G protein γ subunit Gγ13 is essential for olfactory function and aggressive behavior in mice

RNA sequencing of olfactory bulb in Parkinson's disease reveals gene alterations associated with olfactory dysfunction

The olfactory bulb is involved early in the pathophysiology of Parkinson's disease (PD), which is consistent with the early onset of olfactory dysfunction. Identifying the molecular mechanisms through which PD affects the olfactory bulb could lead to a better understanding of the pathophysiology and etiology of olfactory dysfunction in PD. We specifically aimed to assess gene expression changes, affected pathways and co-expression network by whole transcriptomic profiling of the olfactory bulb in subjects with clinicopathologically defined PD. Bulk RNA sequencing was performed on frozen human olfactory bulbs of 20 PD and 20 controls without dementia or any other neurodegenerative disorder, from the Arizona Study of Aging and Neurodegenerative disorders and the Brain and Body Donation Program. Differential expression analysis (19 PD vs 19 controls) revealed 2164 significantly differentially expressed genes (1090 upregulated and 1074 downregulated) in PD. Pathways enriched in downregulated genes included oxidative phosphorylation, olfactory transduction, metabolic pathways, and neurotransmitters synapses while immune and inflammatory responses as well as cellular death related pathways were enriched within upregulated genes. An overrepresentation of microglial and astrocyte-related genes was observed amongst upregulated genes, and excitatory neuron-related genes were overrepresented amongst downregulated genes. Co-expression network analysis revealed significant modules highly correlated with PD and olfactory dysfunction that were found to be involved in the MAPK signaling pathway, cytokine-cytokine receptor interaction, cholinergic synapse, and metabolic pathways. LAIR1 (leukocyte associated immunoglobulin like receptor 1) and PPARA (peroxisome proliferator activated receptor alpha) were identified as hub genes with a high discriminative power between PD and controls reinforcing an important role of neuroinflammation in the olfactory bulb of PD subjects. Olfactory identification test score positively correlated with expression of genes coding for G-coupled protein, glutamatergic, GABAergic, and cholinergic receptor proteins and negatively correlated with genes for proteins expressed in glial olfactory ensheathing cells. In conclusion, this study reveals gene alterations associated with neuroinflammation, neurotransmitter dysfunction, and disruptions of factors involved in the initiation of olfactory transduction signaling that may be involved in PD-related olfactory dysfunction.

High-Quality Chromosome-Level Genome Assembly of the Corsac Fox (Vulpes corsac) Reveals Adaptation to Semiarid and Harsh Environments

The Corsac fox (Vulpes corsac) is a species of fox distributed in the arid prairie regions of Central and Northern Asia, with distinct adaptations to dry environments. Here, we applied Oxford-Nanopore sequencing and a chromosome structure capture technique to assemble the first Corsac fox genome, which was then assembled into chromosome fragments. The genome assembly has a total length of 2.2 Gb with a contig N50 of 41.62 Mb and a scaffold N50 of 132.2 Mb over 18 pseudo-chromosomal scaffolds. The genome contained approximately 32.67% of repeat sequences. A total of 20,511 protein-coding genes were predicted, of which 88.9% were functionally annotated. Phylogenetic analyses indicated a close relation to the Red fox (Vulpes vulpes) with an estimated divergence time of ~3.7 million years ago (MYA). We performed separate enrichment analyses of species-unique genes, the expanded and contracted gene families, and positively selected genes. The results suggest an enrichment of pathways related to protein synthesis and response and an evolutionary mechanism by which cells respond to protein denaturation in response to heat stress. The enrichment of pathways related to lipid and glucose metabolism, potentially preventing stress from dehydration, and positive selection of genes related to vision, as well as stress responses in harsh environments, may reveal adaptive evolutionary mechanisms in the Corsac fox under harsh drought conditions. Additional detection of positive selection for genes associated with gustatory receptors may reveal a unique desert diet strategy for the species. This high-quality genome provides a valuable resource for studying mammalian drought adaptation and evolution in the genus Vulpes.

Non-cell-autonomous disruption of nuclear architecture as a potential cause of COVID-19-induced anosmia

SARS-CoV-2 infects less than 1% of cells in the human body, yet it can cause severe damage in a variety of organs. Thus, deciphering the non-cell-autonomous effects of SARS-CoV-2 infection is imperative for understanding the cellular and molecular disruption it elicits. Neurological and cognitive defects are among the least understood symptoms of COVID-19 patients, with olfactory dysfunction being their most common sensory deficit. Here, we show that both in humans and hamsters, SARS-CoV-2 infection causes widespread downregulation of olfactory receptors (ORs) and of their signaling components. This non-cell-autonomous effect is preceded by a dramatic reorganization of the neuronal nuclear architecture, which results in dissipation of genomic compartments harboring OR genes. Our data provide a potential mechanism by which SARS-CoV-2 infection alters the cellular morphology and the transcriptome of cells it cannot infect, offering insight to its systemic effects in olfaction and beyond.

Identification of Molecular Signatures and Candidate Drugs in Vascular Dementia by Bioinformatics Analyses

Vascular dementia (VaD) is considered to be the second most common form of dementia after Alzheimer’s disease, and no specific drugs have been approved for VaD treatment. We aimed to identify shared transcriptomic signatures between the frontal cortex and temporal cortex in VaD by bioinformatics analyses. Gene ontology and pathway enrichment analyses, protein–protein interaction (PPI) and hub gene identification, hub gene–transcription factor interaction, hub gene–microRNA interaction, and hub gene–drug interaction analyses were performed. We identified 159 overlapping differentially expressed genes (DEGs) between the frontal cortex and temporal cortex that were enriched mainly in inflammation and innate immunity, synapse pruning, regeneration, positive regulation of angiogenesis, response to nutrient levels, and positive regulation of the digestive system process. We identified 10 hub genes in the PPI network (GNG13, CD163, C1QA, TLR2, SST, C1QB, ITGB2, CCR5, CRH, and TAC1), four central regulatory transcription factors (FOXC1, CREB1, GATA2, and HINFP), and four microRNAs (miR-27a-3p, miR-146a-5p, miR-335-5p, and miR-129-2-3p). Hub gene–drug interaction analysis found four drugs (maraviroc, cenicriviroc, PF-04634817, and efalizumab) that could be potential drugs for VaD treatment. Together, our results may contribute to understanding the underlying mechanisms in VaD and provide potential targets and drugs for therapeutic intervention.

GNG13 Is a Potential Marker of the State of Health of Alzheimer's Disease Patients' Cerebellum

Brain regions such as the cerebellum (CB) have been neglected for a long time in the study of Alzheimer's disease (AD) pathogenesis. In reference to a new emerging hypothesis according to which there is an altered cerebellar synaptic processing in AD, we verified the possible role played by new biomarkers in the CB of AD patients compared with not-demented healthy control subjects (NDHS). Using a bioinformatics approach, we have collected several microarray datasets and obtained 626 cerebella sample biopsies belonging to subjects who did not die from causes related to neurological diseases and 199 cerebella belonging to AD. The analysis of logical relations between the transcriptome dataset highlighted guanine nucleotide-binding protein (G protein) gamma 13 (GNG13) as a potential new biomarker for Purkinje cells (PCs). We have correlated GNG13 expression levels with already widely existing bibliography of PC marker genes, such as Purkinje cell protein 2 (PCP2), Purkinje cell protein 4 (PCP4), and cerebellin 3 (CBLN3). We showed that expression levels of GNG13 and PCP2, PCP4, and CBLN3 were significantly correlated with each other in NDHS and in AD and significantly reduced in AD patients compared with NDHS subjects. In addition, we highlighted a negative correlation between the expression levels of PC biomarkers and age. From the outcome of our investigation, it is possible to conclude that the identification of GNG13 as a potentially biomarker in PCs represents also a state of health of CB, in association with the expression of PCP2, PCP4, and CBLN3.

Angiotensin II Stimulates the Proliferation and Migration of Lymphatic Endothelial Cells Through Angiotensin Type 1 Receptors

BACKGROUND/AIM

The proliferation and migration of lymphatic endothelial cells (LECs) is essential for lymphatic vessel growth (also known as lymphangiogenesis), which plays a crucial role in regulating the tissue fluid balance and immune cell trafficking under physiological and pathological conditions. Several growth factors, such as VEGF-C, can stimulate lymphangiogenesis. However, the effects of angiotensin II (Ang II) on the proliferation and migration of mouse LECs and the underlying potential mechanisms remain unknown.

METHODS

Wild-type mice were infused with Ang II (1,000 ng/kg/min) for 1-2 weeks. Murine LECs were stimulated with Ang II (500 nM) or saline for 12-48 h. Cell proliferation was determined with 5-bromo-2-deoxyuridine (BrdU) incorporation assays, while cell migration was assessed by scratch wound healing and transwell chamber assays. The gene expression profiles were obtained by time series microarray and real-time PCR analyses.

RESULTS

Ang II treatment significantly induced lymphangiogenesis in the hearts of mice and the proliferation and migration of cultured LECs in a time-dependent manner. This effect was completely blocked by losartan, an angiotensin II type 1 receptor (AT1R) antagonist. The microarray results identified 1,385 differentially expressed genes (DEGs) at one or more time points in the Ang II-treated cells compared with the control saline-treated cells. These DEGs were primarily involved in biological processes and pathways, including sensory perception of smell, the G protein coupled receptor signaling pathway, cell adhesion, olfactory transduction, Jak-STAT, alcoholism, RIG-I-like receptor and ECM-receptor interaction. Furthermore, these DEGs were classified into 16 clusters, 7 of which (Nos. 13, 2, 8, 15, 7, 3, and 12, containing 586 genes) were statistically significant. Importantly, the Ang II-induced alterations the expression of lymphangiogenesis-related genes were reversed by losartan.

CONCLUSION

The results of the present indicate that Ang II can directly regulate the proliferation and migration of LECs through AT1R in vivo and in vitro, which may provide new potential treatments for Ang II-induced hypertension and cardiac remodeling.

High expression of G protein subunit gamma 13 is associated with poor prognosis of gastrointestinal stromal tumor

The G protein subunit gamma 13 (GNG13) plays an important role in olfaction, vision, and biological behavior. However, our knowledge of the relationship between GNG13 expression and the clinicopathological features of gastrointestinal tumors is insufficient. Therefore, we used the Oncomine database to evaluate the expression of GNG13 mRNA in gastric cancer, the result showed that there was no significant difference in the expression of GNG13 between gastric cancer and adjacent normal tissues, and GNG13 mRNA expression was assessed in 32 matched pairs of Gastrointestinal adenocarcinoma tissues and adjacent normal tissues as well as 32 matched pairs of gastrointestinal stromal tumor (GIST) and adjacent normal tissues by quantitative reverse transcription-polymerase chain reaction analysis. The results suggested that GNG13 is upregulated in gastrointestinal stromal tumors. Immunohistochemical analysis was used to detect the GNG13 in the tissues of 123 patients with GIST. High cytoplasmic expression of GNG13, which was observed in 65.85 % of GIST patients, significantly correlated with mitotic index(P = 0.036) and tumor size(P = 0.024). Multiple logistic regression analysis showed that the expression of GNG13 was significantly associated with tumor size. Kaplan-Meier analysis indicated that high GNG13 expression was associated with poor prognosis of GIST. Multivariate Cox regression analysis indicated that the expression of GNG13, mitotic index and tumor size were independent adverse prognostic factors of GIST. These findings suggest that GNG13 is associated with the malignant phenotype of GIST and may serve as a marker of poor prognosis.

Central role of G protein Gαi2 and Gαi2+ vomeronasal neurons in balancing territorial and infant-directed aggression of male mice

Aggression is controlled by the olfactory system in many animal species. In male mice, territorial and infant-directed aggression are tightly regulated by the vomeronasal organ (VNO), but how diverse subsets of sensory neurons convey pheromonal information to limbic centers is not yet known. Here, we employ genetic strategies to show that mouse vomeronasal sensory neurons expressing the G protein subunit Gαi2 regulate male-male and infant-directed aggression through distinct circuit mechanisms. Conditional ablation of Gαi2 enhances male-male aggression and increases neural activity in the medial amygdala (MeA), bed nucleus of the stria terminalis, and lateral septum. By contrast, conditional Gαi2 ablation causes reduced infant-directed aggression and decreased activity in MeA neurons during male-infant interactions. Strikingly, these mice also display enhanced parental behavior and elevated neural activity in the medial preoptic area, whereas sexual behavior remains normal. These results identify Gαi2 as the primary G protein α-subunit mediating the detection of volatile chemosignals in the apical layer of the VNO, and they show that Gαi2⁺ VSNs and the brain circuits activated by these neurons play a central role in orchestrating and balancing territorial and infant-directed aggression of male mice through bidirectional activation and inhibition of different targets in the limbic system.