Expression and proteasomal degradation of the major vault protein (MVP) in mammalian oocytes and zygotes

Abstract

Major vault protein (MVP), also called lung resistance-related protein is a ribonucleoprotein comprising a major part (>70%) of the vault particle. The function of vault particle is not known, although it appears to be involved in multi-drug resistance and cellular signaling. Here we show that MVP is expressed in mammalian, porcine, and human ova and in the porcine preimplantation embryo. MVP was identified by matrix-assisted laser-desorption ionization-time-of-flight (MALDI-TOF) peptide sequencing and Western blotting as a protein accumulating in porcine zygotes cultured in the presence of specific proteasomal inhibitor MG132. MVP also accumulated in poor-quality human oocytes donated by infertile couples and porcine embryos that failed to develop normally after in vitro fertilization or somatic cell nuclear transfer. Normal porcine oocytes and embryos at various stages of preimplantation development showed mostly cytoplasmic labeling, with increased accumulation of vault particles around large cytoplasmic lipid inclusions and membrane vesicles. Occasionally, MVP was associated with the nuclear envelope and nucleolus precursor bodies. Nucleotide sequences with a high degree of homology to human MVP gene sequence were identified in porcine oocyte and endometrial cell cDNA libraries. We interpret these data as the evidence for the expression and ubiquitin-proteasome-dependent turnover of MVP in the mammalian ovum. Similar to carcinoma cells, MVP could fulfill a cell-protecting function during early embryonic development.

The major vault protein is responsive to and interferes with interferon-γ-mediated STAT1 signals

“…The underlying mechanisms regulating MVP stability are unknown. However, very recently an active mechanism of MVP degradation by the proteasome has been described in mammalian oocytes and zygotes (Sutovsky et al, 2005).…”

Expression of mitochondrial transcription factor A (TFAM) during porcine gametogenesis and preimplantation embryo development

“…In addition to TFAM and ACTB, the cellular content of the major vault protein (MVP) had been evaluated in the cloned embryos. The MVP is a cell-protectant protein that similarly to TFAM accumulates during porcine oocyte maturation and is reduced in content by ubiquitin-dependent proteolysis after fertilization (Sutovsky et al, 2005). The content of TFAM, measured as TFAM-ACTB band density-ratio was highest in the NT2 zygotes (Fig.…”

Protein Abundance Changes and Ubiquitylation Targets Identified after Inhibition of the Proteasome with Syringolin A

“…In order to find the direct targets of the proteasome we therefore aimed at identifying ubiquitylated proteins directly by affinity chromatography using the p62 ubiquitin-binding domain (UBA) (23,60). Using UBAs from various proteins, either alone or in combination, together with non-denaturing buffer conditions have already identified 1556 different Arabidopsis proteins (22)(23)(24)(25)(26).…”