Barzilay Yuval, Eyal Zohar, Noy Yael, Varsano Neta, Olender Tsviya, Bera Sourabh, Lerer-Goldshtein Tali, Kedmi Merav, Porat Ziv, Pinkas Iddo, Levin-Zaidman Smadar, Dezorella Nili, Gur Dvir
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel.
Proc Natl Acad Sci U S A. 2025 Jun 3;122(22):e2424979122. doi: 10.1073/pnas.2424979122. Epub 2025 May 28.
Pigmentation plays a vital role in the survival of organisms, supporting functions such as camouflage, communication, and mate attraction. In vertebrates, these functions are mediated by specialized pigment cells known as chromatophores of which, uric acid crystal-forming leucophores remain the least understood, with little known about their molecular mechanisms. A key question in pigment cell biology is whether different crystal chemistries require distinct molecular pathways, or whether similar cellular processes drive the formation of diverse crystals. This study was designed to unravel the uncharacterized process of uric acid crystallization in leucophores and compare them to guanine crystal formation in iridophores and pterin formation in xanthophores. The results of our transcriptomic, ultrastructural, and metabolomic analyses, demonstrate that leucophores share molecular pathways with iridophores, particularly those connected to organelle organization and purine metabolism, but express discrete genes involved in uric acid biosynthesis and storage. Additionally, leucophores share intracellular trafficking and pterin biosynthesis genes with xanthophores, suggesting universally conserved processes. Ultrastructural studies reveal star-like fibrous structures in leucosomes, which likely serve as scaffolds for unique one-dimensional uric acid assemblies that radiate from the core and act as efficient light scatterers. These findings provide insights into leucophore cell biology and the specialized mechanisms driving molecular crystalline assembly, and reveal that while some cellular processes are conserved, the specific chemistry of each crystal type drives the evolution of distinct molecular pathways.
色素沉着在生物体的生存中起着至关重要的作用，支持着诸如伪装、通讯和吸引配偶等功能。在脊椎动物中，这些功能由称为色素细胞的特殊色素细胞介导，其中，形成尿酸晶体的白色素细胞仍然是了解最少的，对其分子机制知之甚少。色素细胞生物学中的一个关键问题是，不同的晶体化学组成是否需要不同的分子途径，或者相似的细胞过程是否驱动了不同晶体的形成。本研究旨在揭示白色素细胞中尿酸结晶这一未被描述的过程，并将其与虹彩细胞中鸟嘌呤晶体的形成以及黄色素细胞中蝶呤的形成进行比较。我们的转录组学、超微结构和代谢组学分析结果表明，白色素细胞与虹彩细胞共享分子途径，特别是那些与细胞器组织和嘌呤代谢相关的途径，但表达参与尿酸生物合成和储存的离散基因。此外，白色素细胞与黄色素细胞共享细胞内运输和蝶呤生物合成基因，表明存在普遍保守的过程。超微结构研究揭示了白色体中的星形纤维结构，这些结构可能作为独特的一维尿酸聚集体的支架，从核心辐射出来并作为有效的光散射体。这些发现为白色素细胞生物学以及驱动分子晶体组装的特殊机制提供了见解，并揭示出虽然一些细胞过程是保守的，但每种晶体类型的特定化学组成驱动了不同分子途径的进化。
