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Crystallin, alpha A

Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrate eye lens and maintains the transparency and refractive index of the lens. Since lens central fiber cells lose their nuclei during development, these crystallins are made and then retained throughout life, making them extremely stable proteins. Mammalian lens crystallins are divided into alpha, beta, and gamma families; beta and gamma crystallins are also considered as a superfamily. Alpha and beta families are further divided into acidic and basic groups. Seven protein regions exist in crystallins: four homologous motifs, a connecting peptide, and N- and C-terminal extensions. Alpha crystallins are composed of two gene products: alpha-A and alpha-B, for acidic and basic, respectively. Alpha crystallins can be induced by heat shock and are members of the small heat shock protein (sHSP also known as the HSP20) family. They act as molecular chaperones although they do not renature proteins and release them in the fashion of a true chaperone; instead they hold them in large soluble aggregates. Post-translational modifications decrease the ability to chaperone. These heterogeneous aggregates consist of 30-40 subunits; the alpha-A and alpha-B subunits have a 3:1 ratio, respectively. Two additional functions of alpha crystallins are an autokinase activity and participation in the intracellular architecture. Alpha-A and alpha-B gene products are differentially expressed; alpha-A is preferentially restricted to the lens and alpha-B is expressed widely in many tissues and organs. Defects in this gene cause autosomal dominant congenital cataract (ADCC). [provided by RefSeq, Jul 2008] (from NCBI)
Top mentioned proteins: alphaB-crystallin, HAD, AGE, CAE, ACID
Papers on CRYAA
Regulation of c-Maf and αA-crystallin in Ocular Lens by FGF Signaling.
Cvekl et al., United States. In J Biol Chem, Jan 2016
Previously, we have shown that the bZIP proto-oncogene c-Maf regulates expression of αA-crystallin (Cryaa) through binding to its promoter and distal enhancer, DCR1, both activated by FGF2 in cell culture.
Novel mutations in CRYGD are associated with congenital cataracts in Chinese families.
Zhao et al., Beijing, China. In Sci Rep, Dec 2015
Mutation analysis was performed by direct sequencing of the following candidate genes: CRYGC, CRYGD, CRYGS, GJA8, GJA3 and CRYAA.
Mutation analysis of the genes associated with anterior segment dysgenesis, microcornea and microphthalmia in 257 patients with glaucoma.
Zhang et al., Guangzhou, China. In Int J Mol Med, Oct 2015
Of the 27, 6 were identified in BEST1, 4 in EYA1, 3 in GDF6, 2 in BMP4, 2 in CRYBA4, 2 in HCCS, and 1 in each of CRYAA, CRYGC, CRYGD, COL4A1, FOXC1, GJA8, PITX2 and SHH.
Extracellular α-crystallin protects astrocytes from cell death through activation of MAPK, PI3K/Akt signaling pathway and blockade of ROS release from mitochondria.
Reiser et al., Magdeburg, Germany. In Brain Res, Oct 2015
α-Crystallin with two isoforms, αA-crystallin (HSPB4) and αB-crystallin (HSPB5), is found in eye lens, spleen, lung, kidney, cornea, skin, but also in brain.
Mutation analysis of two families with inherited congenital cataracts.
Jie et al., Beijing, China. In Mol Med Report, Sep 2015
Green fluorescent protein‑tagged human wild‑type CRYAA and GJA8 were sub‑cloned, and the mutants were generated by site‑directed mutagenesis.
Phenotypes of Recessive Pediatric Cataract in a Cohort of Children with Identified Homozygous Gene Mutations (An American Ophthalmological Society Thesis).
Alkuraya et al., Riyadh, Saudi Arabia. In Trans Am Ophthalmol Soc, Sep 2015
The remaining 12 families each had mutations in 12 different genes (CRYAA, CRYBA1, AKR1E2, AGK, BFSP2, CYP27A1, CYP51A1, EPHA2, GCNT2, LONP1, RNLS, WDR87) with unique phenotypes noted for CYP27A1 (bilateral juvenile fleck with anterior and/or posterior capsular cataract and later cerebrotendinous xanthomatosis), EPHA2 (bilateral anterior persistent fetal vasculature), and BFSP2 (bilateral flecklike with cloudy cortex).
Exome Sequencing and Epigenetic Analysis of Twins Who Are Discordant for Congenital Cataract.
Yan et al., Wuhan, China. In Twin Res Hum Genet, Aug 2015
METHODS: A patient with a congenital cataract and her twin sister were assessed for genetic factors that might contribute to their discordant phenotypes by mutation screening of 11 candidate genes (CRYGC, CRYGD, CRYAA, CRYAB, CRYBA1, CRYBB1, CRYBB2, MIP, HSF4, GJA3, and GJA8), exome analysis followed by Sanger sequencing of 10 additional candidate genes (PLEKHO2, FRYL, RBP3, P2RX2, GSR, TRAM1, VEGFA, NARS2, CADPS, and TEKT4), and promoter methylation analysis of five representative genes (TRAM1, CRYAA, HSF4, VEGFA, GJA3, DCT) plus one additional candidate gene (FTL).
Rescue of αB Crystallin (HSPB5) Mutants Associated Protein Aggregation by Co-Expression of HSPB5 Partners.
Kampinga et al., Groningen, Netherlands. In Plos One, 2014
Of all members, co-expression of HSPB1, HSPB4 and HSPB5 itself, most effectively prevent the aggregation of these 3 HSPB5 mutants.
A novel 3-base pair deletion of the CRYAA gene identified in a large Chinese pedigree featuring autosomal dominant congenital perinuclear cataract.
Yang et al., Zhengzhou, China. In Genet Mol Res, 2014
Potential mutations in the candidate gene alpha A crystallin (CRYAA) were screened.
Circulating Autoantibodies in Age-Related Macular Degeneration Recognize Human Macular Tissue Antigens Implicated in Autophagy, Immunomodulation, and Protection from Oxidative Stress and Apoptosis.
Health ABC study et al., Winston-Salem, United States. In Plos One, 2014
Following immunoprecipitation, 2D-GE and LC-MS/MS, five of the possible autoreactivity targets were conclusively identified: two members of the heat shock protein 70 (HSP70) family, HSPA8 and HSPA9; another member of the HSP family, HSPB4, also known as alpha-crystallin A chain (CRYAA); Annexin A5 (ANXA5); and Protein S100-A9, also known as calgranulin B that, when complexed with S100A8, forms calprotectin.
Mutations of small heat shock proteins and human congenital diseases.
Gusev et al., Moscow, Russia. In Biochemistry (mosc), 2012
Mutations of HspB4 are described and data on involvement of these mutations in development of cataract are presented.
Transcriptional regulation of small HSP-HSF1 and beyond.
Mezger et al., Dijon, France. In Int J Biochem Cell Biol, 2012
Although historically linked to the heat shock transcription factors (HSFs), the stress-induced or developmental expression of the diverse members, including HSPB1/Hsp27/Hsp25, αA-crystallin/HSPB4, and αB-crystallin/HSPB5, relies on the combinatory effects of many transcription factors.
sHSP in the eye lens: crystallin mutations, cataract and proteostasis.
Slingsby et al., London, United Kingdom. In Int J Biochem Cell Biol, 2012
Dominant missense mutations to the "α-crystallin domain" of αA- (HSPB4) or αB-crystallin (HSPB5) occur on residues predicted to facilitate domain dynamics.
Identification of the HSPB4/TLR2/NF-κB axis in macrophage as a therapeutic target for sterile inflammation of the cornea.
Prockop et al., Temple, United States. In Embo Mol Med, 2012
The Phase II inflammation was responsible for vision-threatening opacity and was markedly suppressed by different means of inhibition of the HSPB4/TLR2/NF-kappaB axis.
Hydroimidazolone modification of the conserved Arg12 in small heat shock proteins: studies on the structure and chaperone function using mutant mimics.
Biswas et al., Cleveland, United States. In Plos One, 2011
Data show that among the three small heat shock proteins, Hsp27, alphaA- and alphaB-crystallin, the R12A mutation improved the chaperone function of only alphaA-crystallin.
The thermal structural transition of alpha-crystallin modulates subunit interactions and increases protein solubility.
Papi et al., Roma, Italy. In Plos One, 2011
The decrease of both Deltamu and gamma at Tc, and a relative increase in solubility, reveal a significative decrease in the strenght of alpha-crystallin subunits interactions, which protects from supramolecolar condensation in hypertermic conditions
Mutations in human αA-crystallin/sHSP affect subunit exchange interaction with αB-crystallin.
Abraham et al., Little Rock, United States. In Plos One, 2011
interaction of the mutants of alphaA-crystallin with alphaB-crystallin was studied. The subunit exchange rates of R21W and R116C with alphaB-wt decreased drastically as compared to alphaA-wt interacting with alphaB-wt.
Cataract-causing defect of a mutant γ-crystallin proceeds through an aggregation pathway which bypasses recognition by the α-crystallin chaperone.
King et al., Cambridge, United States. In Plos One, 2011
The perturbed conformation of human gamma-crystallin D, I90F mutant, was recognized and bound by both alpha-crystallin A and alpha-crystallin B chaperones.
Expression and functions of heat shock proteins in the normal and pathological mammalian eye.
Simon et al., Villeurbanne, France. In Curr Mol Med, 2010
These proteins, particularly those belonging to the family of small Hsps, such as αA-crystallin (HspB4) and αB-crystallin (HspB5), play important roles in the differentiation of lens cells and are essential for the maintenance and protection of the supraorganization of proteins in differentiated corneal and lens fiber cells.
[Progress in pathogenic genes and their functions of congenital cataract].
Cheng et al., Beijing, China. In Zhonghua Yan Ke Za Zhi, 2010
Currently, at least 22 specific genes associated with isolated inherited cataract have been identified: ten crystallin genes: CRYAA, CRYAB, CRYBA1/A3, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, CRYGS; 4 membrane protein genes: GJA3, GJA8, MIP, LIM2; three growth and transcription factor genes: PITX3, MAF, HSF4; two cytoskeletal protein gene: BSFP1, BSFP2; chromatin modifying protein-4B gene: CHMP4B, EPHA2 and NHS, it is likely that more genes remain to be discovered.
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