title: Expression of microfibril-associated glycoprotein-1 (MAGP-1) in human epidermal keratinocytes.
abstract: Microfibril-associated glycoprotein (MAGP) is a major structural component of connective tissue microfibrils. We studied the expression of MAGP-1 in cultured human keratinocytes and its modulation during Ca(++)-induced differentiation. RT-PCR and Western blot assays demonstrated the presence of mRNA and the polypeptide of MAGP-1 in cultured keratinocytes. MAGP-1 mRNA levels in cultured keratinocytes during Ca(++)-induced differentiation were enhanced eightfold with a concomitant increase in involucrin (a marker of terminal differentiation) mRNA levels. Double immunofluorescence labeling of cultured keratinocytes demonstrated that both anti-MAGP-1 and anti-involucrin antibodies reacted with the identical cells. The population of MAGP-1-producing cells in cultured keratinocytes significantly increased during Ca(++)-induced differentiation. These results indicate that MAGP-1 expressed by cultured keratinocytes reaches maximum levels at the stage of terminal differentiation in vitro. Double immunostaining of normal human skin with anti-MAGP-1 and anti-elastin antibodies demonstrated the colocalization of MAGP-1-positive and elastin-positive fibers in the superficial and mid-dermis. MAGP-1 produced by keratinocytes may play some functional role in the formation of dermal matrix organization in the dermis.
authors.affiliation: Department of Dermatology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Fujimoto
authors.forename: S
authors.initials: S
authors.lastname: Tajima
authors.forename: A
authors.initials: A
authors.lastname: Ishibashi
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000032:analysis / Q000235:genetics*; D000078404:Epidermal Cells; D016326:Extracellular Matrix Proteins; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000737:chemistry / Q000166:cytology
chemical_list: D003285:Contractile Proteins; D016326:Extracellular Matrix Proteins; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; C016598:microfibrillar protein; D002122:Calcium Chloride