G Proteins and Autocrine Signaling Differentially Regulate Gonadotropin Subunit Expression in Pituitary Gonadotrope

Abstract

Background:The mechanism for differential control of gonadotropin gene induction by GnRH is not established. Results: GnRH activates G␣ s and G␣ q/11 , which modulate LH and FSH synthesis, respectively, by a mechanism including secreted factors. Conclusion: Different G proteins and autocrine signaling regulate the pattern of FSH and LH expression by GnRH. Significance: A novel G protein and autocrine signaling mechanism has been identified.

Growth Differentiation Factor 9 (GDF9) Forms an Incoherent Feed-forward Loop Modulating Follicle-stimulating Hormone β-Subunit (FSHβ) Gene Expression

“…Male mice were used as a source of cells because cells from randomly cycling female mice result in more abundant multiresponsive and polyhormonal anterior pituitary cells than males (16). Briefly, pituitaries were dispersed by enzymatic digestion with collagenase and pancreatin (5). Undigested tissue and cell aggregates were filtered out using a 52-m pore nylon mesh.…”

“…siRNA Interference-L␤T2 cells were transfected using the Amaxa Cell Line Nucleofector Kit L (Lonza Walkersville, Walkersville, MD), as described previously (5). Immediately after transfection, cells were seeded in a cell culture plate containing DMEM ϩ 10% FBS and incubated at 37°C for 24 h. Next, culture medium was replaced with serum free-DMEM, and cells were incubated overnight at 37°C for serum starvation.…”

“…We recently identified inhibin ␣, a secreted extracellular autocrine factor, as contributing to FSH␤ regulation in the gonadotrope (5). This finding suggested that important regulatory network motifs might be constructed from intracellular pathways and extracellular secreted regulatory factors.…”

“…In mouse gonadotropes, FSH␤ gene expression is preferentially increased by brief, low concentration pulses of GnRH every 2 h. Paradoxically, doubling the amount of GnRH stimulation by increasing the pulse frequency to one pulse/hour leads to lower levels of FSH␤ mRNA (5). This frequency-response pattern contributes to normal reproductive physiology.…”

“…The data reported in this paper have been deposited in the Gene Expression Omnibus (GEO) database, www.ncbi.nlm.nih.gov/geo (accession number GSE52631 syndrome, and underlie the pharmacological treatment of gonadal hormone-dependent diseases, such as endometriosis and prostate cancer. Because of its biological and medical importance, the frequency system underlying gonadotropin regulation has been an area of study for decades, and several factors have been proposed to contribute to FSH␤ frequency sensitivity (2,(5)(6)(7)(8)(9)(10)(11). The major information processing properties of molecular signaling networks are largely determined by simple network motifs, and specific feedback or feed-forward circuits are necessary to create a robust low frequency detector (12)(13)(14).…”