High impact information on MDK

• HB-GAM/pleiotrophin but not RIHB/midkine enhances chondrogenesis in micromass culture [1].
• We have characterized the binding of 125I-labeled RIHB to embryonal chondrocytes in culture [2].
• Retinoic acid-induced heparin binding protein (RIHB) is a highly basic, secreted polypeptide expressed during early chick embryogenesis [2].
• The binding can also be almost completely inhibited by preincubation of the 125I-labeled RIHB with heparin or with a monoclonal antibody which recognizes the heparin binding site of both RIHB and HBNF [2].
• These results demonstrate that RIHB binds to embryonal chondrocytes and cartilage primarily through proteoglycans of both heparan sulfate and chondroitin sulfate types [2].

Biological context of MDK

• Northern blot analysis indicates that RI-HB mRNA is strongly expressed during early chicken embryogenesis and that it is induced by retinoic acid treatment of chicken fibroblasts and myotubes in culture [3].
• We have now isolated genomic clones of the chicken RIHB gene, determined its transcription initiation sites, characterized its promoter region and established the functional activity of the RIHB gene promoter [4].
• Retinoic acid induced heparin-binding protein expression and localization during gastrulation, neurulation, and organogenesis [5].

Anatomical context of MDK

• This new retinoic acid induced heparin binding protein (RI-HB) does stimulate neurite outgrowth and proliferation on PC12 cells [6].
• We have examined the induction of RIHB by retinoic acid in chondrocytes isolated from the sterna of Day 15 chick embryos and the effects of exogenous RIHB on these cells [7].
• During neurulation RIHB is observed in the basement membrane surrounding the neural fold and the notochord, and in the lamina separating the ectodermal, mesodermal, and endodermal layers [5].
• Later in development, RIHB is detected in the basement membrane under the epidermis, throughout the developing limbs, and in the lamina of various developing organs, such as the eye, the pulmonary bud, the intestine, and the mesonephros [5].
• Retinoic acid induced heparin-binding protein (RIHB) is a highly basic, soluble polypeptide of the chick embryonic extracellular matrix [5].

Associations of MDK with chemical compounds

• Analysis of the promoter activity suggests an indirect regulation of transcription by retinoic acid and demonstrates a high degree of complexity of the regulation of the RIHB gene [4].
• Retinoic acid-induced heparin-binding factor (RIHB) is a highly basic polypeptide expressed during early chick embryogenesis [7].
• Retinoic acid-induced heparin binding (RIHB, chicken midkine) factor expression by cultured chondrocytes is strongly enhanced by ascorbic acid [8].
• RIHB is a 121 amino acid secreted polypeptide, rich in basic and cysteine residues (Vigny et al., Eur. J. Biochem. 186: 733-740, 1989) [9].

Analytical, diagnostic and therapeutic context of MDK

• We have examined the expression and localization of RIHB during very early embryogenesis by in situ hybridization and immunohistochemistry [5].

References