. 2017 Sep 14;9(1):42–55. doi: 10.1080/19491034.2017.1361578

Table 1.

Composition and function of different nuclear particles (Cajal bodies, PML bodies, PcG clusters, Insulator speckles, Nuclear speckles and Nucleolus).

Nuclear Particle	Composition	Functions	References
Cajal bodies	Coilin, Fibrillarin, SMN1, Gemins, Nap57, NO38, GAR1,NOPP140, TCAB1. RNAs U85 scaRNA, U87 scaRNA, U88 scaRNA, U89 scaRNA, U90 scaRNA, U91 scaRNA, U92 scaRNA, U2 snRNA, U4 snRNA, U5 snRNA, U6 snRNA, U3 snoRNA, U8 snoRNA, U14 snoRNA, TERC RNA	• Processing 3′ end of histonemRNA. • Involved in the maturation of telomerase. • Processing and assembly of ribonucleoproteins like snRNPS, snoRNPs and sca-RNPs. • Found to interact with gene like RNU1 and RNU2. • Involved in intra- and inter-chromosomal interactions of chr1, chr6 and chr17	⁴⁰^,³⁹^,⁴¹^,⁹⁹^,¹⁰⁰^,¹⁰¹
Promyelotic leukemia (PML) bodies	PML,CBP, and other proteins such as Sp100, BLM, Daxx, Hipk2, Mdm2, p53, SUMO-1, TRF1, TRF2	• Involved in antivirus response, apoptosis, telomere shortening, DNA repair, cell cycle control etc. • Required for IFN-γ MHC II expression. • Also involved in gene repression with Daxx.	⁵⁸^,²⁹^,³⁰^,⁷⁹^,⁸⁰^,¹⁰²^,¹⁰³
PcG clusters/bodies	Mostly components of PRC1 have been found in PcG clusters/bodies PH, Pc, RING1, CBXs and BMI1 PcG like proteins SOR-1 and SOP-2 proteins in C.elegans.	• Involved in genes silencing. • Involved in the compaction of HOX genes. • Maintain proper expression of HOX genes. • Mediates long-range genomic interactions. • A PcG protein, EZH2 helps in the the formation of loop within the GATA-4 locus.	²⁹^,^47-50^,¹⁸^,⁶⁰^,⁶¹^, ⁶⁷^,¹⁰²^,¹⁰³
Insulator bodies/speckles	CTCF (mammals), CP190, Su(Hw), mod(mdg4), BEAF, chromotor, dCTCF (Drosophila).	• Help in shaping chromatin topology, present at inter-TAD boundaries. • Involved in the formation of chromatin loops. • These may be involved in intra-TAD interactions.	⁷⁰_,⁷¹^,⁷²^,⁷⁴^,¹⁶
Nuclear speckles	SR proteins (SF2/ASF, SC35, SRp20, SRp40, SRp55, SRp75, SRp30c, 9G8, and SRp54), CLK/STY, PRP4, PSKH1, eIF4Aiii and protein phosphatase 1. RNAs U1 snRNA, U2 snRNA, MALAT1 RNA, Poly(A)⁺ RNA	• pre-mRNA splicing factors, including snRNPs and serine/arginine-rich (SR) proteins. • Regulates the post-translational modification of splicing factors. • Hubs for gene activation • Mediates interchromosomal interaction events induced by hormones.	³⁰^,¹⁰⁰^,¹⁰⁴
Nucleolus	Nucleolin, B23, Fibrillarin. Transranslational factors and structural proteins including keratin, lamins and tubulin have also been identified in this compartment. RNAs rRNAs, snoRNAs (U3 snoRNA, U8 snoRNA, U13 snoRNA, U14 snoRNA, U17 snoRNA, E2 snoRNA, E3 snoRNA), snRNAs, tRNAs, 7SL RNA.	• Primarily associated with ribosome biogenesis but it is also involved in several different functions like genome organization, stress response, cell cycle and proliferation. • intranuclear and nuclear–cytoplasmic transport, • modification and assembling of snRNAs • sequestrating proteins that control cell-cycle check points including Mdm2, Cdc14, and Pch2.	⁹⁸^,¹⁰⁵^,¹⁰⁶