Ret Finger Protein: An E3 Ubiquitin Ligase Juxtaposed to the XY Body in Meiosis

Isabelle Gillot,Daniel Puel,Pascal Lopez,Cédric Matthews,Frédérique Vidal

doi:10.1155/2009/524858

Abstract

During prophase I of male meiosis, the sex chromosomes form a compact structure called XY body that associates with the nuclear membrane of pachytene spermatocytes. Ret Finger Protein is a transcriptional repressor, able to interact with both nuclear matrix-associated proteins and double-stranded DNA. We report the precise and unique localization of Ret Finger Protein in pachytene spermatocytes, in which Ret Finger Protein takes place of lamin B1, between the XY body and the inner nuclear membrane. This localization of Ret Finger Protein does not seem to be associated with O-glycosylation or sumoylation. In addition, we demonstrate that Ret Finger Protein contains an E3 ubiquitin ligase activity. These observations lead to an attractive hypothesis in which Ret Finger Protein would be involved in the positioning and the attachment of XY body to the nuclear lamina of pachytene spermatocytes.

Highlights

During meiosis, homologous recombination between chromosomes is allowed by synapsis of chromosome’s pairs during pachytene stage
We report here that in pachytene spermatocytes, Ret Finger Protein (RFP) defines a precise and restricted region of nuclear matrix that correlates with the position of the XY body
Of the lamins expressed in somatic cells, lamin B1 is the only one that could be detected in spermatocytes [5, 6]

Summary

Introduction

Homologous recombination between chromosomes is allowed by synapsis of chromosome’s pairs during pachytene stage. At this stage, all the chromosomes are attached to the nuclear membrane by their telomeres. In order to deal with asynchronous synapsis of the XY chromosomes, mammals have adopted a strategy that involves chromatin condensation and seclusion of the sex chromosomes into a specialized and visibly distinct nuclear territory, known as the XY body (see [1, 2] for review). Localization of the condensed XY body to one part of the nucleus suggests that a particular composition of the nuclear matrix could be involved in the positioning and/or attachment of the XY body or sex chromosomes to the nuclear lamina [3, 4]. Lamin B1, as well as specific isoforms of lamin A/C, is evidenced in the nuclear matrix [5, 6]

Methods

Results

Conclusion