Introduction
Heat shock protein is an intracellular protein present in human cells. The function of heat shock protein is to overcome stress. Some heat shock proteins are termed chaperones. In physiological stress, chaperones play a vital role in energy-dependent reactions. Heat shock proteins are proteins produced by cells as a response to stress.
What Are the Heat Shock Proteins?
Heat shock protein is an intracellular protein present in human cells. Heat shock proteins are expressed on exposure to cold, ultraviolet light, and tissue healing or remodeling. The regulation of the heat shock proteins is an important part of the heat shock reaction and is induced by the heat shock factor. Heat-shock proteins are named Hsp 60, Hsp 70, and Hsp 90. Rapid heating can harden cells and provide protection from higher temperatures.
How Are the Heat Shock Proteins Classified?
Heat shock proteins are classified into five groups based on their molecular weight, structure, and function. Heat shock protein 100, 90, 70, 60, and the small heat shock protein a-crystallins.
What Is the Function of Heat Shock Proteins?
Heat shock proteins function as chaperons in the refolding proteins, which are damaged due to heat stress. Production of heat shock proteins is triggered by stress conditions like infection, inflammation, exercise, harmful materials, ultraviolet light, starvation, hypoxia, nitrogen, and water deprivation. The following is the function of heat shock protein:
- Heat shock proteins are expressed as heat shock responses.
- Heat shock proteins help in the embryonic development of mammals.
- Regulation in a stressful situation.
- Fold and unfold proteins.
- Arrange multiprotein complexes.
- Control cell cycle and signaling.
- Protect cells against stress.
- Regulate heat shock proteins.
- Heat shock proteins as therapeutic targets.
How Are the Heat Shock Proteins Activated?
Due to stress produced by heat, outer membrane proteins cannot fold and insert into the outer membrane. These proteins accumulate in the periplasmic space. An increase in damaged proteins activated heat shock proteins. Heat-shock proteins monitor the regular cell proteins. Heat shock proteins transfer old proteins to the proteasome and help newly synthesized proteins fold well. This is called the "cellular stress response" or the "heat-shock response." Heat shock proteins are more susceptible to self-degradation because of their slow proteolytic action.
What Is the Clinical Significance of Heat Shock Proteins?
The heat shock factor helps in the maintenance and regulation of protein expression. Heat shock proteins modify the process of carcinogenesis. Heat shock proteins help in the following areas:
1. Cardiovascular:
Heat shock proteins have a significant cardiovascular role. Hsp 90 binds endothelial nitric oxide synthase and guanylate cyclase, which causes vascular relaxation. Hsp 27 is an important phosphoprotein during female contractions. Hsp 27 has a key role in small muscle migrations.
2. Immunity:
Heat-shock proteins bind whole proteins and peptides. This binding has a low affinity. Hsp stimulate immune receptors and are important in the proper folding of proteins which play an important role in inflammatory signaling pathways. The cancerous or infected cell produces proteins. Fragments of these proteins act as antigens and induce an immune response.
3. Antigen Presentation:
Hsp helps in antigen-presenting pathways, like cross pathways and autophagy.
Antigenic peptides are produced in the proteasome and transported through a protein transporter through the secretory pathway to the plasma membrane. Hsps plays an important part in the transfer of unfolded proteins to proteasomes.
4. Neurodegenerative Diseases:
- Heat shock proteins protect the neurons from adverse conditions.
- They can delay Parkinson's disease (a brain disorder causing uncontrolled movements) and Alzheimer's disease (a type of dementia that destroys one's memories) outcomes.
- They act as a therapeutic agent in neurodegenerative diseases.
5. Cancer:
Heat shock proteins help in the diagnosis, prognosis, and treatment of cancer. Hsp 90 helps in the folding of proteins in signaling pathways and helps in refolding denatured stressed proteins. Kinases involved in malignant transformation are stabilized by heat shock proteins.
6. Reproduction:
Germ cell development increases heat shock protein, and the proteins are produced in the growth of the embryo. Some Hsp (heat shock protein) plays an important role in spermatogenesis.
7. Transplantation:
Heat shock proteins have a role in allograft rejection and autoimmunity.
- Hsp 40 transfers a new amino acid chain to Hsp 70, which helps it to fold in its original form.
- Hsp 60 attracts unstructured amino acids or proteins and helps them acquire their original structure.
- Hsp 90 receives folded proteins and helps them merge into a large protein structure.
What Are the Applications of Heat Shock Proteins?
- Cancer Vaccines: Heat shock proteins are used as immunologic adjuvants as boosters to the vaccine. Heat shock proteins help in binding protein fragments from dead malignant cells and present an immune response. Heat shock proteins help to increase the effectiveness of vaccines. Isolated heat shock proteins act as anti-tumor vaccines. Tumor cells have heat shock proteins because they need to chaperone mutated oncogenes. Tumor cells are under constant stress. Heat shock proteins help stimulate the immune system.
- Anticancer Therapeutics: Intracellular heat shock proteins are present in cancer cells and are required for the survival of cancer cells because of mutated and over-expressed oncogenes. Heat shock proteins have the characteristics of invasiveness and metastasis. Heat shock proteins block apoptosis and are resistant to anticancer drugs.
- Autoimmunity Treatment: Heat shock proteins extracellularly produce autoimmune reactions. These reactions can cause diseases like rheumatoid arthritis or systemic lupus erythematosus. Heat shock proteins can increase immunity and help treat autoimmune diseases.
- Agriculture: Heat shock proteins have a role in stress tolerance in plants; they can help overcome drought and poor soil conditions for farming.
Conclusion
Heat-shock proteins have different functions, like chaperone activity, protein folding, apoptosis, autophagy, and immune response. The heat shock proteins have an effect on stimulating innate immune response via receptors. Heat shock proteins are involved in phagocytosis. Heat shock proteins enhance the antigen response through an endocytic pathway. Heat shock proteins are used in vaccines against infectious and noninfectious diseases. There is a correlation between heat shock proteins and drug resistance, which is still under research. Heat shock proteins are emerging as biomarkers for the detection of tumors. In short, heat shock proteins have a role in biochemical and immunological medicine.
