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Variations in LOXL1 associated with exfoliation glaucoma do not affect amine oxidase activity.

Kim S, Kim Y - Mol. Vis. (2012)

Bottom Line: However, there were no significant differences in amine oxidase activity between the LOXL1 haplotype variants toward the tested substrates.The R141L and G153D variations in the NH(2)-terminal region of LOXL1 do not affect the amine oxidase activity of LOXL1.Our results suggest that other unknown genetic factors or molecular mechanisms may be more relevant to the development of XFG.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, School of Medicine, Wonkwang University, Sinyong-Dong 344-2, Iksan-City, Jeollabuk-Do 570-749, South Korea.

ABSTRACT

Purpose: Lysyl oxidase-like 1 (LOXL1) is a copper-dependant amine oxidase that plays an essential role in elastogenesis. Two non-synonymous single-nucleotide polymorphisms of LOXL1, R141L (rs1048661) and G153D (rs3825942), have been reported to significantly increase susceptibility to exfoliation glaucoma (XFG). To evaluate the impact of the R141L and G153D variations on the amine oxidase activity of LOXL1, we generated four different haplotypes of LOXL1 with R141L and G153D and assessed the amine oxidase activity of the LOXL1 variant proteins.

Methods: The four different haplotype variants of LOXL1 were created by oligonucleotide-directed mutagenesis in an LOXL1 expression vector. Recombinant LOXL1 variant proteins were purified by nickel-affinity chromatography. The amine oxidase activities of the LOXL1 variant proteins were assessed using peroxidase-coupled fluorometric assays.

Results: All of the haplotype variants of LOXL1 (141R-153G, 141R-153D, 141L-153G, and 141L-153D) showed β-aminopropionitrile-inhibitable amine oxidase activity toward elastin, type I collagen, and cadaverine, indicating that each LOXL1 variant functions as an amine oxidase. However, there were no significant differences in amine oxidase activity between the LOXL1 haplotype variants toward the tested substrates.

Conclusions: The R141L and G153D variations in the NH(2)-terminal region of LOXL1 do not affect the amine oxidase activity of LOXL1. This is consistent with recent genetic findings on the reversal of risk alleles of R141L and G153D in different ethnic backgrounds. Our results suggest that other unknown genetic factors or molecular mechanisms may be more relevant to the development of XFG.

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Related in: MedlinePlus

Amine oxidase activity of the four different haplotype variants of LOXL1 toward elastin, type I collagen, or cadaverine. The reactions without BAPN are in gray, and the reactions with BAPN are in white. The amine oxidase activity is expressed as nM of H2O2 produced per μg of the LOXL1 variant protein. Standard deviations are indicated in each graph, and the p-values between the reactions with and without BAPN are less than 0.05 in all cases tested.
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f3: Amine oxidase activity of the four different haplotype variants of LOXL1 toward elastin, type I collagen, or cadaverine. The reactions without BAPN are in gray, and the reactions with BAPN are in white. The amine oxidase activity is expressed as nM of H2O2 produced per μg of the LOXL1 variant protein. Standard deviations are indicated in each graph, and the p-values between the reactions with and without BAPN are less than 0.05 in all cases tested.

Mentions: Amine oxidase activity of the four different haplotype variants of LOXL1 was evaluated using physiologic substrates of LOXL1, elastin and type I collagen, as well as cadaverine, an artificial substrate with a diamine structure. All four haplotype variants of LOXL1 showed significantly higher levels of amine oxidase activity in the absence of BAPN than in the presence of BAPN, a well known specific inhibitor of LOX and LOXL1, indicating that the purified LOXL1 variant proteins had BAPN-inhibitable amine oxidase activity toward the tested substrates (Figure 3). Regardless of the haplotype, the LOXL1 variant proteins showed higher activities toward cadaverine than elastin and type I collagen. However, there were no significant differences in amine oxidase activity between the different haplotype variants toward any of the tested substrates (Figure 3), suggesting that the 141R and 153G variations in the NH2-terminal region do not affect the amine oxidase activity of LOXL1.


Variations in LOXL1 associated with exfoliation glaucoma do not affect amine oxidase activity.

Kim S, Kim Y - Mol. Vis. (2012)

Amine oxidase activity of the four different haplotype variants of LOXL1 toward elastin, type I collagen, or cadaverine. The reactions without BAPN are in gray, and the reactions with BAPN are in white. The amine oxidase activity is expressed as nM of H2O2 produced per μg of the LOXL1 variant protein. Standard deviations are indicated in each graph, and the p-values between the reactions with and without BAPN are less than 0.05 in all cases tested.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275637&req=5

f3: Amine oxidase activity of the four different haplotype variants of LOXL1 toward elastin, type I collagen, or cadaverine. The reactions without BAPN are in gray, and the reactions with BAPN are in white. The amine oxidase activity is expressed as nM of H2O2 produced per μg of the LOXL1 variant protein. Standard deviations are indicated in each graph, and the p-values between the reactions with and without BAPN are less than 0.05 in all cases tested.
Mentions: Amine oxidase activity of the four different haplotype variants of LOXL1 was evaluated using physiologic substrates of LOXL1, elastin and type I collagen, as well as cadaverine, an artificial substrate with a diamine structure. All four haplotype variants of LOXL1 showed significantly higher levels of amine oxidase activity in the absence of BAPN than in the presence of BAPN, a well known specific inhibitor of LOX and LOXL1, indicating that the purified LOXL1 variant proteins had BAPN-inhibitable amine oxidase activity toward the tested substrates (Figure 3). Regardless of the haplotype, the LOXL1 variant proteins showed higher activities toward cadaverine than elastin and type I collagen. However, there were no significant differences in amine oxidase activity between the different haplotype variants toward any of the tested substrates (Figure 3), suggesting that the 141R and 153G variations in the NH2-terminal region do not affect the amine oxidase activity of LOXL1.

Bottom Line: However, there were no significant differences in amine oxidase activity between the LOXL1 haplotype variants toward the tested substrates.The R141L and G153D variations in the NH(2)-terminal region of LOXL1 do not affect the amine oxidase activity of LOXL1.Our results suggest that other unknown genetic factors or molecular mechanisms may be more relevant to the development of XFG.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, School of Medicine, Wonkwang University, Sinyong-Dong 344-2, Iksan-City, Jeollabuk-Do 570-749, South Korea.

ABSTRACT

Purpose: Lysyl oxidase-like 1 (LOXL1) is a copper-dependant amine oxidase that plays an essential role in elastogenesis. Two non-synonymous single-nucleotide polymorphisms of LOXL1, R141L (rs1048661) and G153D (rs3825942), have been reported to significantly increase susceptibility to exfoliation glaucoma (XFG). To evaluate the impact of the R141L and G153D variations on the amine oxidase activity of LOXL1, we generated four different haplotypes of LOXL1 with R141L and G153D and assessed the amine oxidase activity of the LOXL1 variant proteins.

Methods: The four different haplotype variants of LOXL1 were created by oligonucleotide-directed mutagenesis in an LOXL1 expression vector. Recombinant LOXL1 variant proteins were purified by nickel-affinity chromatography. The amine oxidase activities of the LOXL1 variant proteins were assessed using peroxidase-coupled fluorometric assays.

Results: All of the haplotype variants of LOXL1 (141R-153G, 141R-153D, 141L-153G, and 141L-153D) showed β-aminopropionitrile-inhibitable amine oxidase activity toward elastin, type I collagen, and cadaverine, indicating that each LOXL1 variant functions as an amine oxidase. However, there were no significant differences in amine oxidase activity between the LOXL1 haplotype variants toward the tested substrates.

Conclusions: The R141L and G153D variations in the NH(2)-terminal region of LOXL1 do not affect the amine oxidase activity of LOXL1. This is consistent with recent genetic findings on the reversal of risk alleles of R141L and G153D in different ethnic backgrounds. Our results suggest that other unknown genetic factors or molecular mechanisms may be more relevant to the development of XFG.

Show MeSH
Related in: MedlinePlus