The catecholaminergic RCSN-3 cell line: a model to study dopamine metabolism.

RCSN-3 cells are a cloned cell line derived from the substantia nigra of an adult rat. The cell line grows in monolayer and does not require differentiation to express catecholaminergic traits, such as (i) tyrosine hydroxylase; (ii) dopamine release; (iii) dopamine transport; (iv) norepinephrine transport; (v) monoamine oxidase (MAO)-A expression, but not MAO-B; (vi) formation of neuromelanin; (vii) VMAT-2 expression. In addition, this cell line expresses serotonin transporters, divalent metal transporter, DMT1, dopamine receptor 1 mRNA under proliferating conditions, and dopamine receptor 5 mRNA after incubation with dopamine or dicoumarol. Expression of dopamine receptors D(2), D(3) and D(4) mRNA were not detected in proliferating cells or when the cells were treated with dopamine, CuSO(4), dicoumarol or dopamine-copper complex. Angiotensin II receptor mRNA was also found to be expressed, but it underwent down regulation in the presence of aminochrome. Total quinone reductase activity corresponded 94% to DT-diaphorase. The cells also express antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase. This cell line is a suitable in vitro model for studies of dopamine metabolism, since under proliferating conditions the cells express all the pertinent markers.

Neuronal dysfunction in Down syndrome: contribution of neuronal models in cell culture.

Down syndrome (DS) in humans, or trisomy of autosome 21, represents the hyperdiploidy that most frequently survives gestation, reaching an incidence of 1 in 700 live births. The condition is associated with multisystemic anomalies, including those affecting the central nervous system (CNS), determining a characteristic mental retardation. At a neuronal level, our group and others have shown that the condition determines marked alterations of action potential and ionic current kinetics, which may underlie abnormal processing of information by the CNS. Since the use of human tissue presents both practical and ethical problems, animal models of the human condition have been sought. Murine trisomy 16 (Ts16) is a model of the human condition, due to the great homology between human autosome 21 and murine 16. Both conditions share the same alterations of electrical membrane properties. However, the murine Ts16 condition is unviable (animals die in utero), thus limiting the quantity of tissue procurable. To overcome this obstacle, we have established immortal cell lines from normal and Ts16 mice with a method developed by our group that allows the stable in vitro immortalization of mammalian tissue, yielding cell lines which retain the characteristics of the originating cells. Cell lines derived from cerebral cortex, hippocampus, spinal cord and dorsal root ganglion of Ts16 animals show alterations of intracellular Ca2+ signals in response to several neurotransmitters (glutamate, acetylcholine, and GABA). Gene overdose most likely underlies these alterations in cell function, and the identification of the relative contribution of DS associated genes on such specific neuronal dysfunction should be investigated. This could enlighten our understanding on the contribution of these genes in DS, and identify new therapeutic targets.

The chromatin modifying complex CoREST/LSD1 negatively regulates notch pathway during cerebral cortex development.

The development of the cerebral cortex is a dynamic and coordinated process in which cell division, cell death, migration, and differentiation must be highly regulated to acquire the final architecture and functional competence of the mature organ. Notch pathway is an important regulator of differentiation and it is essential to maintain neural stem cell (NSC) pool. Here, we studied the role of epigenetic modulators such as lysine-specific demethylase 1 (LSD1) and its interactor CoREST in the regulation of the Notch pathway activity during the development of the cerebral cortex. We found that CoREST and LSD1 interact in vitro with RBPJ-κ in the repressor complex and these proteins are released upon overexpression of Notch intracellular domain (NICD). We corroborated LSD1 and RBPJ-κ interaction in developing cerebral cortex and also found that LSD1 binds to the hes1 promoter. Knock-down of CoREST and LSD1 by in utero electroporation increases Hes1 expression in vivo and decreases Ngn2. Interestingly, we found a functional interaction between CoREST and LSD1 with Notch pathway. This conclusion is based on the observation that both the defects in neuronal migration and the increase in the number of cells expressing Sox2 and Tbr2 were associated to the knock-down of either CoREST or LSD1 and were reversed by the loss of Notch. These results demonstrate that CoREST and LSD1 downregulate the Notch pathway in the developing cerebral cortex, thus suggesting a role of epigenetic regulation in the fine tuning of cell differentiation. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1360-1373, 2016.

In vitro antiproliferative activity of 3 H-spiro [1-benzofuran-2,1'-cyclohexane] derivatives / Actividad antiproliferativa in vitro de derivados de 3 H-spiro [1-benzofuran-2, 1'-cyclohexano]

The in vitro effect of the resinous exudate of Heliotropium filifolium, of the 3 H-spiro[1-benzofuran-2,1 '-cyclohexane] derivative called filifolinol 1, isolated from the resin and the semi-synthetic compounds filifolinone 2 and filifolinoic acid 3, obtained from filifolinol 1, were evaluated on the proliferation of an immortalized cell line, UCHT1, derived from rat thyroid. We evaluated the effect of these compounds on UCHT1 cell growth parameters by calculating doubling time; and toxicity using the LIVE/DEAD™ in vitro test. The results showed that the resin is not active, while filifolinone 2, filifolinoic acid 3 and filifolinol 1 produced a significant inhibition of cell doubling time, in concentrations equal or greater than 50, 25 and 75 uM, respectively. The LIVE/DEAD test showed no significant toxicity at these concentrations, compared to cultures kept in absence of compounds. These results suggest a possible cytostatic effect of these compounds, and could therefore constitute potential alternatives for antineoplasic therapy.

Se evaluó el efecto in vitro de la resina aislada desde Heliotropium filifolium y del derivado 3 H-spiro[1-benzofuran-2,1'-cyclohexano] llamado filifolinol 1, obtenido desde este exudado resinoso y los compuestos semi-sintéticos filifolinona 2 y ácido filifolinoico 3, obtenidos a partir de filifolinol 1, sobre la proliferación de la línea celular inmortal, UCHT1, derivada de tumor de tiroide de rata. Evaluamos el efecto de estos compuestos en el desarrollo celular de UCHT1 a través de los parámetros tiempo de doblaje y citotoxicidad usando el test LIVE/DEAD™ in vitro. Los resultados mostraron que la resina no presentó actividad y que filifolinona, ácido filifolinoico y filifolinol producen una inhibición significativa del tiempo de doblaje celular, en concentraciones iguales o superiores a 50, 25 y 75 uM, respectivamente. El test LIVE/DEAD no mostró toxicidad significativa en comparación con los cultivos mantenidos en ausencia de compuestos. Estos resultados sugieren un posible efecto citostático de estos compuestos y por lo tanto, constituirían alternativas potenciales para terapia antineoplásica.

Knockdown of amyloid precursor protein normalizes cholinergic function in a cell line derived from the cerebral cortex of a trisomy 16 mouse: An animal model of down syndrome.

We have generated immortal neuronal cell lines from normal and trisomy 16 (Ts16) mice, a model for Down syndrome (DS). Ts16 lines overexpress DS-related genes (App, amyloid precursor protein; Sod1, Cu/Zn superoxide dismutase) and show altered cholinergic function (reduced choline uptake, ChAT expression and fractional choline release after stimulation). As previous evidence has related amyloid to cholinergic dysfunction, we reduced APP expression using specific mRNA antisense sequences in our neuronal cell line named CTb, derived from Ts16 cerebral cortex, compared to a cell line derived from a normal animal, named CNh. After transfection, Western blot studies showed APP expression knockdown in CTb cells of 36% (24 hr), 40.4% (48 hr), and 50.2% (72 hr) compared to CNh. Under these reduced APP levels, we studied 3H-choline uptake in CTb and CNh cells. CTb, as reported previously, expressed reduced choline uptake compared to CNh cells (75%, 90%, and 69% reduction at 1, 2, and 5 min incubation, respectively). At 72 hr of APP knockdown, choline uptake levels were essentially similar in both cell types. Further, fractional release of 3H-choline in response to glutamate, nicotine, and depolarization with KCl showed a progressive increase after APP knockdown, reaching values similar to those of CNh after 72 hr of transfection. The results suggest that APP overexpression in CTb cells contributes to impaired cholinergic function, and that gene knockdown in CTb cells is a relevant tool to study DS-related dysfunction.