Heat Shock Protein Family B (small) member 7 (HSPB7) in humans is a protein encoded by a gene of the same name with four exons that is located on chromosome 1p36.13.[4],.[5] HSPB7 contains 170 amino acids and has a molecular weight of 18,611Da.[6] HSPB7 is a member of human small heat shock protein (HSPB) family, which contains eleven family members of chaperone proteins.[7] HSPB7 and its gene pair SRARP are located 5 kb apart on the opposite strands of chromosome 1p36.13.[8]
Expression and molecular function[]
HSPB7 is widely expressed throughout the body and its highest expression is observed in the cardiac tissue [7],.[9] HSPB protein family, including HSPB7, act protectively on aggregation of several proteins containing an extended polyglutamine (polyQ) stretch that are linked to a variety of neurodegenerative diseases.[10] Among these proteins, HSPB7 is the most potent polyQ aggregation suppressor within the HSPB family of chaperones.[10] In addition, HSPB7 protein contains a HSP20 domain and strongly interacts with the chaperone protein 14-3-3.[8] An interaction with the 14-3-3 protein is a common molecular feature between HSPB7 and SRARP proteins [8],[11]
Role in cardiomyopathy and Cancer[]
HSPB7 has cardiac protective functions and mutations in this gene leads to cardiomyopathies.[10] It has been suggested that HSPB7 cardioprotective function is mediated by facilitating sarcomericproteostasis.[12] Furthermore, HSPB7 is widely inactivated in malignancies by copy-number loss and epigenetic silencing and the overexpression of this protein results in a tumor suppressor function in multiple cancercell lines[8],.[13] The overexpression of HSPB7 and its gene pair SRARP lead to a reduction in the relative phosphorylation and/or expression of Akt and ERK in cancer cells.[8] In addition, it has been suggested that HSBP7 is regulated by p53 tumor suppressor in renal cell carcinoma.[13]