Cleavage bodies

Cleavage bodies usually appear as 1-4 foci of ~0.3-1.0 mm and contain several factors specifically involved in the cleavage and polyadenlylation steps of pre-mRNA processing (Spector, 2001) [1]. These factors include the cleavage stimulation factor (CstF) and the polyadenylation specificity factor (CPSF), both of which are necessary for 3' terminal processing of polyadenlyated mRNAs (Schul et al., 1996) [2]. Usually cleavage bodies either overlap with or are localised adjacent to Cajal bodies, with the subset not associated with Cajal bodies containing nascent RNA. Recently, the human DEAD box protein DDX1 was also found to reside in cleavage bodies that lack nascent RNA, suggesting that biochemically (and perhaps functionally) distinct subclasses of cleavage bodies may exist (Bleoo et al., 2001) [3].

The association of cleavage and Cajal bodies has been shown to be very dynamic and cell cycle dependent. Cleavage bodies appear coincident with Cajal bodies in G1, then adjacent to these structures in S phase and finally appearing less defined or absent altogether in G2 (Schul et al., 1999) [4]. Interestingly, like Cajal bodies, a subclass of cleavage bodies also associate with histone gene clusters in vivo (Schul et al., 1999) [4].

REFERENCES

  1. Spector, D.L. (2001) Nuclear domains. J. Cell Sci. 114 (16):2891-2893
  2. Schul W, Groenhout B, Koberna K, Takagaki Y, Jenny A, Manders EM, Raska I, van Driel R, de Jong L. (1996) The RNA 3' cleavage factors CstF 64 kDa and CPSF 100 kDa are concentrated in nuclear domains closely associated with coiled bodies and newly synthesized RNA. EMBO J. 15(11):2883-2892.
  3. Bleoo S, Sun X, Hendzel MJ, Rowe JM, Packer M, Godbout R. (2001) Association of human dead box protein ddx1 with a cleavage stimulation factor involved in 3'-end processing of pre-mrna. Mol. Biol. Cell. 12(10):3046-3059.
  4. Schul W, van Der Kraan I, Matera AG, van Driel R, de Jong L. (1999) Nuclear domains enriched in RNA 3'-processing factors associate with coiled bodies and histone genes in a cell cycle-dependent manner. Mol. Biol. Cell. 10(11):3815-24.