Unique mouse monoclonal antibodies reactive with maturation-related epitopes on type VII collagen

In this study, we generated a new set of monoclonal antibodies (mAbs) to bovine and human type VII collagen (COL7) by immunizing mice with bovine cornea-derived basement membrane zone (BMZ) fraction. The four mAbs, tentatively named as COL7-like mAbs, showed speckled subepidermal staining in addition to linear BMZ staining of normal human skin and bovine cornea, a characteristic immunofluorescence feature of COL7, but showed no reactivity with COL7 by in vitro biochemical analyses. Taking advantage of the phenomenon that COL7-like mAbs did not react with mouse BMZ, we compared immunofluorescence reactivity between wild-type and COL7-rescued humanized mice and found that COL7-like mAbs reacted with BMZ of COL7-rescued humanized mice. In ELISAs, COL7-like mAbs reacted with intact triple-helical mammalian recombinant protein (RP) of COL7 but not with bacterial RP. Furthermore, COL7-like mAbs did not react with COL7 within either cultured DJM-1 cells or basal cells of skin of a bullous dermolysis of the newborn patient. These results confirmed that COL7-like mAbs reacted with human and bovine COL7. The epitopes for COL7-like mAbs were considered to be present only on mature COL7 after secretion from keratinocytes and deposition to BMZ and to be easily destroyed during immunoblotting procedure. Additional studies indicated association of the speckled subepidermal staining with both type IV collagen and elastin. These unique anti-COL7 mAbs should be useful in studies of both normal and diseased conditions, particularly dystrophic epidermolysis bullosa, which produces only immature COL7.

Epidermal nevi with aberrant epidermal structure in keratinocytes and melanocytes

Epidermal nevi are congenital cutaneous hamartomas caused by embryonic somatic mutations. Ultrastructural features of adult epidermal nevi have rarely been investigated. Herein, we report a case involving a Japanese adult who had epidermal nevi with right congenital blindness and a right accessory nipple. The histopathologic and ultrastructural studies showed divergent abnormal epidermal structures in both melanocytes and keratinocytes. Our case indicates the need to further investigate histopathologic, ultrastructural, and genetic associations in adult epidermal nevi.

Structure and expression of a novel fibroblast growth factor, FGF-17, preferentially expressed in the embryonic brain

We isolated the cDNA encoding a novel member (216 amino acids) of the fibroblast growth factor (FGF) family from rat embryos. As this protein is the 17th documented member of the FGF family, we tentatively termed it FGF-17. We have also determined the structures of mouse and human FGF-17 with high amino acid identity (100 and 98.6%) to rat FGF-17, respectively. Among FGF family members, FGF-17 is most similar (53.7% amino acid identity) to FGF-8. FGF-17 has a typical signal sequence at its amino terminus. As expected, recombinant rat FGF-17 was efficiently secreted by High Five insect cells infected with recombinant baculovirus containing the cDNA indicating that FGF-17 is a secreted protein. FGF-17 mRNA of approximately 2.1 kb was detected in rat embryos at E14.5, but not at E10.5 and E19.5 by Northern analysis. The mRNA was found to be preferentially expressed in the neuroepithelia of the isthmus and septum of the rat embryonic brain at E14.5 by in situ hybridization. The present results indicate that FGF-17 might be a novel secreted signaling molecule in the induction and patterning of the embryonic brain.