References of "Chittajallu, Ramesh"
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See detailShaker-type potassium channel subunits differentially control oligodendrocyte progenitor proliferation
Vautier, Francois; Belachew, Shibeshih ULg; Chittajallu, Ramesh et al

in Glia (2004), 48(4), 337-345

Oligodendrocyte precursor (OP) cells are exposed to multiple extrinsic signals that control their proliferation and differentiation. Previous cell proliferation studies and electrophysiological analysis ... [more ▼]

Oligodendrocyte precursor (OP) cells are exposed to multiple extrinsic signals that control their proliferation and differentiation. Previous cell proliferation studies and electrophysiological analysis in cultured cells and in brain slices have suggested that outward potassium channels, particularly Kv1 subunits, may have a prominent role in OP cell proliferation. In the present study, we assessed to what extent overexpression of Kv1.3, Kv1.4, Kv1.5, and Kv1.6 can affect OP cell proliferation and differentiation in culture. We observed that overexpression of Kv1.3 or Kv1.4 increased OP cell proliferation in the absence of mitogens, whereas Kv1.6 overexpression inhibited mitogen-induced OP cell cycle progression. Interestingly, Kv1.3, Kv1.4, Kv1.5, and Kv1.6 overexpression did not interfere with the kinetics of oligodendrocyte differentiation. This study represents the first demonstration that the activity of potassium channels containing distinct Kv1 subunit proteins directly controls oligodendroglial proliferation in the presence of mitogens, as well as in growth factor-free conditions. (C) 2004 Wiley-Liss, Inc. [less ▲]

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See detailNG2-expressing cells in the subventricular zone are type C-like cells and contribute to interneuron generation in the postnatal hippocampus
Aguirre, Adan A.; Chittajallu, Ramesh; Belachew, Shibeshih ULg et al

in Journal of Cell Biology (2004), 165(4), 575-589

The subventricular zone (SVZ) is a source of neural progenitors throughout brain development. The identification and purification of these progenitors and the analysis of their lineage potential are ... [more ▼]

The subventricular zone (SVZ) is a source of neural progenitors throughout brain development. The identification and purification of these progenitors and the analysis of their lineage potential are fundamental issues for future brain repair therapies. We demonstrate that early postnatal NG2-expressing (NG2(+)) progenitor cells located in the SVZ self-renew in vitro and display phenotypic features of transit-amplifier type C-like multipotent cells. NG2(+) cells in the SVZ are highly proliferative and express the epidermal growth factor receptor, the transcription factors Dlx, Mash1, and Olig2, and the Lewis X (LeX) antigen. We show that grafted early postnatal NG2(+) cells generate hippocampal GABAergic interneurons that propagate action potentials and receive functional glutamatergic synaptic inputs. Our work identifies Dlx(+)/Mash1(+)/LeX(+)/NG2(+)/GFAP-negative cells of the SVZ as a new class of postnatal multipotent progenitor cells that may represent a specific cellular reservoir for renewal of postnatal and adult inhibitory interneurons in the hippocampus. [less ▲]

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See detailPostnatal NG2 proteoglycan-expressing progenitor cells are intrinsically multipotent and generate functional neurons.
Belachew, Shibeshih ULg; Chittajallu, Ramesh; Aguirre, Adan A. et al

in Journal of Cell Biology (2003), 161(1), 169-86

Neurogenesis is known to persist in the adult mammalian central nervous system (CNS). The identity of the cells that generate new neurons in the postnatal CNS has become a crucial but elusive issue. Using ... [more ▼]

Neurogenesis is known to persist in the adult mammalian central nervous system (CNS). The identity of the cells that generate new neurons in the postnatal CNS has become a crucial but elusive issue. Using a transgenic mouse, we show that NG2 proteoglycan-positive progenitor cells that express the 2',3'-cyclic nucleotide 3'-phosphodiesterase gene display a multipotent phenotype in vitro and generate electrically excitable neurons, as well as astrocytes and oligodendrocytes. The fast kinetics and the high rate of multipotent fate of these NG2+ progenitors in vitro reflect an intrinsic property, rather than reprogramming. We demonstrate in the hippocampus in vivo that a sizeable fraction of postnatal NG2+ progenitor cells are proliferative precursors whose progeny appears to differentiate into GABAergic neurons capable of propagating action potentials and displaying functional synaptic inputs. These data show that at least a subpopulation of postnatal NG2-expressing cells are CNS multipotent precursors that may underlie adult hippocampal neurogenesis. [less ▲]

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See detailExpression of the green fluorescent protein in the oligodendrocyte lineage: a transgenic mouse for developmental and physiological studies.
Yuan, Xiaoqing; Chittajallu, Ramesh; Belachew, Shibeshih ULg et al

in Journal of Neuroscience Research (2002), 70(4), 529-45

We generated a transgenic mouse expressing the enhanced green fluorescent protein (EGFP) under the control of the 2'-3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter. EGFP(+) cells were visualized ... [more ▼]

We generated a transgenic mouse expressing the enhanced green fluorescent protein (EGFP) under the control of the 2'-3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter. EGFP(+) cells were visualized in live tissue throughout embryonic and postnatal development. Immunohistochemical analysis in brain tissue and in sciatic nerve demonstrated that EGFP expression was restricted to cells of the oligodendrocyte and Schwann cell lineages. EGFP was also strongly expressed in "adult" oligodendrocyte progenitors (OPs) and in gray matter oligodendrocytes. Fluorescence-activated cell sorting allowed high-yield purification of EGFP(+) oligodendrocyte-lineage cells from transgenic brains. Electrophysiological patch clamp recordings of EGFP(+) cells in situ demonstrated that OP cells displayed large outward tetraethylammonium (TEA)-sensitive K(+) currents and very small inward currents, whereas mature oligodendrocytes were characterized by expression of large inward currents and small outward K(+) currents. The proliferation rate of EGFP(+) cells in developing white matter decreased with the age of the animals and was strongly inhibited by TEA. Oligodendrocyte development and physiology can be studied in live tissue of CNP-EGFP transgenic mice, which represent a source of pure EGFP(+) oligodendrocyte-lineage cells throughout development. [less ▲]

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