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Hair follicle has a novel anagen-specific protein, mKAP13
Abstract:
To identify the anagen hair follicle-specific proteins, we screened the cDNA library prepared from the murine skins of anagen phase by the differential hybridization technique. Fifty-four cDNA clones expressed specifically in anagen phase were isolated, and most were found to correspond to known proteins in the hair follicles. Alternatively, we isolated a cDNA clone encoding a novel protein that possessed an entire open reading frame of 501 base pairs. This protein with a molecular weight of 17.9 kDa has no specific motifs nor significant homology to proteins already reported, although it contains some direct repeats that are often observed in intermediate filament-associated proteins and has a similar amino acid composition as a member of them. Northern blot analysis demonstrates that the transcript of this protein is skin specific, and that it is present in mid- and late anagen but not in catagen, telogen, and early anagen phases. The transcript appears to be expressed specifically in the keratogenous zone of the cortical cells of hair follicles, as exhibited by in situ hybridization. Furthermore, immunohistochemical study confirms that the protein is distributed in the cytoplasms of the keratinizing cortical cells and is undetected in the completely keratinized ones. These results suggest that this protein can be identified as a new member of intermediate filament-associated proteins and is related to the keratinization of the cortical cell layer in mouse hair. Therefore, we have termed this novel protein mKAP13 according to the unified nomenclature.
Insights
Researchers identified a novel protein, mKAP13, specific to the anagen phase of mouse hair follicle development. This protein is involved in the keratinization process of hair cortical cells.
Area of Science:
- Molecular Biology
- Dermatology
- Biochemistry
Background:
- Hair follicle cycling involves distinct phases, including anagen (growth).
- Identifying phase-specific proteins is crucial for understanding hair biology and developing targeted therapies.
- Previous studies have identified numerous hair follicle proteins, but novel candidates continue to emerge.
Purpose of the Study:
- To identify novel proteins specifically expressed during the anagen phase of murine hair follicles.
- To characterize the expression pattern and potential function of a newly discovered protein.
Main Methods:
- Differential hybridization screening of a murine anagen hair follicle cDNA library.
- Northern blot analysis to assess transcript expression across hair cycle phases.
- In situ hybridization to determine precise tissue localization.
- Immunohistochemical analysis to confirm protein distribution within hair follicles.
Main Results:
- Fifty-four anagen-specific cDNA clones were isolated, mostly corresponding to known proteins.
- A novel cDNA clone encoding a 17.9 kDa protein (mKAP13) was identified.
- mKAP13 transcript is skin-specific and expressed only during mid- and late-anagen phases.
- The transcript is localized to the keratogenous zone of hair follicle cortical cells.
- mKAP13 protein is found in the cytoplasm of keratinizing cortical cells, absent in fully keratinized cells.
Conclusions:
- mKAP13 is a novel intermediate filament-associated protein.
- mKAP13 plays a role in the keratinization of mouse hair cortical cells.
- This discovery contributes to the understanding of hair follicle development and differentiation.