scholarly journals 14-3-3 targets keratin intermediate filaments to mechanically sensitive cell–cell contacts

2020 ◽  
Vol 31 (9) ◽  
pp. 930-943 ◽  
Author(s):  
Richard A. Mariani ◽  
Shalaka Paranjpe ◽  
Radek Dobrowolski ◽  
Gregory F. Weber
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Sensitive Cell ◽  
Filament Dynamics ◽  
Keratin 19 ◽  
Keratin Filaments ◽  
Novel Association ◽  
Keratin Intermediate Filaments ◽  
Cell Cell

14-3-3 serves as a major regulator of keratin intermediate filament dynamics in vivo. Migratory mesendoderm tissue of the Xenopus embryo is used to show that the dynamic reorganization of keratin filaments, a consequence of force on cell-cell adhesions, is mediated by a novel association between 14-3-3 and Keratin 19.

scholarly journals 14-3-3 recruits keratin intermediate filaments to mechanically sensitive cell-cell contacts

2018 ◽  
Author(s):  
Richard A. Mariani ◽  
Shalaka Paranjpe ◽  
Radek Dobrowolski ◽  
Gregory F. Weber
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Cell Junctions ◽  
Fusion Construct ◽  
Cell Contacts ◽  
Keratin 19 ◽  
Keratin Filament ◽  
Cytoskeletal Networks ◽  
Keratin Intermediate Filaments ◽  
Cell Cell

AbstractIntermediate filament cytoskeletal networks simultaneously support mechanical integrity and influence signal transduction pathways. Marked remodeling of the keratin intermediate filament network accompanies collective cellular morphogenetic movements that occur during early embryonic development in the frog Xenopus laevis. While this reorganization of keratin is initiated by force transduction on cell-cell contacts mediated by C-cadherin, the mechanism by which keratin filament reorganization occurs remains poorly understood. In this work we demonstrate that 14-3-3 proteins regulate keratin reorganization dynamics in embryonic mesendoderm cells from Xenopus gastrula. 14-3-3 co-localizes with keratin filaments near cell-cell junctions in migrating mesendoderm. Co-immunoprecipitation, mass spectrometry and bioinformatic analyses indicate Keratin 19 is a target of 14-3-3 in the whole embryo and, more specifically, mesendoderm tissue. Inhibition of 14-3-3 results in both the decreased exchange of keratin subunits into filaments and blocks keratin filament recruitment toward cell-cell contacts. Synthetically coupling 14-3-3 to Keratin 19 through a unique fusion construct conversely induces the localization of this keratin population to the region of cell-cell contacts. Taken together, these findings indicate that 14-3-3 acts on keratin intermediate filaments and is involved in their reorganization to sites of cell adhesion.

scholarly journals Keratins and plakin family cytolinker proteins control the length of epithelial microridge protrusions

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Yasuko Inaba ◽  
Vasudha Chauhan ◽  
Aaron Paul van Loon ◽  
Lamia Saiyara Choudhury ◽  
Alvaro Sagasti
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Actin Filaments ◽  
Actin Binding ◽  
Protein Levels ◽  
Skin Cells ◽  
Keratin Filaments ◽  
Actin Binding Domain ◽  
Cytoskeletal Elements ◽  
Keratin Intermediate Filaments

Actin filaments and microtubules create diverse cellular protrusions, but intermediate filaments, the strongest and most stable cytoskeletal elements, are not known to directly participate in the formation of protrusions. Here we show that keratin intermediate filaments directly regulate the morphogenesis of microridges, elongated protrusions arranged in elaborate maze-like patterns on the surface of mucosal epithelial cells. We found that microridges on zebrafish skin cells contained both actin and keratin filaments. Keratin filaments stabilized microridges, and overexpressing keratins lengthened them. Envoplakin and periplakin, plakin family cytolinkers that bind F-actin and keratins, localized to microridges, and were required for their morphogenesis. Strikingly, plakin protein levels directly dictate microridge length. An actin-binding domain of periplakin was required to initiate microridge morphogenesis, whereas periplakin-keratin binding was required to elongate microridges. These findings separate microridge morphogenesis into distinct steps, expand our understanding of intermediate filament functions, and identify microridges as protrusions that integrate actin and intermediate filaments.

scholarly journals Discovery of keratin function and role in genetic diseases: the year that 1991 was

2016 ◽  
Vol 27 (18) ◽  
pp. 2807-2810 ◽  
Author(s):  
Pierre A. Coulombe
Keyword(s):  
Intermediate Filaments ◽  
Cell Biology ◽  
Essential Role ◽  
Genetic Diseases ◽  
Structure And Function ◽  
Mechanical Support ◽  
25Th Anniversary ◽  
Keratin Filaments ◽  
And Function ◽  
Keratin Intermediate Filaments

In 1991, a set of transgenic mouse studies took the fields of cell biology and dermatology by storm in providing the first credible evidence that keratin intermediate filaments play a unique and essential role in the structural and mechanical support in keratinocytes of the epidermis. Moreover, these studies intimated that mutations altering the primary structure and function of keratin filaments underlie genetic diseases typified by cellular fragility. This Retrospective on how these studies came to be is offered as a means to highlight the 25th anniversary of these discoveries.

scholarly journals Assembly of type IV neuronal intermediate filaments in nonneuronal cells in the absence of preexisting cytoplasmic intermediate filaments

1993 ◽  
Vol 122 (6) ◽  
pp. 1323-1335 ◽  
Author(s):  
GY Ching ◽  
RK Liem
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Cultured Cells ◽  
Neuronal Cell ◽  
Intermediate Filament Protein ◽  
Amino Acid Residues ◽  
Intermediate Filament Proteins ◽  
Transfected Cells ◽  
Type Iv

We report here on the in vivo assembly of alpha-internexin, a type IV neuronal intermediate filament protein, in transfected cultured cells, comparing its assembly properties with those of the neurofilament triplet proteins (NF-L, NF-M, and NF-H). Like the neurofilament triplet proteins, alpha-internexin coassembles with vimentin into filaments. To study the assembly characteristics of these proteins in the absence of a preexisting filament network, transient transfection experiments were performed with a non-neuronal cell line lacking cytoplasmic intermediate filaments. The results showed that only alpha-internexin was able to self-assemble into extensive filamentous networks. In contrast, the neurofilament triplet proteins were incapable of homopolymeric assembly into filamentous arrays in vivo. NF-L coassembled with either NF-M or NF-H into filamentous structures in the transfected cells, but NF-M could not form filaments with NF-H. alpha-internexin could coassemble with each of the neurofilament triplet proteins in the transfected cells to form filaments. When all but 2 and 10 amino acid residues were removed from the tail domains of NF-L and NF-M, respectively, the resulting NF-L and NF-M deletion mutants retained the ability to coassemble with alpha-internexin into filamentous networks. These mutants were also capable of forming filaments with other wild-type neurofilament triplet protein subunits. These results suggest that the tail domains of NF-L and NF-M are dispensable for normal coassembly of each of these proteins with other type IV intermediate filament proteins to form filaments.

scholarly journals alpha-Internexin, a 66-kD intermediate filament-binding protein from mammalian central nervous tissues.

1985 ◽  
Vol 101 (4) ◽  
pp. 1316-1322 ◽  
Author(s):  
J S Pachter ◽  
R K Liem
Keyword(s):  
Optic Nerve ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Peptide Mapping ◽  
Exchange Chromatography ◽  
Filament Assembly ◽  
Antigen Antibody

In this paper we describe a 66-kD protein that co-purifies with intermediate filaments from rat optic nerve and spinal cord but can be separated further by ion-exchange chromatography. This protein is distinct from the 68-kD neurofilament subunit protein as judged by isoelectric focusing, immunoblotting, peptide mapping, and tests of polymerization competence. This protein is avidly recognized by the monoclonal anti-intermediate filament antigen antibody, previously demonstrated to recognize a common antigenic determinant in all five known classes of intermediate filaments. Also, when isolated this protein binds to various intermediate filament subunit proteins, which suggests an in vivo interaction with the intermediate filament cytoskeleton, and it appears to be axonally transported in the rat optic nerve. Because of this ability to bind to intermediate filaments in situ and in vitro we have named this protein alpha-internexin. A possible functional role for the protein in organizing filament assembly and distribution is discussed.

Keratin intermediate filament dynamics in cell heterokaryons reveals diverse behaviour of different keratins

1997 ◽  
Vol 110 (9) ◽  
pp. 1099-1111 ◽  
Author(s):  
J.M. Paramio ◽  
M.L. Casanova ◽  
A. Alonso ◽  
J.L. Jorcano
Keyword(s):  
Protein Synthesis ◽  
Intermediate Filament ◽  
Dynamic Nature ◽  
Filament Dynamics ◽  
Filament Assembly ◽  
Different Types ◽  
Form Part ◽  
Filament Network ◽  
Keratin Intermediate Filaments ◽  
Complete Process

To study the dynamics of keratin intermediate filaments, we fused two different types of epithelial cells (PtK2 and BMGE+H) and studied how the keratins from the parental cells recombine and copolymerize to form the heterokaryon cytoskeleton. The behaviour of the keratins during this process was followed by immunofluorescence using specific antibodies. After fusion, the parental cytoskeletons undergo a depolymerization process most apparent in the region adjacent to the fusion area. The depolymerized subunits spread throughout the heterokaryon and copolymerize into a new hybrid cytoskeleton. The complete process is very rapid, occurring in 3–4 hours, thus demonstrating the highly dynamic nature of the keratin cytoskeleton. Although newly synthesised subunits contribute to the formation of the hybrid cytoskeleton, the process takes place with similar kinetics in the absence of protein synthesis, showing the dynamic nature of the keratins from pre-existing cytoskeletons. During this process, specific keratins behave differently. Keratins K8, K18, K5 and K10 are mobilised from the parental cytoskeletons and reassemble rapidly into the hybrid cytoskeleton (3–6 hours), whereas K14 requires a substantially longer period (9–24 hours). Thus, different keratins, even when they form part of the same heterodimeric/tetrameric complexes, as is the case for K5 and K14, exhibit different dynamics. This suggests that individual polypeptides or homopolymeric complexes rather than exclusively heterodimeric/ tetrameric subunits, as is currently thought, can also take part in keratin intermediate filament assembly and dynamics. Biochemical analysis performed in the absence of protein synthesis revealed greater amounts of K5 than of K14 in the soluble pool of BMGE+H cells. Crosslinking and immunoprecipitation experiments indicated an excess of monomeric K5, as well as of K5/K14 heterodimers and K5 homodimers in the soluble pool. These results are in agreement with the different dynamic behaviour of these keratins observed in immunofluorescence. On the contrary, the phosphorylation levels of K5 and K14 are similar in both the soluble pool and the polymerized fraction, suggesting that phosphorylation does not play an important role in the different dynamics displayed by these two proteins. In summary, our results demonstrate that, following fusion, the keratin intermediate filament network reshapes rather rapidly and that keratins are highly dynamic proteins, although this mobility depends on each particular polypeptide.

scholarly journals Deletions in epidermal keratins leading to alterations in filament organization in vivo and in intermediate filament assembly in vitro.

1990 ◽  
Vol 111 (6) ◽  
pp. 3049-3064 ◽  
Author(s):  
P A Coulombe ◽  
Y M Chan ◽  
K Albers ◽  
E Fuchs
Keyword(s):  
Intermediate Filament ◽  
Intermediate Filament Proteins ◽  
Amino Terminal ◽  
Filament Assembly ◽  
Keratin Filaments ◽  
Keratin Filament ◽  
Filament Networks ◽  
10 Nm Filaments

To investigate the sequences important for assembly of keratins into 10-nm filaments, we used a combined approach of (a) transfection of mutant keratin cDNAs into epithelial cells in vivo, and (b) in vitro assembly of mutant and wild-type keratins. Keratin K14 mutants missing the nonhelical carboxy- and amino-terminal domains not only integrated without perturbation into endogenous keratin filament networks in vivo, but they also formed 10-nm filaments with K5 in vitro. Surprisingly, keratin mutants missing the highly conserved L L E G E sequence, common to all intermediate filament proteins and found at the carboxy end of the alpha-helical rod domain, also assembled into filaments with only a somewhat reduced efficiency. Even a carboxy K14 mutant missing approximately 10% of the rod assembled into filaments, although in this case filaments aggregated significantly. Despite the ability of these mutants to form filaments in vitro, they often perturbed keratin filament organization in vivo. In contrast, small truncations in the amino-terminal end of the rod domain more severely disrupted the filament assembly process in vitro as well as in vivo, and in particular restricted elongation. For both carboxy and amino rod deletions, the more extensive the deletion, the more severe the phenotype. Surprisingly, while elongation could be almost quantitatively blocked with large mutations, tetramer formation and higher ordered lateral interactions still occurred. Collectively, our in vitro data (a) provide a molecular basis for the dominance of our mutants in vivo, (b) offer new insights as to why different mutants may generate different phenotypes in vivo, and (c) delineate the limit sequences necessary for K14 to both incorporate properly into a preexisting keratin filament network in vivo and assemble efficiently into 10-nm keratin filaments in vitro.

scholarly journals Structures of the ß-Keratin Filaments and Keratin Intermediate Filaments in the Epidermal Appendages of Birds and Reptiles (Sauropsids)

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 591
Author(s):  
David A.D. Parry
Keyword(s):  
Physical Properties ◽  
Intermediate Filaments ◽  
Epidermal Differentiation ◽  
Defence Mechanisms ◽  
Epidermal Differentiation Complex ◽  
Keratin Filaments ◽  
The Matrix ◽  
The Individual ◽  
Keratin Intermediate Filaments ◽  
Terminal Domains

The epidermal appendages of birds and reptiles (the sauropsids) include claws, scales, and feathers. Each has specialized physical properties that facilitate movement, thermal insulation, defence mechanisms, and/or the catching of prey. The mechanical attributes of each of these appendages originate from its fibril-matrix texture, where the two filamentous structures present, i.e., the corneous ß-proteins (CBP or ß-keratins) that form 3.4 nm diameter filaments and the α-fibrous molecules that form the 7–10 nm diameter keratin intermediate filaments (KIF), provide much of the required tensile properties. The matrix, which is composed of the terminal domains of the KIF molecules and the proteins of the epidermal differentiation complex (EDC) (and which include the terminal domains of the CBP), provides the appendages, with their ability to resist compression and torsion. Only by knowing the detailed structures of the individual components and the manner in which they interact with one another will a full understanding be gained of the physical properties of the tissues as a whole. Towards that end, newly-derived aspects of the detailed conformations of the two filamentous structures will be discussed and then placed in the context of former knowledge.

scholarly journals Physiology, structure, and susceptibility to injury of skeletal muscle in mice lacking keratin 19-based and desmin-based intermediate filaments

2011 ◽  
Vol 300 (4) ◽  
pp. C803-C813 ◽  
Author(s):  
Richard M. Lovering ◽  
Andrea O'Neill ◽  
Joaquin M. Muriel ◽  
Benjamin L. Prosser ◽  
John Strong ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Intermediate Filaments ◽  
Striated Muscle ◽  
Contractile Function ◽  
Double Knockout ◽  
Specific Tension ◽  
Keratin 19 ◽  
Keratin Filaments ◽  
Complete Disruption ◽  
Fast Twitch

Intermediate filaments, composed of desmin and of keratins, play important roles in linking contractile elements to each other and to the sarcolemma in striated muscle. Our previous results show that the tibialis anterior (TA) muscles of mice lacking keratin 19 (K19) lose costameres, accumulate mitochondria under the sarcolemma, and generate lower specific tension than controls. Here we compare the physiology and morphology of TA muscles of mice lacking K19 with muscles lacking desmin or both proteins [double knockout (DKO)]. K19−/− mice and DKO mice showed a threefold increase in the levels of creatine kinase (CK) in the serum. The absence of desmin caused a larger change in specific tension (−40%) than the absence of K19 (−19%) and played the predominant role in contractile function (−40%) and decreased tolerance to exercise in the DKO muscle. By contrast, the absence of both proteins was required to obtain a significantly greater loss of contractile torque after injury (−48%) compared with wild type (−39%), as well as near-complete disruption of costameres. The DKO muscle also showed a significantly greater misalignment of myofibrils than either mutant alone. In contrast, large subsarcolemmal gaps and extensive accumulation of mitochondria were only seen in K19-null TA muscles, and the absence of both K19 and desmin yielded milder phenotypes. Our results suggest that keratin filaments containing K19- and desmin-based intermediate filaments can play independent, complementary, or antagonistic roles in the physiology and morphology of fast-twitch skeletal muscle.

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