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Simple Summary: Pituitary neuroendocrine tumours originate from the endocrine cells of the anterior pituitary gland and may develop from any of the cell lineages responsible for producing the different pituitary hormones. The details related to tumour differentiation and hormone production in these tumours are not fully understood. The aim of our study was to investigate an uncharacterised pituitary enriched protein, transforming growth factor beta-receptor 3 like (TGFBR3L). The TGFBR3L protein is highly expressed in the pituitary compared to other organs. We found the protein to be gonadotroph-specific, i.e., detected in the cells that express follicle-stimulating and luteinizing hormones (FSH/LH). The gonadotroph-specific nature of TGFBR3L, a correlation to both FSH and LH as well as an inverse correlation to membranous E-cadherin and oestrogen receptor beta suggests a role in gonadotroph cell development and function and, possibly, tumour progression. Here, we report the investigation of transforming growth factor beta-receptor 3 like (TGFBR3L), an uncharacterised pituitary specific membrane protein, in non-neoplastic anterior pituitary gland and pituitary neuroendocrine tumours. A polyclonal antibody produced within the Human Protein Atlas project (HPA074356) was used for TGFBR3L staining and combined with SF1 and FSH for a 3-plex fluorescent protocol, providing more details about the cell lineage specificity of TGFBR3L expression. A cohort of 230 pituitary neuroendocrine tumours were analysed. In a subgroup of previously characterised gonadotroph tumours, correlation with expression of FSH/LH, E-cadherin, oestrogen (ER) and somatostatin receptors (SSTR) was explored. TGFBR3L showed membranous immunolabeling and was found to be gonadotroph cell lineage-specific, verified by co-expression with SF1 and FSH/LH staining in both tumour and non-neoplastic anterior pituitary tissues. TGFBR3L immunoreactivity was observed in gonadotroph tumours only and demonstrated int, QC 20210202

Context: Gonadotroph pituitary neuroendocrine tumors (PitNETs) can express follicle-stimulating hormone (FSH) and luteinizing hormone (LH) or be hormone negative, but they rarely secrete hormones. During tumor development, epithelial cells develop a mesenchymal phenotype. This process is characterized by decreased membranous E-cadherin and translocation of E-cadherin to the nucleus. Estrogen receptors (ERs) regulate both E-cadherin and FSH expression and secretion. Whether the hormone status of patients with gonadotroph PitNETs is regulated by epithelial-to-mesenchymal transition (EMT) and ERs is unknown. Objectives: To study the effect of EMT on hormone expression in gonadotroph nonfunctioning (NF)-PitNETs. Design: Molecular and clinical analyses of 105 gonadotroph PitNETs. Immunohistochemical studies and real-time quantitative polymerase chain reaction were performed for FSH, LH, E-cadherin, and ER alpha. Further analyses included blood samples, clinical data, and radiological images. Setting: All patients were operated on in the same tertiary referral center. Results: NF-PitNET with high FSH expression had decreased immunohistochemical staining for membranous E-cadherin (P < .0001) and increased staining for nuclear E-cadherin (P < .0001). Furthermore, high FSH expression was associated with increased ER alpha staining (P = .0002) and ER alpha mRNA (P = .0039). Circulating levels of plasma-FSH (P-FSH) correlated with FSH staining in gonadotroph NF-PitNET (P = .0025). Tumor size and invasiveness was not related to FSH staining, E-cadherin, or ER alpha. LH expression was not associated with E-cadherin or ER alpha. Conclusion: In gonadotroph PitNETs, FSH staining is related to E-cadherin, ER alpha expression, and circulating levels of P-FSH. There was no association between FSH staining and invasiveness. The clinical significance of these findings will be investigated in ongoing prospective studies.

Here, we report the investigation of transforming growth factor beta-receptor 3 like (TGFBR3L), an uncharacterised pituitary specific membrane protein, in non-neoplastic anterior pituitary gland and pituitary neuroendocrine tumours. A polyclonal antibody produced within the Human Protein Atlas project (HPA074356) was used for TGFBR3L staining and combined with SF1 and FSH for a 3-plex fluorescent protocol, providing more details about the cell lineage specificity of TGFBR3L expression. A cohort of 230 pituitary neuroendocrine tumours were analysed. In a subgroup of previously characterised gonadotroph tumours, correlation with expression of FSH/LH, E-cadherin, oestrogen (ER) and somatostatin receptors (SSTR) was explored. TGFBR3L showed membranous immunolabeling and was found to be gonadotroph cell lineage-specific, verified by co-expression with SF1 and FSH/LH staining in both tumour and non-neoplastic anterior pituitary tissues. TGFBR3L immunoreactivity was observed in gonadotroph tumours only and demonstrated intra-tumour heterogeneity with a perivascular location. TGFBR3L immunostaining correlated positively to both FSH (R = 0.290) and LH (R = 0.390) immunostaining, and SSTR3 (R = 0.315). TGFBR3L correlated inversely to membranous E-cadherin staining (R = -0.351) and oestrogen receptor β mRNA (R = -0.274). In conclusion, TGFBR3L is a novel pituitary gland specific protein, located in the membrane of gonadotroph cells in non-neoplastic anterior pituitary gland and in a subset of gonadotroph pituitary tumours.

Adrenaline increases glycogen synthase (GS) phosphorylation and decreases GS activity but also stimulates glycogen breakdown and low glycogen content normally activates GS. To test the hypothesis that glycogen content directly regulates GS phosphorylation, glycogen breakdown was stimulated in condition with decreased GS activation. Saline or adrenaline (0.02mg/100g rat) was injected subcutaneously in Wistar rats (~130 g) with low (24 h fasted), normal (normal diet) and high glycogen content (fasted-refed) and epitrochlearis muscles were removed after 3 h and incubated ex vivo eliminating adrenaline action. Adrenaline injection reduced glycogen content in epitrochlearis muscles with high (120.7±17.8 vs 204.6±14.5 mmol•kg(-1); p<0.01) and normal glycogen (89.5±7.6 vs 152.6±8.1 mmol•kg(-1); p<0.01), but not significantly in muscles with low glycogen (90.0±5.0 vs 102.8±7.8 mmol•kg(-1); p=0.17). In saline-injected rats, GS phosphorylation at sites 2+2a, 3a+3b and 1b was higher and GS activity lower in muscles with high compared to low glycogen. GS site 2+2a and 3a+3b phosphorylation decreased and GS activity increased in muscles where adrenaline decreased glycogen content; these parameters were unchanged in epitrochlearis from fasted rats where adrenaline injection did not decrease glycogen content. Incubation with insulin decreased GS site 3a+3b phosphorylation independent of glycogen content. Insulin-stimulated glucose uptake was increased in muscles where adrenaline injection decreased glycogen content. In conclusion, adrenaline stimulates glycogenolysis in epitrochlearis muscles with normal and high, but not low glycogen content. Adrenaline-stimulated glycogenolysis decreased GS phosphorylation and increased GS activity. These data for the first time document direct regulation of GS phosphorylation by glycogen content.