Cajal-body formation correlates with differential coilin phosphorylation in primary and transformed cell lines

Abstract

Transcription-dependent colocalization of the U1, U2, U4/U6 and U5 snRNPs in coiled bodies.

Cajal bodies and their role in plant stress and disease responses

“…This is consistent with other reports which have found that the N-terminal 92 amino acid sequence of coilin is critical for CB assembly, self-interaction, targeting to CBs, and de novo CB formation. 27,32,33 It is thought that this process is also influenced by 10 residues of the most distal end of the C-terminus, which may control N-terminus self-interaction, which may in turn regulate coilin localization, 34 CB formation and number. 35 Possible mechanisms of coilin involvement in CB assembly have recently been discussed in detail by Machyna et al 25,36 Briefly, the model suggests that CBs may be nucleated by tethering different CB components, proteins or RNAs, to a specific site (usually transcriptionally active region) inside the nucleus in a stochastic manner.…”

Coilin: The first 25 years

“…12,79,95,96 Perhaps contributing to cell cycle variation in CB number, cdk2/cyclin E and the nuclear phosphatase PPM1G phosphorylate and dephosphorylate coilin in vitro. 97,98 It was suggested that the interplay between coilin phosphorylation and dephosphorylation affects coilin selfassociation and interaction with snRNPs, SMN and RNAs. 16,[98][99][100] Future perspective During the first 25 years, we learned that coilin is a tricky protein to deal with.…”

“…97,98 It was suggested that the interplay between coilin phosphorylation and dephosphorylation affects coilin selfassociation and interaction with snRNPs, SMN and RNAs. 16,[98][99][100] Future perspective During the first 25 years, we learned that coilin is a tricky protein to deal with. Coilin often proves insoluble when expressed or otherwise purified, and little structural information exists.…”

Specific genomic cues regulate Cajal body assembly

“…In human primary cells, which typically lack CBs, coilin is hyperphosphorylated on C-terminal phosphoserine residues and this is proposed to reduce its ability to self-interact. 102 By contrast, in transformed cells, which typically have a high number of CBs, coilin is hypophosphorylated at these sites and able to pull the body together. To date, 18 distinct human coilin phosphorylation residues have been reported, with several known regulators of their modification, including the phosphatase PPM1G.…”

“…This phenotype is not observed in cells overexpressing coilin-GFP only. 102 We believe that tagging of the N-or C-terminal regions of coilin by GFP potentially inhibits the enlargement of CBs in these embryonic cells, possibly by disrupting coilin's self-association ability. These data indicate that attaching fluorescent tags to either the C-or N-termini of coilin and fixed using 4% paraformaldehyde were stained with antibodies to detect CBs (CB marker protein coilin, green) and HLBs (histone transcription factor NPAT, far red) and imaged using the Opera 5020 high-content automated confocal microscopy system (PerkinElmer, Waltham MA).…”