Abstract
Interferon-tau (IFNT), serves as a signal to maintain the corpus luteum (CL) during early pregnancy in domestic ruminants. We investigated here whether IFNT directly affects the function of luteinized bovine granulosa cells (LGCs), a model for large-luteal cells. Recombinant ovine IFNT (roIFNT) induced the IFN-stimulated genes (ISGs; MX2, ISG15, and OAS1Y). IFNT induced a rapid and transient (15–45 min) phosphorylation of STAT1, while total STAT1 protein was higher only after 24 h. IFNT treatment elevated viable LGCs numbers and decreased dead/apoptotic cell counts. Consistent with these effects on cell viability, IFNT upregulated cell survival proteins (MCL1, BCL-xL, and XIAP) and reduced the levels of gamma-H2AX, cleaved caspase-3, and thrombospondin-2 (THBS2) implicated in apoptosis. Notably, IFNT reversed the actions of THBS1 on cell viability, XIAP, and cleaved caspase-3. Furthermore, roIFNT stimulated proangiogenic genes, including FGF2, PDGFB, and PDGFAR. Corroborating the in vitro observations, CL collected from day 18 pregnant cows comprised higher ISGs together with elevated FGF2, PDGFB, and XIAP, compared with CL derived from day 18 cyclic cows. This study reveals that IFNT activates diverse pathways in LGCs, promoting survival and blood vessel stabilization while suppressing cell death signals. These mechanisms might contribute to CL maintenance during early pregnancy.
Highlights
Animals suggested extra-uterine, endocrine effects of IFNT16,18,23,24
In agreement with the model of an endocrine action of IFNT acting directly on the corpus luteum (CL) during early pregnancy, we have previously demonstrated that recombinant ovine IFNT enhanced luteal endothelial cell proliferation and suppressed a battery of luteolytic genes in luteal endothelial cells and CL slices[25]
Cells were incubated with various concentrations of recombinant ovine IFNT (roIFNT) (0.01–10 ng/mL), and the expression of classical IFN-stimulated genes (ISGs) was assessed to investigate whether IFNT directly affects luteinized granulosa cells (LGCs). roIFNT dose-dependently, robustly, and markedly elevated the mRNA concentrations of MX2, ISG15, and OAS1Y in LGCs (Fig. 1a–c)
Summary
In agreement with the model of an endocrine action of IFNT acting directly on the CL during early pregnancy, we have previously demonstrated that recombinant ovine IFNT (roIFNT) enhanced luteal endothelial cell proliferation and suppressed a battery of luteolytic genes in luteal endothelial cells and CL slices[25]. The CL is a transient endocrine gland that contains multiple cell populations in which two progesterone-producing cells exist—large and small luteal cells[1,26,27]. Unlike small luteal cells, large luteal cells produced progesterone in a LH-independent manner[29,30,31], consistent with a key role for this cell type during pregnancy when circulating progesterone is elevated and GnRH and LH pulse frequencies are decreased[32]. This study investigated the direct actions of IFNT on large luteal cells, utilizing luteinized granulosa cells (LGCs) as an in vitro model. We evaluated here CL of early pregnant cows (on day 18) to complement the in vitro data
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