Regulation of prolactin receptor expression in ovine skin in relation to circulating prolactin and wool follicle growth status

Abstract

Seasonal patterns of hair growth are governed, at least in part, by levels of prolactin in circulation, and although receptors for prolactin (PRLR) have been demonstrated in hair follicles, little is known of their regulation in relation to follicular cycles. In this study, a photoperiod-generated increase in prolactin was used to induce a wool follicle cycle during which changes in PRLR expression in sheep skin were determined by ribonuclease protection assay and in situ hybridisation. mRNA for prolactin and both isoforms of PRLR were also detected in skin by reverse transcription and polymerase chain reaction. As circulating prolactin began to rise from low levels, PRLR mRNA in the skin initially fell. These changes immediately preceded the catagen (regressive) phase of the hair cycle. Further increase in prolactin resulted in up-regulation of PRLR during telogen (dormancy), particularly in the epithelial hair germ, to reach a peak during proanagen (reactivation). In anagen (when follicle growth was fully re-established), PRLR mRNA returned to levels similar to those observed before the induced cycle. Hence, this longer term rise and fall of PRLR expression followed that of plasma prolactin concentration with a lag of 12-14 days. PRLR mRNA was most abundant in the dermal papilla, outer root sheath, hair germ, skin glands and epidermis. Location of PRLR in the dermal papilla and outer root sheath indicates action of prolactin on the growth-controlling centres within wool follicles. These cycle-related patterns of PRLR expression suggest dynamic regulation of PRLR by prolactin, thereby modulating hormonal responsiveness of seasonally growing hair follicles.

Prolactin and Its Receptor Are Expressed in Murine Hair Follicle Epithelium, Show Hair Cycle-Dependent Expression, and Induce Catagen

“…17 In contrast, Wiltshire sheep show increased PRL levels after experimentally in-creased photoperiods associated with a short-term inhibitory effect on growing anagen follicles. 18,19 This is consistent with previous observations that shortening of the photoperiod accompanied by reduced PRL plasma levels results in initiation of fiber growth of the winter fur. 11,13,20 Thus, systemic PRL levels seem to play a dual role during the seasonal dependent hair growth cycle by operating to induce both transitional phases: catagen and proanagen.…”

“…11,13,20 Thus, systemic PRL levels seem to play a dual role during the seasonal dependent hair growth cycle by operating to induce both transitional phases: catagen and proanagen. 10,18,19 In humans with their seasonally independent hair cycles, 2 hyperprolactinemia is associated with androgenetic alopecia, amenorrhea, infertility, and hirsutism. [21][22][23] PRL may increase adrenal androgen production, and can attenuate 5-␣-reductase activity both in vivo and in vitro thus increasing dihydro testosterone (DTH) synthesis.…”

Calcineurin/Nfatc1 signaling links skin stem cell quiescence to hormonal signaling during pregnancy and lactation

“…Prl can control skin molting in newts (Dent et al 1973) and feather molting in avian species (Dawson and Sharp 1998;Dawson et al 2009;Crossin et al 2012). Seasonal Prl in combination with other hormones is thought to modulate annual changes in hair growth of several species, including sheep, deer, and voles (Duncan and Goldman 1984;Curlewis et al 1988;Smale et al 1990;Dicks et al 1996;Nixon et al 2002;Randall 2007). Our data are consistent with these roles in epidermal renewal and suggest that Prl may have evolved as a general regulator of regeneration in the epidermis and its appendages.…”

“…In humans, patients with elevated serum Prl levels (or hyperprolactinemia) can experience hair loss (Orfanos and Hertel 1988;Foitzik et al 2009;Lutz 2012). Additionally, Prl has been implicated in the regulation of epidermal appendage growth in several avian and mammalian species (Duncan and Goldman 1984;Pearson et al 1996;Dawson and Sharp 1998;Nixon et al 2002;Dawson et al 2009). Prl receptors (Prlrs) are expressed within the HF in both mice and humans, and Prl can induce follicle death in cultured skin tissue from both species (Foitzik et al 2003(Foitzik et al , 2006.…”

Short Communication A novel single-nucleotide polymorphism in the 5' upstream region of the prolactin receptor gene is associated with fiber traits in Liaoning cashmere goats

“…On the other hand, this genotype may eventually be induced by the long-term artificial selection towards fiber quality. Previous studies suggest that PRLR appeared to be a promising candidate gene, because it may regulate important functions in hair growth cycles (Choy et al, 1997;Nixon et al, 2002). The main finding of this study was the association of the C970T polymorphism with CFW, which has not been reported before.…”