Type I and type II keratins have evolved from lower eukaryotes to form the epidermal intermediate filaments in mammalian skin.

Fuchs, Elaine; Marchuk, Douglas A.

doi:10.1073/pnas.80.19.5857

Cited by 136 publications

(97 citation statements)

References 55 publications

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“…The coordinate expression and coordinate evolutionary conservation of two distinct types of keratins in all vertebrate epithelia make it likely that the type I and type II keratins are, in some as yet unidentified way, essential in the formation of the coiled-coil protofilament backbone of the intermediate filament of epithelial cells (12)(13)(14)18). In this study, we have shown that during terminal differentiation of the keratinocyte, when numerous changes in the keratin pattern take place, the ratio of the type I and type II keratins is not disrupted.…”

Section: Discussionmentioning

confidence: 99%

“…these keratins play a unique and important role in terminal differentiation (14). Precisely what this role might be must await the sequencing and characterization of these proteins.…”

Section: Are Large Keratins Of Differentiating Epidermis Expressed Frmentioning

confidence: 99%

“…These antisera were shown to cross-react with a number of other type I and type II keratins, respectively (14). Northern Blot Analysis: RNAs were first subjected to electrophoresis through formaldehyde agarose gels and were then transferred to nitrocellulose paper according to the procedure of Thomas (23).…”

Section: Isolation and Characterization Of Thementioning

confidence: 99%

“…Other epithelia express different subsets of keratins, but most if not all of these seem to be similar to one or the other of the two epidermal keratin subfamilies (12). The small (40-52 kd) and relatively acidic keratins have been named the type I class, and the large (53-58 kd) and more basic keratins have been named the type II class (13,14). At least one member of each of the two keratin types seem to be expressed in all cells at all times, suggesting their combined importance in filament assembly (14).…”

mentioning

confidence: 99%

“…The small (40-52 kd) and relatively acidic keratins have been named the type I class, and the large (53-58 kd) and more basic keratins have been named the type II class (13,14). At least one member of each of the two keratin types seem to be expressed in all cells at all times, suggesting their combined importance in filament assembly (14). Sequence analyses (13,(15)(16)(17)(18) have shown that while the two types of keratins share only low (<30%) homology, their predicted secondary structures are strikingly similar and are compatible with their playing an essential role in forming the coiled-coil backbone of the protofilament of the 8-nm keratin filament (13,18).…”

mentioning

confidence: 99%

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Expression of unusually large keratins during terminal differentiation: balance of type I and type II keratins is not disrupted.

Kim¹,

Marchuk²,

Fuchs³

1984

The Journal of Cell Biology

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When a basal epidermal cell undergoes a commitment to terminally differentiate, it ceases to divide and begins to migrate outward towards the surface of the skin. Dramatic changes in its cytoskeletal architecture take place, accompanied by numerous changes in the expression of keratins, a family of related polypeptides that form 8-nm filaments in these cells. We show here that a shift to the synthesis of unusually large keratins occurs that does not seem to disrupt the ratio of two distinct subfamilies of keratins. Preliminary studies indicate that this differentiation-specific shift may be at the level of transcriptional rather than post-trancriptional regulation. The striking similarities between these large keratins and the type I and type II keratins of basal epidermal cells suggests the important role that both classes of large keratin sequences must play in the assembly of the intermediate filaments within the differentiating keratinocyte.Several laboratories have reported differences between the keratins of stratum corneum and those of the living layers of epidermis (1--4). During the course of terminal differentiation, changes occur in the expression of the keratin polypeptides that comprise the 8-nm tonofilaments (5-10). For the human, keratins of size 46, 48.5, 50, 52, 56, and 58 kd are synthesized by the basal epidermal cells (Fig. 1, lane 1), whereas additional keratins of size 67, 65.5, and 56.5 kd are produced by the terminally differentiating epidermis (lane 3). As the cells pass through the granular layer to the stratum corneum, a slight reduction in the size of the keratins takes place. As judged by in vitro translation of mRNAs isolated from basal (lane 2) and differentiating (lane 4) keratinocytes, the changes in keratin pattern that occur early in the course of terminal differentiation are clearly at the level of mRNA biosynthesis (5).Recently, it was demonstrated that the keratins produced by basal epidermal cells can be divided into two distinct groups based on the ability of their mRNAs to cross-hybridize with two different cloned keratin cDNAs (11). Other epithelia express different subsets of keratins, but most if not all of these seem to be similar to one or the other of the two epidermal keratin subfamilies (12). The small (40-52 kd) and relatively acidic keratins have been named the type I class, and the large (53-58 kd) and more basic keratins have been named the type II class (13,14). At least one member of each of the two keratin types seem to be expressed in all cells at all times, suggesting their combined importance in filament assembly (14). Sequence analyses (13,(15)(16)(17)(18) have shown that while the two types of keratins share only low (<30%) homology, their predicted secondary structures are strikingly similar and are compatible with their playing an essential role in forming the coiled-coil backbone of the protofilament of the 8-nm keratin filament (13,18).The keratins typical of terminally differentiating keratinocytes seem to be unusually large and are not fo...

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Section: Discussionmentioning

confidence: 99%

“…these keratins play a unique and important role in terminal differentiation (14). Precisely what this role might be must await the sequencing and characterization of these proteins.…”

Section: Are Large Keratins Of Differentiating Epidermis Expressed Frmentioning

confidence: 99%

Section: Isolation and Characterization Of Thementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Expression of unusually large keratins during terminal differentiation: balance of type I and type II keratins is not disrupted.

Kim¹,

Marchuk²,

Fuchs³

1984

The Journal of Cell Biology

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Immunohistochemical identification of the cytoskeletal elements in the notochord cells of bony fishes

Schmitz

1998

J. Morphol.

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The medulla of the unconstricted notochords of the shortnose sturgeon, Acipenser brevirostratus, and African lungfish, Protopterus annectens, and the cellular component of the intervertebral joint tissue of the teleost fish, Perca flavescens, are comprised of cells with a large central vacuole. Previous studies on the fine structure of this tissue revealed that the cytoplasm surrounding these vacuoles consists of 10‐nm‐diameter intermediate filaments. Since in mammals there are a large number of tissue‐specific types of intermediate filaments, this study uses antibodies to mammalian intermediate filaments to determine the type of filaments present in the notochord cells of bony fishes. Positive labeling using a polyclonal antibody to human skin keratins is observed in the cytoplasm of the notochord cells in the intervertebral tissues of Perca. These tissues are also probed with the AE series antibodies that label keratins found in mammalian epithelial cells. In both Protopterus and Acipenser the peripheral cytoplasm of the notochord cells is labeled with all three AE antibodies. In Perca only the AE3 antibody probe produces positive staining. These staining patterns are consistent with previous studies on the localization of cytokeratins in fish tissues and indicate that the intermediate filaments in the notochord cells of bony fishes are immunologically similar to the mammalian keratins. J. Morphol. 236:105–116, 1998. © 1998 Wiley‐Liss, Inc.

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Immunocytochemical and electrophoretic distribution of cytokeratins in the regenerating epidermis of the lizardPodarcis muralis

2000

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Using immunocytochemistry at light‐ and electron‐microscope levels, we studied the distribution of three monoclonal antibodies (AE1, AE2, AE3) specific for mammalian α‐keratins in regenerating lizard epidermis. We also characterized the keratins expressed during this process by immunoblotting after electrophoretic separation. The AE1 antibody is localized in the basal and suprabasal layers of prescaling and scaling epidermis. During the first stages of scale neogenesis, the AE1 antibody also marks the differentiating oberhautchen and β‐layer, but it disappears from these layers as they mature. This antibody does not stain the prekeratinized and keratinized outermost layers in the hinge region. The AE2 antibody labels the superficial wound epidermis, prekeratinizing and keratinized β‐ and α‐layers, but not basal and suprabasal cells. The AE3 antibody labels all living and keratinized epidermal layers, although AE3 immunoreactivity decreases and disappears as the β‐layer matures. The ultrastructural study shows that the AE2 and AE3, but not the AE1, antibodies specifically label small electron‐dense areas within the β‐layer, suggesting retention of α‐keratins. In the stages of tail regeneration examined, immunoblotting with the three antibodies used for the immunolocalization gives a pattern similar to that of the normal epidermis, except distally, where the process of scale differentiation begins. In this region, in addition to the keratin forms discovered in the normal and in proximal regenerating epidermis, an intense low molecular weight band at 40–41 kDa, positive to all three antibodies, is clearly detectable. Furthermore, in the distal region AE1 and AE3 antibodies, but not the AE2, recognize a weak band at 77–78 kDa not present in the normal and proximal epidermis. The localization and the possible role of the different keratins in the regenerating epidermis is discussed. J. Morphol. 246:179–191, 2000. © 2000 Wiley‐Liss, Inc.

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Type I and type II keratins have evolved from lower eukaryotes to form the epidermal intermediate filaments in mammalian skin.

Cited by 136 publications

References 55 publications

Expression of unusually large keratins during terminal differentiation: balance of type I and type II keratins is not disrupted.

Expression of unusually large keratins during terminal differentiation: balance of type I and type II keratins is not disrupted.

Immunohistochemical identification of the cytoskeletal elements in the notochord cells of bony fishes

Immunocytochemical and electrophoretic distribution of cytokeratins in the regenerating epidermis of the lizardPodarcis muralis

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