Thyroid hormone signaling specifies cone subtypes in human retinal organoids.
Thyroid hormone signaling specifies cone subtypes in human retinal organoids.
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DOI：
10.1126/science.aau6348
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发表时间：
2018-10-12
期刊：
影响因子：
--
通讯作者：
Johnston RJ Jr
中科院分区：
文献类型：
--
作者：
Eldred KC;Hadyniak SE;Hussey KA;Brenerman B;Zhang PW;Chamling X;Sluch VM;Welsbie DS;Hattar S;Taylor J;Wahlin K;Zack DJ;Johnston RJ Jr
人类视网膜中的锥状光感受器使白天、彩色和高敏锐度视觉成为可能。人类视锥细胞的三种亚型由它们表达的视觉色素定义：蓝色视蛋白（短波长; S），绿色视蛋白（中波长; M）或红色视蛋白（长波长; L）。影响视蛋白表达或功能的突变导致各种形式的色盲和视网膜变性。我们目前对脊椎动物眼睛的了解主要来自对模式生物的研究。我们研究了人类视网膜，以了解产生相互排斥的视锥亚型马赛克的发育机制。人类视锥细胞的规格化分两步进行。首先，在S与L/M锥体命运之间发生决定。如果选择L/M命运，则在L-视蛋白或M-视蛋白的表达之间进行后续选择。为了确定控制S和L/M视锥细胞命运之间的第一个决定的机制，我们研究了来源于干细胞的人视网膜类器官。我们发现，人类类器官和视网膜具有相似的分布，基因表达谱和锥亚型的形态。在发育过程中，首先指定S视锥，然后是L/M视锥。这种从S视锥的特异性到L/M视锥的产生的时间转换由甲状腺激素（TH）信号传导控制。在缺乏甲状腺激素受体β（Thrβ）的视网膜类器官中，所有视锥细胞都发育成S亚型。Thrβ以高亲和力结合三碘甲腺原氨酸（T3），更活跃的形式TH，调节基因表达。我们观察到，除了T3早期在发展过程中诱导L/M的命运在几乎所有的锥。因此，通过Thrβ的TH信号传导对于诱导L/M视锥细胞命运和抑制S命运是必要的和充分的。TH主要以两种状态存在：甲状腺素（T4），TH的最丰富的循环形式，和T3，其以高亲和力结合TH受体。我们假设视网膜本身可以调节TH水平来控制亚型的命运。我们发现脱碘酶3（DIO 3），一种降解T3和T4的酶，在类器官和视网膜发育的早期表达。相反，脱碘酶2（DIO 2），一种将T4转化为活性T3的酶，以及TH载体和转运蛋白，在发育后期表达。TH-降解和激活蛋白的时间动态表达支持视网膜本身控制TH水平的模型，确保低TH信号早期指定S锥和高TH信号在发展后期产生L/M锥。对模式生物和人类流行病学的研究往往会产生无法在人类中研究的关于人类生物学的假设。类器官提供了一个系统来确定人类发育的机制，从而能够直接测试发育人类组织的假设。我们的研究确定TH信号的时间调节作为一种机制，控制锥亚型规范在人类。与我们的研究结果一致，低T3和T4的早产儿色觉缺陷的发生率增加。此外，我们确定了一种产生一种锥细胞亚型同时抑制另一种亚型的机制，再加上成功移植和纳入干细胞衍生的光感受器在小鼠中，表明治疗人类疾病如色盲，视网膜色素变性和黄斑变性的治疗方法的承诺将在不久的将来实现。时间调节的TH信号传导指定视锥细胞亚型。(A)胚胎干细胞衍生的人视网膜类器官[野生型（WT）]产生S和L/M视锥细胞。蓝色，S-视蛋白;绿色，L/M-视蛋白。(B)缺乏甲状腺激素受体β（Thrβ KO）的类器官产生所有S锥。(C)TH信号传导的早期激活（WT + T3）指定几乎所有的L/M视锥。(D)TH降解酶（如DIO 3）在发育早期表达，降低TH并促进S命运，而TH激活调节剂（如DIO 2）在发育后期表达，促进L/M命运。人类神经系统内神经元亚型的潜在特化机制在很大程度上是未知的。视网膜的蓝色（S）、绿色（M）和红色（L）视锥能够实现高敏锐度的日间视觉和色觉。为了确定控制S与L/M命运的机制，我们研究了人视网膜类器官的分化。类器官和视网膜具有相似的视锥细胞亚型的分布、表达谱和形态。首先指定S锥，然后是L/M锥，甲状腺激素信号控制这种时间开关。甲状腺激素降解和激活蛋白在视网膜内的动态表达确保了低信号早期指定S锥和高信号后期产生L/M锥。这项工作建立了类器官作为确定人类发育机制的模型，具有治疗和视力修复的前景。
Cone photoreceptors in the human retina enable daytime, color, and high-acuity vision. The three subtypes of human cones are defined by the visual pigment that they express: blue-opsin (short wavelength; S), green-opsin (medium wavelength; M), or red-opsin (long wavelength; L). Mutations that affect opsin expression or function cause various forms of color blindness and retinal degeneration. Our current understanding of the vertebrate eye has been derived primarily from the study of model organisms. We studied the human retina to understand the developmental mechanisms that generate the mosaic of mutually exclusive cone subtypes. Specification of human cones occurs in a two-step process. First, a decision occurs between S versus L/M cone fates. If the L/M fate is chosen, a subsequent choice is made between expression of L- or M-opsin. To determine the mechanism that controls the first decision between S and L/M cone fates, we studied human retinal organoids derived from stem cells. We found that human organoids and retinas have similar distributions, gene expression profiles, and morphologies of cone subtypes. During development, S cones are specified first, followed by L/M cones. This temporal switch from specification of S cones to generation of L/M cones is controlled by thyroid hormone (TH) signaling. In retinal organoids that lacked thyroid hormone receptor β (Thrβ), all cones developed into the S subtype. Thrβ binds with high affinity to triiodothyronine (T3), the more active form of TH, to regulate gene expression. We observed that addition of T3 early during development induced L/M fate in nearly all cones. Thus, TH signaling through Thrβ is necessary and sufficient to induce L/M cone fate and suppress S fate. TH exists largely in two states: thyroxine (T4), the most abundant circulating form of TH, and T3, which binds TH receptors with high affinity. We hypothesized that the retina itself could modulate TH levels to control subtype fates. We found that deiodinase 3 (DIO3), an enzyme that degrades both T3 and T4, was expressed early in organoid and retina development. Conversely, deiodinase 2 (DIO2), an enzyme that converts T4 to active T3, as well as TH carriers and transporters, were expressed later in development. Temporally dynamic expression of TH-degrading and -activating proteins supports a model in which the retina itself controls TH levels, ensuring low TH signaling early to specify S cones and high TH signaling later in development to produce L/M cones. Studies of model organisms and human epidemiology often generate hypotheses about human biology that cannot be studied in humans. Organoids provide a system to determine the mechanisms of human development, enabling direct testing of hypotheses in developing human tissue. Our studies identify temporal regulation of TH signaling as a mechanism that controls cone subtype specification in humans. Consistent with our findings, preterm human infants with low T3 and T4 have an increased incidence of color vision defects. Moreover, our identification of a mechanism that generates one cone subtype while suppressing the other, coupled with successful transplantation and incorporation of stem cell-derived photoreceptors in mice, suggests that the promise of therapies to treat human diseases such as color blindness, retinitis pigmentosa, and macular degeneration will be achieved in the near future. ■ Temporally regulated TH signaling specifies cone subtypes. (A) Embryonic stem cell-derived human retinal organoids [wild type (WT)] generate S and L/M cones. Blue, S-opsin; green, L/M-opsin. (B) Organoids that lack thyroid hormone receptor β (Thrβ KO) generate all S cones. (C) Early activation of TH signaling (WT + T3) specifies nearly all L/M cones. (D) TH-degrading enzymes (such as DIO3) expressed early in development lower TH and promote S fate, whereas TH-activating regulators (such as DIO2) expressed later promote L/M fate. The mechanisms underlying specification of neuronal subtypes within the human nervous system are largely unknown. The blue (S), green (M), and red (L) cones of the retina enable high-acuity daytime and color vision. To determine the mechanism that controls S versus L/M fates, we studied the differentiation of human retinal organoids. Organoids and retinas have similar distributions, expression profiles, and morphologies of cone subtypes. S cones are specified first, followed by L/M cones, and thyroid hormone signaling controls this temporal switch. Dynamic expression of thyroid hormone–degrading and –activating proteins within the retina ensures low signaling early to specify S cones and high signaling late to produce L/M cones. This work establishes organoids as a model for determining mechanisms of human development with promising utility for therapeutics and vision repair.
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影响因子：
16.2
作者：
Chen, SM;Wang, QL;Zack, DJ
通讯作者：
Zack, DJ
影响因子：
7
作者：
Harrow J;Frankish A;Gonzalez JM;Tapanari E;Diekhans M;Kokocinski F;Aken BL;Barrell D;Zadissa A;Searle S;Barnes I;Bignell A;Boychenko V;Hunt T;Kay M;Mukherjee G;Rajan J;Despacio-Reyes G;Saunders G;Steward C;Harte R;Lin M;Howald C;Tanzer A;Derrien T;Chrast J;Walters N;Balasubramanian S;Pei B;Tress M;Rodriguez JM;Ezkurdia I;van Baren J;Brent M;Haussler D;Kellis M;Valencia A;Reymond A;Gerstein M;Guigó R;Hubbard TJ
通讯作者：
Hubbard TJ
影响因子：
5.4
作者：
MARTINO, E;NARDI, M;BASCHIERI, L
通讯作者：
BASCHIERI, L
影响因子：
64.5
作者：
Furukawa, T;Morrow, EM;Cepko, CL
通讯作者：
Cepko, CL
影响因子：
4.6
作者：
Barnea-Cramer AO;Wang W;Lu SJ;Singh MS;Luo C;Huo H;McClements ME;Barnard AR;MacLaren RE;Lanza R
通讯作者：
Lanza R