Novel Role for p110β PI 3-Kinase in Male Fertility through Regulation of Androgen Receptor Activity in Sertoli Cells

We thank Anna-Lena Berg (AstraZeneca, Lund) and Cheryl Scudamore (MRC, Harwell, UK) for histological analysis, Julie Foster (Barts Cancer Institute, London) for CT scans, Johan Swinnen and Frank Claessens (Leuven University, Belgium) for discussion and AR-luciferase reporter plasmids, Florian Guillou (INRA, CNRS, Université de Tours, France) for the AMH-Cre mouse line and Laura Milne (MRC Centre for Reproductive Health, The University of Edinburgh) for technical support. We thank the members of the Cell Signalling group for critical input.International audienceThe organismal roles of the ubiquitously expressed class I PI3K isoform p110β remain largely unknown. Using a new kinase-dead knockin mouse model that mimics constitutive pharmacological inactivation of p110β, we document that full inactivation of p110β leads to embryonic lethality in a substantial fraction of mice. Interestingly, the homozygous p110β kinase-dead mice that survive into adulthood (maximum ~26% on a mixed genetic background) have no apparent phenotypes, other than subfertility in females and complete infertility in males. Systemic inhibition of p110β results in a highly specific blockade in the maturation of spermatogonia to spermatocytes. p110β was previously suggested to signal downstream of the c-kit tyrosine kinase receptor in germ cells to regulate their proliferation and survival. We now report that p110β also plays a germ cell-extrinsic role in the Sertoli cells (SCs) that support the developing sperm, with p110β inactivation dampening expression of the SC-specific Androgen Receptor (AR) target gene Rhox5, a homeobox gene critical for spermatogenesis. All extragonadal androgen-dependent functions remain unaffected by global p110β inactivation. In line with a crucial role for p110β in SCs, selective inactivation of p110β in these cells results in male infertility. Our study is the first documentation of the involvement of a signalling enzyme, PI3K, in the regulation of AR activity during spermatogenesis. This developmental pathway may become active in prostate cancer where p110β and AR have previously been reported to functionally interac

Novel role for p110beta PI 3-Kinase in male fertility through regulation of androgen receptor activity in sertoli cells

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Novel Role for p110β PI 3-Kinase in Male Fertility through Regulation of Androgen Receptor Activity in Sertoli Cells

The organismal roles of the ubiquitously expressed class I PI3Kisoform p110 beta remain largely unknown. Using a new kinase- deadknockin mouse model that mimics constitutive pharmacological inactivation of p110 beta, we document that full inactivation of p110 beta leads to embryonic lethality in a substantial fraction of mice. Interestingly, the homozygous p110 beta kinase- dead mice that survive into adulthood (maximum similar to 26% on a mixed genetic background) have no apparent phenotypes, other than subfertility in females and complete infertility in males. Systemic inhibition of p110 beta results in a highly specific blockade in the maturation of spermatogonia to spermatocytes. p110 beta was previously suggested to signal downstream of the c- kit tyrosine kinase receptor in germ cells to regulate their proliferation and survival. We now report that p110 beta also plays a germ cell- extrinsic role in the Sertoli cells (SCs) that support the developing sperm, with p110 beta inactivation dampening expression of the SC- specific Androgen Receptor (AR) target gene Rhox5, a homeobox gene critical for spermatogenesis. All extragonadal androgen- dependent functions remain unaffected by global p110 beta inactivation. In line with a crucial role for p110 beta in SCs, selective inactivation of p110 beta in these cells results in male infertility. Our study is the first documentation of the involvement of a signalling enzyme, PI3K, in the regulation of AR activity during spermatogenesis. This developmental pathway may become active in prostate cancer where p110 beta and AR have previously been reported to functionally interact

Maternal and embryonic p110β kinase activity regulate preimplantation embryogenesis.

<p><b>A</b>) Females of the indicated genotype were crossed with WT males (n = 5 females crossed with 2 different males). The percentage of ovulations which became implanted embryos (left panel) was calculated as follows: [numbers of implanted E13.5 embryos + number of resorptions]/corpus luteum numbers in the ovaries (indicative of the number of ovulated oocytes)] x 100 (right panel). Mann-Whitney: *, p<0.05. <b>B</b>) Females of the indicated genotype were superovulated and mated with a p110β^{<b>D931A/WT</b>} male. Two-cell embryos were recovered from the oviducts and cultured <i>in vitro</i> for 4 days, at which time embryos were scored for development to the morula/blastocyst stage or any earlier developmental stage, and genotyped. Mann-Whitney: *, p<0.05.</p

p110β kinase activity positively regulates female and male fertility.

<p><b>A</b>) Weight of organs in 12-week-old mice (n = 4). <b>B</b>) Mice with the indicated genotype were bred for a 6-month period (cages of 2 females with 1 male; > 3 couples) and the average number of litters per month was assessed. Mann-Whitney: **, p<0.01. <b>C</b>) Average size of litters obtained from breeding pairs (2 females with one male for ≥4 months). Unpaired t-test: *, p<0.05; **, p<0.01.</p