scholarly journals Role of Heat-Shock Proteins in Cellular Function and in the Biology of Fungi

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Shraddha Tiwari ◽  
Raman Thakur ◽  
Jata Shankar
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Posttranslational Modifications ◽  
Biological Processes ◽  
Current Review ◽  
Hsp60 Expression ◽  
Response To Stress ◽  
Aggregation And Disaggregation ◽  
Shock Proteins

Stress (biotic or abiotic) is an unfavourable condition for an organism including fungus. To overcome stress, organism expresses heat-shock proteins (Hsps) or chaperons to perform biological function. Hsps are involved in various routine biological processes such as transcription, translation and posttranslational modifications, protein folding, and aggregation and disaggregation of proteins. Thus, it is important to understand holistic role of Hsps in response to stress and other biological conditions in fungi. Hsp104, Hsp70, and Hsp40 are found predominant in replication and Hsp90 is found in transcriptional and posttranscriptional process. Hsp90 and Hsp70 in combination or alone play a major role in morphogenesis and dimorphism. Heat stress in fungi expresses Hsp60, Hsp90, Hsp104, Hsp30, and Hsp10 proteins, whereas expression of Hsp12 protein was observed in response to cold stress. Hsp30, Hsp70, and Hsp90 proteins showed expression in response to pH stress. Osmotic stress is controlled by small heat-shock proteins and Hsp60. Expression of Hsp104 is observed under high pressure conditions. Out of these heat-shock proteins, Hsp90 has been predicted as a potential antifungal target due to its role in morphogenesis. Thus, current review focuses on role of Hsps in fungi during morphogenesis and various stress conditions (temperature, pH, and osmotic pressure) and in antifungal drug tolerance.

ORF-C4 from the early branching eukaryote Giardia lamblia displays characteristics of α-crystallin small heat-shock proteins

2008 ◽  
Vol 29 (1) ◽  
pp. 25-34 ◽  
Author(s):  
María J. Nores ◽  
César G. Prucca ◽  
Rodrigo Quiroga ◽  
Eliana V. Elías ◽  
Lucas Cavallín ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Giardia Lamblia ◽  
Protozoan Parasite ◽  
Small Heat Shock Proteins ◽  
Reading Frame ◽  
Response To Stress ◽  
Shock Proteins ◽  
Basal Position

Giardia lamblia is a medically important protozoan parasite with a basal position in the eukaryotic lineage and is an interesting model to explain the evolution of biochemical events in eukaryotic cells. G. lamblia trophozoites undergo significant changes in order to survive outside the intestine of their host by differentiating into infective cysts. In the present study, we characterize the previously identified Orf-C4 (G. lamblia open reading frame C4) gene, which is considered to be specific to G. lamblia. It encodes a 22 kDa protein that assembles into high-molecular-mass complexes during the entire life cycle of the parasite. ORF-C4 localizes to the cytoplasm of trophozoites and cysts, and forms large spherical aggregates when overexpressed. ORF-C4 overexpression and down-regulation do not affect trophozoite viability; however, differentiation into cysts is slightly delayed when the expression of ORF-C4 is down-regulated. In addition, ORF-C4 protein expression is modified under specific stress-inducing conditions. Neither orthologous proteins nor conserved domains are found in databases by conventional sequence analysis of the predicted protein. However, ORF-C4 contains a region which is similar structurally to the α-crystallin domain of sHsps (small heat-shock proteins). In the present study, we show the potential role of ORF-C4 as a small chaperone which is involved in the response to stress (including encystation) in G. lamblia.

scholarly journals Induction of mitochondrial heat shock proteins and mitochondrial biogenesis in endothelial cells upon acute methylglyoxal stress: Evidence for hormetic autofeedback

2021 ◽  
Author(s):  
Ruben Bulkescher ◽  
Thomas Fleming ◽  
Claus Rodemer ◽  
Rebekka Medert ◽  
Marc Freichel ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Mitochondrial Biogenesis ◽  
Metabolic Flux ◽  
Metabolic Stress ◽  
Oxidative Capacity ◽  
Mitochondrial Proteins ◽  
Shock Proteins

Increased metabolic flux produces potentially harmful side-products, such as reactive dicarbonyl and oxygen species. The reactive dicarbonly methylglyoxal (MG) can impair oxidative capacity, which is downregulated in type 2 diabetes. Heat shock proteins (HSPs) of subfamily A (Hsp70s) promote ATP-dependent processing of damaged proteins during MG exposure which also involve mitochondrial proteins. Since the protection of mitochondrial proteins could promote higher production of reactive metabolites due to increased substrate flux, tight regulation of HspA-mediated protein handling is important. We hypothesized that stress-inducible HspAs (HspA1A/HspA1B) are pivotal for maintaining mitochondrial biogenesis during acute MG-stress. To analyze the role of stress-inducible HspA1A/HspA1B for maintenance of mitochondrial homeostasis during acute MG exposure, we knocked out HSPA1A/HSPA1B in mouse endothelial cells. HSPA1A/HSPA1B KO cells showed upregulation of the mitochondrial chaperones HspA9 (mitochondrial Hsp70/mortalin) and HspD1 (Hsp60) as well as induction of mitochondrial biogenesis upon MG exposure. Increased mitochondrial biogenesis was reflected by elevated mitochondrial branching, total count and area as well as by upregulation of mitochondrial proteins and corresponding transcription factors. Our findings suggest that mitochondrial HspA9 and HspD1 promote mitochondrial biogenesis during acute MG stress, which is counterregulated by HspA1A/HspA1B to prevent mitochondrial overstimulation and to maintain balanced oxidative capacity under metabolic stress conditions. These data support an important role of HSPs in MG-induced hormesis.

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