title: Molecular identification of the skin transformation center of anuran larval skin using genes of Rana adult keratin (RAK) and SPARC as probes.
abstract: Anuran larval skin undergoes a process of metamorphosis into pre-adult and adult skin. Basal skein, larval basal and adult basal cells are basement membrane-attaching cells in the larval, pre-adult and adult epidermis, respectively, and are identified as cells expressing genes of RLK (Rana larval keratin), both RLK and RAK (Rana adult keratin), and RAK. Larval to pre-adult skin conversion takes place in the histological entity called the skin transformation center (STC). The present study performed a cDNA subtractive gene screening on cDNA of the larval and the pre-adult skin, and cloned the secreted protein acidic and rich in cysteine (SPARC) gene as an upregulated gene in the larva to pre-adult skin conversion. RAK gene-positive basal skein cells and fibroblasts in and around the STC were weakly and strongly sparc-positive, respectively. Using sparc and rak, we redefined the STC and visualized it on a histological section as an approximately 150 microm-long region that contained about 20 rak-negative and weakly sparc-positive basal cells. Intense sparc expression was observed in basal skein cells, but not in larval basal cells, suggesting that SPARC acts as a suppressor of rak during epidermal differentiation. This suggestion was tested by investigating the effect of SPARC on cultured larval basal cells. We observed that SPARC suppressed the expression of rak, but not rlk.
authors.affiliation: Laboratory of Developmental Biology, Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1, Kagamiyama, Higashihiroshima, 739-8526, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ishida
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Suzuki
authors.forename: Rie
authors.initials: R
authors.lastname: Utoh
authors.forename: Masanobu
authors.initials: M
authors.lastname: Obara
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Yoshizato
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura; D002454:Cell Differentiation; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004817:Epidermis / Q000196:embryology*; D004847:Epithelial Cells / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D015723:Gene Library; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007633:Keratins / Q000235:genetics*; D008648:Mesoderm / Q000166:cytology; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000494:pharmacology*; D015676:Osteonectin / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D011892:Rana catesbeiana; D012867:Skin / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D015345:Oligonucleotide Probes; D015676:Osteonectin; D012333:RNA, Messenger; D007633:Keratins