Functionally distinct POMC-expressing neuron subpopulations in hypothalamus revealed by intersectional targeting

AbstractPro-opiomelanocortin (POMC)-expressing neurons in the arcuate nucleus of the hypothalamus represent key regulators of metabolic homeostasis. Electrophysiological and single-cell sequencing experiments have revealed a remarkable degree of heterogeneity of these neurons. However, the exact molecular basis and functional consequences of this heterogeneity have not yet been addressed. Here, we have developed new mouse models in which intersectional Cre/Dre-dependent recombination allowed for successful labeling, translational profiling and functional characterization of distinct POMC neurons expressing the leptin receptor (Lepr) and glucagon like peptide 1 receptor (Glp1r). Our experiments reveal that POMCLepr+ and POMCGlp1r+ neurons represent largely nonoverlapping subpopulations with distinct basic electrophysiological properties. They exhibit a specific anatomical distribution within the arcuate nucleus and differentially express receptors for energy-state communicating hormones and neurotransmitters. Finally, we identify a differential ability of these subpopulations to suppress feeding. Collectively, we reveal a notably distinct functional microarchitecture of critical metabolism-regulatory neurons.

Download Full-text

Functional characterization of high-affinity Na+/dicarboxylate cotransporter found in Xenopus laevis kidney and heart

AJP Cell Physiology ◽

10.1152/ajpcell.00295.2004 ◽

2005 ◽

Vol 289 (5) ◽

pp. C1159-C1168 ◽

Cited By ~ 9

Author(s):

Naomi Oshiro ◽

Ana M. Pajor

Keyword(s):

Xenopus Laevis ◽

Cdna Sequence ◽

Citric Acid Cycle ◽

Functional Characterization ◽

Activation Kinetics ◽

Electrophysiological Properties ◽

High Affinity ◽

The Family ◽

Kidney Liver

The SLC13 gene family includes sodium-coupled transporters for citric acid cycle intermediates and sulfate. The present study describes the sequence and functional characterization of a SLC13 family member from Xenopus laevis, the high-affinity Na+/dicarboxylate cotransporter xNaDC-3. The cDNA sequence of xNaDC-3 codes for a protein of 602 amino acids that is ∼70% identical to the sequences of mammalian NaDC-3 orthologs. The message for xNaDC-3 is found in the kidney, liver, intestine, and heart. The xNaDC-3 has a high affinity for substrate, including a Km for succinate of 4 μM, and it is inhibited by the NaDC-3 test substrates 2,3-dimethylsuccinate and adipate. The transport of succinate by xNaDC-3 is dependent on sodium, with sigmoidal activation kinetics, and lithium can partially substitute for sodium. As with other members of the family, xNaDC-3 is electrogenic and exhibits inward substrate-dependent currents in the presence of sodium. However, other electrophysiological properties of xNaDC-3 are unique and involve large leak currents, possibly mediated by anions, that are activated by binding of sodium or lithium to a single site.

Download Full-text

Functional Architecture of Deleterious Genetic Variants in the Genome of a Wrangel Island Mammoth

Genome Biology and Evolution ◽

10.1093/gbe/evz279 ◽

2020 ◽

Vol 12 (3) ◽

pp. 48-58 ◽

Cited By ~ 1

Author(s):

Erin Fry ◽

Sun K Kim ◽

Sravanthi Chigurapti ◽

Katelyn M Mika ◽

Aakrosh Ratan ◽

...

Keyword(s):

Functional Characterization ◽

Small Population ◽

Deleterious Mutations ◽

Developmental Defects ◽

Wrangel Island ◽

Relict Populations ◽

Deleterious Alleles ◽

Large Populations ◽

Functional Consequences

Abstract Woolly mammoths were among the most abundant cold-adapted species during the Pleistocene. Their once-large populations went extinct in two waves, an end-Pleistocene extinction of continental populations followed by the mid-Holocene extinction of relict populations on St. Paul Island ∼5,600 years ago and Wrangel Island ∼4,000 years ago. Wrangel Island mammoths experienced an episode of rapid demographic decline coincident with their isolation, leading to a small population, reduced genetic diversity, and the fixation of putatively deleterious alleles, but the functional consequences of these processes are unclear. Here, we show that a Wrangel Island mammoth genome had many putative deleterious mutations that are predicted to cause diverse behavioral and developmental defects. Resurrection and functional characterization of several genes from the Wrangel Island mammoth carrying putatively deleterious substitutions identified both loss and gain of function mutations in genes associated with developmental defects (HYLS1), oligozoospermia and reduced male fertility (NKD1), diabetes (NEUROG3), and the ability to detect floral scents (OR5A1). These data suggest that at least one Wrangel Island mammoth may have suffered adverse consequences from reduced population size and isolation.

Download Full-text

Functional architecture of deleterious genetic variants in the Wrangel Island mammoth genome

10.1101/137455 ◽

2017 ◽

Cited By ~ 1

Author(s):

Erin Fry ◽

Sun K. Kim ◽

Sravanthi Chigurapti ◽

Katelyn M. Mika ◽

Aakrosh Ratan ◽

...

Keyword(s):

Functional Characterization ◽

Small Population ◽

Developmental Defects ◽

Wrangel Island ◽

Relict Populations ◽

Deleterious Alleles ◽

Large Populations ◽

Population Sizes ◽

Functional Consequences

Woolly mammoths were among the most abundant cold adapted species during the Pleistocene. Their once large populations went extinct in two waves, an end-Pleistocene extinction of continental populations followed by the mid-Holocene extinction of relict populations on St. Paul Island ~5,600 years ago and Wrangel Island ~4,000 years ago. Wrangel Island mammoths experienced an episode of rapid demographic decline coincident with their isolation, leading to a small population, reduced genetic diversity, and the fixation of putatively deleterious alleles, but the functional consequences of these processes are unclear. Here we show that the Wrangel Island mammoth accumulated many putative deleterious mutations that are predicted to cause diverse behavioral and developmental defects. Resurrection and functional characterization of Wrangel Island mammoth genes carrying these substitutions identified both loss and gain of function mutations in genes associated with developmental defects (HYLS1), oligozoospermia and reduced male fertility (NKD1), diabetes (NEUROG3), and the ability to detect floral scents (OR5A1). These results suggest that Wrangel Island mammoths may have suffered adverse consequences from their reduced population sizes and isolation.

Download Full-text

ACE2 Netlas: In-silico functional characterization and drug-gene interactions of ACE2 gene network to understand its potential involvement in COVID-19 susceptibility

10.1101/2020.10.27.20220665 ◽

2020 ◽

Author(s):

Gita A Pathak ◽

Frank R Wendt ◽

Aranyak Goswami ◽

Flavio De Angelis ◽

Renato Polimanti ◽

...

Keyword(s):

Gene Network ◽

Functional Characterization ◽

Gene Interaction ◽

Biological Properties ◽

Angiotensin Converting Enzyme 2 ◽

Interaction Database ◽

Functional Consequences ◽

Multi Level ◽

Ace2 Gene

AbstractAngiotensin-converting enzyme-2 (ACE2) receptor has been identified as the key adhesion molecule for the transmission of the SARS-CoV-2. However, there is no evidence that human genetic variation in ACE2 is singularly responsible for COVID-19 susceptibility. Therefore, we performed a multi-level characterization of genes that interact with ACE2 (ACE2-gene network) for their over-represented biological properties in the context of COVID-19.The phenome-wide association of 51 genes including ACE2 with 4,756 traits categorized into 26 phenotype categories, showed enrichment of immunological, respiratory, environmental, skeletal, dermatological, and metabolic domains (p<4e-4). Transcriptomic regulation of ACE2-gene network was enriched for tissue-specificity in kidney, small intestine, and colon (p<4.7e-4). Leveraging the drug-gene interaction database we identified 47 drugs, including dexamethasone and spironolactone, among others.Considering genetic variants within ± 10 kb of ACE2-network genes we characterized functional consequences (among others) using miRNA binding-site targets. MiRNAs affected by ACE2-network variants revealed statistical over-representation of inflammation, aging, diabetes, and heart conditions. With respect to variants mapped to the ACE2-network, we observed COVID-19 related associations in RORA, SLC12A6 and SLC6A19 genes.Overall, functional characterization of ACE2-gene network highlights several potential mechanisms in COVID-19 susceptibility. The data can also be accessed at https://gpwhiz.github.io/ACE2Netlas/

Download Full-text

Anatomical and Functional Characterization of Central Amygdala Glucagon-Like Peptide 1 Receptor Expressing Neurons

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2021.724030 ◽

2021 ◽

Vol 15 ◽

Author(s):

Ningxiang Zeng ◽

Elam J. Cutts ◽

Christian B. Lopez ◽

Simran Kaur ◽

Miguel Duran ◽

...

Keyword(s):

Mrna Level ◽

Functional Characterization ◽

Cellular Level ◽

Central Nucleus ◽

Whole Cell Patch Clamp ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1 ◽

The Impact ◽

The Brain

Glucagon-like peptide 1 receptors (GLP-1Rs) are highly expressed in the brain and are responsible for mediating the acute anorexigenic actions of widely prescribed GLP-1R agonists. Neurobiological efforts to localize the hypophagic effects of GLP-1R agonists in the brain have mainly focused on the hypothalamus and hindbrain. In this study, we performed a deep anatomical and neurophysiological characterization of GLP-1Rs in the central nucleus of the amygdala (CeA). At an mRNA level, we found that Glp1r is diffusely coexpressed in known CeA subpopulations like protein kinase c δ (Prkcd), somatostatin (Sst), or tachykinin2 (Tac2). At a cellular level, we used Glp1r-Cre mice and viral Cre-dependent tracing to map the anatomical positions of GLP-1R cells across the rostral-caudal axis of the CeA and in CeA subdivisions. We found that Glp1rCeA cells are highly enriched in the medial subdivision of the CeA (CeM). Using whole cell patch clamp electrophysiology, we found that Glp1rCeA neurons are characterized by the presence of Ih-like currents and resemble a low threshold bursting neuronal subtype in response to hyperpolarizing and depolarizing current injections. We observed sex differences in the magnitude of Ih-like currents and membrane capacitance. At rest, we observed that nearly half of Glp1rCeA neurons are spontaneously active. We observed that active and inactive neurons display significant differences in excitability even when normalized to an identical holding potential. Our data are the first to deeply characterize the pattern of Glp1r in the CeA and study the neurophysiological characteristics of CeA neurons expressing Glp1r. Future studies leveraging these data will be important to understanding the impact of GLP-1R agonists on feeding and motivation.

Download Full-text

Functional characterization of human brown adipose tissue metabolism

Biochemical Journal ◽

10.1042/bcj20190464 ◽

2020 ◽

Vol 477 (7) ◽

pp. 1261-1286 ◽

Cited By ~ 3

Author(s):

Marie Anne Richard ◽

Hannah Pallubinsky ◽

Denis P. Blondin

Keyword(s):

Adipose Tissue ◽

Brown Adipose Tissue ◽

Functional Characterization ◽

Human Infants ◽

Positron Emission ◽

Brown Adipose ◽

Treatment Of Obesity ◽

And Function

Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.

Download Full-text