Biology subjects

Lipina, T. V.

Publications and source records attributed to Lipina, T. V..

6 recordsLinked to original sources

bioRxiv2026

Characterization of the Grin1Q536R/+ mouse: a preclinical model for GRIN1-related neurodevelopmental disorder

N-methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors playing critical roles in brain development, synaptic plasticity, and cognition. GRIN1-Related Neurodevelopmental Disorder (GRIN1-NDD) is a rare genetic condition caused by pathogenic variations in the GRIN1 gene, which encodes the obligatory subunit of NMDARs. The spectrum of GRIN1 clinical symptoms is hypothesized to result from the functional consequences that different missense variants have on NMDARs. To investigate the disease mechanism in vivo, we generated a novel heterozygous Grin1Q536R/+ knock-in mouse model that carries the identical variation as an adolescent male patient. We describe the clinical presentation of this patient and conduct comprehensive molecular, morphological, electrophysiological, and behavioural characterization in the juvenile, adult, and aging mice. Compared to wildtype littermates, Grin1Q536R/+ mice displayed reduced whole-cell NMDA-induced currents in cortical pyramidal neurons, and reduced NMDAR-mediated synaptic transmission, decreased long-term potentiation, but intact depotentiation at the hippocampal CA1 synapses. Morphological change was observed in the dentate gyrus region of the Grin1Q536R/+ mice. Behavioral phenotyping revealed age- and sex-dependent differences from controls, including hyperlocomotion, reduced muscle strength, and spatial learning deficits. These phenotypes are in line with the clinical manifestations and the relative disease severity of the male patient. The age-dependent phenotypic shift in Grin1Q536R/+ mice highlights the model's value for investigating GRIN1-NDD disease progression and informing longitudinal monitoring as well as potential therapeutic adjustments with age. Taken together, our findings establish a novel and robust in vivo model for studying NMDAR mechanisms and disease pathology in GRIN1-NDD, while supporting the preclinical development of new therapeutic strategies.

neuroscience↗

bioRxiv2025

Characterization of a novel mouse model of Dopamine Transporter Deficiency Syndrome and pharmacological therapeutic strategies

The dopamine transporter (DAT) is an essential protein in the maintenance of dopamine homeostasis in the brain. Thus, single amino acid changes in the gene that encodes for DAT can be sufficient to induce disease, such as Dopamine Transporter Deficiency Syndrome (DTDS). DTDS-associated variants are posited to cause DAT protein misfolding, retention in the endoplasmic reticulum, and a consequent depletion or loss of DAT at the cell surface. In turn, proper dopaminergic regulation is lost. Current treatments for DTDS are largely ineffective, and improved therapeutic options are greatly needed. To this end, we have created a novel mouse model of DTDS harboring the A313V knock-in DAT variant, a proxy for the DTDS-causing A314V variant in humans. We show that the A313V knock-in DAT mice are hyperactive, have increased striatal tissue content of dopamine and its metabolites homovanillic acid (HVA) and DOPAC, and impaired dopamine uptake. We demonstrate that FDA approved compounds alpha-methyl-para-tyrosine ([a]MPT) and amphetamine (AMPH) ameliorate hyperactivity in this mouse model. Moreover, [a]MPT may be a disease-modifying treatment by addressing the hyperdopaminergic tone underlying this hyperactivity. In contrast, noribogaine, a pharmacological chaperone for DAT, is unable to rescue DAT expression. Taken together, these findings show that the A313V knock-in DAT variant mice recapitulate several defining phenotypes seen in patients with DTDS, and provide evidence for two novel treatments for the disease.

pharmacology and toxicology↗

bioRxiv2024

Long-read transcriptomic identification of synaptic adaptation to amyloid pathology in the App(NL-G-F) knock-in mouse model of the earliest phase of Alzheimer's disease

Genome-wide association studies (GWAS) have identified a transcriptional network of Alzheimers disease (AD) risk genes that are primarily expressed in microglia and are associated with AD pathology. However, traditional short-read sequencers have limited our ability to fully characterize how GWAS variants exert their effects on gene expression regulation or alternative splicing in response to the pathology, particularly resulting in inaccurate detection of splicing. To address this gap, we utilized long-read RNA-sequencing (RNA-seq) in the AppNL-G-F knock-in mouse model to identify changes in splicing and novel transcript isoforms in response to amyloid-{beta}. We show that long-read RNA-seq can recapitulate the expected induction of microglial expressed risk genes such as Trem2 in response to amyloid-{beta} at 9 months of age associated with ageing-dependent deficiencies in spatial short-term memory in the AppNL-G-F knock-in mice. Our results not only identified novel splicing events and transcript isoform abundance in genes associated with AD, but also revealed the complex regulation of gene expression through splicing in response to amyloid plaques. Surprisingly, the regulation of alternative splicing in response to amyloid was seen in genes previously not identified as AD risk genes, expressed in microglia, neurons and oligodendrocytes, and included genes such as Syngr1 that modulate synaptic physiology. We saw alternative splicing in genes such as Ctsa, Clta, Dennd2a, Irf9 and Smad4 in mice in response to amyloid, and the orthologues of these genes also showed transcript usage changes in human AD brains. Our data suggests a model whereby induction of AD risk gene expression associated with microglial proliferation and activation is concomitant with alternative splicing in a different class of genes expressed by microglia and neurons, which act to adapt or preserve synaptic activity in response to amyloid-{beta} during early stages of the disease. Our study provides new insights into the mechanisms and effects of the regulation of genes associated with amyloid pathology, which may ultimately enable better disease diagnosis, and improved tracking of disease progression. Additionally, our findings identify new therapeutic avenues for treatment of AD.

genetics↗

bioRxiv2024

Combination of Haloperidol with UNC9994, β-arrestin-biased analog of Aripiprazole, ameliorates schizophrenia-related phenotypes induced by NMDAR deficit in mice.

BackgroundGlutamatergic system dysfunction, particularly involving the N-methyl-D-aspartate receptor (NMDAR), contributes to a full spectrum of schizophrenia-like symptoms, including the cognitive and negative symptoms that are resistant to treatment with antipsychotic drugs (APDs). Aripiprazole, an atypical antipsychotic drug (APD), acts as a dopamine partial agonist and its combination with haloperidol (a typical APD) has been suggested as a potential strategy to improve schizophrenia symptoms. Recently, an analog of aripiprazole - UNC9994 was developed. UNC9994 does not affect D2R-mediated Gi/o protein signaling but acts as a partial agonist for D2R/{beta}-arrestin interactions. Hence, our objective was to probe the effects of co-administrating haloperidol with UNC9994 in NMDAR mouse models of schizophrenia. MethodsNMDAR hypofunction was induced pharmacologically by acute injection of MK-801 (NMDAR pore blocker; 0.15 mg/kg) and genetically by knockdown of Grin1 gene expression in mice, which have a 90% reduction in NMDAR levels (Grin1-KD). After intraperitoneal injections of vehicle, haloperidol (0.15 mg/kg), UNC9994 (0.25 mg/kg) or their combination mice were tested in open field, Pre-Pulse inhibition (PPI), Y-maze and Puzzle box. ResultsOur findings indicate that low dose co-administration of UNC9994 and haloperidol reduces hyperactivity in MK-801-treated animals and in Grin1-KD mice. Furthermore, this dual administration effectively reverses PPI deficits, repetitive/rigid behavior in the Y-maze, and deficient executive function in the Puzzle box in both animal models. ConclusionsThe dual administration of haloperidol with UNC9994 at low doses represents a promising approach to ameliorate positive, negative, and cognitive symptoms of schizophrenia. Significance statementSchizophrenia is a devastating mental disorder and characterized by positive, negative, and cognitive symptoms. Cognitive and negative symptoms remain a focus of research dedicated to development of effective antipsychotic drugs (APDs). Aripiprazole, an atypical APD, acts as a dopamine partial agonist and its combination with haloperidol (a typical APD) has been suggested as a potential strategy to improve schizophrenia symptoms. An analog of aripiprazole - UNC9994 was recently developed, which does not affect D2R-mediated Gi/o protein signaling but acts as a partial agonist for D2R/{beta}-arrestin interactions. Our pre-clinical findings on pharmacological (MK-801, 0.15 mg/kg) and genetic (Grin1-KD) mouse models of NMDAR deficiency showed that the dual administration of UNC9994 (0.25 mg/kg) with haloperidol (0.15 mg/kg) at low doses reduces hyperactivity, corrects prepulse inhibition (PPI) deficits, rigid behavior in the Y-maze, and deficient executive function in the Puzzle box. Further studies of the polypharmacy of UNC9994 with APDs is essential to facilitate translational studies in clinics.

pharmacology and toxicology↗

bioRxiv2023

Tricyclic and tetracyclic antidepressants upregulate VMAT2 activity and rescue disease-causing VMAT2 variants

Vesicular monoamine transporter 2 (VMAT2) is an essential transporter that regulates brain monoamine transmission and is important for mood, cognition, motor activity, and stress regulation. However, VMAT2 remains underexplored as a pharmacological target. In this study, we report that tricyclic and tetracyclic antidepressants acutely inhibit, but persistently upregulate VMAT2 activity by promoting VMAT2 protein maturation. Importantly, the VMAT2 upregulation effect was greater in BE(2)-M17 cells that endogenously express VMAT2 as compared to a heterologous expression system (HEK293). The net sustained effect of tricyclics and tetracyclics is an upregulation of VMAT2 activity, despite their acute inhibitory effect. Furthermore, imipramine and mianserin, two representative compounds, also demonstrated rescue of nine VMAT2 variants that cause Brain Vesicular Monoamine Transport Disease (BVMTD). VMAT2 upregulation could be beneficial for disorders associated with reduced monoamine transmission, including mood disorders and BVMTD, a rare but often fatal condition caused by a lack of functional VMAT2. Our findings provide the first evidence that small molecules can upregulate VMAT2 and have potential therapeutic benefit for various neuropsychiatric conditions.

pharmacology and toxicology↗

bioRxiv2023

Lung lipid deposition in pneumonias of viral and non-viral aetiology

Pneumonia is an acute respiratory disease of varying etiology that has drawn much attention during the COVID-19 pandemic. Among the many thoroughly studied aspects of pneumonia, lipid metabolism has not been sufficiently addressed. Here, we investigated lipid deposition in the post mortem lung specimens of patients who died from COVID-19 and non-COVID-19 pneumonias. We used semi-thin sections and cryosections stained with Sudan III to visualize lipid droplet deposition within cells and in the extracellular space, most notably in small lung vessels. Electron microscopy analysis of the ultrathin sections was used to confirm the homogeneous structure of the droplets. Morphometric analysis revealed that the area of lipid deposition was increased in pneumonia compared to control lung tissue. Likewise, it was increased in the macroscopically inflamed vs. the macroscopically intact area of the same pneumonia lung. The lipid profiling by chromato-mass spectrometry revealed that lipid droplet accumulation in pneumonia was associated with a specific fatty acid content of the inflamed lung tissue. The gene expression analysis pointed to changes of lipid metabolism in the inflamed lung tissue compared to control lungs. Taken together, our data indicate a number of morphologic and metabolic changes associated with inflammation and common for pneumonias of different etiologies that likely contribute to pneumonia pathogenesis. Therefore, targeting lipid metabolism can be considered a new therapeutic strategy.

pathology↗