Disease relevance of Hspa9

• To address the inherent problem of serological cross-reactivity among the hsp70 family members, an influenza virus hemagglutinin epitope tag was introduced into the PBP74 cDNA [1].

High impact information on Hspa9

• By confocal microscopy, PBP74 was localized to cytoplasmic vesicles but not to the nucleus, mitochondria, or plasma membrane by using antibodies specific for the N-terminal 16 residues of PBP74 [2].
• Here we report the cloning and sequencing of the cDNA encoding PBP74 in mice and in humans, accomplished by using amino acid sequence information obtained from the purified protein [2].
• Inactivation of tumor suppressor p53 by mot-2, a hsp70 family member [3].
• Transfection of mot-2 but not mot-1 resulted in the repression of p53-mediated transactivation in p53-responsive reporter assays [3].
• Inactivation of p53 by mot-2 was supported by the down-regulation of p53-responsive genes p21(WAF-1) and mdm-2 in mot-2-transfected cells only [3].

Biological context of Hspa9

• Furthermore, NIH 3T3 cells transfected with expression plasmid encoding green fluorescent protein-tagged mot-2 but not mot-1 showed an abrogation of nuclear translocation of wild-type p53 [3].
• The new heat shock protein has a molecular mass of 75 kDa and has been designated as Grp75, PBP74, CSA or p66mot-1 in mice and humans with purported roles in transformation and antigen processing [4].
• Mortalin: a potential candidate for biotechnology and biomedicine [5].
• Induction of cellular senescence by transfection of cytosolic mortalin cDNA in NIH 3T3 cells [6].
• Here, we report that the cytosolic (mot-1) and the perinuclear (mot-2) forms of mortalin cDNA cloned from mortal and immortal cells, respectively, differ by only two bases in the open reading frame, resulting in two amino acid changes [6].

Anatomical context of Hspa9

• After coupled transcription-translation the precursor of PBP74 is imported into isolated yeast mitochondria, where it becomes processed to the mature protein [1].
• Here we report the mortalin immunostaining observations on 21 human cell lines [7].
• Differential subcellular distribution of mortalin in mortal and immortal mouse and human fibroblasts [8].
• Four patterns of mortalin immunostaining were observed: granular-juxtanuclear cap, granular-gradient from nuclear to cell membrane, granular-juxtanuclear arch, and fibrous-perinuclear [7].
• The mRNA for GRP75, a mitochondrial chaperone, HSC70, a cytoplasmic chaperone, protein disulfide isomerase, an endoplasmic reticulum chaperone, and C/EBPalpha, a transcription factor, was not regulated [9].

Associations of Hspa9 with chemical compounds

• It was also cloned as glucose regulated protein, GRP75 and peptidebinding protein, PBP74 [5].
• Western blot analysis indicates that one out of these two residues, arginine at residue 578 in the PBP74/CSA sequence of C3H mouse, contributes to the immunogenicity of CSA [10].
• These six oxidation-sensitive proteins were identified by mass spectrometry as glial fibrillary acidic protein, creatine kinase BB, disulfide isomerase, chaperonin subunit 5, dihydropyrimidase-related protein 2, and mortalin [11].
• Conversely, when phosphorylated mortalin was treated with tyrosine phosphatase, its interaction with FGF-1 was abrogated [12].
• Interestingly, mortalin was preferentially tyrosine phosphorylated at the same time, and when its normally weak phosphorylation in early G1 phase was augmented by treating the cells with vanadate, a strong interaction between mortalin and FGF-1 was established [12].

Physical interactions of Hspa9

• An N-terminal region of mot-2 binds to p53 in vitro [13].
• We previously reported that endogenously expressed, intracellularly localized fibroblast growth factor (FGF)-1 interacts with mortalin [12].

Regulatory relationships of Hspa9

• Cell-cycle dependent tyrosine phosphorylation on mortalin regulates its interaction with fibroblast growth factor-1 [12].

Other interactions of Hspa9

• Western analyses of transient and stable clones revealed that upregulation of p21WAF1 in stable NIH 3T3/mot-2 cells may be mediated by cyclin D1 and cdk-2 [14].
• Our results show that mortalin and HisRS genes, which map closely to the Egr1 locus, have conserved the 129/Sv haplotype despite numerous back-crossing of the null mice progeny with C57Bl/6J animals [15].
• Finally, we report the identification of new isoforms of HisRS and mortalin (mot-3) encoded by the 129/Sv haplotype [15].

Analytical, diagnostic and therapeutic context of Hspa9

• By confocal immunofluorescence microscopy PBP74 is detected in mitochondria, colocalizing with the mitochondrial 60-kDa heat shock protein [1].
• Cell fractionation studies demonstrated PBP74 in purified mitochondria in a protease-protected location [1].
• To determine the genetic relation between the pancytosolic (uniformly distributed in cytoplasm-p66mot-1) and the perinuclear (p66mot-2) mortalin proteins found in normal and immortal mouse cells, respectively, we initiated the present study using PCR cloning, sequencing, and single nucleotide primer extension analyses [16].
• In the present study, we report mot-2 cDNA cloning from RS-4 cells--an immortal clone from CD1-ICR mouse embryonic fibroblasts--and the chromosomal assignments of mortalin related genes to mouse chromosomes 18 and X by fluorescence in situ hybridization [17].
• We describe here the use of quantum dots in mortalin imaging of normal and cancer cells [18].

References