Nw. Rufaut et al., Identification of differentially expressed genes during a wool follicle growth cycle induced by prolactin, J INVES DER, 113(6), 1999, pp. 865-872
The wool follicles of New Zealand Wiltshire sheep can be induced to undergo
growth cycles by manipulating circulating prolactin levels. Altered patter
ns of gene expression through this cycle were examined using differential d
isplay, and nine sequence tags for differentially expressed genes were isol
ated. Four of these tags were identified as fragments of known genes, encod
ing a wool keratin, KRTAP3.2, a desmosome component, desmoglein 1, an epith
elial cell marker, stratifin, and a protein kinase, Clk3. All four genes we
re shown to be downregulated in telogen skin compared with anagen, In situ
hybridization showed that all had localization patterns which included cell
s that are absent in telogen, The stratifin tag was used to clone a cDNA th
at incorporated a complete open-reading frame for ovine stratifin. Ovine st
ratifin is similar to the human form, showing only six single residue diffe
rences in the predicted amino acid sequence. Stratifin probably acts as a r
egulator of other proteins involved in trichocyte cell cycling and differen
tiation, Clk3 is involved in regulating RNA splicing. KRTAP3.2 and Dsg1 bot
h play structural roles in hair follicles, The other five tags, including t
wo representing genes that were upregulated during catagen, could not be id
entified by homology. Differential display is an effective means of identif
ying genes involved in follicle function and, potentially, of genes control
ling the growth cycle.