Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA264

Poster Communications

Differential regulation of renin transcript levels by glucose depletion, anoxia, proliferation and differentiation in PC12 cells

A. Fischer1, H. Wanka1, P. Lutze1, J. Peters1, B. Grunow1

1. Institute for Physiology, Karlsburg, Mecklenburg-Vorpommern, Germany.

The Renin-Angiotensin System (RAS) exerts pro-inflammatory and pro-fibrotic effects thereby promoting cardiovascular diseases [1]. Apart from secretory renin that mediates detrimental effects of the RAS an alternative renin transcript (cyto-renin) has been identified in several species [2]. In contrast to secretory renin, cyto-renin surprisingly protected cardiac cells from necrotic death [3]. We therefore suspect that cyto-renin may play a protective role in the brain. As a first step, we analysed the effects of glucose depletion and anoxia on renin expression in proliferating, stationary and differentiated neuronal cells. We utilized PC12 cells as a neuronal in vitro model system. With BrdU- and propidium iodide staining and Ki-67 qRT-PCR we evaluated the degree of proliferation. Differentiation was induced by nerve growth factor and confirmed by synaptotagmin expression. We quantified renin-mRNAs in proliferating, stationary and differentiated PC12 cells and in PC12 cells subjected to glucose depletion and/or anoxia. During the first day of culture only cyto-renin was detected in adherent PC12 cells. At this point, 55.8±1.8% of PC12 cells was in the proliferating stage. During 5 days of culture, cyto-renin expression increased and secretory renin was induced (cyto-renin - 1 d: 0.4*10-7±0.1*10-7, 5 d: 1.7*10-7±0.4*10-7; secretory renin - 5 d: 1.3*10-6 ±1.4*10-6). By this time 51.5±6% of the PC12 cells were in the stationary phase. This was supported by a reduced BrdU-incorporation (1 d: 5.9*10-3±2*10-3 OD, 5 d: 3.3*10-3±4.9*10-4 OD) and a lowered Ki-67-expression (1 d: 6.6*10-5±1.5*10-5, - 5d: 3.3*10-5±2.1*10-5). Thus, the increase of renin expression presumably correlates with PC12 cells entering the stationary phase. NGF-induced differentiation enhanced cyto- and secretory renin expression in adherent PC12 cells (cyto-renin: control: 6.3*10-5±3.4*10-6, NGF: 9.1*10-5±9.9*10-6; secretory renin: control: 1.4*10-4±6.6*10-6; NGF: 4.5*10-4±6.3*10-5). Thus, renin expression apparently also depends on the extent of differentiation of PC12 cells. In proliferating adherent PC12 cells glucose depletion with anoxia resulted in a significantly enhanced expression of cyto-renin (control: 2.9*10-8±1.5*10-8, -Glc/-O2: 7.3*10-8±1.1*10-8), whereas the secretory renin transcript remained absent. Our analyses show that cyto- and secretory renin transcript levels are differentially regulated with respect to proliferation, differentiation and ischemia related conditions in PC12 cells. The upregulation of cyto-renin under combined glucose-depletion with anoxia suggests that cyto-renin may play a role during ischemic events. The data indicate that cell cycle as well as the degree of differentiation has to be considered principally for further examination of the regulation and functions of renin transcripts.

Where applicable, experiments conform with Society ethical requirements