Heat Shock Protein 90α Research Articles

A subunit gIV vaccine, produced by transfected mammalian cells in culture, induces mucosal immunity against bovine herpesvirus-1 in cattle

A truncated version of bovine herpesvirus-1 (BHV-1) glycoprotein IV (tgIV) was produced in a novel, non-destructive expression system based upon regulation of gene expression by the bovine heat-shock protein 70A (hsp70) gene promoter in Madin Darby bovine kidney (MDBK) cells. In this system, up to 20 micrograms ml-1 of secreted tgIV, which is equivalent to the yield from 4 x 10(6) cells, was produced daily over a period of up to 18 days. Different doses of tgIV were injected intramuscularly into seronegative calves. Virus-neutralizing antibodies were induced by all doses of tgIV, both in the serum and in the nasal superficial mucosa. However, the low dose (2.3 micrograms) induced significantly (p < 0.05) lower antibody titres than the medium (7 micrograms) and high (21 micrograms) doses. The medium and high doses of tgIV conferred protection from BHV-1 infection, as demonstrated by a significant (p < 0.05) reduction in clinical signs of respiratory disease and virus shedding in the nasal secretions postchallenge. However, the 2.3 micrograms group, although partially protected, was not significantly (p > 0.05) different from the placebo group. This study demonstrated the potential of an intramuscularly administered tgIV subunit vaccine to induce mucosal immunity to BHV-1 using an economic protein production system and an acceptable vaccine formulation. In addition, a strong correlation was observed between neutralizing antibodies in the serum and nasal superficial mucosa, virus shedding and clinical disease. Thus, serum neutralizing antibody levels in tgIV-immunized animals may be a good prognosticator of protection from BHV-1 infection and disease.

Induction of HSP90α heat shock mRNA after transient global ischemia in gerbil hippocampus

Distribution of heat shock protein (HSP) 90α mRNA induction after 10 min of transient global ischemia was investigated in gerbil hippocampus by in situ hybridization. A small amount of HSP90α mRNA was normally present in hippocampal cells and the mRNA was further induced with a peak at 8 h after ischemia. In hippocampal CA1 cells that are vulnerable to ischemia, HSP90α mRNA was continuously induced by 1 day and finally diminished at 2 days. The temporal profile of HSP90α mRNA induction in hippocampal CA1 cells was similar to that of HSP70 mRNA reported previously, suggesting a cooperative role of HSP90α with other HSPs after ischemia.

Growth stimulating activity of heat shock protein 90α to lymphoid cell lines in serum-free medium

A growth stimulating factor was purified from the culture supernatant of human-human hybridoma SH-76 cells in serum-free RPMI 1640 medium by the serial use of DEAE anion and heparin affinity chromatographies. The factor was a 85 kDa protein on SDS-polyacrylamide gel electrophoresis. N-terminal amino acid sequence (PEETQTQDQPME) of the protein was coincident with that of heat shock protein 90 alpha (HSP90 alpha). The protein reacted with anti-HSP90 monoclonal antibody. These results suggest that the protein was a member of HSP90 alpha family after taking other circumstantial evidence into account. The protein stimulated the growth of some lymphoid cell lines such as human B-lymphoblastoid cell line HO-323-3 hybridomas derived from HO-323, and several other lymphoid cell lines. There were several lymphoid cell lines which did not respond to the protein. Growth stimulating activity of the protein was heat-unstable and significantly decreased at above 60 degrees C. These are the first data that describe growth-stimulating activity of heat shock protein 90 alpha.

High constitutive expression of heat shock protein 90α in human acute leukemia cells

The constitutive expression of the genes for four heat shock proteins (hsps) was studied in leukemia cell lines, cells obtained from patients with acute leukemia, and normal blood cells by means of Northern-blot analysis. Western-blot analysis with hsp90 antibody showed that the leukemia cells contained larger amounts of hsp90 than the normal peripheral mononuclear cells. The expression of the hsp90α gene was enhanced in the leukemia cell lines and the acute leukemia cells from patients as compared with the normal blood cells. In contrast, the expression of the hsp90β gene could hardly be recognized in either the acute leukemia cells or the normal blood cells. An increased expression of hsp70 gene was observed in only one patient. The expression of the hsp27 gene was enhanced in one-half the patients with common acute lymphoblastic leukemia. Thus, exclusively the hsp90α gene was expressed highly in the leukemia cells, indicating its association with cellular proliferation.

Mapping of the gene family for human heat-shock protein 90α to chromosomes 1, 4, 11, and 14

The HSP90 family of heat-shock proteins (encoded by genes for HSP90α and β) constitutes one of the major groups of proteins that are synthesized at increased rates in response to heat and other forms of stress. We previously isolated two distinct cDNA clones for HSP90α from human peripheral blood lymphocytes and from HeLa cells transfected with the adenovirus E1A gene, respectively. To determine the organization of this complex multigene family in the human genome, we used three complementary approaches: Southern analysis of a panel of human/hamster somatic cell hybrids, molecular cloning of the cosmid HSP90α clones from libraries prepared with DNAs from human lymphoblastoid cells, and in situ hybridization to human chromosomes. We demonstrate here that nucleotide sequences that encode HSP90α map to human chromosomes 1q21.2–q22, 4q35, 11p14.1–p14.2, and 14q32.3. The chromosomal mapping of the loci, HSPCAL1, HSPCAL2, HSPCAL3, HSPCAL4, and the characterization of the respective genes should facilitate clarification of the organization of this gene family and lead to a better understanding of the biological functions of the gene product.