Related Experiment Video
Updated: Jul 19, 2026
07:07
Evaluation of Planar-Cell-Polarity Phenotypes in Ciliopathy Mouse Mutant Cochlea
Published on: February 21, 2016
Mammalian lin-7 stabilizes polarity protein complexes
Samuel W Straight1, Jay N Pieczynski, Eileen L Whiteman
1Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
The Journal of Biological Chemistry
|October 3, 2006
Summary
Mammalian Lin-7 protein is crucial for maintaining tight junctions in epithelial cells. Its absence leads to PALS1 protein instability, disrupting cell polarity and barrier function.
Area of Science:
- Cell Biology
- Epithelial Biology
- Protein Interactions
Background:
- Mammalian Lin-7 protein complexes are involved in determining epithelial cell polarity.
- Lin-7 interacts with proteins like PALS1, crucial for cell structure and function.
Purpose of the Study:
- To investigate the role of Lin-7 in maintaining tight junction formation and protein stability in polarized epithelial cells.
- To identify the specific domains of Lin-7 and its binding partners essential for its function.
Main Methods:
- Utilized small hairpin RNA (shRNA) to knock down Lin-7 expression in Madin-Darby canine kidney II cells.
- Assessed tight junction integrity via transepithelial electrical resistance (TEER) measurements and ZO-1 protein localization.
- Performed rescue experiments using exogenous expression of Lin-7 constructs and PALS1.
Main Results:
- Lin-7 knockdown caused defects in tight junction formation, indicated by reduced TEER and ZO-1 mislocalization.
- Loss of Lin-7 led to decreased expression of binding partners PALS1 and PATJ.
- Exogenous expression of Lin-7's L27 domain or PALS1 rescued the observed defects, restoring PATJ levels.
- Lin-7 knockdown resulted in PALS1 protein instability and increased degradation.
Conclusions:
- Mammalian Lin-7 stabilizes PALS1 protein, which is essential for maintaining tight junction integrity in epithelial cells.
- Lin-7's L27 domain is critical for its function in stabilizing PALS1 and preserving cell polarity.
- Lin-7 plays a vital role in epithelial barrier function through PALS1 stabilization.
More Related Videos
12:15The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging
Published on: October 3, 2017
06:55Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling
Published on: May 26, 2011
Related Concept Videos
01:21Cell Polarization by Rho Proteins
Cell polarity is the asymmetric distribution of cellular and membrane components, making one side of the cell different from the other. This polarity is essential to many processes such as embryogenesis, axon migration, glucose transport across epithelial cells, and directional cell migration. A migrating cell responds to intracellular or extracellular signals via molecular cascades that reorganize the actin cytoskeleton to establish this polarity. In these cells, the Rho family proteins Cdc42,...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
01:18Polarity of the Cytoskeleton
The intrinsic polarity of cells can be primarily attributed to two factors- i) the asymmetric accumulation of mobile components such are regulatory molecules and subcellular components across the cell and ii) the orientation of polar cytoskeletal filaments that make up the cytoskeletal networks, specifically microfilaments, and microtubules arranged along the axis of polarity. Interactions between the cytoskeletal filaments are crucial for the establishment and maintenance of the polar nature...
01:31Mechanism of Lamellipodia Formation
Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
01:32Cytoskeletal Coordination in Cell Migration
A migrating cell changes its shape during the cyclic events of attachment and detachment from the substratum and repositions the cell organelles correspondingly. These complex events are orchestrated by the dynamic cytoskeletal network comprising actin filaments, intermediate filaments, and microtubules. Cytoskeletal crosstalk — the direct and indirect communication between the different components — is crucial for this coordination. Direct communication involves various linker proteins that...
01:42Microtubule Associated Proteins (MAPs)
Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...