We have a ton of neurons. And each of those neurons has many dendrites. And each dendrite has countless little dendritic spines. Thinking about how complex one single neuron is in order to receive a signal from another cell gives me an identity crisis. What if we are all just little dendritic spines on our universe’s neuron?! Was that stupid stampede for Walmart’s Black Friday sale worth it for those folks? Was my self-restraint when faced with leftover pumpkin pie worth it? Is any of it worth it?!
Dendritic spines are small actin-rich protrusions on a neuron’s dendrite, the structure that receives information from other neurons. The morphology and density of the dendritic spines can be regulated by neurotransmitters, actin dynamics, and actin-regulating proteins. The neuron-specific actin regulator cortactin-binding protein 2 (CTTNBP2) regulates the formation and maintenance of dendritic spines, and is even associated with autism spectrum disorder. A recent paper investigates the role of a CTTNBP2 homologue, CTTNBP2NL (CTTNBP2 N-terminal-like protein). Chen and colleagues found that while CTTNBP2 expression is found in the brain, CTTNBP2NL is not. In addition, CTTNBP2NL does not appear to play a role in dendritic spine formation. Although both CTTNBP2 and CTTNBP2NL associate with cortactin, a well-studied actin regulator, CTTNBP2 is associated with the cell’s cortex while CTTNBP2NL is found on actin stress fibers. In addition, Chen and colleagues found a link between CTTNBP2 and the protein phosphatase 2A (PP2A) complex, specifically with CTTNBP2 targeting the PP2A complex to dendritic spines. In the images above, cells show labels for cortactin (red) and actin fibers (blue). CTTNBP2NL (green, top) associates with stress fibers (arrows), while CTTNBP2 (green, bottom) is distributed around the cortex (arrowheads).
Chen, Y., Chen, C., Hu, H., & Hsueh, Y. (2012). CTTNBP2, but not CTTNBP2NL, regulates dendritic spinogenesis and synaptic distribution of the striatin-PP2A complex Molecular Biology of the Cell, 23 (22), 4383-4392 DOI: 10.1091/mbc.E12-05-0365