Minimal molecular determinants of isoform-specific differences in efficacy in the HCN channel family

Alvarez-Baron, Claudia P.; Klenchin, Vadim A.; Chanda, Baron

doi:10.1085/jgp.201812031

Cited by 13 publications

(6 citation statements)

References 33 publications

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“…In summary, we mapped out distinct routes within the CL-CNBD that modulate different cAMP binding responses in HCN2 channels through disjunct salt bridge interactions. With respect to other studies investigating the role of functionally relevant modules in HCN channel function (17,(53)(54)(55)(56), our results signify that functionally relevant submodules may exist within and across structurally discernable subunits.…”

Section: Discussionsupporting

confidence: 67%

Allosteric signaling in C-linker and cyclic nucleotide-binding domain of HCN2 channels

Pfleger

Kusch

Kondapuram

et al. 2021

Biophysical Journal

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Opening of hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels is controlled by membrane hyperpolarization and binding of cyclic nucleotides to the tetrameric cyclic nucleotide-binding domain (CNBD), attached to the C-linker disk (CL). Confocal patch-clamp fluorometry revealed a pronounced cooperativity of ligand binding among protomers. However, by which pathways allosteric signal transmission occurs remained elusive. Here, we investigate how changes in the structural dynamics of the CL-CNBD of mouse HCN2 upon cAMP binding relate to inter-and intrasubunit signal transmission. Applying a rigidity theory-based approach, we identify two intersubunit and one intrasubunit pathways that differ in allosteric coupling strength between cAMP binding sites or towards the CL. These predictions agree with results from electrophysiological and patch-clamp fluorometry experiments. Our results map out distinct routes within the CL-CNBD that modulate different cAMP binding responses in HCN2 channels. They signify that functionally relevant submodules may exist within and across structurally discernable subunits in HCN channels.

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Section: Discussionsupporting

confidence: 67%

Allosteric signaling in C-linker and cyclic nucleotide-binding domain of HCN2 channels

Pfleger

Kusch

Kondapuram

et al. 2021

Biophysical Journal

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“…While our results show no difference in their expression in the absence of Er81, these voltage-sensitive channels could be modulated by second messengers, such as phosphatidylinositol-4,5-bisphosphate and calcium for KCNQ2/3 (Wilson and Goldberg, 2006;Falkenburger et al, 2010;Kim et al, 2016), and cAMP for HCN2 (Z. Zhao et al, 2016;Alvarez-Baron et al, 2018). We propose that the enhanced I sAHP in the Er81 cKO cells is because of a higher intracellular calcium concentration mediated through mGluR5 (Niswender and Conn, 2010).…”

Section: Control Of the Cholinergic Interneuron Identitycontrasting

confidence: 62%

“…Lower CIN excitability in the absence of Er81 can indeed result in a decreased acetylcholine recruitment at the CIN membrane, reduced M2 muscarinic receptor activity and consequently, to higher levels of intracellular cAMP (Z. Zhao et al, 2016;Alvarez-Baron et al, 2018). We propose that the changes in CIN activity in the absence of Er81 modify their connectivity and morphology via homeostatic compensations during maturation.…”

Section: Control Of the Cholinergic Interneuron Identitymentioning

confidence: 94%

Er81 Transcription Factor Fine-Tunes Striatal Cholinergic Interneuron Activity and Drives Habit Formation

et al. 2021

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The molecular mechanisms tuning cholinergic interneuron (CIN) activity, although crucial for striatal function and behavior, remain largely unexplored. Previous studies report that the Etv1/Er81 transcription factor is vital for regulating neuronal maturation and activity. While Er81 is known to be expressed in the striatum during development, its specific role in defining CIN properties and the resulting consequences on striatal function is unknown. We report here that Er81 is expressed in CINs and its specific ablation leads to prominent changes in their molecular, morphologic, and electrophysiological features. In particular, the lack of Er81 amplifies intrinsic delayed-rectifier and hyperpolarization-activated currents, which subsequently alters the tonic and phasic activity of CINs. We further reveal that Er81 expression is required for normal CIN pause and time-locked responses to sensorimotor inputs in awake mice. Overall, this study uncovers a new cell type-specific control of CIN function in the striatum which drives habit formation in adult male mice.

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“…KCNQ2/3 and HCN2 channels in CINs underlie the I Kr and the I h , respectively. Whilst our results show no difference in their expression in the absence of Er81, these voltage-sensitive channels could be modulated by second messengers such as phosphatidylinositol-4,5-bisphosphate (PIP 2 ) and calcium for KCNQ2/3 (Wilson and Goldberg, 2006) (Falkenburger et al, 2010) , and cAMP for HCN2 (Zhao et al, 2016) (Alvarez-Baron et al, 2018. We propose that the enhanced I Kr in the Er81 cKO cells is due to a higher intracellular calcium concentration mediated through mGluR5 (Niswender and Conn, 2010).…”

Section: Mechanisms Regulating Tonic and Phasic Activity Of The Striacontrasting

confidence: 57%

“…We also suggest that enhanced cAMP signalling leads to the increase in the I h current. Lower CIN excitability in the absence of Er81 can indeed result in a decreased acetylcholine recruitment at the CIN membrane, reduced M2 muscarinic receptor activity and consequently, to higher levels of intracellular cAMP (Zhao et al, 2016) (Alvarez-Baron et al, 2018.…”

Section: Mechanisms Regulating Tonic and Phasic Activity Of The Striamentioning

confidence: 99%

Loss of the Er81 Transcription Factor in Cholinergic Cells Alters Striatal Activity and Habit Formation

Ranjbar-Slamloo

Ahmed

Abed

et al. 2020

Preprint

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Highlights-The Er81 transcription factor is expressed in striatal cholinergic interneurons (CINs) -Conditional deletion of Er81 alters key molecular, morphological and electrophysiological properties of CINs in adult mice -Deletion of Er81 reduces the intrinsic excitability of CINs by upregulating delayed rectifier and hyperpolarization-activated currents -Deletion of Er81 alters in vivo striatal activity and habit formation SUMMARYThe finely-tuned activity of cholinergic interneurons (CINs) in the striatum is key for motor control, learning, and habit formation. Yet, the molecular mechanisms that determine their unique functional properties remain poorly explored. Using a combination of genetic and biochemical assays, in vitro and in vivo physiological characterisation, we report that selective ablation of the Er81 transcription factor leads to prominent changes in CIN molecular, morphological and electrophysiological features. In particular, the lack of Er81 amplifies intrinsic delayed-rectifier and hyperpolarization-activated currents, which subsequently alters the tonic and phasic activity of CINs. We further demonstrate that these alterations enhance their pause and time-locked responses to sensorimotor inputs in awake mice. Finally, this study reveals an Er81-dependent developmental mechanism in CINs essential for habit formation in adult mice. RESULTS Er81 is expressed in the striatal cholinergic interneuronsWe first analysed the expression of Er81 from birth to adulthood and found that both mRNA ( Figure 1A) and protein levels (Figure 1B) significantly drop from postnatal day 6 (P6) to P30 in the total striatum. In the CINs specifically, we observed similar decrease of Er81 protein levels from P6 to P30 (Figure 1C). To determine the proportion of CINs expressing Er81 at any stage during development, we analysed β-galactosidase staining, which perdures long after being synthesised (Dehorter et al., 2015). We found that most of CINs (62 ± 7 %) in the Er81 nlsLacZ/+ mice express β-galactosidase (and therefore Er81) in the striatum (Figure S1A), unlike cholinergic cells in the basal forebrain (6 ± 2%; Figure S1B). As Er81 can have an important role in cell function (Dehorter et al., 2015), we analysed the consequences of removing Er81 from CINs, using conditional knockout mice (cKO: ChAT-Cre; Er81 f/f ; comparing with control mice: ChAT-Cre; Er81 +/+ ). We did not observe any change in cholinergic cell density at P2 and P30 within the striatum between control and Er81 cKO conditions (Figure 1D-Fsuggesting that the specific deletion of Er81 does not affect CIN neurogenesis and migration. Cholinergic interneuron properties change in the absence of Er81To determine the role of Er81 in CIN specification and maturation, we assessed the molecular properties of these cells following Er81 deletion. The LIM homeodomain transcription factorLhx6 is expressed in about half of striatal CINs (Lozovaya et al., 2018)and is necessary for MGE-derived GABAergic interneuron specification (Liodis et al., 2007) (Fragkouli et al., ...

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Minimal molecular determinants of isoform-specific differences in efficacy in the HCN channel family

Cited by 13 publications

References 33 publications

Allosteric signaling in C-linker and cyclic nucleotide-binding domain of HCN2 channels

Allosteric signaling in C-linker and cyclic nucleotide-binding domain of HCN2 channels

Er81 Transcription Factor Fine-Tunes Striatal Cholinergic Interneuron Activity and Drives Habit Formation

Loss of the Er81 Transcription Factor in Cholinergic Cells Alters Striatal Activity and Habit Formation

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