Brain mRNAs in single neuron cell bodies and dendrites
Subcellular RNA sequencing reveals unique dynamics in cell-type specific compartments
Brain cells communicate at specialized connections called “synapses” which are distributed throughout extensive tree-like protrusions (axons and dendrites). Specialized proteins present at synapses allow synapses to communicate with neighbors and to store information during learning and memory. Synapses can rapidly adjust their proteins by making use of messenger RNA molecules (the “blue-prints” for proteins) that are present immediately adjacent to (or even inside) the synapse.
The constellation of mRNA molecules present in a cellular compartment is called the “transcriptome”. Although thousands of mRNA molecules have been detected in neuronal processes, it is still unknown whether these subcellular transcriptomes vary according to neuron type. To address this question, Perez et al. established a single cell RNAs-sequencing method with subcellular resolution. They used a laser beam to capture the dendritic arbor and cell body of single neurons, and then used a very sensitive protocol to prepare mRNAs present in each compartment for sequencing. Almost 4000 different mRNAs were present in the dendrites of the two major neuron classes, glutamatergic and GABAergic neurons. The transcriptome of individual cell bodies was more variable than the transcriptome of dendritic arbors.
Additionally, by comparing the dendritic and cell body transcriptome of each neuron, Perez et al, found dendritic mRNAs that did not simply reflect their abundance in the cell bodies. In addition, using imaging methods and special labeling of a mutant mouse line, they showed that GABAergic neurons synthesize proteins in their dendrites and axons. This study shows that many different classes of neurons use local translation to supply their processes and synapses with protein.
Julio D. Perez, Susanne tom Dieck, Beatriz Alvarez-Castelao, Georgi Tushev, Ivy C.W. Chan, Erin M. Schuman.
Subcellular sequencingof single neurons reveals the dendritic transcriptome of GABAergic interneurons. Elife, January 6, 2021 DOI: 10.7554/eLife.63092