New mouse tool to study late-born spinal cord neurons

SISTER, CATERINA LAURA; LANUZA, GUILLERMO

Chascomús

Taller; V Taller de Biología Celular y del Desarrollo; 2022

The mammalian spinal cord is an excellent model system for analyzing how neurons are specified and assembled into functional circuits. Cerebrospinal fluid-contacting neurons (CSF-cNs), an intriguing spinal cord central canal population, are characterized by expression of transcription factors Gata2 and Gata3, and ionic channels Pkd2l1 and Pkd1l2. To selectively study distinct neural populations, it is important to develop efficient and precise mouse molecular tools. We have previously shown that the proneural factor Ascl1 is expressed in CSF-cNs progenitors. The Ascl1CreER line allows labeling of Ascl1+ lineages, including central canal neurons, and to analyze aspects of their differentiation. However, this strategy is not restricted to central canal cells, since Ascl1 is also present in dorsal neuron precursors and astrocytes. Here we characterize the use of a new tool, the Pkd2l1Cre line, to label and manipulate CSF-cNs during their development. We used the Pkd2l1Cre driver in combination with the conditional Tomato reporter, and found that 77± 5% Pkd2l1+ were marked in the spinal cord of newborn (P0) pups. This labeling increases to 90% in P15 young mice. Importantly, Pkd2l1Cre driver was only expressed in Pkd2l1+ cells, indicating that the recombinase faithfully recapitulates Pkd2l1 expression, and is absent in other cells types. At earlier stages (E15.5) we found half of Pkd2l1+ cells labeled, consistent with Cre- mediated recombination delay of endogenous Pkd2l1 expression. Using this approach together with flox conditional alleles, we have started to dissect the function of Gata transcription during CSF-cN maturation. In summary, we provide compelling evidences that Pkd2l1Cre line is selective for central canal neurons, and it is a useful tool to manipulate this neuron type with fidelity and specificity.