Experimental polycystic ovarian syndrome is associated with reduced expression and function of P2Y2 receptors in rat theca cells.

Extracellular purines through specific receptors have been recognized as new regulators of ovarian function. It is known that P2Y2 receptor activity induces theca cell proliferation, we hypothesized that purinergic signaling controls the changes related to hyperthecosis in polycystic ovarian syndrome (PCOS). The aim of this study was to analyze the expression of UTP-sensitive P2Y receptors and their role in theca cells (TC) proliferation in experimentally-induced PCOS (EI-PCOS). In primary cultures of TC from intact rats, all the transcripts of P2Y receptors were detected by polymerase chain reaction; in these cells, UTP (10 µM) induced extracellular signal-regulated kinases (ERK) phosphorylation. Rats with EI-PCOS showed a reduced expression of P2Y2R in TC whereas P2Y4R did not change. By analyzing ERK phosphorylation, it was determined that P2Y2R is the most relevant receptor in TC. UTP promoted cell proliferation in TC from control but not from EI-PCOS rats. The in silico analysis of P2yr2 promoter indicated the presence of androgen response elements; the stimulation of TC primary cultures with testosterone promoted a significant reduction in the expression of the P2yr2 transcript. We concluded that P2Y2R participates in controlling the proliferative rate of TCs from healthy ovaries, but this regulation is lost during EI-PCOS.

Synchronization by Daytime Restricted Food Access Modulates the Presence and Subcellular Distribution of ß-Catenin and Its Phosphorylated Forms in the Rat Liver.

ß-catenin, the principal effector of the Wnt pathway, is also one of the cadherin cell adhesion molecules; therefore, it fulfills signaling and structural roles in most of the tissues and organs. It has been reported that ß-catenin in the liver regulates metabolic responses such as gluconeogenesis and histological changes in response to obesity-promoting diets. The function and cellular location of ß-catenin is finely modulated by coordinated sequences of phosphorylation-dephosphorylation events. In this article, we evaluated the levels and cellular localization of liver ß-catenin variants, more specifically ß-catenin phosphorylated in serine 33 (this phosphorylation provides recognizing sites for ß-TrCP, which results in ubiquitination and posterior proteasomal degradation of ß-catenin) and ß-catenin phosphorylated in serine 675 (phosphorylation that enhances signaling and transcriptional activity of ß-catenin through recruitment of different transcriptional coactivators). ß-catenin phosphorylated in serine 33 in the nucleus shows day-night fluctuations in their expression level in the Ad Libitum group. In addition, we used a daytime restricted feeding (DRF) protocol to show that the above effects are sensitive to food access-dependent circadian synchronization. We found through western blot and immunohistochemical analyses that DRF protocol promoted (1) higher total ß-catenins levels mainly associated with the plasma membrane, (2) reduced the presence of cytoplasmic ß-catenin phosphorylated in serine 33, (3) an increase in nuclear ß-catenin phosphorylated in serine 675, (4) differential co-localization of total ß-catenins/ß-catenin phosphorylated in serine 33 and total ß-catenins/ß-catenin phosphorylated in serine 675 at different temporal points along day and in fasting and refeeding conditions, and (5) differential liver zonation of ß-catenin variants studied along hepatic acinus. In conclusion, the present data comprehensively characterize the effect food synchronization has on the presence, subcellular distribution, and liver zonation of ß-catenin variants. These results are relevant to understand the set of metabolic and structural liver adaptations that are associated with the expression of the food entrained oscillator (FEO).