Regionally regulated conversion of protein expression in the skin during anuran metamorphosis

Abstract

The back skin of anuran larvae undergoes drastic metamorphic changes which are quite different from the tail skin. To have an insight into the mechanism of the region‐dependent changes, we made a thorough survey of metamorphic alterations in protein expression in both the body and tail skin of Xenopus laevis tadpoles utilizing high‐resolution two‐dimensional electrophoresis. Approximately 400 proteins were detected, 9 of which were identified as known proteins and were used as index proteins to standardize the readout of distribution of protein spots on gels. The overall pattern of polypeptide distribution (map) was classified into “larval type” and “adult type.” The maps showed stage‐specific changes. Up to stage 58 the back skin map remained the larval type, showed remarkable changes for the first time at stage 60 (whose pattern was a combination of both larval and adult types), and became the adult type at stage 62. The basic feature of the tail skin map remained the larval type through the climax stage of metamorphosis. Experiments using tadpoles treated with an antithyroid drug showed that most of back skin proteins detected on the map are thyroid hormone responsive in their expression. Expression of keratin II (adult‐type keratin) was found to be uniquely regulated. As expected, silver staining detected it in the back but not in the tail. However, the protein‐labeling experiment with [35S]methionine showed that the tail skin is actively synthesizing the adult keratin, suggesting that tail cells have a specific elimination mechanism of the protein. © 1996 Wiley‐Liss, Inc.

Novel Rana keratin genes and their expression during larval to adult epidermal conversion in bullfrog tadpoles

“…We also cloned novel 3 cDNAs of keratins (XLK, XAK‐A, and XAK‐B) from Xenopus laevis and revealed their unique expression during skin metamorphosis (Watanabe et al, 2001) as discussed below. XLK was isolated by Kobayashi et al (1996) and xlk was cloned by Watanabe et al (2001). mRNA and protein of XLK were expressed in larval epidermal cells through the tadpole life but not in adult cells.…”

“…This gene shows a consecutive two step expression, basal and high level expression (Mathisen and Miller 1987, 1989), the former being independent on TH and the latter being regulated by TH and glucocorticoid (Mathisen and Miller 1987, 1989; Nishikawa et al, 1992). Changes in the expression of larval keratins during Xenopus metamorphosis were also studied by Ellison et al (1985) and Kobayashi et al (1996). Xenopus larval keratin (XLK) was reported as a type II keratin whose gene is expressed in the larval epidermis but not in the adult one (Kobayashi et al, 1996; Watanabe et al, 2001).…”

“…Changes in the expression of larval keratins during Xenopus metamorphosis were also studied by Ellison et al (1985) and Kobayashi et al (1996). Xenopus larval keratin (XLK) was reported as a type II keratin whose gene is expressed in the larval epidermis but not in the adult one (Kobayashi et al, 1996; Watanabe et al, 2001). Recently, we also identified new Xenopus genes ( xak‐a , and xak‐b ) of type I keratins which are expressed exclusively in the adult epidermis (Watanabe et al, 2001).…”

Mapping of phosphorylated proteins on two-dimensional polyacrylamide gels using protein phosphatase

“…Currently, 2-D PAGE is the only method capable of simultaneously resolving several thousands of proteins [7][8][9][10] including protein variants produced by the co-or posttranslational processing such as phosphorylation, glycosylation, and sulfation [11]. Therefore, 2-D PAGE is well suited for the comprehensive analysis of protein phosphorylation in cells and tissues.…”

Metabolic Action of Thyroid Hormones: Insights from Functional and Proteomic Studies

“…Domanski and Helbing (2007), in the field of amphibian metamorphosis, went through proteomics to study the relationship between the most well established transcriptomic events involved in tail regression and the changes in the proteome also in view of non-classical THs action trough phosphorylation signalling pathways. Following previous proteomic scale studies in the field (Ray and Dent, 1986;Kobayashi et al, 1996;Helbing et al, 2003), the authors (Domanski and Helbing, 2007), by means of two-dimentional gel electrophoresis and phosphoprotein-specific stain, identified novel changes in the proteome and phosphoproteome associated with the induction of T3-dependent tail regression of Rana catesbeiana tadpoles. They identified, in particular, a novel keratin that is a target for T3-mediated changes in the tail that can serve as an indicator of early response to this hormone.…”