7 research outputs found
Direct conversion of astrocytes into neuronal cells by drug cocktail
Direct conversion of astrocytes into neuronal cells by
drug cocktail
Cell Research advance online publication 2 October 2015; doi:10.1038/cr.2015.120
Dear Editor,
Neurological disorder is one of the greatest threats
to public health according to the World Health Organization.
Because neurons have little or no regenerative
capacity, conventional therapies for neurological disorders
yielded poor outcomes. While the introduction of
exogenous neural stem cells or neurons holds promise,
many challenges still need to be tackled, including cell
resource, delivery strategy, cell integration and cell
maturation. Reprogramming of fibroblasts into induced
pluripotent stem cells or directly into desirable neuronal
cells by transcription factors (TFs) or small molecules
can solve some problems, but other issues remain to be
addressed, including safety, conversion efficiency and
epigenetic memory [1, 2].
Astrocytes are considered to be the ideal starting
candidate cell type for generating new neurons, due to
their proximity in lineage distance to neurons and ability
to proliferate after brain damage. Many studies have
already revealed that astrocytes of the central nervous
system can be reprogrammed into induced neuronal cells
by virus-mediated overexpression of specific TFs in vitro
and in vivo [3-6]. However, application of this virus-mediated
direct conversion is still limited due to concerns
on clinical safety. We have previously reported direct
conversion of somatic cells into neural progenitor cells
(NPCs) in vitro by cocktail of small molecules under hypoxia
[7]. Here we set out to explore whether astrocytes
can be induced into neuronal cells by the chemical cocktail
in vitro
Direct Generation of Human Neuronal Cells from Adult Astrocytes by Small Molecules
Astrocytes, due to the proximity to neuronal lineage and capability to proliferate, are ideal starting cells to regenerate neurons. Human fetal astrocytes have been successfully converted into neuronal cells by small molecules, which offered a broader range of further applications than transcription factor-mediated neuronal reprogramming. Here we report that human adult astrocytes could also be converted into neuronal cells by a different set of small molecules. These induced cells exhibited typical neuronal morphologies, expressed neuronal markers, and displayed neuronal electrophysiological properties. Genome-wide RNA-sequencing analysis showed that the global gene expression profile of induced neuronal cells resembled that of human embryonic stem cell-differentiated neurons. When transplanted into post-natal mouse brains, these induced neuronal cells could survive and become electrophysiologically mature. Altogether, our study provides a strategy to directly generate transgene-free neuronal cells from human adult astrocytes by small molecules
Genetically identified amygdala-striatal circuits for valence-specific behaviors
The basolateral amygdala (BLA) plays essential roles in behaviors motivated by stimuli with either positive or negative valence, but how it processes motivationally opposing information and participates in establishing valence-specific behaviors remains unclear. Here, by targeting Fezf2-expressing neurons in the BLA, we identify and characterize two functionally distinct classes in behaving mice, the negative-valence neurons and positive-valence neurons, which innately represent aversive and rewarding stimuli, respectively, and through learning acquire predictive responses that are essential for punishment avoidance or reward seeking. Notably, these two classes of neurons receive inputs from separate sets of sensory and limbic areas, and convey punishment and reward information through projections to the nucleus accumbens and olfactory tubercle, respectively, to drive negative and positive reinforcement. Thus, valence-specific BLA neurons are wired with distinctive input-output structures, forming a circuit framework that supports the roles of the BLA in encoding, learning and executing valence-specific motivated behaviors
A fluorescent sensor for spatiotemporally resolved imaging of endocannabinoid dynamics in vivo
Endocannabinoids (eCBs) are retrograde neuromodulators with important functions in a wide range of physiological processes, but their in vivo dynamics remain largely uncharacterized. Here we developed a genetically encoded eCB sensor called GRABeCB2.0. GRABeCB2.0 consists of a circular-permutated EGFP and the human CB1 cannabinoid receptor, providing cell membrane trafficking, second-resolution kinetics with high specificity for eCBs, and shows a robust fluorescence response at physiological eCB concentrations. Using GRABeCB2.0, we monitored evoked and spontaneous changes in eCB dynamics in cultured neurons and acute brain slices. We observed spontaneous compartmentalized eCB transients in cultured neurons and eCB transients from single axonal boutons in acute brain slices, suggesting constrained, localized eCB signaling. When GRABeCB2.0 was expressed in the mouse brain, we observed foot shock-elicited and running-triggered eCB signaling in the basolateral amygdala and hippocampus, respectively. In a mouse model of epilepsy, we observed a spreading wave of eCB release that followed a Ca2+ wave through the hippocampus. GRABeCB2.0 is a robust probe for eCB release in vivo