| Research Abstract |
We have cloned eleven novel cDNAs in full length of mouse and human HSP40/DNAJ homologs using EST (expressed sequence tag) clones in the DDBJ/GenBank/EMBL DNA database. In this report, we tentatively designated them mHsp40, mDj3, mmDjA4, mDj4, mDj5, mDj6, mDj7, mDj8, hDj9, mDj10 and mDj11. Based on the identity of deduced amino acid sequences, mHsp40, mDj3 and mDj11 are orthologs of human Hsp40, rat Rdj2 and human Tpr2, respectively. We determined that mDj4 is identical with the recently isolated mouse Mrj (mammalian relative of Dnaj). PSORT analysis revealed that hDj9 (human) has an N-terminal signal peptide and its localization might be extracellular, suggesting that there may be a partner Hsp70 protein which act together with the hDj8 outside of the cell. mDj7 and mDj10 may have transmembrane domains.
We also propose here a new rule for the nomenclature of mammalian HSP40/DNAJ homologs, in order to simplify the complicated and confusing nomenclature of recently identified homologs. The proposed nomenclature includes 1) name of species with two lowercase letters such as hs (human), mm (mouse) and rn (rat), 2) Dj standing for DnaJ, 3) the name of types with A, B and C, which were previously classified as type I, II and III according to the domain structure of the homologs, and finally 4) Arabic numerals according to the chronological order of registration of the sequence data into the database.
Spinal and bulbar muscular atrophy (SBMA) is inherited neurodegenerative disease and one of the triplet repeat diseases. It is cause by the expansion of an unstable CAG repeat in the coding region of androgen receptor (AR). Here, we demonstrated the inhibitory effect of molecular chaperones (Hsp70 and Hsp40) on the aggregate formation of mutant AR.
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