Identification and characterization of zebrafish fibronectins
Abstract
The goal of this study was to identify the fibronectin (FN) isoforms present in the zebrafish and determine their structure and pattern of expression. Sequence analysis of zebrafish FN cDNAs indicates that at least two forms of the protein exist in fish. One form (FN1) is very similar to FNs identified in other vertebrates possessing 12 type I, 2 type II, 17 type III repeats including two alternative splice sites (EIIIA and EIIIB) and a variable region (V). It exhibits 59% identity with Xenopus FN. Partial sequence analysis of zebrafish FN genomic DNA reveals that the FN gene organization in zebrafish is also similar to other vertebrates. However, unlike other vertebrates, zebrafish FN1 does not produce any splicing variant at the EIIIB, EIIIA and V regions. FN1 mRNA is widely present in zebrafish embryos and adult tissues. Whole mount in situ hybridization shows FNl mRNA is stored at early cleavage and blastula stages and present in the regions that are involved in cell movement during gastrulation. Unlike mouse and chicken, zebrafish does not possess obvious level of FN1 message in the regions of the developing somites and notochord during segmentation, but FN1 mRNA is abundant in otic vesicle during early ear development. In addition to FN1, zebrafish has a novel truncated form of FN (FN2). The predicted structure of FN2 is identical to FN1 at the N-terminal region possessing 9 type I, 2 type II and the first three type III repeats. Following the third type III repeat, the protein contains a unique 20 amino acid C-terminal tail that is completely different from the C-terminus of FN. Sequence analysis of FN genomic DNA demonstrates that FN2 is a unique splice variant of FN1. Like FN1, FN2 message is also widely present in zebrafish embryos and adult tissues although its abundance is much lower than FN1. The production of zebrafish FNs was investigated in a zebrafish liver cell line (ZFL). Results show that ZFL cells secrete FN proteins that can bind fish gelatin but not pork gelatin. The expression of the proteins in ZFL cells is not regulated by TGFP and retinoic acid.
Degree
Ph.D.
Advisors
Collodi, Purdue University.
Subject Area
Molecular biology|Anatomy & physiology|Animals
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