title: High TMEM45A expression is correlated to epidermal keratinization.
abstract: TMEM45A (DERP7, DNAPTP4 or FLJ10134) gene, belonging to the TMEM family encoding predicted transmembrane proteins, is highly expressed in epidermal keratinocytes. To investigate the potential involvement of TMEM45A during the differentiation and keratinization processes, its expression has been characterized in normal human keratinocytes and the protein subcellular localization has been studied in this cell type, both in vitro and in vivo. TMEM45A expression is upregulated with differentiation, either induced by cultured keratinocyte confluence or enhanced Ca(2+) concentration in medium. In vivo, TMEM45A mRNA and protein are mostly found in the granular layer of the epidermis. TMEM45A expression is linked to keratinization, as accumulation of the protein is detected in native and reconstructed epidermis as well as in thymic Hassal bodies, but not in non-keratinized stratified epithelia. At the subcellular level, co-detection with ER and Golgi markers reveals that TM protein 45A is associated with the Golgi apparatus and more specifically with the trans-Golgi/trans-Golgi network in vitro and in granular layer in vivo. The protein is neither related to lysosomes nor transported within corneodesmosin-containing lamellar bodies. These data demonstrate a strong correlation between TMEM45A expression and epidermal keratinization, indicating the relevance of this gene in this process.
authors.affiliation: Cell and Tissue Laboratory-URPhyM-NARILIS, University of Namur, Namur, Belgium.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Hayez
authors.forename: Jérémy
authors.initials: J
authors.lastname: Malaisse
authors.forename: Edith
authors.initials: E
authors.lastname: Roegiers
authors.forename: Marie
authors.initials: M
authors.lastname: Reynier
authors.forename: Chantal
authors.initials: C
authors.lastname: Renard
authors.forename: Marek
authors.initials: M
authors.lastname: Haftek
authors.forename: Vincent
authors.initials: V
authors.lastname: Geenen
authors.forename: Guy
authors.initials: G
authors.lastname: Serre
authors.forename: Michel
authors.initials: M
authors.lastname: Simon
authors.forename: Catherine Lambert
authors.initials: CL
authors.lastname: de Rouvroit
authors.forename: Carine
authors.initials: C
authors.lastname: Michiels
authors.forename: Yves
authors.initials: Y
authors.lastname: Poumay
mesh_terms: D002118:Calcium / Q000737:chemistry; D002454:Cell Differentiation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism*; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D007633:Keratins / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012867:Skin / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D012333:RNA, Messenger; C581204:TMEM45A protein, human; D007633:Keratins; D002118:Calcium
keywords: Golgi apparatus; epidermis; granular layer; keratinization; keratinocyte