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8.A.172.  The α-Crystallin Chaperone (CryA) Family 

Lens epithelial cells are the parental cells responsible for growth and development of the transparent ocular lens. Factors that initiate and regulate lens epithelial cell differentiation have been well characterized (Andley 2008). They serve key transport and cell maintenance functions and are the primary source of metabolic activity in the lens. The molecular chaperones, the α-crystallins, are abundant proteins. Besides their important roles in the refractive and light focusing properties of the lens, alpha-crystallins have been implicated in a number of non-refractive pathways including those involving stress response, apoptosis and cell survival. Evidence for their importance in the lens epithelium resulted from studies on the properties of lens epithelial cells from alphaA and alphaB-crystallin gene knockout mice (Andley 2008).

Among the transport proteins known to depend on α-crystallins are the Na+ channel, Nav1.5 (Nguyen et al. 2021), mitochondrial electron transport (Alam et al. 2020), amyloid-beta aggregation (Ren et al. 2020), members of the TREK‑TRAAK K2P channel family (including TREK‑1, TREK‑2 and TRAAK) (Huang et al. 2018), the Wilson Disease copper ATPase, ATP7B, (Allocca et al. 2018), the muscle calcium ATPase, SERCA (Dremina et al. 2012), and many others.

References associated with 8.A.172 family:

Alam, S., C.S. Abdullah, R. Aishwarya, M. Morshed, S.S. Nitu, S. Miriyala, M. Panchatcharam, C.G. Kevil, A.W. Orr, and M.S. Bhuiyan. (2020). Dysfunctional Mitochondrial Dynamic and Oxidative Phosphorylation Precedes Cardiac Dysfunction in R120G-αB-Crystallin-Induced Desmin-Related Cardiomyopathy. J Am Heart Assoc 9: e017195. 33208022
Allocca, S., M. Ciano, M.C. Ciardulli, C. D''Ambrosio, A. Scaloni, D. Sarnataro, M.G. Caporaso, M. D''Agostino, and S. Bonatti. (2018). An αB-Crystallin Peptide Rescues Compartmentalization and Trafficking Response to Cu Overload of ATP7B-H1069Q, the Most Frequent Cause of Wilson Disease in the Caucasian Population. Int J Mol Sci 19:. 29954118
Andley, U.P. (2008). The lens epithelium: focus on the expression and function of the α-crystallin chaperones. Int J Biochem. Cell Biol. 40: 317-323. 18093866
Dremina, E.S., V.S. Sharov, and C. Schöneich. (2012). Heat-shock proteins attenuate SERCA inactivation by the anti-apoptotic protein Bcl-2: possible implications for the ER Ca2+-mediated apoptosis. Biochem. J. 444: 127-139. 22360692
Huang, H., H. Li, K. Shi, L. Wang, X. Zhang, and X. Zhu. (2018). TREK‑TRAAK two‑pore domain potassium channels protect human retinal pigment epithelium cells from oxidative stress. Int J Mol Med 42: 2584-2594. 30106090
Nguyen, L.K.C., A. Shimizu, J.E.C. Soh, M. Komeno, A. Sato, and H. Ogita. (2021). Transmembrane protein 168 mutation reduces cardiomyocyte cell surface expression of Nav1.5 through αB-crystallin intracellular dynamics. J Biochem. [Epub: Ahead of Print] 34086898
Reddy, V.S. and G.B. Reddy. (2015). Emerging role for αB-crystallin as a therapeutic agent: pros and cons. Curr Mol Med 15: 47-61. 25601468
Ren, Z., Z. Dong, P. Xie, J. Lv, Y. Hu, Z. Guan, C. Zhang, and W. Yu. (2020). PNU282987 inhibits amyloid‑β aggregation by upregulating astrocytic endogenous αB‑crystallin and HSP‑70 via regulation of the α7AChR, PI3K/Akt/HSF‑1 signaling axis. Mol Med Rep 22: 201-208. 32377707
Thornell, E. and A. Aquilina. (2015). Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis. Cell Mol Life Sci 72: 4127-4137. 26210153