神經元中間絲蛋白inaa及inab在斑馬魚神經系統的表現分析

Abstract

α-Internexin is one of the neuronal intermediate filament (nIF) proteins, which also include peripherin and neurofilament (NF) triplet proteins. Previous studies found that expression of α-internexin precedes the NF triplet proteins in mammals and suggested that α-internexin may play a key role in neuronal cytoskeleton network during development. α-Internexin is able to form homopolymers, while NF triplet proteins are obligate heteropolymers in neurons. Therefore, α-internexin and NF triplet proteins are suggested to play different spatial and temporal roles in neuronal development. The zebrafish (Danio rerio) is a vertebrate animal model and an ideal model for the study of developmental neuroscience. One homolog of mammalian α-internexin, gefiltin (or inab), has been characterized for its expression in the early development of zebrafish. Still, little is known about the other α-internexin homolog, zebrafish inaa, as well as the distribution of both inaa and inab in developing zebrafish. In this study, we aim to analyze the expression pattern of inaa during zebrafish development and then to compare expression patterns of both inaa and inab proteins during zebrafish development. We demonstrated that zebrafish inaa is an α-internexin homolog and shares the similar characteristics of nIFs. We generated specific anti-zebrafish inaa and inab antibodies to detect inaa and inab proteins, respectively. Immunohistochemical analysis of zebrafish revealed that both inaa and inab proteins were found in telencephalon, optic tectum and cerebellum during development. Moreover, inaa could act distinctively as the scaffold of zebrafish cone photoreceptors during retinal development, whereas inab was obviously located in the ganglion cell layer (GCL), optic fiber layer (OFL) and optic nerve. Besides, inaa was also expressed in the double cone-like photoreceptors of pineal gland where inab was sparsely found. Therefore, we suggest that inaa may be a useful marker for studies of zebrafish cone photoreceptor not only in the retina but also in the pineal gland. In conclusion, we illustrated the distribution of both inaa and inab proteins is conserved in telencephalon, optic tectum and cerebellum phylogenetically, but inaa and inab proteins have distinct expression patterns in zebrafish pineal gland and retina. The distribution of inaa and inab may support the investigation of their functional roles in various neuronal development of zebrafish.