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CDK5 regulates cell–cell and cell–matrix adhesion in human keratinocytes
Author(s) -
Nakano N.,
Nakao A.,
Ishidoh K.,
Tsuboi R.,
Kominami E.,
Okumura K.,
Ogawa H.
Publication year - 2005
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.2005.06583.x
Subject(s) - hacat , cyclin dependent kinase 5 , microbiology and biotechnology , epidermis (zoology) , cell adhesion , keratinocyte , fibronectin , cyclin dependent kinase , integrin , cell adhesion molecule , biology , kinase , extracellular matrix , chemistry , cell culture , cell , protein kinase a , cell cycle , cyclin dependent kinase 2 , biochemistry , anatomy , genetics
Summary Background CDK5 is a member of proline‐directed serine/threonin kinases. Although its cDNA was originally cloned as a homologue to those for the other members of the cyclin‐dependent kinase (CDK) family, CDK5 has been shown to function differently from other CDKs. CDK5 is activated by non‐cyclin partners, p35 and p39, and important during brain development by influencing adhesion, migration and differentiation of neurones. Objectives We sought to investigate the expression and functions of CDK5 in human keratinocytes. Methods Expression of CDK5/p35, interaction of CDK5/p35 with adhesion molecules, and its roles in cell–cell and cell–matrix adhesion were studied by reverse transcriptase–polymerase chain reaction, immunoblotting and aggregation/adhesion assays in primary cultured normal human keratinocytes from infant foreskins and a human keratinocyte HaCaT cell line. Localization of CDK5 and p35 in normal human epidermis and psoriatic epidermis was studied by immunohistochemistry. Results Both CDK5 and p35 were expressed in primary cultured keratinocytes, HaCaT cells and normal human epidermis. Roscovitine, an inhibitor of CDK5, enhanced Ca 2+ ‐dependent (cadherin‐dependent) aggregation of HaCaT cells whereas it inhibited adhesion of HaCaT cells to fibronectin associated with reduced active states of β1 integrin. Interestingly, psoriatic skin showed reduced CDK5 and p35 expression in the lower half of the epidermis, which might be associated with decreased amount of activated β1 integrin in the epidermis of psoriatic skin. Conclusions CDK5/p35 may be involved in cell–cell and cell–matrix adhesion in human keratinocytes by differently regulating cadherins and integrins. Furthermore, reduced expression of CDK5/p35 in the epidermis might be involved in the pathogenesis of psoriasis.