Cajal body

Cajal Body

Micrograph showing Cajal bodies in a cell nucleus.

A Cajal body is a subnuclear structure that is involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs) and other RNA-related processes. Cajal bodies are named after the Spanish neuroscientist Santiago Ramón y Cajal, who first described them in 1903. They are typically found in the nuclei of proliferative cells, such as neurons, and are associated with the nucleolus.

Structure

Cajal bodies are spherical structures that range in size from 0.2 to 2.0 micrometers in diameter. They are not surrounded by a membrane, which classifies them as non-membranous organelles. Cajal bodies are composed of a variety of proteins and RNA molecules, including coilin, a marker protein that is essential for their formation and maintenance.

Function

Cajal bodies play a crucial role in the maturation and assembly of snRNPs, which are essential components of the spliceosome, the complex responsible for RNA splicing. They are also involved in the modification and assembly of other RNA-protein complexes, such as small nucleolar ribonucleoproteins (snoRNPs) and telomerase.

Dynamics

Cajal bodies are dynamic structures that can change in number and size depending on the cell cycle and the metabolic state of the cell. They are often more numerous in cells that are actively transcribing genes and processing RNA. The formation and disassembly of Cajal bodies are regulated by various signaling pathways and post-translational modifications of their constituent proteins.

Clinical Significance

Alterations in the number or function of Cajal bodies have been associated with several diseases, including spinal muscular atrophy and systemic lupus erythematosus. In these conditions, the disruption of normal Cajal body function can lead to defects in RNA processing and gene expression.

Related pages

• Nucleolus
• Spliceosome
• RNA splicing
• Santiago Ramón y Cajal