Review Advance Articles

Physiological and pathological functions of βB2-crystallins in multiple organs: a systematic review

Meihui Li1, *, , Shengnan Liu1, *, , Wei Huang1, , Junjie Zhang1, &, ,

  • 1 Department of Obstetrics and Gynecology, Changhai Hospital, Naval Military Medical University, Yangpu, Shanghai 200433, China
* Equal contribution

Received: February 10, 2021       Accepted: May 18, 2021       Published: June 11, 2021      

https://doi.org/10.18632/aging.203147
How to Cite

Copyright: © 2021 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Crystallins, the major constituent proteins of mammalian lenses, are significant not only for the maintenance of eye lens stability, transparency, and refraction, but also fulfill various physiopathological functions in extraocular tissues. βB2-crystallin, for example, is a multifunctional protein expressed in the human retina, brain, testis, ovary, and multiple tumors. Mutations in the βB2 crystallin gene or denaturation of βB2-crystallin protein are associated with cataracts, ocular pathologies, and psychiatric disorders. A prominent role for βB2-crystallins in axonal growth and regeneration, as well as in dendritic outgrowth, has been demonstrated after optic nerve injury. Studies in βB2-crystallin-null mice revealed morphological and functional abnormalities in testis and ovaries, indicating βB2-crystallin contributes to male and female fertility in mice. Interestingly, although pathogenic significance remains obscure, several studies identified a clear correlation between βB2 crystallin expression and the prognosis of patients with breast cancer, colorectal cancer, prostate cancer, renal cell carcinoma, and glioblastoma in the African American population. This review summarizes the physiological and pathological functions of βB2-crystallin in the eye and other organs and tissues and discusses findings related to the expression and potential role of βB2-crystallin in tumors.

Abbreviations

CRYBB2/Crybb2: βB2-crystallin; WNT: Wingless-related integration site; Tmsb4X: thymosin β4; RPE: retinal pigment epithelium; RGCs: retinal ganglion cells; CNTF: ciliary neurotrophic factor; CaMKIV: Ca2+/calmodulin-dependent protein kinase IV; Bcl-2: B-cell lymphoma 2; CDK4: Cyclin-dependent kinase 4; CCND2: G1/S-specific cyclin-D2; P2rx7: purinergic receptor P2X7; PSPHL: phospho serine phosphatase-like protein; EMT: epithelial-mesenchymal transition.