hINADl/PATJ, a Homolog of Discs Lost, Interacts with Crumbs and Localizes to Tight Junctions in Human Epithelial Cells

Abstract

dCrumbs is an apical organizer crucial for the maintenance of epithelial polarity in Drosophila (1). It is known that dCrumbs interacts with Discs lost (Dlt), a protein with four PDZ (PSD95/Discs Large/ZO-1) domains (2), and Stardust (Sdt), a protein of the MAGUK (membrane-associated guanylate kinase) family (3, 4). We have searched for potential homologs of Dlt in human epithelial cells and characterized one of them in intestinal epithelial cells. Human INAD-like (hINADl) contains 8 PDZ domains, is concentrated in tight junctions, and is also found at the apical plasma membrane. Overexpression of hINADl disrupted the tight junctions localization of ZO-1 and 3. We also identified a partial cDNA coding the transmembrane and cytoplasmic domains of a new human crumbs (CRB3) expressed in Caco-2 cells. This CRB3 was able to interact through its C-terminal end with the N-terminal domain of hINADl. Taken together, the data indicate that hINADl is likely to represent a Dlt homolog in mammalian epithelial cells and might be involved in regulating the integrity of tight junctions. We thus propose to rename hINADl PATJ for protein associated to tight junctions.

Downregulation of basal myosin‐ II is required for cell shape changes and tissue invagination

“…To identify a suitable optogenetic anchor for basal recruitment, we generated a battery of fusion proteins consisting of CIBN linked to different proteins or protein domains that have been previously shown to localize to the basal surface of the cells during cellularization. Out of the six anchors tested, two were based on Bottleneck (Schejter & Wieschaus, 1993; Reversi et al , 2014), one on Slam (Lecuit et al , 2002), and three on PatJ (Lemmers et al , 2002; Pielage et al , 2003; Fig 5B). Live imaging of embryos expressing each anchor individually demonstrates restricted basal localization (Fig 5C) and efficient localized recruitment of RhoGEF2‐CRY2::mCherry (Fig 5D).…”

The epithelial polarity program: machineries involved and their hijacking by cancer

“…How exactly Cdc42 and the Par complex contribute to TJ formation has not been fully elucidated, but it appears to be a facilitating role, as TJs are formed but slower if the complex is disrupted (Joberty et al, 2000;Lin et al, 2000;Rojas et al, 2001;Etienne-Manneville and Hall, 2003). The mechanism involves interactions of Par6 with Crumbs 3, (which is found in most epithelial cells, unlike Crumbs 1, which localizes to brain and eye) by its associated proteins PALS and PATJ (Lemmers et al, 2002;Hurd et al, 2003;Roh et al, 2003).…”

PDZ Protein Interactions Underlying NMDA Receptor-Mediated Excitotoxicity and Neuroprotection by PSD-95 Inhibitors

“…The INAD protein has been shown to interact via a PDZ domain with transient receptor potential (TRP) calcium channels that contribute to capacitative calcium entry into Drosophila photoreceptor cells, and may function as a TRP channel regulatory subunit (Shieh and Zhu, 1996). Human INAD-like (hINADl or INADL) protein contains 8 PDZ domains, is widely expressed in diverse tissues including the CNS, and is also concentrated in tight junctions of epithelial cells, whose integrity it may regulate (Lemmers et al, 2002). hINADl has significant sequence homology to the Drosophila INAD (Philipp and Flockerzi, 1997) and may therefore have similar signaling roles, such as regulating capacitative calcium entry into cells.…”