Distinct Expression Patterns of Osteopontin and Dentin Matrix Protein 1 Genes in Pituitary Gonadotrophs

Discussion The expression of OPN mRNA in pituitary gonadotrophs has been reported previously (33). Here we provide further evidence that Spp1 is expressed in gonadotrophs but not in other pituitary cell types. First, the developmental pattern of Spp1/OPN is sex-specific and comparable to that observed for Lhb, Fshb, and Gnrhr (35), the well-established marker genes for gonadotrophs (40). Second, there was no correlation between Spp1 vs. Gh1, Prl, Tshb, and Pomc, the marker genes for somatotrophs, lactotrophs, thyrotrophs, and corticotrophs, respectively. Third, immuno-histochemical analysis showed the expression of OPN only in LHβ- and LHβ/FSHβ- positive cells. Our recent single cell RNA-sequence also showed the expression of Spp1 in gonadotrophs only (NCBI Sequence Read Archive accession SRP151788). Thus, Spp1 is an additional gonadotroph-specific gene. The expression of gonadotroph-marker genes, such as Lhb, Fshb, and Gnrhr, is regulated by GnRH (41). Previously we also showed that pulsatile GnRH application facilitated expression of numerous genes, including Fshb, Cga, and Gnrhr, but not Spp1 (32). Here we show that both in vitro and in vivo activations of GnRHR were ineffective in induction of Spp1. We also show that Spp1 expression varies during estrous cycle, with the pattern not comparable to endogenous GnRH release. Activation of other G protein-coupled receptors expressed in gonadotrophs was also ineffective. In other tissues, the expression...
Source: Frontiers in Endocrinology - Category: Endocrinology Source Type: research