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Using both tumor specimen and cultured tumor cells, we have studied the differentiation of a pineocytoma by light and electron microscopy (EM) and immunohistochemical demonstration of glial, neuronal and neuroendocrine markers. Only interstitial cells were labeled with anti-glial fibrillary acidic protein and anti-S100 protein antibodies. Synaptophysin, neurofilaments and tau labeling was found in cells forming the pineocytomatous rosettes. Some cells also bound the anti-tryptophan hydroxylase antibody (TPOH), but no staining was seen after application of anti-chromogranin A or S-antigen antibodies. EM provided evidence for neurosensory differentiation demonstrating the presence of vesicle-crowned rodlets, cilia (9+0) and fibrous filaments. In culture, tumor cells proliferated slowly and showed positive immunolabeling for vimentin and TPOH. Expression of mRNA coding for TPOH, serotonin N-acetyltransferase, hydroxyindole-O-methyl-transferase and c-myc was found in the tumor using reverse transcriptase-polymerase chain reaction. These results demonstrate neuronal differentiation of this pineocytoma and suggest that the neoplastic pineal cells are capable of synthesizing serotonin and melatonin.

Gamma-Aminobutyric acid (GABA) transporters (GAT-1, GAT-2, and GAT-3) play a key role in the termination of GABA transmission and the regulation of extracellular GABA concentrations. In the present study, pharmacological, cellular, and molecular analyses provide evidence for a modulatory effect of serotoninergic neurons on the activity and expression of glial GABA transporters in the rat cerebellum. Degeneration of serotoninergic neurons after in vivo 5,7-dihydroxytryptamine (5,7-DHT) treatment resulted in a significant decrease (-27%) in [3H]-GABA uptake into cerebellar punches. This decrease probably occurred via inhibition of GAT-2 or GAT-3 activity since their inhibitor, beta-alanine, induced a decrease in [3H]-GABA uptake in punches of sham-operated rats (-28%), but not in punches of 5,7-DHT-treated rats, demonstrating that serotonin terminal degeneration had already impaired the beta-alanine-sensitive component of GABA uptake. In contrast, nipecotic acid, a preferential inhibitor of GAT-1, induced comparable decreases in [3H]-GABA uptake comparable in punches of 5,7-DHT (-38%) versus sham-operated rats (-37%). The decreases in GAT-1 (-16%), GAT-2 (-34%), and GAT-3 (-32%) mRNA levels after 5,7-DHT treatment (detected by quantitative RT-PCR) are consistent with a serotoninergic control of GABA transporter expression at the transcriptional level. The cellular distribution of GAT-2 and GAT-3 mRNA, shown by in situ hybridization, suggests a glial localization of these transporters in the cerebellum and demonstrated a preferential anatomical localization of GAT-2 mRNA in the granular layer and of GAT-3 mRNA in the deep cerebellar nuclei. A direct serotoninergic control of glial GABA uptake was further demonstrated in vitro since serotonin stimulated the activity and mRNA expression of the GABA transporters in cerebellar astrocyte cultures.

The facultative intracellular pathogen Brucella abortus interacts with several organelles of the host cell to reach its replicative niche inside the endoplasmic reticulum. However, little is known about the interplay between the intracellular bacteria and the host cell mitochondria. Here, we showed that B. abortus triggers substantive mitochondrial network fragmentation, accompanied by mitophagy and the formation of mitochondrial Brucellacontaining vacuoles during the late steps of cellular infection. Brucella-induced expression of the mitophagy receptor BNIP3L is essential for these events and relies on the iron-dependent stabilisation of the hypoxia-inducible factor 1α. Functionally, BNIP3Lmediated mitophagy appears to be advantageous for bacterial exit from the host cell as BNIP3L depletion drastically reduces the number of reinfection events. Altogether, these findings highlight the intricate link between Brucella trafficking and the mitochondria during host cell infection.