The keratin-binding protein Albatross regulates polarization of epithelial cells

Abstract

The keratin intermediate filament network is abundant in epithelial cells, but its function in the establishment and maintenance of cell polarity is unclear. Here, we show that Albatross complexes with Par3 to regulate formation of the apical junctional complex (AJC) and maintain lateral membrane identity. In nonpolarized epithelial cells, Albatross localizes with keratin filaments, whereas in polarized epithelial cells, Albatross is primarily localized in the vicinity of the AJC. Knockdown of Albatross in polarized cells causes a disappearance of key components of the AJC at cell–cell borders and keratin filament reorganization. Lateral proteins E-cadherin and desmoglein 2 were mislocalized even on the apical side. Although Albatross promotes localization of Par3 to the AJC, Par3 and ezrin are still retained at the apical surface in Albatross knockdown cells, which retain intact microvilli. Analysis of keratin-deficient epithelial cells revealed that keratins are required to stabilize the Albatross protein, thus promoting the formation of AJC. We propose that keratins and the keratin-binding protein Albatross are important for epithelial cell polarization.

Biological Functions of Cytokeratin 18 in Cancer

“…Albatross (also known as Fas-binding factor-1) also has a trichohyalin and plectin homology (TPHD) domain, which binds to CK18 directly in a yeast two-hybrid system. Albatross regulates the apical junctional complex and lateral domains in epithelial cells (33). In turn, keratins stabilize Albatross, which promotes the formation of the apical junctional complex.…”

“…In addition to plectin and H3 histones, trichoplein and Albatross were also identified as CK8/18-binding proteins (32,33). Trichoplein shows a low degree of sequence similarity to trichohyalin, plectin, and myosin heavy chain, and colocalizes with CK8/18 filaments in HeLa cells (32).…”

Truncation of monocyte chemoattractant protein 1 by plasmin promotes blood–brain barrier disruption

“…After fixation, in -20°C methanol for 10 minutes or in 4% paraformaldehyde for 20 minute, the cells were incubated overnight with mouse anti-occludin antibody (1:300; Zymed) (Sugimoto et al, 2008) and rabbit anti-ZO-1 antibody (1:300; Zymed) followed by fluorescent anti-(mouse Ig) or anti-(rabbit Ig) antibodies (1:1000; Invitrogen). Next, the cells were washed and mounted on slides using Fluoromount with DAPI.…”

Trichoplein controls microtubule anchoring at the centrosome by binding to Odf2 and ninein

“…Similarly to another keratin IF scaffold protein, Albatross (Sugimoto et al, 2008), this protein has a trichohyalin and plectin homology domain (TPHD; also see supplementary material Fig. S3A), which has similarities to classical keratin IF scaffold proteins (Izawa and Inagaki, 2006).…”