Biology subjects

Sanetra, A. M.

Publications and source records attributed to Sanetra, A. M..

5 recordsLinked to original sources

bioRxiv2026

Serotype-dependent bioenergetic and electrophysiological remodelling in iPSC-derived cardiomyocytes from rheumatoid arthritis patients

BackgroundPatients with rheumatoid arthritis (RA) exhibit increased cardiovascular morbidity and mortality that are not fully explained by traditional risk factors, with cardiovascular outcomes differing between seropositive (spRA) and seronegative (snRA) disease. The cellular mechanisms linking chronic inflammation to cardiac dysfunction remain poorly defined, and no patient-specific cardiomyocyte model has resolved cellular phenotypes by RA serotype. MethodsHuman induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were generated from healthy donors and patients with spRA and snRA. Bioenergetic and electrophysiological responses to key RA proinflammatory cytokines (TNF-, IL-1{beta}, IL-6) and anti-rheumatic drugs (adalimumab, tofacitinib) were assessed using Seahorse assays, patch-clamp electrophysiology, multi-electrode array recordings and RT-qPCR. ResultssnRA cardiomyocytes exhibited impaired TNF--induced oxidative phosphorylation, accompanied by attenuated expression of ATP5B, LDHA and DLD. In contrast, spRA cardiomyocytes showed baseline electrophysiological alterations, including shortened APD90 and increased action-potential triangulation. TNF- depolarised the maximum diastolic potential in both RA serotypes. At the multicellular level, cytokine effects were serotype-specific: IL-1{beta} selectively prolonged QT interval in spRA monolayers (p < 0.001), whereas IL-6 prolonged QT in snRA (p < 0.05). Both RA serotypes showed impaired TNF--driven induction of KCNJ3 and KCNA5. Adalimumab selectively induced ATP5B in spRA but failed to engage either pathway in snRA, while tofacitinib selectively induced KCNJ3 in healthy but not RA cardiomyocytes. ConclusionsThese findings define distinct, serotype-specific pathways of cardiac remodelling in RA that converge on a shared proarrhythmic phenotype, provide a cellular framework for cardiovascular risk in RA and identify candidate mechanisms relevant to therapy-associated cardiovascular safety. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/727798v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@ceb808org.highwire.dtl.DTLVardef@1942a26org.highwire.dtl.DTLVardef@5b32eforg.highwire.dtl.DTLVardef@16cf774_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Synaptic vesicles that store monoamines and glutamate differ in protein composition.

Neuromodulators such as the monoamines are known to differ from classical neurotransmitters like glutamate in the time scale of signaling due to activation of slower G protein-coupled receptors. Recent work has suggested that the mode of release also differs between classical and modulatory transmitters. Although many components of neurotransmitter release machinery have been identified, we still understand little about the mechanisms responsible for differences in release. In this study, we address the differences between release of dopamine and glutamate by comparing the composition of synaptic vesicles (SVs) that contain the vesicular monoamine transporter 2 (VMAT2) versus vesicular glutamate transporter 2 (VGLUT2). Previous work has shown that these SV populations differ in frequency dependence, recycling kinetics and biogenesis. Taking advantage of a CRISPR-generated knock-in mouse with a cytoplasmic hemagglutinin (HA) tag at the N-terminus of VMAT2 to immunoisolate monoamine SVs, we find differences in the abundance and isoform expression of many SV protein families. Validation in primary neurons and in brain tissue confirms these differences in SV protein abundance between dopamine and glutamate release sites. Functional analysis reveals that the loss of differentially expressed SCAMP5 selectively impairs the recycling of VGLUT2 SVs, sparing VMAT2 vesicles in the same neuronal population. These findings provide new insights into the molecular diversity of SVs and the mechanisms that regulate the release of dopamine and glutamate, with implications for the physiological role of these transmitters and behavior.

neuroscience↗

bioRxiv2021

Intrinsic circadian timekeeping properties of the thalamic lateral geniculate nucleus

Circadian rhythmicity in mammals is sustained by the central brain clock - the suprachiasmatic nucleus of the hypothalamus (SCN), entrained to the ambient light-dark conditions through a dense retinal input. However, recent discoveries of autonomous clock gene expression cast doubt on the supremacy of the SCN and suggest circadian timekeeping mechanisms devolve to local brain clocks. Here we use a combination of molecular, electrophysiological and optogenetic tools to evaluate intrinsic clock properties of the main retinorecipient thalamic centre - the lateral geniculate nucleus (LGN). We identify the dorsolateral geniculate nucleus (DLG) as a slave oscillator, which exhibits core clock gene expression exclusively in vivo. Additionally, we provide compelling evidence for intrinsic clock gene expression accompanied by circadian variation in neuronal activity in the intergeniculate leaflet (IGL) and ventrolateral geniculate nucleus (VLG). Finally, our optogenetic experiments propose the VLG as a light-entrainable oscillator, whose phase may be advanced by retinal input at the beginning of the projected night. Altogether, this study for the first time demonstrates autonomous timekeeping mechanisms shaping circadian physiology of the LGN.

neuroscience↗

bioRxiv2021

Rhythmic neuronal activities of the rat nucleus of the solitary tract are impaired by short-term high fat diet - implications for daily control of satiety by the brainstem

Temporal partitioning of daily food intake is crucial for survival and involves the integration of internal circadian states and external influences such as the light-dark cycle and the composition of diet. These intrinsic and extrinsic factors are interdependent with misalignment of circadian rhythms promoting body weight gain, while consumption of a calorie dense diet elevates the risk of obesity and blunts circadian rhythms. Since cardiovascular disease, metabolic disorders, and cancer are comorbid with obesity, understanding the relationships between brain activity and diet is of pivotal importance. Recently, we defined for the first time the circadian properties of the dorsal vagal complex of the brainstem, a structure implicated in the control of food intake and autonomic tone, but if and how 24 h rhythms in this area are influenced by diet remains unresolved. Here we focused on a key structure of this complex, the nucleus of the solitary tract, and using a range of approaches, we interrogated how its neuronal and cellular rhythms are affected by high-fat diet. We report that short term consumption of this diet increases food intake during the day and blunts daily rhythms in gene expression and neuronal discharge in the nucleus of the solitary tract. These alterations in this structure occur without prominent body weight gain, suggesting that high-fat diet acts initially to reduce activity in the nucleus of the solitary tract, thereby disinhibiting mechanisms that suppress daytime feeding. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/433567v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@243b7borg.highwire.dtl.DTLVardef@bd3886org.highwire.dtl.DTLVardef@c9f427org.highwire.dtl.DTLVardef@bc52cd_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2021

Daily changes in neuronal activities of the dorsal motor nucleus of the vagus under standard and short-term high fat diet - implications for circadian modulation of parasympathetic outflow

The suprachiasmatic nuclei (SCN) of the hypothalamus functions as the brains primary circadian clock, but circadian clock genes are also rhythmically expressed in several extra-SCN brain sites where they can exert local temporal control over physiology and behaviour. Recently, we found that the hindbrain dorsal vagal complex possesses strong daily timekeeping capabilities, with the area postrema and nucleus of the solitary tract exhibiting the most robust clock properties. The possibility that the executory part of this complex - the dorsal motor nucleus of the vagus (DMV), also exhibits daily changes has not been extensively studied. The DMV is the source of vagal efferent motoneurons largely responsible for the regulation of gastric motility and emptying and consequently influence meal size and energy homeostasis. We used a combination of multi-channel electrophysiology and patch clamp recordings to gain insight into possible daily variation in these DMV cells and how this is influenced by diet. We found that DMV neurons increase their spontaneous activity, excitability and responsiveness to metabolic neuromodulators at late day which was paralleled with an enhanced synaptic input to these neurons. A high-fat diet typically damps circadian rhythms, but we found that short-term exposure to a high-fat diet paradoxically amplified daily variation of DMV neuronal activity, while blunting their responsiveness to metabolic neuromodulators. In summary, we show for the first time that neural activity at a source of vagal efferents varies with time of day and that this temporal variation is modulated by diet. These findings have clear implications for our understanding of the daily control of parasympathetic outflow.

neuroscience↗