cyclin-d1 and Arterial-Occlusive-Diseases

An objective of therapeutic intervention after cerebral ischemia is to promote improved functional outcome. Improved outcome may be associated with a reduction of the volume of cerebral infarction and the promotion of cerebral plasticity. In the developing brain, neuronal growth is concomitant with expression of particular proteins, including microtubule-associated protein 2 (MAP-2), growth-associated protein 43 (GAP-43), and cyclin D1. In the present study we measured the expression of select proteins associated with neurite damage and plasticity (MAP-2 and GAP-43) as well as cell cycle (cyclin D1) after induction of focal cerebral ischemia in the rat.. Brains from rats (n=28) subjected to 2 hours of middle cerebral artery occlusion and 6 hours, 12 hours, and 2, 7, 14, 21, and 28 days (n=4 per time point) of reperfusion and control sham-operated (n=3) and normal (n=2) rats were processed by immunohistochemistry with antibodies raised against MAP-2, GAP-43, and cyclin D1. Double staining of these proteins for cellular colocalization was also performed.. Loss of immunoreactivity of both MAP-2 and GAP-43 was observed in most damaged neurons in the ischemic core. In contrast, MAP-2, GAP-43, and cyclin D1 were selectively increased in morphologically intact or altered neurons localized to the ischemic core at an early stage (eg, 6 hours) of reperfusion and in the boundary zone to the ischemic core (penumbra) during longer reperfusion times.. The selective expressions of the neuronal structural proteins (MAP-2 in dendrites and GAP-43 in axons) and the cyclin D1 cell cycle protein in neurons observed in the boundary zone to the ischemic core are suggestive of compensatory and repair mechanisms in ischemia-damaged neurons after transient focal cerebral ischemia.

Topics: Animals; Arterial Occlusive Diseases; Brain Chemistry; Cyclin D1; GAP-43 Protein; Immunoenzyme Techniques; Ischemic Attack, Transient; Male; Microtubule-Associated Proteins; Neuronal Plasticity; Neurons; Rats; Rats, Wistar

Following 30 min of forebrain ischaemia in the rat, delayed neuronal death occurs in the CA1 sector of the hippocampus within two to three days, whereas neurons in other selectively vulnerable regions, such as the dorsolateral striatum, die within 6-12 h. In this study, we investigated cyclin D1 expression, which codes for a regulatory protein in cell cycle regulation, but it is also induced in sympathetic neurons undergoing programmed cell death. Cyclin D1 messenger RNA could not be detected by in situ hybridization techniques in brains of control rats, but was found at one and two days after ischaemia in regions of the dorsolateral striatum with neuronal degeneration. DNA fragmentation in this region, identified by the terminal transferase biotinylated-UTP nick end labelling (TUNEL) procedure, was observed from 6 h after ischaemia onward. In the hippocampus, increased levels of cyclin D1 messenger RNA were found at two and three days after ischaemia in the striatum pyramidale of the CA1 sector. This expression was associated with the occurrence of neuronal damage and TUNEL-stained neurons. By seven days cyclin D1 messenger RNA was found in hardly any brain structure. There was no temporospatial overlap of cyclin D1 expression with the expression of the immediate-early genes c-fos, c-jun, and mkp-1, a result which is clearly distinct from findings in sympathetic ganglion neurons undergoing programmed cell death. These results do not suggest a role for cyclin D1 in neuronal cell death following transient forebrain ischaemia. The similarity of the cyclin D1 expression profile with that of the microglia-specific CR3 complement receptor beta-subunit messenger RNA, and the results of combined in situ hybridization and microglia-specific immunohistochemistry suggest that microglia are the source of cyclin D1 messenger RNA in the postischaemic brain. Since cyclin D1 codes for a critical regulatory protein for progression of the G0 to G1 phase in the cell cycle and we did not observe prominent occurrence of DNA fragmentation in microglial cells in the hippocampus at time points when cyclin D1 messenger RNA was found, we suggest that cyclin D1 induction is involved in the onset of microglial cell proliferation.

Topics: Animals; Antibody Specificity; Arterial Occlusive Diseases; Astrocytes; Base Sequence; Biotin; Cell Death; Cyclin D1; Cyclins; Deoxyuracil Nucleotides; DNA Damage; Gene Expression Regulation; Genes, Immediate-Early; HSP70 Heat-Shock Proteins; In Situ Hybridization; Ischemic Attack, Transient; Male; Microglia; Neurons; Oncogene Proteins; Prosencephalon; Rats; Rats, Wistar; Receptors, Complement; RNA, Messenger; Staining and Labeling