TY  - JOUR
A1  - Göb, Eva
A1  - Meyer-Natus, Elisabeth
A1  - Benavente, Ricardo
A1  - Alsheimer, Manfred
T1  - Expression of individual mammalian Sun1 isoforms depends on the cell type
N2  - Mammalian Sun1 belongs to an evolutionarily conserved family of inner nuclear membrane proteins, which are known as SUN domain proteins. SUN domain proteins interact with KASH domain partners to form bridging complexes, so-called LINC complexes, that physically connect the nuclear interior to the cytoskeleton. LINC complexes are critical for nuclear integrity and play fundamental roles in nuclear positioning, shaping and movement. The mammalian genome codes for at least five different SUN domain proteins used for the formation of a number of different LINC complexes. Recently, we reported on the identification of everal Sun1 isoforms, which tremendously enlarges the alternatives to form functional LINC complexes. We now confirmed that Sun1 actually exists in at least seven distinct splice variants. Besides that, we observed that expression of individual Sun1 isoforms remarkably depends on the cell type, suggesting a cell type-specific adaption of Sun1 dependent LINC complexes to specific cellular and physiological requirements.
KW  - Biologie
KW  - Sun1
KW  - SUN domain protein
KW  - LINC complex
KW  - mouse
KW  - nuclear envelope
KW  - isoform
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68750
ER  - 
TY  - JOUR
A1  - Schramm, Sabine
A1  - Fraune, Johanna
A1  - Naumann, Ronald
A1  - Hernandez-Hernandez, Abrahan
A1  - Höög, Christer
A1  - Cooke, Howard J.
A1  - Alsheimer, Manfred
A1  - Benavente, Ricardo
T1  - A Novel Mouse Synaptonemal Complex Protein Is Essential for Loading of Central Element Proteins, Recombination, and Fertility
N2  - The synaptonemal complex (SC) is a proteinaceous, meiosis-specific structure that is highly conserved in evolution. During meiosis, the SC mediates synapsis of homologous chromosomes. It is essential for proper recombination and segregation of homologous chromosomes, and therefore for genome haploidization. Mutations in human SC genes can cause infertility. In order to gain a better understanding of the process of SC assembly in a model system that would be relevant for humans, we are investigating meiosis in mice. Here, we report on a newly identified component of the murine SC, which we named SYCE3. SYCE3 is strongly conserved among mammals and localizes to the central element (CE) of the SC. By generating a Syce3 knockout mouse, we found that SYCE3 is required for fertility in both sexes. Loss of SYCE3 blocks synapsis initiation and results in meiotic arrest. In the absence of SYCE3, initiation of meiotic recombination appears to be normal, but its progression is severely impaired resulting in complete absence of MLH1 foci, which are presumed markers of crossovers in wild-type meiocytes. In the process of SC assembly, SYCE3 is required downstream of transverse filament protein SYCP1, but upstream of the other previously described CE–specific proteins. We conclude that SYCE3 enables chromosome loading of the other CE–specific proteins, which in turn would promote synapsis between homologous chromosomes.
KW  - Maus
KW  - Genetik
KW  - Cytologie
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68895
ER  -