Biology subjects

Racz, G.

Publications and source records attributed to Racz, G..

4 recordsLinked to original sources

bioRxiv2025

Deep transcriptome profiling of human hypothalamic agouti-related protein and proopiomelanocortin neurons regulating energy homeostasis

We have developed and validated a pioneering IHC/LCM-Seq method for transcriptome profiling of spatially defined neuronal cell types detected with immunohistochemistry in sections of formaldehyde-fixed human brains. IHC/LCM-Seq provided unprecedented insight, with 14,000-16,000 transcripts identified, into the gene expression landscape of human agouti-related peptide (AgRP) neurons, which drive appetite and energy storage, and proopiomelanocortin (POMC) neurons, which suppress feeding and promote energy expenditure. These cells differed from each other, and from fertility-regulating kisspeptin neurons, in their distinct enrichments of co-transmitters, transcription factors, and receptors. The AgRP neuron transcriptome was rich in receptors for proinflammatory cytokines, metabolic hormones and growth hormone, whereas POMC neurons expressed reproductive hormone-, glucagon-like peptide- and endocannabinoid receptors. IHC/LCM-Seq, a versatile spatial transcriptomic approach for characterizing cell types in postmortem brains, opened a new window onto molecular mechanisms regulating energy homeostasis in the human hypothalamus and highlighted possible pharmacological targets for weight management.

neuroscience↗

bioRxiv2021

The cryptic gonadotropin-releasing hormone neuronal system of human basal ganglia

Human reproduction is controlled by [~]2,000 hypothalamic gonadotropin-releasing hormone (GnRH) neurons. Here we report the discovery and characterization of additional 150-200,000 GnRH-synthesizing cells in the human basal ganglia and basal forebrain. Extrahypothalamic GnRH neurons were cholinergic. Though undetectable in adult rodents, the GnRH-GFP transgene was expressed transiently by caudate-putamen cholinergic interneurons in newborn transgenic mice. In slice electrophysiological studies, GnRH inhibited these interneurons via GnRHR1 autoreceptors. Whole-transcriptome analysis of cholinergic interneurons and medium spiny projection neurons laser-microdissected from the human putamen confirmed selective expression of GNRH1 and GNRHR1 autoreceptors in cholinergic cells and uncovered the detailed transcriptome profile and molecular connectome of these two cell types. Higher- order non-reproductive functions regulated by GnRH under physiological conditions in the human basal ganglia and basal forebrain require clarification. GnRH/GnRHR1 signaling as a potential therapeutic target in the treatment of neurodegenerative disorders affecting cholinergic neurocircuitries, including Parkinsons and Alzheimers diseases, needs to be explored.

cell biology↗

bioRxiv2019

jULIEs: extracellular probes for recordings and stimulation in the structurally and functionally intact mouse brain

High signal-to-noise, scalable and minimally invasive recording and stimulation of the nervous system in intact animals is of fundamental importance to advance the understanding of brain function. Extracellular electrodes are among the most powerful tools capable of interfacing with large neuronal populations1-3. Neuronal tissue damage remains a major limiting factor in scaling electrode arrays, and has been found to correlate with electrode diameter across different electrode materials, such as microfabricated Michigan and Utah-style arrays4, MEMS and microsystems5, soft polymer or tungsten electrodes6 and Parylene C probes7. Small diameter ultramicroelectrodes (UMEs), while highly desirable, pose significant technical challenges such as reaching sufficient electrolyte-electrode coupling and limiting stray signal loss. To overcome these challenges, we have designed juxtacellular Ultra-Low Impedance Electrodes (jULIEs), a scalable technique for achieving high signal-to-noise electrical recordings as well as stimulation with UMEs. jULIEs are metal-glass composite UMEs thermally drawn to outer diameters (OD) of <25 {micro}m, with metal core diameters (ID) of as little as 1 {micro}m. We introduce a two-step electrochemical modification strategy that reduces UME coupling impedances by two orders of magnitude. Modifications enabled high signal-to-noise neural recordings in vivo through wires with micrometer scale core diameters. Histological and imaging experiments indicated that local vascular damage is minimal. Spikes reached amplitudes over 1 mV in vivo, indicating that recordings are possible in close proximity to intact neurons. Recording sites can be arranged in arbitrary patterns tailored to various neuroanatomical target structures and allowing parallel penetrations. jULIEs thus represent a versatile platform that allows for reliable recording and manipulation of neural activity in any areas of the functionally intact mammalian brain.

neuroscience↗

bioRxiv2018

CRISPR/Cas9-mediated knock-out of dUTPase in mice leads to early embryonic lethality

Sanitization of nucleotide pools is essential for genome maintenance. Among the enzymes significant in this mechanism, deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase) performs cleavage of dUTP into dUMP and inorganic pyrophosphate. By this reaction the enzyme efficiently prevents uracil incorporation into DNA and provides dUMP, the substrate for de novo thymidylate biosynthesis. Despite its physiological significance, knock-out models of dUTPase have not yet been investigated in mammals, only in unicellular organisms, such as bacteria and yeast. Here we generate CRISPR/Cas9-mediated dUTPase knock-out in mice. We find that heterozygous dut +/-animals are viable while the decreased dUTPase level is clearly observable. We also show that the enzyme is essential for embryonic development. Based on the present results, early dut -/-embryos can still reach the blastocyst stage, however, they die shortly after implantation. Analysis of preimplantion embryos indicate perturbed growth of both inner cell mass (ICM) and trophectoderm (TE). We conclude that dUTPase is indispensable for post-implantation development in mice. The gene targeting model generated in the present study will allow further detailed studies in combination with additional gene knock-outs.

developmental biology↗