Biology subjects

Marquez-Gomez, R.

Publications and source records attributed to Marquez-Gomez, R..

4 recordsLinked to original sources

bioRxiv2026

Phenotypic screening in Parkinson's iPSC-dopamine neurons identifies the FASN-SREBP1 axis as a potential therapeutic target

Parkinson's disease (PD) remains highly challenging to model in vitro, particularly when seeking robust functional phenotypes for target discovery. Patient-derived induced pluripotent stem cell dopaminergic neurons (iPSC-DANs) offer a promising platform to address this challenge. Because calcium dyshomeostasis is well-described in PD pathophysiology, it offers a platform for phenotypic screening. We have previously shown that GBA-N370S iPSC-DANs display impaired intracellular calcium release. Here, we used this disease-relevant phenotype to undertake a 4,108-compound phenotypic screen in GBA-N370S (GBA-NS) iPSC-DANs. This screen identified fatty acid synthase (FASN) as the most enriched protein target. The ability of compounds to rescue calcium release correlated with biochemical potency against FASN across multiple chemical series. We confirmed that FASN knockdown increased intracellular calcium release, supporting an on-target effect. Untargeted lipidomics demonstrated broad remodelling of the neuronal lipidome after FASN inhibition, confirming target engagement. FASN inhibition also increased active a-glucocerebrosidase (GCase), reduced extracellular a-synuclein release and ER stress, and altered RASGRF1 expression. Mechanistically, FASN inhibition activated sterol regulatory element-binding protein 1 (SREBP1), and SREBP1 overexpression alone was sufficient to increase intracellular calcium release, identifying a FASN-SREBP1-calcium homeostasis axis in human neurons. Finally, the FASN inhibitor BI 99179 achieved brain exposure and reduced brain fatty acid levels while inducing an SRE-associated transcriptional response in a Parkinson's mouse model, providing evidence of in vivo target engagement. These findings establish patient iPSC-neuron functional screening as a tractable discovery platform to identify targets which can be taken in vivo and nominate the FASN-SREBP1 axis as a candidate therapeutic pathway in PD.

neuroscience↗

bioRxiv2023

Histamine originating from the BNST modulates corticostriatal synaptic transmission during early postnatal development

The neuromodulator histamine regulates key processes in many regions of both the adult and developing brain including the striatum. However, striatal innervation by histaminergic afferents is very sparse making the physiological sources of histamine controversial. Here potential sources of striatal histamine were investigated during early postnatal development and specifically in the second postnatal week, in acute mouse brain slices. Firstly, a combination of whole-cell patch-clamp recordings and optogenetic stimulation demonstrates that during this period exogenously applied histamine modulates the intrinsic properties of developing D1 and D2 striatal spiny projection neurons (SPNs) as well as synaptic transmission at afferents coming from the mPFC and visual cortex. Secondly, immunohistochemistry for histamine reveals a brain region proximal and caudal to striatum densely innervated by histaminergic axons and corresponding to the oval nucleus of the bed nucleus of stria terminalis (ovBNST). Thirdly, direct electrical stimulation of the ovBNST leads to significant and detectable levels of histamine in the striatum, as assessed by both fast scan cyclic voltammetry and fluorescent histamine sensors. Lastly, electrical stimulation of the ovBNST nucleus, at frequencies mimicking active histaminergic neurons, can release sufficient levels of histamine to modulate excitatory synaptic transmission from mPFC onto striatal SPNs by acting at histamine H3 receptors. Together, these results provide evidence for the existence of the ovBNST as an extrastriatal source of histamine during early brain development and postulates a new view of the modus operandi of histamine in that it can cross anatomical boundaries and act as a paracrine neuromodulator. Significance statementHistamine is synthesized by neurons in the hypothalamic tuberomammillary nucleus (TMN) and released from their axons in many brain regions controlling key physiological processes. When dysregulated this can result in neurological and neurodevelopmental disorders such as Tourettes syndrome and OCD. To understand the physiological roles for histamine and to facilitate the generation of new therapeutic interventions it is key to define the sources of histamine and its mode of action. Here we provide evidence, using the developing striatum as an exemplar, that sources of histamine can lie beyond anatomical boundaries with histamine acting as a paracrine neuromodulator. This also has potential implications for our mechanistic understanding of deep brain stimulation of the BNST in treating severe Tourettes syndrome and OCD.

neuroscience↗

bioRxiv2023

Early striatal hyperexcitability in an in vitro human striatal microcircuit model carrying the Parkinson's GBA-N370S mutation

Understanding medium spiny neuron (MSN) physiology is essential to understand motor impairments in Parkinsons disease (PD) given the architecture of the basal ganglia. Here, we developed a custom three-chamber microfluidic platform and established a cortico-striato-nigral microcircuit recapitulating the striatal presynaptic triad in vitro using induced pluripotent stem cell (iPSC)-derived neurons. We found that, although cortical glutamatergic projections facilitated MSN synaptic activity, dopaminergic transmission was essential for excitability maturation of MSNs in vitro. Replacement of wild-type iPSC-dopamine neurons (iPSC-DaNs) in the striatal microcircuit with those carrying the PD-related GBA-N370S mutation induced early hyperexcitability in iPSC-MSNs through reduction of voltage-gated sodium and potassium intrinsic currents. Such deficits were resolved in aged cultures or with antagonism of protein kinase A activity in nigrostriatal iPSC-DaNs. Hence, our results highlight the unique utility of modelling striatal neurons in a modular and highly physiological circuit which is essential to reveal mechanistic insights of the loss of electrical functional integrity in the striata of GBA1 PD patients.

neuroscience↗

bioRxiv2017

Functional histamine H3 and adenosine A2A receptor heteromers in recombinant cells and rat striatum

In the striatum, histamine H3 receptors (H3Rs) are co-expressed with adenosine A2A receptors (A2ARs) in the cortico-striatal glutamatergic afferents and the GABAergic medium-sized spiny neurons that originate the indirect pathway of the basal ganglia. This location allows H3Rs and A2ARs to regulate the striatal GABAergic and glutamatergic transmission. However, whether these receptors interact to modulate the intra-striatal synaptic transmission has not yet been assessed. To test this hypothesis a heteromer-selective in vitro assay was used to detect functional complementation between a chimeric A2AR302-Gqi4 and wild-type H3Rs in transfected HEK-293 cells. H3R activation with the agonist RAMH resulted in Ca2+ mobilization (pEC50 7.31 {+/-} 0.23; maximal stimulation, Emax 449 {+/-} 25 % of basal) indicative of receptor heterodimerization. This response was not observed with histamine, suggesting a RAMH bias for heteromers. Functional A2AR-H3R heteromers were confirmed by co-immunoprecipitation and observations of differential cAMP signaling when both receptors were co-expressed in the same cell. In membranes from rat striatal synaptosomes, H3R activation decreased A2AR affinity for the agonist CGS-21680 (pKi values 8.10 {+/-} 0.04 and 7.70 {+/-} 0.04). Moreover, H3Rs and A2ARs co-immunoprecipitated in protein extracts from striatal synaptosomes. These results support the existence of a H3R/A2AR heteromer, and reveal a new mechanism by which these receptors may modulate the unction of the striatum and the basal ganglia.

neuroscience↗