Characterization of human epiplakin: RNAi-mediated epiplakin depletion leads to the disruption of keratin and vimentin IF networks

Jang, Shyh‐Ing; Kalinin, Alexandr; Takahashi, Kazutaka; Marekov, Lyuben N.; Steinert, Peter M.

doi:10.1242/jcs.01647

Cited by 46 publications

(66 citation statements)

References 51 publications

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“…Knockdown of epiplakin in simple epithelial cells results in disruption of keratin and vimentin networks (Jang et al, 2005). Thus, siRNA experiments indicate that epiplakin is required for maintenance of simple epithelial keratin network, whereas periplakin is involved in keratin bundling at epithelial wound edge.…”

Section: Periplakin Participates In Re-organisation Of Keratin Intermmentioning

confidence: 99%

Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets

Long

Boczonadi

McInroy

et al. 2006

Journal of Cell Science

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Collective migration of epithelial sheets requires maintenance of cell-cell junctions and co-ordination of the movement of the migrating front. We have investigated the role of keratin intermediate filaments and periplakin, a cytoskeletal linker protein, in the migration of simple epithelial cells. Scratch wounding induces bundling of keratins into a cable of tightly packed filaments adjacent to the free wound edge. Keratin re-organisation is preceded by a re-distribution of periplakin away from the free wound edge. Periplakin participates with dynamic changes in the keratin cytoskeleton via its C-terminal linker domain that co-localises with okadaic-acid-treated keratin granules. Stable expression of the periplakin C-terminal domain increases keratin bundling and Ser431 keratin phosphorylation at wound edge resulting in a delay in wound closure. Ablation of periplakin by siRNA inhibits keratin cable formation and impairs wound closure. Knockdown of keratin 8 with siRNA results in (1) a loss of desmoplakin localisation at cell borders, (2) a failure of MCF-7 epithelial sheets to migrate as a collective unit and (3) accelerated wound closure in vimentin-positive HeLa and Panc-1 cell lines. Thus, keratin 8 is required for the maintenance of epithelial integrity during migration and periplakin participates in the re-organisation of keratins in migrating cells.

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Section: Periplakin Participates In Re-organisation Of Keratin Intermmentioning

confidence: 99%

Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets

Long

Boczonadi

McInroy

et al. 2006

Journal of Cell Science

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“…Using dot blot in vitro binding assays, Jang et al (Jang et al, 2005) demonstrated binding of one of the human epiplakin repeats (the most C-terminal) to various intermediate filament proteins, including K5/K14, K8/K18 and vimentin. Comparable results were obtained when immobilized module 8, linker 9, and module 8 plus linker 9 were incubated with keratin, vimentin or desmin in slot blot assays (Wang et al, 2006).…”

Section: Epiplakin Associates With Epidermal Keratins Via Multiple Bimentioning

confidence: 99%

“…Association with keratin filaments has also been shown for envoplakin and periplakin (Karashima and Watt, 2002;Kazerounian et al, 2002). In the case of epiplakin, binding of the most C-terminal PRD to keratins was shown in dot blot assays (Jang et al, 2005) and, in a recent study, keratin binding of module 8 has been demonstrated using slot blot assays (Wang et al, 2006). It is not known, however, whether all the PRDs in epiplakin can actually bind to keratin.…”

Section: Introductionmentioning

confidence: 95%

“…It is not known, however, whether all the PRDs in epiplakin can actually bind to keratin. Furthermore, colocalization of epiplakin with keratin filament networks has been reported so far only for human carcinoma (HeLa) and keratinocyte (HaCaT) cell lines, whereas it was not observed in primary keratinocytes (Jang et al, 2005). Thus, it remains an open question whether the interaction of epiplakin with keratins K5 and K14 observed in vitro is of biological significance.…”

Section: Introductionmentioning

confidence: 99%

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Stress-induced recruitment of epiplakin to keratin networks increases their resistance to hyperphosphorylation-induced disruption

Spazierer

Raberger

Groß

et al. 2008

Journal of Cell Science

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Epiplakin is a large (>725 kDa) cytoskeletal protein exclusively expressed in epithelial tissues. It has a unique structure, consisting entirely of plakin repeat domains (PRDs), one of the hallmarks of spectraplakin protein family members. Previous studies, including the phenotypic analyses of knockout mice, failed to reveal the biological function of epiplakin. Using in vitro binding assays, we show here that all but one of the 16 PRDs of mouse epiplakin bind to keratins of basal keratinocytes. Nevertheless, in primary keratinocyte cell cultures, epiplakin only partially colocalized with keratin intermediate filament networks. However, upon application of cellular stress in the form of keratin hyperphosphorylation, osmotic shock or UV irradiation, the entire cytoplasmic epiplakin pool became associated with keratin. In response to such types of stress, epiplakin initially translocated to the stillintact keratin filament network and remained associated with keratin after its disruption and transformation into granular aggregates. Time-course experiments revealed that serine/threonine (okadaic acid) and tyrosine (orthovanadate) phosphatase inhibitor-induced filament disruption in differentiated keratinocytes proceeded faster in epiplakindeficient cells compared with wild-type cells. Our data suggest that epiplakin plays a role in keratin filament reorganization in response to stress, probably by protecting keratin filaments against disruption in a chaperone-like fashion.

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“…As a result, the cell has assembled an abundant array of transcriptional, translational, and posttranslational mechanisms to carefully control cytoskeletal morphology and function. One of the more recent findings encompassing cytoskeletal regulation has been the discovery of crosslinker proteins that act by crosslinking cytoskeletal filament systems (i.e., actin, microtubules, and intermediate filaments), linking cytoskeletal filament systems to intercellular junctions (i.e., adherens junctions, desmosomes, gap junctions, and tight junctions), and linking different types of cellular junctions to each other (Sobel, 1990;Yang et al, 1996Yang et al, , 1999Karakesisoglou et al, 2000;Leung et al, 2002;Weber and Bement, 2002;Giepmans, 2004;Jang et al, 2005;Winder and Ayscough, 2005).…”

Section: Introductionmentioning

confidence: 99%

Dynamics and unexpected localization of the plakin binding protein, kazrin, in mouse eggs and early embryos

Gallicano

Foshay

Pengetnze

et al. 2005

Developmental Dynamics

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The cell uses the cytoskeleton in virtually every aspect of cell survival and function. One primary function of the cytoskeleton is to connect to and stabilize intercellular junctions. To accomplish this task, microtubules, actin filaments, and intermediate filaments utilize cytolinker proteins, which physically bind the cytoskeletal filament to the core proteins of the adhesion junction. The plakin family of linker proteins have been in the spotlight recently as critical components for embryo survival and, when mutated, the cause of diseases such as muscular dystrophy and cardiomyopathies. Here, we reveal the dynamics of a recently discovered plakin binding protein, kazrin (kaz), during early mouse development. Kaz was originally found in adult tissues, primarily epidermis, linking periplakin to the plasma membrane and colocalizing with desmoplakin in desmosomes. Using reverse transcriptase-polymerase chain reaction, Western blots, and confocal microscopy, we found kaz in unfertilized eggs associated with the spindle apparatus and cytoskeletal sheets. As quickly as 5 min after egg activation, kaz relocates to a diffuse peri-spindle position, followed 20 -30 min later by clear localization to the presumptive cytokinetic ring. Before the blastocyst stage of development, kaz associates with the nuclear matrix in a cell cycle-dependent manner, and also associates with the cytoplasmic actin cytoskeleton. After blastocyst formation, kaz localization and potential function(s) become highly complex as it is found associating with cell-cell junctions, the cytoskeleton, and nucleus. Postimplantation stages of development reveal that kaz retains a multifunctional, tissue-specific role as it is detected at diverse locations in various embryonic tissue types.

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Characterization of human epiplakin: RNAi-mediated epiplakin depletion leads to the disruption of keratin and vimentin IF networks

Cited by 46 publications

References 51 publications

Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets

Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets

Stress-induced recruitment of epiplakin to keratin networks increases their resistance to hyperphosphorylation-induced disruption

Dynamics and unexpected localization of the plakin binding protein, kazrin, in mouse eggs and early embryos

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