An additional exon of stress-inducible heat shock protein 70 gene (HSP70-1)

Pattern of heat shock factor and heat shock protein expression in lymphocytes of bipolar patients: increased HSP70-glucocorticoid receptor heterocomplex

Bipolar disorder (BD), a stress-related disease, is characterized by altered glucocorticoid receptor (GR) signalling. Stress response includes activation of heat shock factor (HSF) and subsequent heat shock protein (HSP) synthesis which regulate GR folding and function. The objective of this study was to investigate the possible role of HSFs, HSPs and their interaction with GR in BD. We applied immunoprecipitation, SDS-PAGE/Western blot analysis and electrophoretic mobility shift assay (EMSA) in lymphocytes (whole cell or nuclear extracts) from BD patients and healthy subjects and determined the HSPs (HSP90 and HSP70), the heterocomplexes HSP90-GR and HSP70-GR, the HSFs (HSF1 and HSF4) as well as the HSF-DNA binding. The HSP70-GR heterocomplex was elevated (p < 0.05) in BD patients vs healthy subjects, and nuclear HSP70 was reduced (p ≤ 0.01) in bipolar manic patients. Protein levels of HSF1, HSF4, HSP90, HSP90-GR heterocomplex, and HSF-DNA binding remained unaltered in BD patients vs healthy subjects. The corresponding effect sizes (ES) indicated a large ES for HSP70-GR, HSP70, HSF-DNA binding and HSF4, and a medium ES for HSP90, HSF1 and HSP90-GR between healthy subjects and bipolar patients. Significant correlations among HSFs, HSPs, GR and HSP70-GR heterocomplex were observed in healthy subjects, which were abrogated in bipolar patients. The higher interaction between GR and HSP70 and the disturbances in the relations among heat shock response parameters and GR as observed in our BD patients may provide novel insights into the contribution of these factors in BD aetiopathogenesis.

Complexity of Hsp90 in organelle targeting

Heat shock protein 90 (Hsp90) is an abundant and highly conserved molecular chaperone. In Arabidopsis, the Hsp90 gene family consists of seven members. Here, we report that the AtHsp90-6 gene gives rise to two mRNA populations, termed AtHsp90-6L and AtHsp90-6S due to alternative initiation of transcription. The AtHsp90-6L and AtHsp90-6S transcription start sites are located 228 nucleotides upstream and 124 nucleotides downstream of the annotated translation start site, respectively. Both transcripts are detected under normal or heat-shock conditions. The inducibility of AtHsp90-6 mRNAs by heat shock implies a potential role of both isoforms in stress management. Stable transformation experiments with fusion constructs between the N-terminal part of each AtHsp90-6 isoform and green fluorescent protein indicated import of both fusion proteins into mitochondria. In planta investigation confirmed that fusion of the AtHsp90-5 N-terminus to green fluorescent protein (GFP) did result in specific chloroplastic localization. The mechanisms of regulation for mitochondria- and plastid-localized chaperone-encoding genes are not well understood. Future work is needed to address the possible roles of harsh environmental conditions and developmental processes on fine-tuning and compartmentalization of the AtHsp90-6L, AtHsp90-6S, and AtHsp90-5 proteins in Arabidopsis.

Proposed multigenic Composite Inheritance in major depression

Various rationale have been considered in the familial inheritance pattern of major depression ranging from simple one-gene Mendelian inheritance to pseudo-additive gene action. We instead predict broad genetic expressivity patterns in the progeny of parents where at least one parent has recurrent major depression. In keeping with this idea, we feel that recurrent major depression could involve an expression imbalance of "normal" genes either exclusively or along with allelic variation(s). The patterns of pathology are theoretically conceptualized as qualitative and quantitative, meaning that expressivity of the genetic pattern in these children may range from minimal to complete even among siblings. Thus, prediction of the particular genetic pattern expressed by a particular child might prove difficult. The complex inheritance pattern that we propose is referred to as Composite Inheritance. Composite Inheritance considers that both the up- and down-regulation of luxury genes and housekeeping genes are involved in this dichotomous qualitative inheritance pattern and also the wide quantitative expressivity. The luxury genes include such genes as those coding for the neurotransmitter transporters and receptors. The housekeeping genes found to date include those that code for proteins involved in gene transcription, secondary signaling systems, fatty acid metabolism and transport, and intracellular calcium homeostasis. Other luxury and housekeeping genes no doubt remain to be discovered. Our current research utilizes an empirical approach involving advanced genomics and specialized pattern recognition mathematics in families having at least one parent with recurrent major depression. The goal of our research is to develop a pattern recognition system of genetic expressivity in major depression to which prevention and early intervention may be tailored.

Major depression and heat shock protein 70-1 gene

BACKGROUND

Heat shock protein (HSP) expression can be induced by any stress such as with adrenocorticotropic hormones and catecholamines. It has been reported that patients with major depression have a 162-base deletion in the 5'-flanking region of heat shock protein 70 (HSP70)-1 gene mRNA.

METHODS

To detect the HSP70-1 gene mRNA, total RNA was isolated and amplified by RT-PCR, and the sequence was confirmed in all five patients by DNA direct sequencing analysis.

RESULTS

RT-PCR produced was no deletions of 162 bp in the human heat shock protein 70-1 gene in any of the patients with major depression or the nine controls.

CONCLUSION

This finding is inconsistent with previous reports. We suggest that the 162-base deletion in the 5'-flanking region of the HSP70-1 gene mRNA is not associated with major depression. Further studies are required to determine the amounts of HSP70 and its mRNA in stress disorders such as major depression.

Structure of gene flanking regions and functional analysis of sequences upstream of the rat hsp70.1 stress gene

We present structural and comparative analysis of the flanking regions of the rat hsp70.1 stress gene. Several repetitive sequences, microsatellites and short interspersed repetitive elements (SINEs) were found, as well as a significant gap in the 3' UTR, as compared to the orthologous mouse gene. We also show that the complex microsatellite region composed of partially overlapping inverted repeat and long homopurine-homopyrimidine sequence, which is localized 1.8 kbp upstream of the transcription start site, is capable to adopt non-B DNA structures (an H-DNA and a cruciform structure) in vitro. Functional analysis performed with the use of various fragments of the 5'end flanking regions ligated to the chloramphenicol acetyltransferase (CAT) reporter gene revealed a crucial role of cooperation between heat shock element (HSE) regulatory sequences, while none of the three HSEs alone is able to drive efficient heat induced transcription of the reporter gene. We also found that the microsatellite region does not influence transcription by itself, however, it abolishes the effect of the adjacent putative silencing element. To our knowledge, this is a first extensive structural and functional analysis of the promoter region of the mammalian heat inducible hsp70i gene localized distally to the hsp70-related spermatid-specific gene in the major histocompatibility complex III.