Microtubules regulate brush border formation

Abstract

Most epithelial cells contain apical membrane structures associated to bundles of actin filaments, which constitute the brush border. Whereas microtubule participation in the maintenance of the brush border identity has been characterized, their contribution to de novo microvilli organization remained elusive. Hereby, using a cell model of individual enterocyte polarization, we found that nocodazole induced microtubule depolymerization prevented the de novo brush border formation. Microtubule participation in brush border actin organization was confirmed in polarized kidney tubule MDCK cells. We also found that centrosome, but not Golgi derived microtubules, were essential for the initial stages of brush border development. During this process, microtubule plus ends acquired an early asymmetric orientation toward the apical membrane, which clearly differs from their predominant basal orientation in mature epithelia. In addition, overexpression of the microtubule plus ends associated protein CLIP170, which regulate actin nucleation in different cell contexts, facilitated brush border formation. In combination, the present results support the participation of centrosomal microtubule plus ends in the activation of the polarized actin organization associated to brush border formation, unveiling a novel mechanism of microtubule regulation of epithelial polarity.

Akap350 Recruits Eb1 to The Spindle Poles, Ensuring Proper Spindle Orientation and Lumen Formation in 3d Epithelial Cell Cultures

“…In contrast, our present study demonstrates that AKAP350 expression is not necessary for proper centrosome localization at the apical pole of MDCK, which is the first stage for the formation of the apical cilia. These results are also in agreement with our findings in Ls174T-W4 cells 33 , thus unveiling significant differences in the machinery involved in centrosome positioning during the development of epithelial polarity, when compared with immune synapse and migratory polarity.…”

“…Ls174T-W4 cells derive from the Ls174T colon epithelial cell line, which have been genetically engineered to produce an enterocyte-like phenotype in absence of cell-cell or cell-extracellular matrix contact 32 . Similarly to our studies in MDCK cells, our previous observations in Ls174T-W4 cells indicated that, even though the decrease in AKAP350 expression was associated to defective microtubule nucleation at the Golgi apparatus, it did not interfere with the development of the actin rich apical structures (brush borders) 33 . Therefore, our present studies provide additional evidence supporting that, compared with cells with hepatocyte type of epithelial polarity, epithelial cells with simple polarity have different requirements regarding the protein complexes that regulate their cytoskeleton dynamics during the initial events that condition the development of their apico-basal asymmetry.…”

Cholemic Nephropathy Causes Acute Kidney Injury and Is Accompanied by Loss of Aquaporin 2 in Collecting Ducts

“…Heterodimers of α‐tubulins and β‐tubulins assemble to tubulin and form microtubules that are major components of the cytoskeleton. Tubulins are also responsible for brush border formation . Kidney injury like ischemia increases tubulin expression as an adaptive response .…”

Mutated in colorectal cancer (MCC) : a novel centrosomal protein involved in intestinal homeostasis and disease

“…Fundamentally, enterocyte polarization depends on a number of cellular structures and machineries, including the compartmentalization of the cell space into the characteristic apical-basal membrane domains established by the rearrangement of the cytoskeleton; the assembly of microvilli at the apical domain; appropriate formation of lateral junctions with tight junctions distributed apically and desmosomes basolaterally (Shin et al, 2006); and finally, the appropriate localization of proteins to their specific intracellular sites. Several of these processes have been described in detail elsewhere (Assimakopoulos et al, 2011;Engevik and Goldenring, 2018;Schneeberger et al, 2018;Tonucci et al, 2018).…”

“…The formation of the microvilli (commonly referred to the brush border (BB)) at the apical membrane domain of enterocytes is a distinguishing feature of enterocyte cell polarity. Microvilli are extensions of the apical membrane providing the AE an elongated surface of contact for maximum absorption of nutrients as they pass through the lumen ( Figure 06A) (Crawley et al, 2014;Noordstra et al, 2016;Tonucci et al, 2018 (Casaletto et al, 2011;Ferrary et al, 1999;Mazerik and Tyska, 2012;Saotome et al, 2004).…”