Cajal bodies are nuclear bodies which are composed of the scaffolding protein Coilin and high concentrations of small nuclear ribonucleoproteins (snRNPs) which are involved in pre-mRNA splicing.These condensates are also suggested to contribute to RNA metabolism including snRNP biogenesis and telomerase biogenesis.
Useful reviews: 5970135, 27775477, 27627834, 27661468, 7819531).
Formation, Composition & dynamics (Assembly and disassembly)
Cajal body (CB) is a site for the modification of small nuclear RNAs (snRNAs) and snoRNAs, as well as for the assembly and trafficking of RNPs. In addition to coilin, the Cajal body is enriched in spliceosomal small nuclear RNPs (snRNPs), snoRNPs, the telomerase RNP and in the factors that assemble and mature RNPs, as well as the survival of the motor neurons (SMN) complex. The multiprotein Integrator complex, which processes the 3' end of snRNAs and maintains Cajal body integrity, may also be a member of the Cajal body (reviewed in 24040563). Coilin's ability to operate as a molecular hub and interact with many CB components via hetero-oligomerization, which stabilizes the forming structure, is thought to be responsible for this sub-nuclear phase change. Although many CB proteins have been identified as structurally important for CB integrity, little is known about their biochemical characteristics or regulation. Coilin and SMN, which are the typical CB marker proteins, as well as a small number of additional proteins, account for the vast majority of our information about the proteins required for CB assembly (details on the regulation of Cajal body assembly is reviewed in 27715441).
1636114 discovered that knockdown of the splicing factor TCERG1 disturbs the integrity of Cajal bodies and localization of its components.
Cajal bodies are linked to motor neuron diseases and the therapeutic action of small molecules like Spinraza and Flunarizine in rescuing motor neuron function through elevating the level of SMN is recently evidenced (9391529, 2612161).
Relation to human diseases
Disruption and loss of neuronal Cajal bodies is associated with severe neuronal dysfunctions in neurological disorders such as motor neuron diseases (27627892, 31090908).
7819531 reviewed the components of Cajal bodies.
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