features of respiratory and gastrointestinal brush cells (14). A significant additional population of urethral villin-positive cells (≥50%) lacked ChAT-eGFP fluorescence (Fig.…”