Lateral cortical Cdca7 expression levels are regulated by Pax6 and influence the production of intermediate progenitors

Abstract Background We studied whether regulation of Cdca7 (Cell division cycle associated 7) expression by transcription factor Pax6 contributes to Pax6’s cellular actions during corticogenesis. The function of Cdca7 in mediating Pax6’s effects during corticogenesis has not been explored. Pax6 is expressed by radial glial progenitors in the ventricular zone of the embryonic cortical neuroepithelium, where it is required for the development of a normal complement of Tbr2-expressing intermediate progenitor cells in the subventricular zone. Pax6’s expression levels are graded across the ventricular zone, with highest levels laterally where Tbr2-expressing progenitors are generated in greatest numbers at early stages of corticogenesis. Methods We used in situ hybridization and immunohistochemistry to analyse patterns of Cdca7 and Pax6 expression in cortical tissue from wild-type and Pax6 −/− embryos. In each genotype we compared the graded expression of the two genes quantitatively at several ages. To test whether defects in Cdca7 expression in lateral cortical cells might contribute to the cellular defects in this region caused by Pax6 loss, we electroporated a Cdca7 expression vector into wild-type lateral cortex and examined the effect on the production of Tbr2-expressing cells. Results We found that Cdca7 is co-expressed with Pax6 in cortical progenitors, at levels opposite to those of Pax6. Lowest levels of Cdca7 are found in the radial glial progenitors of lateral cortex, where Pax6 levels are highest. Higher levels of Cdca7 are found in ventral telencephalon, where Pax6 levels are low. Loss of Pax6 causes Cdca7 expression to increase in the lateral cortex. Elevating Cdca7 in normal lateral cortical progenitors to levels close to those normally found in ventral telencephalon reduces their production of Tbr2-expressing cells early in lateral cortical formation. Conclusion Our results suggest that Pax6 normally represses Cdca7 expression in the lateral cortex and that repression of Cdca7 in cells of this region is required for their production of a normal complement of Tbr2-expressing intermediate progenitors

Long-term risk of stroke and myocardial infarction in middle-aged men with a hypertensive response to exercise : a 44-year follow-up study

Introduction: Data on the prognostic value of hypertensive response to exercise in cardiovascular disease are limited. The aim was to determine whether SBP reactions during exercise have any prognostic value in relation to the long-term risk of stroke and myocardial infarction (MI). Patients and methods: A representative cohort of men from Gothenburg, Sweden, born in 1913, who performed a maximum exercise test at age 54 years, (n = 604), was followed-up for a maximum of 44 years with regard to stroke and MI. Results: Among the 604 men, the mean resting and maximum SBP was 141.5 (SD 18.8) and 212.1 (SD 24.6) mmHg, respectively. For maximum SBP, the risk of stroke increased by 34% (hazard ratio 1.34, 95% confidence interval 1.11-1.61) per 1-SD increase, while no risk increase was observed for MI. The highest risk of stroke among blood pressure groups was observed among men with a resting SBP of at least 140 mmHg and a maximum SBP of at least 210 mmHg with an hazard ratio of 2.09 (95% confidence interval 1.29-3.40), compared with men with a resting SBP of less than 140 mmHg and a maximum SBP of less than 210 mmHg, independent of smoking, blood glucose, cholesterol and BMI. Conclusion: Among middle-aged men with high resting and maximum blood pressure during maximum exercise workload, an increased risk of stroke was observed but not for MI. Further studies with larger sample sizes are needed to investigate the underlying mechanisms of the increased risk of stroke among individuals with hypertensive response to exercise