Hsp20 Explained

The heat shock protein Hsp20 family, also known as small heat shock proteins (sHSPs), is a family of heat shock proteins.

Prokaryotic and eukaryotic organisms respond to heat shock or other environmental stress by inducing the synthesis of proteins collectively known as heat-shock proteins (hsp).^[1] Amongst them is a family of proteins with an average molecular weight of 20 kDa, known as the hsp20 proteins.^[2] These seem to act as protein chaperones that can protect other proteins against heat-induced denaturation and aggregation. Hsp20 proteins seem to form large heterooligomeric aggregates. Structurally, this family is characterised by the presence of a conserved C-terminal domain, alpha-crystallin domain, of about 100 residues. Recently, small heat shock proteins (sHSPs) were found in marine viruses (cyanophages).^[3]

Function and regulation

Hsp20, like all heat shock proteins, is in abundance when cells are under stressed conditions.^[4] Hsp20 is known to be expressed in many human tissues, including the brain and heart.^[5] Hsp20 has been studied extensively in cardiac myocytes and is known to act as a chaperon protein, binding to protein kinase 1 (PDK1) and allowing its nuclear transport.^[6] In addition, the phosphorylation of hsp20 has been shown to effect the structure of cells cytoskeletons.^[7] Due to hsp20 commonly forming dimers with itself when heated, its function of chaperoning can be greatly affected.^[8]

Human small heat shock proteins

• HSPB1
• HSPB2
• HSPB3
• HSPB4 (CRYAA)
• HSPB5 (CRYAB)
• HSPB6
• HSPB7
  • HSPB8 HSPB9
• HSPB10

Notes and References

1. Lindquist S, Craig EA . The heat-shock proteins . Annu. Rev. Genet. . 22 . 631–677 . 1988 . 2853609 . 10.1146/annurev.ge.22.120188.003215 .
2. Merck KB, de Jong WW, Bloemendal H, Groenen PJ . Structure and modifications of the junior chaperone alpha-crystallin. From lens transparency to molecular pathology . Eur. J. Biochem. . 225 . 1 . 1–9 . 1994 . 7925426 . 10.1111/j.1432-1033.1994.00001.x. free .
3. Maaroufi H, Tanguay RM . Analysis and phylogeny of small heat shock proteins from marine viruses and their cyanobacteria host. . PLOS ONE . 8 . 11 . e81207 . 2013 . 24265841 . 10.1371/journal.pone.0081207 . 3827213. 2013PLoSO...881207M . free .
4. LI. D.C.. Lan. Fan. Chen. Dian-Fu. Yang. Wei-Jun. Lu. Bo. Thermotolerance and molecular chaperone function of the small heat shock protein HSP20 from hyperthermophilic archaeon, Sulfolobus solfataricus P2. 3227843. 21853411. 10.1007/s12192-011-0289-z. 17. 1. Cell Stress & Chaperones. 103–8. 2012.
5. G.C. Fan. G. Chu. EG. Kranies. Hsp20 and its cardioprotection. 16099377. 10.1016/j.tcm.2005.05.004. 15. 4. May 2005. Trends Cardiovasc. Med.. 138–41.
6. Yan Sin. Yuan. Currie. Susan. P Martin. Lauren. Wills. Tamara. S Baillie. George. Small heat shock protein 20 (Hsp20) facilitates nuclear import of protein kinase D 1 (PKD1) during cardiac hypertrophy. 4356135. 25889640. 10.1186/s12964-015-0094-x. 13. Cell Commun Signal. 16. 2015 . free .
7. M. Dreiza. Catherine. M. Brophy. Colleen. Komalavilas. Padmini. J. Furnish. Elizabeth. Joshi. Lokesh. A. Pallero. Manuel. E. Murphy-Ullrich. Joanne. von Rechenberg. Moritz. J. Ho. Yew-Seng. Richardson. Bonnie. Xu. Nafei. Zhen. Yuejun. M. Peltier. John. Panitch. Alyssa. Transducible heat shock protein 20 (HSP20) phosphopeptide alters cytoskeletal dynamics. The FASEB Journal. 19. 2. 261–263. 10.1096/fj.04-2911fje. 15598710. 2005. free . 28781928.
8. van Montfort. RL. Basha. E. Friedrich. KL. Slingsby. C. Vierling. E. Crystal structure and assembly of a eukaryotic small heat shock protein. Nature Structural Biology. 8. 12. 1025–1030. 10.1038/nsb722. 11702068. 2001. 618916.