Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterised by occurrence of parathyroid tumours and neuroendocrine tumours (NETs) of the pancreatic islets and anterior pituitary. The MEN1 gene, encoding menin, is a tumour suppressor, but its precise role in initiating in vivo tumourigenesis remains to be elucidated. The availability of a temporally controlled conditional MEN1 mouse model would greatly facilitate the study of such early tumourigenic events, and overcome the limitations of other MEN1 knockout models, in which menin is lost from conception or tumour development occurs asynchronously. To generate a temporally controlled conditional mouse model, we crossbred mice with the MEN1 gene floxed by LoxP sites (Men1 L/L), and mice expressing tamoxifen-inducible Cre recombinase under the control of the rat insulin promoter (RIP2-CreER), to establish a pancreatic β-cell-specific NET model under temporal control (Men1 L/L/RIP2-CreER). Men1 L/L/RIP2-CreER mice aged ~3 months were given tamoxifen in the diet for 5 days, and pancreata harvested 2–2.5, 2.9–3.5 and 4.5–5.5 months later. Control mice did not express Cre and did not receive tamoxifen. Immunostaining of pancreata from tamoxifen-treated Men1 L/L/RIP2-CreER mice, compared to control mice, showed at all ages: loss of menin in all islets; increased islet area (>4.2-fold); increased proliferation of insulin immunostaining β-cells (>2.3-fold) and decreased proliferation of glucagon immunostaining α-cells (>1.7-fold). There were no gender and apoptotic or proliferation differences, and extra-pancreatic tumours were not detected. Thus, we have established a mouse model (Men1 L/L/RIP2-CreER) to study early events in the development of pancreatic β-cell NETs.
K E Lines, R P Vas Nunes, M Frost, C J Yates, M Stevenson and R V Thakker
M A Webb, H Mani, S J Robertson, H L Waller, D R Webb, C L Edwardson, D H Bodicoat, T Yates, K Khunti and M J Davies
Physical activity has been proposed to be an effective non-pharmacological method of reducing systemic inflammation and therefore may prove particularly efficacious for women with polycystic ovary syndrome (PCOS) who have been shown to have high levels of inflammation and an increased risk of type 2 diabetes (T2DM) and cardiovascular disease (CVD). Therefore, the aim of the present study was to assess whether modest changes in daily step count could significantly reduce levels of inflammatory markers in women with PCOS.
Subjects and Methods
Sixty-five women with PCOS were assessed at baseline and again at 6 months. All had been provided with an accelerometer and encouraged to increase activity levels. Multivariate linear regression analyses (adjusted for age, ethnicity, baseline step count, change in BMI and change in accelerometer wear-time) were used to assess changes in daily step count against clinical and research biomarkers of inflammation, CVD and T2DM.
Mean step count/day at baseline was 6337 (±270). An increase in step count (by 1000 steps) was associated with a 13% reduction in IL6 (β: −0.81 ng/L; 95% CI, −1.37, −0.25, P = 0.005) and a 13% reduction in CRP (β: −0.68 mg/L; 95% CI, −1.30, −0.06, P = 0.033). Additionally, there was a modest decrease in BMI (β: 0.20 kg/m2; 95% CI, −0.38, −0.01, P = 0.038). Clinical markers of T2DM and CVD were not affected by increased step count.
Modest increases in step count/day can reduce levels of inflammatory markers in women with PCOS, which may reduce the future risk of T2DM and CVD.