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The functional diversity of epidermal keratins revealed by the partial rescue of the keratin 14 phenotype by keratin 16.

Paladini RD, Coulombe PA - J. Cell Biol. (1999)

Bottom Line: Degenstein, E.Fuchs. 1995.Despite their high sequence similarity, K16 and K14 are not functionally equivalent in the epidermis and other stratified epithelia and it is primarily the carboxy-terminal approximately 105 amino acids of K16 that define these differences.

View Article: PubMed Central - PubMed

Affiliation: Departments of Biological Chemistry and Dermatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

ABSTRACT
The type I epidermal keratins K14 and K16 are remarkably similar at the primary sequence level. While a structural function has been clearly defined for K14, we have proposed that a function of K16 may be to play a role in the process of keratinocyte activation that occurs after acute injury to stratified epithelia. To compare directly the functions of the two keratins we have targeted the expression of the human K16 cDNA to the progenitor basal layer of the epidermis of K14 mice. Mice for K14 blister extensively and die approximately 2 d after birth (Lloyd, C., Q.C. Yu, J. Cheng, K. Turksen, L. Degenstein, E. Hutton, and E. Fuchs. 1995. J. Cell Biol. 129:1329-1344). The skin of mice expressing K16 in the absence of K14 developed normally without evidence of blistering. However, as the mice aged they featured extensive alopecia, chronic epidermal ulcers in areas of frequent physical contact, and alterations in other stratified epithelia. Mice expressing a control K16-C14 cDNA also rescue the blistering phenotype of the K14 mice with only a small percentage exhibiting minor alopecia. While K16 is capable of rescuing the blistering, phenotypic complementation in the resulting skin is incomplete due to the multiple age dependent anomalies. Despite their high sequence similarity, K16 and K14 are not functionally equivalent in the epidermis and other stratified epithelia and it is primarily the carboxy-terminal approximately 105 amino acids of K16 that define these differences.

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Light microscopy analysis and transgene expression in replacement skin. 7-d-old trunk skin was fixed, embedded in paraffin, and 5-μm sections were stained with hematoxylin and eosin (H & E) or subjected to immunohistochemistry using the HRP procedure. H & E staining of K16 (A) and K16-C14 (B) replacement skin. Both epidermides featured a normal cellular morphology along with multiple anagen staged hair follicles. There were no detectable differences when compared with wild-type 7-d-old epidermis (data not shown). (C–F) Transgene detection. The K16 transgene protein was detected using the 1275 antibody (C) and was restricted to the basal layer of the epidermis and the outer root sheath of the hair follicle. The K16-C14 transgene protein was detected (F) using the LL001 antibody and showed the same distribution. There was no detection of K16 in the K16-C14 replacement sample (D) and there was no detection of K14 in the K16 replacement sample (E). (G and H) Both samples were also stained with an antibody against K10. K10 expression was detected throughout the suprabasal layers of the epidermis in both the K16 (G) and K16-C14 (H) samples indicating that there is no evidence of abnormal differentiation. Hf, hair follicle. Arrowheads, demarcate the dermal-epidermal junction. Asterisks, melanin granules in hair follicle profiles. Bar, 100 μm.
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Figure 1: Light microscopy analysis and transgene expression in replacement skin. 7-d-old trunk skin was fixed, embedded in paraffin, and 5-μm sections were stained with hematoxylin and eosin (H & E) or subjected to immunohistochemistry using the HRP procedure. H & E staining of K16 (A) and K16-C14 (B) replacement skin. Both epidermides featured a normal cellular morphology along with multiple anagen staged hair follicles. There were no detectable differences when compared with wild-type 7-d-old epidermis (data not shown). (C–F) Transgene detection. The K16 transgene protein was detected using the 1275 antibody (C) and was restricted to the basal layer of the epidermis and the outer root sheath of the hair follicle. The K16-C14 transgene protein was detected (F) using the LL001 antibody and showed the same distribution. There was no detection of K16 in the K16-C14 replacement sample (D) and there was no detection of K14 in the K16 replacement sample (E). (G and H) Both samples were also stained with an antibody against K10. K10 expression was detected throughout the suprabasal layers of the epidermis in both the K16 (G) and K16-C14 (H) samples indicating that there is no evidence of abnormal differentiation. Hf, hair follicle. Arrowheads, demarcate the dermal-epidermal junction. Asterisks, melanin granules in hair follicle profiles. Bar, 100 μm.

Mentions: The hyperproliferative phenotype of the K16 ectopic mice is most severe ∼7 d after birth 39. To determine if there were any comparable morphological or molecular aberrations at the same age in the replacement mice, trunk skin from 7-d-old K16 and K16-C14 replacement mice was examined by light microscopy (Fig. 1A and Fig. B). Skin tissue sections were analyzed by hematoxylin and eosin staining or by immunohistochemistry. The skin of both types of replacement mice appeared equivalent and normal compared with wild-type skin (Fig. 1A and Fig. B, data not shown). In both cases, there were abundant hair follicles correctly oriented in the hypodermis and the epidermides were of normal thickness. No aberrations could be observed in any layers of the epidermis in either type of replacement mouse. In addition, there was no evidence of blistering in the basal layer.


The functional diversity of epidermal keratins revealed by the partial rescue of the keratin 14 phenotype by keratin 16.

Paladini RD, Coulombe PA - J. Cell Biol. (1999)

Light microscopy analysis and transgene expression in replacement skin. 7-d-old trunk skin was fixed, embedded in paraffin, and 5-μm sections were stained with hematoxylin and eosin (H & E) or subjected to immunohistochemistry using the HRP procedure. H & E staining of K16 (A) and K16-C14 (B) replacement skin. Both epidermides featured a normal cellular morphology along with multiple anagen staged hair follicles. There were no detectable differences when compared with wild-type 7-d-old epidermis (data not shown). (C–F) Transgene detection. The K16 transgene protein was detected using the 1275 antibody (C) and was restricted to the basal layer of the epidermis and the outer root sheath of the hair follicle. The K16-C14 transgene protein was detected (F) using the LL001 antibody and showed the same distribution. There was no detection of K16 in the K16-C14 replacement sample (D) and there was no detection of K14 in the K16 replacement sample (E). (G and H) Both samples were also stained with an antibody against K10. K10 expression was detected throughout the suprabasal layers of the epidermis in both the K16 (G) and K16-C14 (H) samples indicating that there is no evidence of abnormal differentiation. Hf, hair follicle. Arrowheads, demarcate the dermal-epidermal junction. Asterisks, melanin granules in hair follicle profiles. Bar, 100 μm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2169494&req=5

Figure 1: Light microscopy analysis and transgene expression in replacement skin. 7-d-old trunk skin was fixed, embedded in paraffin, and 5-μm sections were stained with hematoxylin and eosin (H & E) or subjected to immunohistochemistry using the HRP procedure. H & E staining of K16 (A) and K16-C14 (B) replacement skin. Both epidermides featured a normal cellular morphology along with multiple anagen staged hair follicles. There were no detectable differences when compared with wild-type 7-d-old epidermis (data not shown). (C–F) Transgene detection. The K16 transgene protein was detected using the 1275 antibody (C) and was restricted to the basal layer of the epidermis and the outer root sheath of the hair follicle. The K16-C14 transgene protein was detected (F) using the LL001 antibody and showed the same distribution. There was no detection of K16 in the K16-C14 replacement sample (D) and there was no detection of K14 in the K16 replacement sample (E). (G and H) Both samples were also stained with an antibody against K10. K10 expression was detected throughout the suprabasal layers of the epidermis in both the K16 (G) and K16-C14 (H) samples indicating that there is no evidence of abnormal differentiation. Hf, hair follicle. Arrowheads, demarcate the dermal-epidermal junction. Asterisks, melanin granules in hair follicle profiles. Bar, 100 μm.
Mentions: The hyperproliferative phenotype of the K16 ectopic mice is most severe ∼7 d after birth 39. To determine if there were any comparable morphological or molecular aberrations at the same age in the replacement mice, trunk skin from 7-d-old K16 and K16-C14 replacement mice was examined by light microscopy (Fig. 1A and Fig. B). Skin tissue sections were analyzed by hematoxylin and eosin staining or by immunohistochemistry. The skin of both types of replacement mice appeared equivalent and normal compared with wild-type skin (Fig. 1A and Fig. B, data not shown). In both cases, there were abundant hair follicles correctly oriented in the hypodermis and the epidermides were of normal thickness. No aberrations could be observed in any layers of the epidermis in either type of replacement mouse. In addition, there was no evidence of blistering in the basal layer.

Bottom Line: Degenstein, E.Fuchs. 1995.Despite their high sequence similarity, K16 and K14 are not functionally equivalent in the epidermis and other stratified epithelia and it is primarily the carboxy-terminal approximately 105 amino acids of K16 that define these differences.

View Article: PubMed Central - PubMed

Affiliation: Departments of Biological Chemistry and Dermatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

ABSTRACT
The type I epidermal keratins K14 and K16 are remarkably similar at the primary sequence level. While a structural function has been clearly defined for K14, we have proposed that a function of K16 may be to play a role in the process of keratinocyte activation that occurs after acute injury to stratified epithelia. To compare directly the functions of the two keratins we have targeted the expression of the human K16 cDNA to the progenitor basal layer of the epidermis of K14 mice. Mice for K14 blister extensively and die approximately 2 d after birth (Lloyd, C., Q.C. Yu, J. Cheng, K. Turksen, L. Degenstein, E. Hutton, and E. Fuchs. 1995. J. Cell Biol. 129:1329-1344). The skin of mice expressing K16 in the absence of K14 developed normally without evidence of blistering. However, as the mice aged they featured extensive alopecia, chronic epidermal ulcers in areas of frequent physical contact, and alterations in other stratified epithelia. Mice expressing a control K16-C14 cDNA also rescue the blistering phenotype of the K14 mice with only a small percentage exhibiting minor alopecia. While K16 is capable of rescuing the blistering, phenotypic complementation in the resulting skin is incomplete due to the multiple age dependent anomalies. Despite their high sequence similarity, K16 and K14 are not functionally equivalent in the epidermis and other stratified epithelia and it is primarily the carboxy-terminal approximately 105 amino acids of K16 that define these differences.

Show MeSH
Related in: MedlinePlus