Reprint of: Keratin intermediate filaments: Differences in the sequences of the Type I and Type II chains explain the origin of the stability of an enzyme-resistant four-chain fragment

2014 ◽  
Vol 186 (3) ◽  
pp. 481-490
Author(s):  
R.D. Bruce Fraser ◽  
David A.D. Parry
Keyword(s):  
Intermediate Filaments ◽  
Type I ◽  
Type Ii ◽  
Chain Fragment ◽  
The Stability ◽  
Keratin Intermediate Filaments

scholarly journals A keratin scaffold regulates epidermal barrier formation, mitochondrial lipid composition, and activity

2015 ◽  
Vol 211 (5) ◽  
pp. 1057-1075 ◽  
Author(s):  
Vinod Kumar ◽  
Jamal-Eddine Bouameur ◽  
Janina Bär ◽  
Robert H. Rice ◽  
Hue-Tran Hornig-Do ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Lipid Composition ◽  
Comparative Proteomics ◽  
Type I ◽  
Type Ii ◽  
Barrier Formation ◽  
Strong Adhesion ◽  
A Cell ◽  
Mitochondrial Lipid ◽  
Keratin Intermediate Filaments

Keratin intermediate filaments (KIFs) protect the epidermis against mechanical force, support strong adhesion, help barrier formation, and regulate growth. The mechanisms by which type I and II keratins contribute to these functions remain incompletely understood. Here, we report that mice lacking all type I or type II keratins display severe barrier defects and fragile skin, leading to perinatal mortality with full penetrance. Comparative proteomics of cornified envelopes (CEs) from prenatal KtyI−/− and KtyII−/−K8 mice demonstrates that absence of KIF causes dysregulation of many CE constituents, including downregulation of desmoglein 1. Despite persistence of loricrin expression and upregulation of many Nrf2 targets, including CE components Sprr2d and Sprr2h, extensive barrier defects persist, identifying keratins as essential CE scaffolds. Furthermore, we show that KIFs control mitochondrial lipid composition and activity in a cell-intrinsic manner. Therefore, our study explains the complexity of keratinopathies accompanied by barrier disorders by linking keratin scaffolds to mitochondria, adhesion, and CE formation.

Hagfish biopolymer: a type I/type II homologue of epidermal keratin intermediate filaments

1995 ◽  
Vol 17 (5) ◽  
pp. 283-292 ◽  
Author(s):  
Elizabeth A. Koch ◽  
Robert H. Spitzer ◽  
Ron B. Pithawalla ◽  
Francisco A. Castillos ◽  
David A.D. Parry
Keyword(s):  
Intermediate Filaments ◽  
Type I ◽  
Type Ii ◽  
Keratin Intermediate Filaments

scholarly journals Making a connection: direct binding between keratin intermediate filaments and desmosomal proteins.

1994 ◽  
Vol 127 (4) ◽  
pp. 1049-1060 ◽  
Author(s):  
P D Kouklis ◽  
E Hutton ◽  
E Fuchs
Keyword(s):  
Intermediate Filaments ◽  
Transmembrane Domain ◽  
Direct Interaction ◽  
Cell Types ◽  
Epidermal Keratinocytes ◽  
Type I ◽  
Type Ii ◽  
Amino Terminal ◽  
Keratin Intermediate Filaments

In epidermal cells, keratin intermediate filaments connect with desmosomes to form extensive cadherin-mediated cytoskeletal architectures. Desmoplakin (DPI), a desmosomal component lacking a transmembrane domain, has been implicated in this interaction, although most studies have been conducted with cells that contain few or no desmosomes, and efforts to demonstrate direct interactions between desmoplakin and intermediate filaments have not been successful. In this report, we explore the biochemical nature of the connections between keratin filaments and desmosomes in epidermal keratinocytes. We show that the carboxy terminal "tail" of DPI associates directly with the amino terminal "head" of type II epidermal keratins, including K1, K2, K5, and K6. We have engineered and purified recombinant K5 head and DPI tail, and we demonstrate direct interaction in vitro by solution-binding assays and by ligand blot assays. This marked association is not seen with simple epithelial type II keratins, vimentin, or with type I keratins, providing a possible explanation for the greater stability of the epidermal keratin filament architecture over that of other cell types. We have identified an 18-amino acid residue stretch in the K5 head that is conserved only among type II epidermal keratins and that appears to play some role in DPI tail binding. This finding might have important implications for understanding a recent point mutation found within this binding site in a family with a blistering skin disorder.

scholarly journals Microfilament modification by dihydrocytochalasin B causes retinoic acid-modulated chondrocytes to reexpress the differentiated collagen phenotype without a change in shape.

1988 ◽  
Vol 106 (1) ◽  
pp. 161-170 ◽  
Author(s):  
P D Benya ◽  
P D Brown ◽  
S R Padilla
Keyword(s):  
Retinoic Acid ◽  
Cell Shape ◽  
Articular Chondrocytes ◽  
Type Ii Collagen ◽  
Phenotypic Change ◽  
Type Iii Collagen ◽  
Type I ◽  
Type Ii ◽  
The Stability ◽  
Rabbit Articular Chondrocytes

Primary monolayers of rabbit articular chondrocytes synthesize high levels of type II collagen and proteoglycan. This capacity was used as a marker for the expression of the differentiated phenotype. Such cells were treated with 1 microgram/ml retinoic acid (RA) for 10 d to produce a modulated collagen phenotype devoid of type II and consisting of predominantly type I trimer and type III collagen. After transfer to secondary culture in the presence of RA, the stability of the RA-modulated phenotype was investigated by culture in the absence of RA. Little reexpression of type II collagen synthesis occurred in this period unless cultures were treated with 3 X 10(-6) M dihydrocytochalasin B to modify microfilament structures. Reexpression of the differentiated phenotype began between days 6-8 and was essentially complete by day 14. Substantial reexpression occurred by day 8 without a detectable increase in cell rounding. Colony formation, characteristic of primary chondrocytes, was infrequent even after reexpression was complete. These data suggest that the integrity of microfilament cytoskeletal structures can be a source of regulatory signals that mechanistically appear to be more proximal to phenotypic change than the overt changes in cell shape that accompany reexpression of subculture-modulated chondrocytes in agarose culture.

scholarly journals Insights into the Dynamic Properties of Keratin Intermediate Filaments in Living Epithelial Cells

2001 ◽  
Vol 153 (3) ◽  
pp. 503-516 ◽  
Author(s):  
Kyeong Han Yoon ◽  
Miri Yoon ◽  
Robert D. Moir ◽  
Satya Khuon ◽  
Frederick W. Flitney ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Fluorescence Recovery After Photobleaching ◽  
Fluorescent Protein ◽  
Dynamic Properties ◽  
Cell Periphery ◽  
Type I ◽  
Wide Range ◽  
Different Types ◽  
Green Fluorescent ◽  
Keratin Intermediate Filaments

The properties of keratin intermediate filaments (IFs) have been studied after transfection with green fluorescent protein (GFP)-tagged K18 and/or K8 (type I/II IF proteins). GFP-K8 and -K18 become incorporated into tonofibrils, which are comprised of bundles of keratin IFs. These tonofibrils exhibit a remarkably wide range of motile and dynamic activities. Fluorescence recovery after photobleaching (FRAP) analyses show that they recover their fluorescence slowly with a recovery t1/2 of ∼100 min. The movements of bleach zones during recovery show that closely spaced tonofibrils (<1 μm apart) often move at different rates and in different directions. Individual tonofibrils frequently change their shapes, and in some cases these changes appear as propagated waveforms along their long axes. In addition, short fibrils, termed keratin squiggles, are seen at the cell periphery where they move mainly towards the cell center. The motile properties of keratin IFs are also compared with those of type III IFs (vimentin) in PtK2 cells. Intriguingly, the dynamic properties of keratin tonofibrils and squiggles are dramatically different from those of vimentin fibrils and squiggles within the same cytoplasmic regions. This suggests that there are different factors regulating the dynamic properties of different types of IFs within the same cytoplasmic regions.

scholarly journals Tailless keratins assemble into regular intermediate filaments in vitro

1990 ◽  
Vol 97 (2) ◽  
pp. 317-324
Author(s):  
M. Hatzfeld ◽  
K. Weber
Keyword(s):  
Intermediate Filaments ◽  
Consensus Sequence ◽  
In Vitro Mutagenesis ◽  
Type I ◽  
Type Ii ◽  
Tail Domain ◽  
Filament Formation ◽  
Wild Type ◽  
Keratin 8

To study the influence of the non alpha-helical tail domain of keratins in filament formation, we prepared a truncated keratin 8 mutant, K8/tailless. Using site-directed in vitro mutagenesis we introduced a stop codon in the position coding for amino acid number 417 of the K8/wild-type sequence, thereby deleting 86 amino acids of the non alpha-helical tail domain but leaving the consensus sequence at the end of the rod domain intact. Expression of the truncated keratin 8 in Escherichia coli allowed us to purify the protein by a two-step procedure. The filament-forming capacity of the truncated K8 with wild-type K18 and K19 was analyzed using in vitro reconstitution. The in vitro assembly studies with K8/tailless and K18 wild-type indicate that the C-terminal tail domain of a type II keratin, including the homologous subdomain H2, is not required for filament formation. Moreover, reconstitution experiments with K8/tailless and K19, a naturally occurring tailless keratin I, show that the tail domains of type I as well as type II keratins are not an essential requirement for in vitro filament formation. Our results suggest that in vitro filament elongation does not depend on interactions between head and tail domains, although the tail domain might have a role in stabilization of intermediate filaments arising from certain keratin pairs.

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