Engineering CREB-activated promoters for adenosine-induced gene expression

Accumulation of the ribonucleoside, adenosine (ADO), triggers a cAMP response element binding protein (CREB)-mediated signaling pathway to suppress the function of immune cells in tumors. Here, we describe a collection of CREB-activated promoters that allow for strong and tunable ADO-induced gene expression in human cells. By optimizing number of CREB transcription factor binding sites and altering the core promoter region of CREB-based hybrid promoters, we created synthetic constructs that drive gene expression to higher levels than strong, endogenous mammalian promoters in the presence of ADO. These synthetic promoters are induced up to 47-fold by ADO, with minimal expression in their "off" state. We further determine that our CREB-based promoters are activated by other compounds that act as signaling analogs, and that combinatorial addition of ADO and these compounds has a synergistic impact on gene expression. Surprisingly, we also detail how background ADO degradation caused by the common cell culture media additive, fetal bovine serum (FBS), confounds experiments designed to determine ADO dose-responsiveness. We show that only after long-term heat deactivation of FBS can our synthetic promoters enable gene expression induction at physiologically relevant levels of ADO. Finally, we demonstrate that the strength of a CREB-based promoter is enhanced by incorporating other transcription factor binding sites.

Coronary, aortic and cerebral atherosclerosis in swine of 3 age-groups: implications

CORONARY, AORTIC AND INTERCRANIAL ATHEROSCLEROSIS HAS BEEN COMPARED IN SWINE MAINTAINED UNDER THE FOLLOWING CONDITIONS: (1) adequate food and housing but animals held in test social situations for 1 year; postmortem examination at ages of 13 to 15 months; (2) food and management designed for high productivity; postmortem examination at ages of 6 to 9 years; (3) an outdoor system of husbandry and a cooked garbage diet; postmortem examination at ages of 8 to 14 years.Extramural coronary, aortic and intracranial atherosclerosis was most advanced in swine that were fed garbage. Cerebral infarction (cerebromalacia) also was most advanced in these swine but developed in swine of the younger groups in which it was associated with atherosclerosis of small intracranial extracerebral arteries rather than with stenosis of the larger intracranial extracerebral arteries as in the oldest swine. The lesions of atherosclerosis in swine of these 3 age-groups form a continuous series and are morphologically identical with corresponding stages of atherosclerosis of man.It is concluded that swine can replace non-human primates as subjects for studies of atherosclerotic vascular disease, and that experimental designs must allow for age and behaviour patterns of the species.