Validation of a UchL1‐H2BCherry:gpiGFP BAC transgenic for imaging of neuronal progenitors and innervation in the lower urinary tract

Ubiquitin carboxy‐terminal hydrolase L1 ( UchL1 ) also known as PGP9.5, is expressed in migrating neural crest‐derived progenitors and mature neurons in autonomic ganglia throughout the peripheral nervous system. While a broad range of neuronal transgenic reporters have been developed for analysis of the central nervous system, tools that facilitate imaging of neuronal progenitors in the peripheral nervous system have been lacking. Expression of UchL1 has been thoroughly documented in the peripheral nervous system but only a single LacZ knock‐in allele that ablates gene expression has previously been available. To visualize expression of UchL1 in living cells in the context of normal development, we generated a bacterial artificial chromosomal (BAC) transgenic that drives expression of a H2BmonoCherry:gpiGFP dual fluorescent reporter from the regulatory regions of this gene. This strategy does not alter the endogenous UchL1 locus and thus facilitates analysis of normal progenitors expressing the reporter during peripheral nervous system development and maturation. The H2BmonoCherry moiety allows clear discrimination of individual cells and pinpoints the locations of discrete ganglia as a consequence of nuclear–localized monoCherry fluorescence in neuronal nuclei. Membrane expression of the gpiEGFP moiety illuminates axonal processes and cell connections in autonomic ganglia. We have compared the expression of the new BAC transgenic to the knock‐in allele and determined that the transgenic allele possesses regulatory elements capable of recapitulating endogenous gene expression in multiple sites including enteric nervous system, pelvic ganglia, kidney pelvis, and genital tubercle. Supported by National Institutes of Health grant U01DK070219‐04S3