Regulatory mechanisms governing the oocyte-specific synthesis of the karyoskeletal protein NO145.
Given the prominence and the biological importance of the nucleus it is remarkable how little is still known about structure-forming proteins in the nuclear interior. The karyoskeletal protein NO145 has been identified as a major constituent of a filamentous network surrounding the amplified nucleoli of Xenopus laevis oocytes. We now show that an orthologous protein also occurs in female germ cells of a wide range of other vertebrates, where it forms dot-like structures. Using the Xenopus oocyte system we further report a specific regulatory mechanism responsible for (1) the rapid degradation of the NO145 protein during meiotic maturation, and (2) the cell-type-dependent translation of NO145 mRNA. Microinjection experiments have revealed that NO145 is a target of proteasomes and the use of the rapid amplification of cDNA ends-polyadenylation test (RACE-PAT) has disclosed the existence of NO145 mRNAs differing in their 3' UTRs. Reporter systems as well as polyribosome profiling experiments have revealed the regulatory importance of the 3' UTRs, which affect the translational efficiency as well as the stability of the encoded protein. The highly conserved cell-type specificity and the extremely tight temporal regulation of NO145 synthesis suggest an important role of this protein in female meiotic prophase.
Voltmer-Irsch
Susanne
S
Division of Cell Biology, German Cancer Research Center, 69120 Heidelberg, Germany.
Kneissel
Sandra
S
Adenot
Pierre G
PG
Schmidt-Zachmann
Marion S
MS
D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D029867:Xenopus Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D014982:Xenopus laevis
D020413:3' Untranslated Regions; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D012333:RNA, Messenger; C455108:SYCP2L protein, Xenopus; D029867:Xenopus Proteins