High impact information on Dnajb3

• The deubiquitinating enzyme mUBPy interacts with the sperm-specific molecular chaperone MSJ-1: the relation with the proteasome, acrosome, and centrosome in mouse male germ cells [1].
• Protein interaction assays showed that sperm UBPy interacts with MSJ-1, the sperm-specific DnaJ protein evolutionarily conserved for spermiogenesis [1].
• In Rana esculenta testis, detection of high levels of MSJ-1 protein coincided with the appearance of postmeiotic germ cells during the annual sexual cycle [2].
• Msj-1 (mouse sperm cell-specific DnaJ first homologue) is a gene specifically expressed in germ cells at haploid stages [2].
• Here, we examined Msj-1 expression in the spinal cord of the mutants and their controls [3].

Anatomical context of Dnajb3

• mUBPy and MSJ-1, a deubiquitinating enzyme and a molecular chaperone specifically expressed in testis, associate with the acrosome and centrosome in mouse germ cells [4].
• The MSJ-1 gene encodes a murine DnaJ homologue that is expressed specifically in adult testis [5].
• Similarly, numbers of spermatids that stained by immunofluorescence for MSJ-1 appeared to be progressively reduced in adult +/+, +/wr, and wr/wr mouse testes, respectively [2].
• On the whole, our findings are consistent with a role for MSJ-1 in acrosome formation and centrosome adjustment during spermatid development, whereas its presence in mature spermatozoa suggests a special function during fertilization, shortly afterward, or both [5].
• MSJ-1 is also maintained in testicular and epididymal spermatozoa, where it sharply demarcates into two distinct cell areas; the outer surface of the acrosomal vesicle, and the centrosomal area [5].

Associations of Dnajb3 with chemical compounds

• However, androgen treatment did not affect MSJ-1 protein levels in either frogs or mice [2].
• The predicted protein, named MSJ-1, is 242 amino acid residues-long, containing the fingerprinting J domain in the NH2 terminus [6].

Physical interactions of Dnajb3

• MSJ-1 is able to interact with the testis-specific Hsp70-2 protein and can be coimmunoprecipitated with Hsp70-2 from spermatogenic cells; binding of these two chaperones is consistent with the presence of a third component, which is so far unknown [5].

Other interactions of Dnajb3

• This new member of the DnaJ family of 241 amino acid residues showed 94% identity with mouse Mrj (accession number, AF035962) and 71% identity with mouse Msj-1 (accession number, U95607) along its entire sequence [7].
• Hsp70-2, which is known to be highly expressed in meiotic cells, shows a subcellular localization in late differentiating spermatids that overlaps that of MSJ-1 [5].
• In a wide immunoscreening of mouse tissues, affinity-purified MSJ-1 antibodies recognize a unique protein of 30 kDa in male germ cells only [5].

Analytical, diagnostic and therapeutic context of Dnajb3

• A wide tissutal Northern blot analysis reveals that MSJ-1 is expressed only in the testis, while in situ hybridization analyses demonstrate that the mRNA is first transcribed in spermatids [6].
• Molecular cloning and developmental pattern of expression of MSJ-1, a new male germ cell-specific DNAJ homologue [6].

References