Disease relevance of HSP90B1

• The complete nucleotide sequence for a chicken heat shock protein (hsp108) was determined from cDNA clones isolated from hen oviduct and bursal lymphoma recombinant DNA libraries [1].
• HSP108 was expressed in the ganglion cell layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, inner segments of photoreceptors and retinal pigment epithelium [2].

High impact information on HSP90B1

• All these properties taken together strongly suggest that the estrogen-inducible membrane glycoprotein is a novel transferrin-binding protein, structurally related to the stress-regulated proteins [3].
• The nucleotide sequence codes for peptides present in hsp108 as determined by protein microsequencing [1].
• In another paper, evidence is presented that hsp108 shows a high degree of amino acid sequence homology with two heat shock proteins, hsp90 (yeast) and hsp83 (Drosophila), and is indeed inducible by heat shock [Sargan, D. R., Tsai, M.-J., & O'Malley, B. W. (1986) Biochemistry (following paper in this issue)] [1].
• Immunohistochemical techniques were used in conjunction with an avian-specific probe for oligodendrocyte (OLG) marker, the antibody for transferrin binding protein (TfBP), to study the characteristics and distribution of OLGs in the retina of chickens and quails [4].
• Transferrin binding protein (TfBP) is a glycoprotein originally purified from chicken oviduct that exhibits transferrin binding activity [5].

Biological context of HSP90B1

• These results suggest that HSP108 expression might be developmentally regulated throughout eye organogenesis and that it plays a role in ocular development [6].
• Heat shock protein gene HSP108 and a replication histone gene cluster are linked in the chicken [7].
• In work aimed at extending the chicken genome linkage map, a heat shock protein gene, HSP108, was shown by restriction fragment length polymorphism (RFLP) analysis to be linked to one of two replication histone gene clusters located on chromosome 1 [7].

Anatomical context of HSP90B1

• Distribution of transferrin binding protein immunoreactivity in the chicken central and peripheral nervous systems [5].
• HSP108 mRNAs were found to be mainly localized in the small neuroglial cells of various regions of the brain, although some neuronal cells also showed positive signals [8].
• A competition assay, based on the binding of 125I-Fe-OTf to liver membranes, was utilized to examine the binding specificity of HSP108 [9].
• This tendency is observed to be more marked in the cerebellum; HSP108 signals were not found in the Purkinje cells, but in Bergmann glial cells and oligodendrocytes [8].
• The constitutive expression of heat shock protein 108 (HSP108) mRNA is mapped in a normal chicken central nervous system using in situ hybridization technique [8].

Associations of HSP90B1 with chemical compounds

• Recent work has shown that TfBP is a post-translationally modified form of the heat shock protein (HSP108), the avian homologue of a glucose regulated protein, GRP94 [5].

Other interactions of HSP90B1

• We have demonstrated that transferrin binding protein (TfBP), ferritin, and iron, are specifically localized in Bergmann glia, while the transferrin receptor is confined to Purkinje cells in the chicken cerebellum [10].

Analytical, diagnostic and therapeutic context of HSP90B1

• The protein purified from oviduct by SDS-PAGE or from liver by ovotransferrin-affinity chromatography reacts with a monoclonal antibody raised against HSP108 [11].
• The developmental expression of heat shock protein 108 (HSP108) mRNA was mapped in chicken brain using in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR) [12].
• RT-PCR showed that HSP108 mRNA increased from embryonic day 5 (E5) to 13 (E13), significantly decreased from E17 to E21 and then increased again at the adult stage [12].
• The localization of HSP108 in embryonic days 15 (E15), E18, and postnatal day 2 (P2) chick retina was examined immunohistochemically using monoclonal antibody 9G10 specific for chick HSP108, while the expression levels of HSP108 in developing chick retina from E12 to P2 and adult were measured by Western blot analysis [2].

References