26.19:
Role of Septins
In eukaryotic cells, septins have diverse roles in cytoskeletal dynamics, cell division, and vesicle trafficking.
During cilia formation, septins detect the outward curvature of the plasma membrane and interact to form a diffusion barrier at the base of the cilium. This barrier allows the selective transport of solute particles between the cilium and the cytoplasm.
During cell division, septins identify the cleavage furrow in the plasma membrane and form a septin ring around it. The ring then recruits structural proteins, like microfilaments and myosin II filaments to form the contractile ring for cytokinesis.
In neurons, septins function as microtubule-associated proteins for vesicle trafficking. They bind with microtubules and regulate the movement of cargo transport by motor proteins including kinesins.
26.19:
Role of Septins
Septins are the recently discovered fourth major protein component of the cytoskeleton, along with microfilaments, microtubules, and intermediate filaments. These proteins can associate with other cytoskeletal filaments and carry out varied roles or can be free-floating in the cytoplasm.
Cellular Functions of Septins
Recent studies have revealed the multifaceted roles of septins in various cellular processes such as cytokinesis, ciliogenesis, and neurogenesis. Septins act as scaffolds and promote protein-protein interactions; for example, in S. cerevisiae, septin scaffolding protein helps recruit different filament proteins to form contractile rings during cytokinesis.
Septin was first found in the sperm flagella's annulus, which compartmentalizes the anterior and posterior tail regions. Mutation in the septin-forming genes like SEPT12 affects sperm motility and its structural integrity. Other septins like SEPT2 are involved in forming a diffusion barrier between the cilia and the cytoplasm.
Septins also play a role in stabilizing the membrane by binding and modifying the membrane and action-myosin interactions.
Diseases Related to Septins
Studies have shown septins are associated with proteins involved in neurodegenerative diseases like Parkinson's and Alzheimer's. In Parkinson's disease, septin interacts with parkin, an E3 ubiquitin ligase. Septins' mutation has also been linked with tumorigenesis or cancer. Studies on cancerous cells suggest septin mutations are also related to resistance to cells, metastasis, proliferation, and angiogenesis.
Leitura Sugerida
- Mostowy, S. and Cossart, P., 2012. Septins: the fourth component of the cytoskeleton. Nature reviews Molecular cell biology, 13(3), pp.183-194.
- Palander, O., El-Zeiry, M. and Trimble, W.S., 2017. Uncovering the roles of septins in cilia. Frontiers in cell and developmental biology, 5, p.36.