Transcriptional targets of Trps1 in vibrissae

Mutations in TRPS1 cause trichorhinophalangeal syndrome types I and III, which are characterized by sparse scalp hair in addition to craniofacial and skeletal abnormalities. Trps1 is a vertebrate transcription factor containing nine zinc-finger domains, including a GATA-type zinc finger through which it binds DNA. Mice in which the GATA domain of Trps1 has been deleted (Trps1∆gt/∆gt) have a reduced number of pelage follicles and lack vibrissae follicles postnatally. To identify the transcriptional targets of Trps1 in the developing vibrissa follicle, we performed microarray hybridization analysis comparing expression patterns in the whisker pads of wild-type versus Trps1∆gt/∆gt embryos. We identified a number of transcription factors and Wnt inhibitors among transcripts downregulated in the mutant embryos, and several extracellular matrix proteins there were upregulated in the mutant samples. Whole whisker pads were dissected from E12.5 embryos and total RNA was isolated using the RNeasy Mini Kit (Qiagen). Triplicate RNA samples from three independent embryos of each genotype were amplified and labeled for hybridization to Affymetrix GeneChip MOE430A microarrays using Affymetrix reagents and protocols. The data output was analyzed using GeneSpring GX 10.0 commercial software (Agilent Technologies). P-values were calculated using an unpaired t-test. Expression values with a p-value less than or equal to 0.05 and a fold difference of at least 1.5 relative to wild-type baseline expression levels were considered significant.