Cohesin SMC1beta protects telomeres in meiocytes.
Meiosis-specific mammalian cohesin SMC1beta is required for complete sister chromatid cohesion and proper axes/loop structure of axial elements (AEs) and synaptonemal complexes (SCs). During prophase I, telomeres attach to the nuclear envelope (NE), but in Smc1beta(-/-) meiocytes, one fifth of their telomeres fail to attach. This study reveals that SMC1beta serves a specific role at telomeres, which is independent of its role in determining AE/SC length and loop extension. SMC1beta is necessary to prevent telomere shortening, and SMC3, present in all known cohesin complexes, properly localizes to telomeres only if SMC1beta is present. Very prominently, telomeres in Smc1beta(-/-) spermatocytes and oocytes loose their structural integrity and suffer a range of abnormalities. These include disconnection from SCs and formation of large telomeric protein-DNA extensions, extended telomere bridges between SCs, ring-like chromosomes, intrachromosomal telomeric repeats, and a reduction of SUN1 foci in the NE. We suggest that a telomere structure protected from DNA rearrangements depends on SMC1beta.
Adelfalk
Caroline
C
Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Dresden University of Technology, 01307 Dresden, Germany.
Janschek
Johannes
J
Revenkova
Ekaterina
E
Blei
Cornelia
C
Liebe
Bodo
B
Göb
Eva
E
Alsheimer
Manfred
M
Benavente
Ricardo
R
de Boer
Esther
E
Novak
Ivana
I
Höög
Christer
C
Scherthan
Harry
H
Jessberger
Rolf
R
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000172:deficiency / Q000378:metabolism*; D005260:Female; D008297:Male; D008540:Meiosis; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism; D016615:Telomere / Q000378:metabolism*; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D000097722:Cohesins; C438001:Smc1l2 protein, mouse