Disease relevance of Crybb2

• Using rat epsilon BP cDNA, we have succeeded in expressing recombinant epsilon BP in Escherichia coli [1].
• Influenza virus A/Phil/82 (H3N2) grew to significantly higher titers in the lungs of diabetic than nondiabetic mice [2].
• We chose to study the effects of loss of GH signaling on growth and aging in a mouse model for Laron Syndrome (LS) in which the GHR/BP gene has been disrupted [3].
• In their study Philp and coworkers address the issue of the effect of 17beta-estradiol on ventricular vulnerability in a rat model of ischemia [4].
• While mutations in betaB2-crystallin are known to result in lens opacities, alterations in tissues besides the lens have not been previously investigated in these mutants [5].

High impact information on Crybb2

• To create a mammalian model for this disease, we generated mice bearing a disrupted GHR/binding protein (GHR/BP) gene through a homologous gene targeting approach [6].
• The purified r epsilon BP exhibits binding activity to various saccharides, with affinity for N-acetyllactosamine greater than thiodigalactoside greater than lactose much greater than D-galactose greater than L-arabinose, an order identical to that exhibited by native epsilon BP isolated from RBL cells [1].
• Although epsilon BP shares sequence homology to other lectins containing S-type (thiol-dependent) carbohydrate-recognition domains, r epsilon BP is resistant to air oxidation and does not require reducing agents for maintaining its activity [1].
• The availability of a source for a large quantity of epsilon BP should facilitate the analysis of biological function(s) and structure-activity relationships of this lectin [1].
• More recently, CBP35 (epsilon BP) was found to be equivalent to Mac-2, a surface marker on activated macrophages [1].

Biological context of Crybb2

• Two of them are lens fiber cell structural proteins: the Cryba1 locus encoding crystallinbetaA3/A1 maps to chromosome 11, 2.5 +/- 2.5 cM distal to D11Mit31, and the Crybb2 locus encoding crystallinbetaB2 maps to chromosome 5, 9.1 +/- 4.3 cM distal to D5Mit88 [7].
• Sequence, initial functional analysis and protein-DNA binding sites of the mouse beta B2-crystallin-encoding gene [8].
• An 800-bp fragment of genomic DNA upstream from the origin of transcription of the mouse beta B2-crystallin-encoding gene (beta B2-Cry) has been isolated and its nucleotide sequence determined [8].
• The epsilon BP gene is composed of six exons separated by five introns [9].
• This alternative splicing results in different 5' untranslated regions of the murine epsilon BP mRNA [9].

Anatomical context of Crybb2

• Surprisingly, blot hybridization analysis of RNA from nine various normal rat tissues showed that the epsilon BP gene is transcribed in all the tissues tested as well as in a mouse macrophage-like cell line [10].
• We show that IgE-binding protein (epsilon BP) is found primarily in the cytoplasm of rat basophilic leukemia (RBL) cells and COS-1 cells transfected with epsilon BP cDNA [10].
• RESULTS: In the mouse testis, betaB2-crystallin mRNA is found at low levels at birth, but its expression upregulates in this tissue as the testis is primed to initiate spermatogenesis [5].
• To characterize alternative 5'UTR usage in mouse GHR/BP mRNA, we carried out 5' rapid amplification of cDNA ends using RNA from non-pregnant mouse liver and adipose tissue [11].
• Western blotting detected betaB2-crystallin protein in sperm obtained from mice, cattle, and humans while immunolocalization detected this protein in developing sperm from the spermatocyte stage onward [5].

Associations of Crybb2 with chemical compounds

• Milligram quantities of homogeneous epsilon BP could be obtained from bacterial lysate in a one-step affinity purification procedure utilizing lactosyl-Sepharose 4B and elution with a lactose gradient [1].
• To elucidate the novel WNK1 BP control pathway active in distal nephron, WNK1 expression in mouse was studied [12].
• Glucose is a ligand for SP-D, and neutralization of A/Phil/82 virus by SP-D was abolished in the presence of glucose at levels commonly found in diabetic mice [2].

Analytical, diagnostic and therapeutic context of Crybb2

• Sequence analysis revealed a mutation of T-->A at position 553 in the Crybb2 gene, leading to an exchange of Val for GLU: It affects the same region of the Crybb2 gene as in the Philly mouse [13].
• The sequence of the mutant beta B2 was analyzed against the reported structure of the normal bovine beta B2-crystallin determined by x-ray crystallography [14].
• The energetics of betaA3- and betaB2-crystallin association was studied using site-directed mutagenesis and analytical ultracentrifugation [15].
• Antibodies to a synthetic peptide internal to epsilon BP were generated that specifically recognized epsilon BP by protein immunoblotting [10].
• Recombinant mouse betaB2-crystallin has an estimated monomer molecular weight of 24 kDa by SDS-PAGE, appropriate immunoreactivity and appropriate secondary structure as assessed by circular dichroism analysis [16].

References