Journal:

Article Title: Foxo3 is a PI3K-Dependent Molecular Switch Controlling the Initiation of Oocyte Growth

doi: 10.1016/j.ydbio.2008.06.017

Figure Lengend Snippet: Pten regulates primordial follicle activation via PI3K and Foxo3. Pten ablation leads to increased PIP3, Akt activation, Foxo3 hyperphosphorylation, and nuclear export. Panels show Pten, PIP3, p-Akt (Ser473), Foxo3 and p-Foxo3 (Thr32) in PD3 ovaries counterstained with hematoxylin or DAPI (PIP3).

Article Snippet: Frozen sections (5μ) were obtained and detection of PIP3 was performed as described ( Kitamura et al., 2004 ) with Biotin-PIP3 (1:100) (Echelon Biosciences # Z-B345b) and streptavidin-alexa fluor 488 (1:200) (Invitrogen # {"type":"entrez-protein","attrs":{"text":"S11223","term_id":"112468","term_text":"pir||S11223"}} S11223 ).

Techniques: Activation Assay

Journal:

Article Title: Foxo3 is a PI3K-Dependent Molecular Switch Controlling the Initiation of Oocyte Growth

doi: 10.1016/j.ydbio.2008.06.017

Figure Lengend Snippet: Model of Foxo3 regulation by PI3K-Akt signaling pathway within oocytes in the control of primordial follicle activation. In resting state, absence of a presumptive ligand engaging receptor tyrosine kinase (RTK) complex or other cell surface receptor is associated with diminished Akt signalling in primordial oocytes. Foxo3 is unphosphorylated and thus localized to the nucleus, where Foxo3 acts to suppresses primordial follicle activation. Binding of presumptive ligand activates PI3K (consisting of p85 regulatory and p110 catalytic subunits), which phosphorylates the 3’OH group of PI[4,5]P2 (PIP2) to form PI[3,4,5]P3 (PIP3) at the oocyte membrane. Pten acts as a potent negative regulator of this pathway by dephosphorylating PIP3. Pten inactivation results in accumulation of PIP3 at the oocyte membrane and hyperactivation of Akt, resulting in Foxo3 phosphorylation and nuclear export, thereby triggering primordial follicle activation. In this model, Pten inactivation is functionally equivalent to the binding of presumptative ligand at a cell surface receptor.

Article Snippet: Frozen sections (5μ) were obtained and detection of PIP3 was performed as described ( Kitamura et al., 2004 ) with Biotin-PIP3 (1:100) (Echelon Biosciences # Z-B345b) and streptavidin-alexa fluor 488 (1:200) (Invitrogen # {"type":"entrez-protein","attrs":{"text":"S11223","term_id":"112468","term_text":"pir||S11223"}} S11223 ).

Techniques: Activation Assay, Cell Surface Receptor Assay, Binding Assay