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Gene Review

DNAJB9  -  DnaJ (Hsp40) homolog, subfamily B, member 9

Homo sapiens

Synonyms: DnaJ homolog subfamily B member 9, ER-resident protein ERdj4, ERdj4, Endoplasmic reticulum DNA J domain-containing protein 4, MDG-1, ...
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High impact information on DNAJB9

  • We found that ERdj4 was highly induced at both the mRNA and protein level in response to ER stress, indicating that this protein might be involved in either protein folding or ER-associated degradation [1].
  • High levels of the molecular chaperone Mdg1/ERdj4 reflect the activation state of endothelial cells [2].
  • To elucidate the stimuli that induce ER stress and thus upregulate Mdg1/ERdj4, we investigated the effect of several endothelium specific stressors on its expression [2].
  • This indicates that Mdg1/ERdj4 protein has diverse mechanisms to protect stressed cells from apoptosis [2].
  • Mdg1/ERdj4, a mammalian chaperone that belongs to the HSP40 protein family, has been reported to be located in the endoplasmic reticulum (ER), is induced by ER stress, and protects ER stressed cells from apoptosis [2].

Biological context of DNAJB9


Anatomical context of DNAJB9

  • Microvascular differentiation gene 1 (Mdg1) has been isolated from differentiating microvascular endothelial cells that had been cultured in collagen type I gels (3D culture) [3].
  • In adult human tissue Mdg1 is expressed in endothelial and epithelial cells [3].
  • Mdg1 is also upregulated in primary endothelial and mesangial cells when subjected to various stress stimuli [3].

Analytical, diagnostic and therapeutic context of DNAJB9

  • Sequence analysis of the full-length cDNA revealed that the N-terminal region of the putative Mdg1-protein exhibits a high sequence similarity to the J-domain of Hsp40 chaperones [3].


  1. Identification and characterization of a novel endoplasmic reticulum (ER) DnaJ homologue, which stimulates ATPase activity of BiP in vitro and is induced by ER stress. Shen, Y., Meunier, L., Hendershot, L.M. J. Biol. Chem. (2002) [Pubmed]
  2. High levels of the molecular chaperone Mdg1/ERdj4 reflect the activation state of endothelial cells. Berger, B.J., Müller, T.S., Buschmann, I.R., Peters, K., Kirsch, M., Christ, B., Pröls, F. Exp. Cell Res. (2003) [Pubmed]
  3. Upregulation of the cochaperone Mdg1 in endothelial cells is induced by stress and during in vitro angiogenesis. Pröls, F., Mayer, M.P., Renner, O., Czarnecki, P.G., Ast, M., Gässler, C., Wilting, J., Kurz, H., Christ, B. Exp. Cell Res. (2001) [Pubmed]
  4. Assignment of the microvascular endothelial differentiation gene 1 (MDG1) to human chromosome band 14q24.2-->q24.3 by fluorescence in situ hybridization. Pröls, F., Liehr, T., Rinke, R., Rautenstrauss, B. Cytogenet. Cell Genet. (1997) [Pubmed]
  5. MDG1/ERdj4, an ER-resident DnaJ family member, suppresses cell death induced by ER stress. Kurisu, J., Honma, A., Miyajima, H., Kondo, S., Okumura, M., Imaizumi, K. Genes Cells (2003) [Pubmed]
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