The LIM-only protein FHL2 acts as a transcriptional modulator that positively or negatively regulates multiple signaling pathways. We recently reported that FHL2 cooperates with CBP/p300 in the activation of -catenin/TCF target gene cyclin D1. In this paper, we demonstrate that FHL2 is associated with the cyclin D1 promoter at the TCF/CRE site, providing evidence that cyclin D1 is a direct target of FHL2. We show that deficiency of FHL2 greatly reduces the proliferative capacity of spontaneously immortalized mouse fibroblasts which is associated with decreased expression of cyclin D1 and p16INK4a, and hypophosphorylation of Rb. Reexpression of FHL2 in FHL2-null fibroblasts efficiently restores cyclin D1 levels and cell proliferative capacity, indicating that FHL2 is critical for cyclin D1 activation and cell growth. Moreover, ectopic cyclin D1 expression is sufficient to override growth inhibition of immortalized FHL2-null fibroblasts. Gene expression profiling revealed that FHL2 deficiency triggers a broad change of the cell cycle program that is associated with downregulation of several G1/S and G2/M cyclins, E2F transcription factors and DNA replication machinery, thus correlating with reduced cell proliferation. This change also involves downregulation of the negative cell cycle regulators, particularly INK4 inhibitors, which could counteract the decreased expression of cyclins, allowing cells to grow. Our study illustrates that FHL2 can act on different aspects of the cell cycle program to finely regulate cell proliferation.
The LIM-only protein FHL2 regulates cyclin D1 expression and cell proliferation.
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View SamplesMammalian females are born with a finite number of non-renewing primordial follicles, the majority of which remain in a quiescent state for many years. Due to their non-renewing nature, these resting oocytes are particularly vulnerable to xenobiotic insult, resulting in premature ovarian senescence and the formation of dysfunctional oocytes. In this study we characterised the mechanisms of ovotoxicity for three ovotoxic agents, 4-Vinylcyclohexene Diepoxide (VCD), Methoxychlor (MXC), and Menadione (MEN), all of which target immature follicles. Neonatal mouse ovaries (PND3-4) were cultured in the presence of 4-Vinylcyclohexene Diepoxide (50uM), Methoxychlor (50uM), and Menadione (5uM) for 96 hours to observe their effects on the ovarian transcriptome. This was done in the hopes of gaining a better understanding of the mechanisms underpinning xenobiotic induced pre-antral ovotoxicity.
Adding insult to injury: effects of xenobiotic-induced preantral ovotoxicity on ovarian development and oocyte fusibility.
Specimen part
View SamplesBackground: It has been shown previously that administration of Francisella tularensis (Ft) LVS lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response.
Modulation of hepatic PPAR expression during Ft LVS LPS-induced protection from Francisella tularensis LVS infection.
Age, Specimen part
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