GUCY2D mutations in retinal guanylyl cyclase 1 provide biochemical reasons for dominant cone-rod dystrophy but not for stationary night blindness.
GUCY2D mutations in retinal guanylyl cyclase 1 provide biochemical reasons for dominant cone-rod dystrophy but not for stationary night blindness.
复制标题
DOI：
10.1074/jbc.ra120.015553
复制
发表时间：
2020-12-25
期刊：
影响因子：
--
通讯作者：
Dizhoor AM
中科院分区：
文献类型：
--
作者：
Peshenko IV;Olshevskaya EV;Dizhoor AM
编码二聚体人视网膜膜鸟苷酸环化酶（RetGC）同工酶RetGC 1的GUCY 2D基因突变导致各种形式的失明，从视杆功能障碍到视杆和视锥变性。我们测试了导致隐性先天性静止性夜盲（CSNB），隐性Leber先天性黑蒙（LCA 1）和显性视锥-视杆细胞营养不良-6（CORD 6）的突变如何影响RetGC 1活性以及RetGC激活蛋白（GCAP）和视网膜变性-3蛋白（RD 3）的调节。CSNB突变R666 W、R761 W和L911 F以及LCA 1突变R768 W和G982 VfsX 39使RetGC 1不能被人GCAP 1、-2和-3激活。R666 W和R761 W取代损害了HEK 293细胞中GCAP 1与RetGC 1的结合。与此相反，G982 VfsX 39和L911 F RetGC 1保留了在细胞中结合GCAP 1的能力，但未能有效地结合RD 3。R768 W RetGC 1不结合GCAP 1或RD 3。与CSNB连接的GUCY 2D等位基因组合的共表达在体外没有恢复RetGC 1活性。RetGC 1二聚化结构域中的CORD 6突变R838 S强烈主导了由WT和R838 S亚基共表达产生的RetGC 1异源二聚体中GCAP 1对环化酶调节的Ca 2+敏感性。它需要更高的Ca 2+浓度来降低GCAP激活的RetGC 1异二聚体-比WT高6倍，比Ser 838携带的同源二聚体高2倍。异二聚体也比同二聚体更耐RD 3的抑制。观察到的生化变化可以解释显性CORD 6失明和隐性LCA 1失明，这两种失明都影响视杆细胞和视锥细胞，但它们不能解释隐性CSNB中视杆细胞功能的选择性丧失。
Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB.