BDNF profoundly and specifically increases KCNQ4 expression in neurons derived from embryonic stem cells

Abstract

Neurons resembling the spiral ganglion neurons (SGNs) of the auditory nerve can be generated from embryonic stem cells through induced over-expression of the transcription factor Neurogenin-1 (Neurog1). While recapitulating this developmental pathway produces glutamatergic, bipolar neurons reminiscent of SGNs, these neurons are functionally immature, being characterized by a depolarized resting potential and limited excitability. We explored the effects of two neurotrophins known to be present in the inner ear, brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), on the electrophysiology of neurons following Neurog1-induction. Our data reveal a significant reduction in resting membrane potential (RMP) following neurotrophin exposure, with BDNF producing a more robust effect than NT-3. This effect was accompanied by a profound and specific upregulation of the KCNQ4 subtype, where a 9-fold increase was observed with quantitative PCR. The other neuronally-expressed KCNQ subtypes (2, 3, and 5) exhibited upregulation which was 3-fold or less in magnitude. Quantitative immunohistochemistry confirmed the increase in KCNQ4 expression at the protein level. The present data show a novel link between BDNF and KCNQ4 expression, yielding insight into the restricted expression pattern of a channel known to play a special roles in setting the resting potential of auditory cells and in the etiology of progressive high frequency hearing loss.

Electrophysiological properties of neurosensory progenitors derived from human embryonic stem cells

“…more hyperpolarized) RMP, which in our stem cell-derived neurons remained in the order of − 50 mV across the 5 weeks in vitro, is also suggestive of a maturing neural phenotype and may also be assisted by the presence of BDNF in the culture media (Purcell et al, 2013). As recently demonstrated by Purcell et al (2013), expression of the K + channel KCNQ4 dramatically increased in stem cell-derived neurons following BDNF exposure. These authors also reported a concomitant reduction in RMP, thereby highlighting the potential to produce specific neuronal subtypes using appropriate soluble molecules.…”

“…Interestingly, the stem cell-derived neurons used by Chen et al (2012) displayed similar basic firing properties prior to their transplantation, to the stem cell-derived neurons described in the present study. Moreover, the voltage-gated ion channels that control neural activity are sensitive to changes in their environment, including concentration of neurotrophic factors (Adamson et al, 2002a;Zhou et al, 2005;Needham et al, 2012;Purcell et al, 2013) and excitatory input (Leao et al, 2005;Holt et al, 2006;Hassfurth et al, 2009), both of which are likely to play a role following their transplantation into the deaf cochlea. Determining how to harness and balance both in vitro and in vivo factors to derive functionally appropriate stem cell-derived neurons will be an important task in developing a stem cell therapy for the deaf cochlea.…”

Kv7 channels are upregulated during striatal neuron development and promote maturation of human iPSC-derived neurons

“…Evidence has been provided for a role of Ca V 3.1 voltage-gated L-type Ca 2+ channels in the differentiation of neural stem/progenitor cells [9] and of Kv3.1 K + channels in the proliferation and neuronal differentiation of adult neural precursor cells [43]. Expression of Kv7.4 channels was recently reported in neurons derived from embryonic stem cells [28], and a potential role of Kv7.2/7.3 channels in differentiation, synaptogenesis and synaptic function of mouse hippocampal and embryonic stem cell-derived neurons has been indicated [44]. …”

Combined Growth Factor and Gene Therapy: An Approach for Hair Cell Regeneration and Hearing Recovery

“…BDNF can increase the expression of potassium voltage-gated channel subfamily Q member 4 (KCNQ4) and it is necessary for the differentiation of neurons derived from ESCs into Spiral Ganglion Neuron (SGN) [58]. In a study, mouse ESCs (mESCs) were treated with the BDNF and glial cell line-derived neurotrophic factor after transient expression of Neurog 1 and 75% of neuronal cells derived from mESCs exhibited the glutamatergic phenotype after a 5-day culture in vitro.…”