Premium
Identification of insulin‐like growth factor binding proteins from cultured human epidermal keratinocytes
Author(s) -
Murashita Mari M.,
Russo Vincenzo C.,
Edmondson Stephanie R.,
Wraight Christopher J.,
Werther George A.
Publication year - 1995
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041630215
Subject(s) - paracrine signalling , epidermal growth factor , growth factor , biology , receptor , insulin like growth factor binding protein , cell culture , keratinocyte , blot , immunoprecipitation , autocrine signalling , epidermal growth factor receptor , radioimmunoassay , microbiology and biotechnology , insulin like growth factor , endocrinology , medicine , biochemistry , gene , genetics
The role and mechanisms of action of insulin‐like growth factors (IGFs) in skin remain unclear. Epidermal keratinocytes possess IGF‐I receptors and are responsive to IGF‐I, which is primarily derived from underlying dermal fibroblasts. IGF binding proteins (IGFBPs), also synthesized by fibroblasts, may be involved in paracrine targeting of IGF‐I to its receptors. We therefore examined whether human keratinocytes synthesize IGFBPs and their mRNAs. Following culture in complete medium (containing bovine pituitary extract and epidermal growth factor) Western ligand blotting (WLB) of cell conditioned medium revealed a major band of 32 kD, a less abundant IGFBP of 24 kD at all passages, and a 37–42 kD IGFBP which increased in abundance in late passage. Immunoprecipitation followed by WLB confirmed that the predominant 32 kD band was IGFBP‐2. Radioimmunoassay of IGFBP‐1, ‐3, and ‐6 revealed detectable levels of IGFBP‐3 and significant levels of IGFBP‐6, but not IGFBP‐1. Northern analysis following culture in complete medium revealed that at early passage IGFBP‐1, ‐2, ‐4, and ‐6 mRNAs were detectable. IGFBP‐3 and ‐5 mRNAs were not detectable. Following culture in growth factor‐free medium a 37–42 kD band, consistent with IGFBP‐3, was predominant and a 24 kD band consistent with IGFBP‐4 was also present. These data demonstrate the expression of a distinct pattern of IGFBPs by cultured human keratinocytes dependent on culture conditions. Keratinocyte‐derived IGFBPs are likely to play a role in the transport and targeting of IGF‐I from dermally derived fibroblasts to the epidermis. © 1995 Wiley‐Liss, Inc.