K. H. Schlingensiepen

Block of c-Fos and JunB Expression by Antisense Oligonucleotides Inhibits Light-induced-Phase Shifts of the Mammalian Circadian Clock

Light‐induced phase shifts of circadian rhythmic locomotor activity are associated with the expression of c‐Jun, JunB, c‐Fos and FosB transcription factors in the rat suprachiasmatic nucleus, as shown in the present study. In order to explore the importance of c‐Fos and JunB, the predominantly expressed AP‐1 proteins for the phase‐shifting effects of light, we blocked the expression of c‐Fos and JunB in the suprachiasmatic nucleus of male rats, housed under constant darkness, by intracerebroventricular application of 2 μ1 of 1 mM antisense phosphorothioate oligodeoxynucleotides (ASO) specifically directed against c‐fos and JunB mRNA. A light pulse (300 lux for 1 h) at circadian time 15 induced a significant phase shift (by 125 ± 15 min) of the circadian locomotor activity rhythm, whereas application of AS0 6 h before the light pulse completely prevented this phase shift. Application of control nonsense oligodeoxynucleotides had no effect. ASO strongly reduced the light‐induced expression of c‐Fos and JunB proteins. In contrast, light pulses with or without the control nonsense oligodeoxynucleotides evoked strong nuclear c‐Fos and JunB immunoreactivity in the rat suprachiasmatic nucleus. These results demonstrate for the first time that inducible transcription factors such as c‐Fos and JunB are an essential part of fundamental biological processes in the adult mammalian nervous system, e.g. of light‐induced phase shifts of the circadian pacemaker.

Transient expression of PKC[gamma] mRNA in cerebellar granule cells during rat brain development.

The localization of PKC gamma mRNA expression during the maturation of rat cerebellum has been studied by in situ hybridization. We found a transient expression over the granule cell layer and persistent high expression in the Purkinje cells during postnatal development. Expression in granule cells appeared as early as postnatal day 5 over the external granule cell layer, when Purkinje cells are multiply innervated by climbing fibres in contrast to their mono-innervation in the adult. As the regression of the poly-innervation during the following weeks is known to require granule cell input, our findings suggest that the PKC gamma expression over the migrating granule cell layer is linked to the process of selective stabilization of synapses during the maturation of the cerebellum.

Ca2+/calmodulin protein kinase and protein kinase C expression during development of rat hippocampus.

The expression of the genes encoding the alpha subunit of type-II calcium/calmodulin-dependent protein kinase (CAM-KII alpha) and the gamma subspecies of protein kinase C (PKC gamma) was examined throughout postnatal rat brain development by in situ hybridization histochemistry. CAM-KII alpha was found to be expressed sequentially over the different hippocampal subregions, beginning with expression in the pyramidal cells of CA3 at birth, followed by expression in the external blade of the dentate gyrus and in CA1 on postnatal day (PND) 5 and, finally, on PND 8 in the internal blade of the dentate gyrus. PKC gamma expression, in contrast, rose simultaneously in the hippocampal subregions CA1 and CA3, with little expression over the dentate gyrus. This fashion of expression corresponds to the similar maturational state of the pyramidal cells in CA1 and CA3, whereas CAM-KII alpha expression during development of the rat hippocampus follows the time table of afferent lamination, which is delayed in CA1 compared to CA3. Furthermore, we found a temporal overexpression of CAM-KII alpha in the hippocampal subfields CA1 and CA3 at the end of the second postnatal week which coincides with the development of N-methyl-D-aspartate receptor binding.

Complementary expression patterns of c-jun and jun B in rat brain and analysis of their function with antisense oligonucleotides

How do cells alter their genetic programs to allow long term changes in function and structure? Which genes reprogram the cell to allow e.g. proliferation after quiescence or terminal differentiation of currently proliferating cells? These processes require the coordinated induction of a large number of previously silent genes and at the same time the repression of certain active genes. To coordinate changes in gene expression, the set of transcription factors that is active in a certain cell needs to be altered.