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SLC7A14 linked to autosomal recessive retinitis pigmentosa.

Jin ZB, Huang XF, Lv JN, Xiang L, Li DQ, Chen J, Huang C, Wu J, Lu F, Qu J - Nat Commun (2014)

Bottom Line: In zebrafish, downregulation of slc7a14 expression leads to an abnormal eye phenotype and defective light-induced locomotor response.Furthermore, targeted knockout of Slc7a14 in mice results in retinal degeneration with abnormal ERG response.This suggests that SLC7A14 has an important role in retinal development and visual function.

View Article: PubMed Central - PubMed

Affiliation: 1] The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou 325027, China [2] State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou 325027, China.

ABSTRACT
Retinitis pigmentosa (RP) is characterized by degeneration of the retinal photoreceptors and is the leading cause of inherited blindness worldwide. Although few genes are known to cause autosomal recessive RP (arRP), a large proportion of disease-causing genes remain to be revealed. Here we report the identification of SLC7A14, a potential cationic transporter, as a novel gene linked to arRP. Using exome sequencing and direct screening of 248 unrelated patients with arRP, we find that mutations in the SLC7A14 gene account for 2% of cases of arRP. We further demonstrate that SLC7A14 is specifically expressed in the photoreceptor layer of the mammalian retina and its expression increases during postnatal retinal development. In zebrafish, downregulation of slc7a14 expression leads to an abnormal eye phenotype and defective light-induced locomotor response. Furthermore, targeted knockout of Slc7a14 in mice results in retinal degeneration with abnormal ERG response. This suggests that SLC7A14 has an important role in retinal development and visual function.

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Knockdown of SLC7A14 in zebrafish.(a) Injection of 1 nl of a 0.25 mM solution of slc7a14-MO dramatically reduces eye size in zebrafish. (b) At 2dpf, 4dpf and 5dpf, the eye-to-body ratio of fish injected with the slc7a14-MO was significantly smaller than that of fish injected with the control MO. N=6, Dunnett test, ***P<0.001. (c) Light-induced locomotor response with sudden light-to-dark transitions demonstrated significant visual impairment in zebrafish injected with the slc7a14-MO. N=6 in each group. (d) Dunnett tests of the light-induced locomotor responses indicate that significant differences exist between the responses of fish with small eyes and those with normal eyes during the light-ON phase. N=10, Dunnett test, **P<0.01. Bars in the graph represent standard errors of the mean (s.e.m.).
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f4: Knockdown of SLC7A14 in zebrafish.(a) Injection of 1 nl of a 0.25 mM solution of slc7a14-MO dramatically reduces eye size in zebrafish. (b) At 2dpf, 4dpf and 5dpf, the eye-to-body ratio of fish injected with the slc7a14-MO was significantly smaller than that of fish injected with the control MO. N=6, Dunnett test, ***P<0.001. (c) Light-induced locomotor response with sudden light-to-dark transitions demonstrated significant visual impairment in zebrafish injected with the slc7a14-MO. N=6 in each group. (d) Dunnett tests of the light-induced locomotor responses indicate that significant differences exist between the responses of fish with small eyes and those with normal eyes during the light-ON phase. N=10, Dunnett test, **P<0.01. Bars in the graph represent standard errors of the mean (s.e.m.).

Mentions: To test our hypothesis that disruption of the slc7a14 gene can lead to visual dysfunction, we developed a zebrafish model of slc7a14 knockdown. Morpholino oligonucleotides (MOs) targeting the splice sites of the slc7a14 gene and a fluoresceinated standard control MO (Gene-Tools, LLC, Corvallis, OR) were microinjected into embryos at the one- to two-cell stage. The fluoresceins were observed after injection (Supplementary Fig. 5a) and RT–PCR verified the alteration in splicing (Supplementary Figs 5b, 9). Injection of the slc7a14-MO led to abnormal phenotypes in 46.9% of fish (total number of examined fish is 130). These phenotypes included smaller eyes (39.2%) and severe malformations (body disfigurement; 7.7%), whereas a normal phenotype was observed in 95.4% of fish (n=108) injected with the control MO (Supplementary Fig. 6). We did not observe significant retinal structural change in the 5dpf slc7a14-MO zebrafish (Supplementary Fig. 5c). This finding suggests that knockdown of slc7a14 in zebrafish results in a significantly abnormal phenotype. Compared with the larvae that were injected with the control MO, larvae injected with the slc7a14-MO displayed an eye phenotype of significantly smaller eyes (Fig. 4a,b). To determine the effect of slc7a14 knockdown on visual function, we assessed the swimming response of 5dpf larvae to sudden light-to-dark transitions by using a previously established light-induced locomotor response8 in conjunction with a ZebraBox behaviour monitoring station. The behavioural testing demonstrated that zebrafish larvae with reduced levels of slc7a14 exhibited an aberrant locomotor response during the light-ON phase (Fig. 4c). The aberrant behaviour was significantly different from the normal behaviour (P<0.01, N=10, Dunnett test; Fig. 4d). These findings strongly indicate that Slc7a14 has an important role in photoreceptor development and function and that its dysfunction can lead to visual impairment.


SLC7A14 linked to autosomal recessive retinitis pigmentosa.

Jin ZB, Huang XF, Lv JN, Xiang L, Li DQ, Chen J, Huang C, Wu J, Lu F, Qu J - Nat Commun (2014)

Knockdown of SLC7A14 in zebrafish.(a) Injection of 1 nl of a 0.25 mM solution of slc7a14-MO dramatically reduces eye size in zebrafish. (b) At 2dpf, 4dpf and 5dpf, the eye-to-body ratio of fish injected with the slc7a14-MO was significantly smaller than that of fish injected with the control MO. N=6, Dunnett test, ***P<0.001. (c) Light-induced locomotor response with sudden light-to-dark transitions demonstrated significant visual impairment in zebrafish injected with the slc7a14-MO. N=6 in each group. (d) Dunnett tests of the light-induced locomotor responses indicate that significant differences exist between the responses of fish with small eyes and those with normal eyes during the light-ON phase. N=10, Dunnett test, **P<0.01. Bars in the graph represent standard errors of the mean (s.e.m.).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3974215&req=5

f4: Knockdown of SLC7A14 in zebrafish.(a) Injection of 1 nl of a 0.25 mM solution of slc7a14-MO dramatically reduces eye size in zebrafish. (b) At 2dpf, 4dpf and 5dpf, the eye-to-body ratio of fish injected with the slc7a14-MO was significantly smaller than that of fish injected with the control MO. N=6, Dunnett test, ***P<0.001. (c) Light-induced locomotor response with sudden light-to-dark transitions demonstrated significant visual impairment in zebrafish injected with the slc7a14-MO. N=6 in each group. (d) Dunnett tests of the light-induced locomotor responses indicate that significant differences exist between the responses of fish with small eyes and those with normal eyes during the light-ON phase. N=10, Dunnett test, **P<0.01. Bars in the graph represent standard errors of the mean (s.e.m.).
Mentions: To test our hypothesis that disruption of the slc7a14 gene can lead to visual dysfunction, we developed a zebrafish model of slc7a14 knockdown. Morpholino oligonucleotides (MOs) targeting the splice sites of the slc7a14 gene and a fluoresceinated standard control MO (Gene-Tools, LLC, Corvallis, OR) were microinjected into embryos at the one- to two-cell stage. The fluoresceins were observed after injection (Supplementary Fig. 5a) and RT–PCR verified the alteration in splicing (Supplementary Figs 5b, 9). Injection of the slc7a14-MO led to abnormal phenotypes in 46.9% of fish (total number of examined fish is 130). These phenotypes included smaller eyes (39.2%) and severe malformations (body disfigurement; 7.7%), whereas a normal phenotype was observed in 95.4% of fish (n=108) injected with the control MO (Supplementary Fig. 6). We did not observe significant retinal structural change in the 5dpf slc7a14-MO zebrafish (Supplementary Fig. 5c). This finding suggests that knockdown of slc7a14 in zebrafish results in a significantly abnormal phenotype. Compared with the larvae that were injected with the control MO, larvae injected with the slc7a14-MO displayed an eye phenotype of significantly smaller eyes (Fig. 4a,b). To determine the effect of slc7a14 knockdown on visual function, we assessed the swimming response of 5dpf larvae to sudden light-to-dark transitions by using a previously established light-induced locomotor response8 in conjunction with a ZebraBox behaviour monitoring station. The behavioural testing demonstrated that zebrafish larvae with reduced levels of slc7a14 exhibited an aberrant locomotor response during the light-ON phase (Fig. 4c). The aberrant behaviour was significantly different from the normal behaviour (P<0.01, N=10, Dunnett test; Fig. 4d). These findings strongly indicate that Slc7a14 has an important role in photoreceptor development and function and that its dysfunction can lead to visual impairment.

Bottom Line: In zebrafish, downregulation of slc7a14 expression leads to an abnormal eye phenotype and defective light-induced locomotor response.Furthermore, targeted knockout of Slc7a14 in mice results in retinal degeneration with abnormal ERG response.This suggests that SLC7A14 has an important role in retinal development and visual function.

View Article: PubMed Central - PubMed

Affiliation: 1] The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou 325027, China [2] State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou 325027, China.

ABSTRACT
Retinitis pigmentosa (RP) is characterized by degeneration of the retinal photoreceptors and is the leading cause of inherited blindness worldwide. Although few genes are known to cause autosomal recessive RP (arRP), a large proportion of disease-causing genes remain to be revealed. Here we report the identification of SLC7A14, a potential cationic transporter, as a novel gene linked to arRP. Using exome sequencing and direct screening of 248 unrelated patients with arRP, we find that mutations in the SLC7A14 gene account for 2% of cases of arRP. We further demonstrate that SLC7A14 is specifically expressed in the photoreceptor layer of the mammalian retina and its expression increases during postnatal retinal development. In zebrafish, downregulation of slc7a14 expression leads to an abnormal eye phenotype and defective light-induced locomotor response. Furthermore, targeted knockout of Slc7a14 in mice results in retinal degeneration with abnormal ERG response. This suggests that SLC7A14 has an important role in retinal development and visual function.

Show MeSH
Related in: MedlinePlus