Mutations in the voltage‐sensing domain affect the alternative ion permeation pathway in the TRPM3 channel

Held, Katharina; Gruss, Fabian; Aloi, Vincenzo Davide; Janssens, Annelies; Ulens, Chris; Voets, Thomas; Vriens, Joris

doi:10.1113/jp274124

Cited by 30 publications

(27 citation statements)

References 35 publications

(131 reference statements)

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“…These results suggest a mechanism in which the increase in Trpm3 expression in dominant males leads to a persistent increase in MDT-ACC feedforward inhibition with significant behavioral consequences. Trpm3 can be activated by a number of stimuli, including voltage (Held et al, 2018) and pregnenolone sulfate (PregS), a neurosteroid that has been linked to aggression (Baulieu, 1998; Held et al, 2018). Future studies should shed light on how TRPM3 expression is regulated during social competition.…”

Section: Discussionmentioning

confidence: 99%

Molecular and Circuit Architecture of Social Hierarchy

Nelson

Kapoor

Vaughn

et al. 2019

Preprint

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1 4 nearly 20 areas sent mono-synaptic inputs to MDT Glut neurons, including hypothalamic areas associated with arousal, feeding, and pain (e.g., lateral hypothalamus (LH), preoptic area (POA)), basal forebrain areas associated with reward learning and voluntary movement (e.g., NDB, ventral pallidum (VP), substantia innominata (SI)), deep-layer cortical areas associated with executive function (ACC, OFC, PL), areas associated with olfaction (piriform cortex, olfactory tubercle, OFC), and intra-thalamic information processing areas (reticular thalamus and zona incerta) ( Fig. 3B-C).Projections from MDT Glut neurons were visualized using two combined AAVs driving expression of reporter fluorophores in axons (tdTomato) and presynaptic terminals (Synaptophysin-GFP fusion protein) ( Fig. 3D). As previously described, layer II/III in cortical areas associated with executive, perceptual and memory functions (e.g., ACC, OFC, PL) received the majority of MDT Glut projections (Delevich et al., 2015; Krettek and Price, 1977). The ACC, from its most rostral (> bregma +2.0) to caudal (< bregma -2.0) coordinates, received the greatest fraction of inputs ( Fig. 3E-F). Additional targets included cortical (retrosplenial and infralimbic cortex) and basal ganglia areas (i.e., globus pallidus, dorsomedial caudate putamen, and nucleus accumbens). The MDT Glut circuit is therefore poised to integrate aspects of learned interactions, emotional valance, innate behavioral responses, and olfactory communication, all functions that are highly relevant to hierarchy formation. Activity of MDT-cAAC projections during social competitionThe cACC, a major target of MDT Glut projections, showed decreased activity in rank-1 males after tube tests ( Fig. 2A). Because rank-1 males showed increased activity in MDT, we hypothesized that MDT may inhibit the cACC. Indeed, reports using viral tracing (Delevich et al., 2015; Lu et al., 2017), optogenetic assisted circuit mapping (Delevich et al., 2015; Ferguson and Gao, 2018; Miller et al., 2017), and neurophysiological studies of decision making (Schmitt et al., 2017) suggest that MDT projections can drive feedforward inhibition of the PFC through

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Section: Discussionmentioning

confidence: 99%

Molecular and Circuit Architecture of Social Hierarchy

Nelson

Kapoor

Vaughn

et al. 2019

Preprint

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“…In earlier work, we have demonstrated that this inwardly rectifying current component represents ion flux through an alternative ion permeation pathway located in the voltage sensor domain of TRPM3, which can be distinguished from the central pore based on its voltage dependence, insensitivity to pore block by La 3+ and ion selectivity (including a lower permeability for monomethylammonium (MMA + ) compared to Na + ) (10, 14). Notably, the V990M mutation is located in close vicinity of Asp988 and Gly991, which we recently identified as critical determinants of the alternative ion permeation pathway (15). We therefore hypothesized that gating of the alternative ion permeation pathway is facilitated in V990M, such that it can be activated by PS even when Clt is not co-applied.…”

Section: Resultsmentioning

confidence: 99%

“…HEK293T cells were cultured as described previously (15). HEK293T cells were transiently transfected with 2 µg of DNA using TransIT transfection reagent (Mirus) 36-48 hours before the measurements.…”

Section: Supplementary Sectionmentioning

confidence: 99%

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Gain of channel function and modified gating properties in TRPM3 mutants causing intellectual disability and epilepsy

Hoeymissen

Held

Freitas

et al. 2020

Preprint

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33Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of disorders 34 characterized by epilepsy with comorbid intellectual disability. Recently, two de novo 35 heterozygous mutations in the gene encoding TRPM3, a calcium permeable ion channel, were 36 identified as the cause of DEE in eight probands, but the functional consequences of the 37 mutations remained elusive. Here we demonstrate that both mutations (V990M and P1090Q) 38 have distinct effects on TRPM3 gating, including increased basal activity, higher sensitivity to 39 stimulation by the endogenous neurosteroid pregnenolone sulphate (PS) and heat, and altered 40 response to ligand modulation. Most strikingly, the V990M mutation affected the gating of the 41 non-canonical pore of TRPM3, resulting in large inward cation currents via the voltage sensor 42 domain in response to PS stimulation. Taken together, these data indicate that the two DEE 43 mutations in TRPM3 result in a profound gain of channel function, which may lie at the basis 44 of epileptic activity and neurodevelopmental symptoms in the patients. 45 48 neurosteroid pregnenolone sulphate (PS) (2). TRPM3 is expressed in a large subset of mouse 49 and human somatosensory neurons, where it is involved in the detection of noxious heat and 50 the development of inflammatory pain (1, 3). Moreover, TRPM3 is expressed in several brain 51 areas, including the choroid plexus, cerebellum, cortex and the hippocampal formation (4-6), 52 but its functional role in these areas is unknown. Recently, two de novo substitutions in TRPM3 53 (V990M and P1090Q) were identified as the cause of intellectual disability and epilepsy in 54 eight probands with developmental and epileptic encephalopathy (DEE) (7). However, the 55 consequences of these mutations on TRPM3 function remained elusive. We here demonstrate 56 that both mutations lead to significant gain-of-channel function, including increased basal 57 activity and higher sensitivity to PS and heat. V990M exhibits further pronounced functional 58 alterations, including anomalous activation of the alternative current through the voltage-sensor 59 domain, reduced sensitivity to receptor-mediated inhibition and calcium-dependent 60 inactivation, and lower sensitivity to block by the anticonvulsant primidone.61 4 Results & Discussion 62When performing Fura-2-based calcium imaging on transiently transfected HEK293T cells, we 63 observed significantly higher intracellular Ca 2+ concentrations ([Ca 2+ ]i) in cells expressing the 64 two DEE mutants compared to wild type human TRPM3 (WT) ( Figure 1A,B), an effect that 65 was much more pronounced in the V990M mutant. Application of primidone or isosakuranetin, 66 both potent TRPM3 antagonists (8, 9), reduced [Ca 2+ ]i in cells expressing WT or mutant 67 TRPM3. In absolute terms, the antagonist-induced reduction in [Ca 2+ ]i was the largest for the 68 V990M mutant, yet [Ca 2+ ]i did not fully return to the level of cells expressing WT ( Figure 69 1A,C). These results suggest that the DEE...

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“…Recently, a second, distinct cation conductance pore has been discovered in native mTRPM3α2 channels that is analogous to the 'gating-pore' or 'omega-pore' associated with artificial and disease-causing mutations in the voltage-sensor domain (S4-helix) of classical voltagegated K + , Ca 2+ , and Na + channels [42,[114][115][116]. Simultaneous opening of the canonical and non-canonical pores was achieved by co-stimulation with PS and the antifungal agent clotrimazole (Clt) or its structural analogs (e.g., tamoxifen) or by administration of a synthetic Clt-like ligand CIM0216 that represents the most potent and specific agonist known for TRPM3 channels [42,114].…”

Section: Canonical Trpm3 Cation Pore (S5-p-s6)mentioning

confidence: 99%

TRPM3_miR-204: a complex locus for eye development and disease

Shiels

2020

Hum Genomics

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First discovered in a light-sensitive retinal mutant of Drosophila, the transient receptor potential (TRP) superfamily of non-selective cation channels serve as polymodal cellular sensors that participate in diverse physiological processes across the animal kingdom including the perception of light, temperature, pressure, and pain. TRPM3 belongs to the melastatin sub-family of TRP channels and has been shown to function as a spontaneous calcium channel, with permeability to other cations influenced by alternative splicing and/or non-canonical channel activity. Activators of TRPM3 channels include the neurosteroid pregnenolone sulfate, calmodulin, phosphoinositides, and heat, whereas inhibitors include certain drugs, plant-derived metabolites, and G-protein subunits. Activation of TRPM3 channels at the cell membrane elicits a signal transduction cascade of mitogen-activated kinases and stimulus response transcription factors. The mammalian TRPM3 gene hosts a non-coding microRNA gene specifying miR-204 that serves as both a tumor suppressor and a negative regulator of post-transcriptional gene expression during eye development in vertebrates. Ocular co-expression of TRPM3 and miR-204 is upregulated by the paired box 6 transcription factor (PAX6) and mutations in all three corresponding genes underlie inherited forms of eye disease in humans including early-onset cataract, retinal dystrophy, and coloboma. This review outlines the genomic and functional complexity of the TRPM3_miR-204 locus in mammalian eye development and disease.

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Mutations in the voltage‐sensing domain affect the alternative ion permeation pathway in the TRPM3 channel

Cited by 30 publications

References 35 publications

Molecular and Circuit Architecture of Social Hierarchy

Molecular and Circuit Architecture of Social Hierarchy

Gain of channel function and modified gating properties in TRPM3 mutants causing intellectual disability and epilepsy

TRPM3_miR-204: a complex locus for eye development and disease

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