Biology subjects

Ramos, K.

Publications and source records attributed to Ramos, K..

4 recordsLinked to original sources

bioRxiv2022

Prefrontal cortex melanocortin 4 receptors (MC4R) mediate food intake behavior in mice

BackgroundMelanocortin 4 receptor (MC4R) activity in the hypothalamus is crucial for regulation of metabolism and food intake. The peptide ligands for the MC4R are associated with feeding, energy expenditure, and also with complex behaviors that orchestrate energy intake and expenditure, but the downstream neuroanatomical and neurochemical targets associated with these behaviors are elusive. In addition to strong expression in the hypothalamus, the MC4R is highly expressed in the medial prefrontal cortex, a region involved in executive function and decision-making. MethodsUsing viral techniques in genetically modified mice combined with molecular techniques, we identify and describe the neuronal dynamics, and define the effects on feeding behavior of a novel population of MC4R expressing neurons in the infralimbic region of the cortex. ResultsHere, we describe a novel population of MC4R-expressing neurons in the infralimbic (IL) region of the mouse prefrontal cortex that are glutamatergic, receive input from melanocortinergic neurons of the arcuate hypothalamus, and project to multiple regions that coordinate appetitive responses to food-related stimuli. The neurons are depolarized by application of MC4R-specific peptidergic agonist, THIQ. Deletion of MC4R from the IL neurons causes increased food intake and body weight gain and impaired executive function in simple food-related behavior tasks. ConclusionTogether, these data suggest that MC4R neurons of the IL play a critical role in the regulation of food intake.

neuroscience↗

bioRxiv2022

Circuit-Specific Targeting of Astrocytes for Genetic Control

Astrocytes are integral functional components of brain circuits. They ensheath the connections between neurons to form tripartite synapses. They react to local neuronal activities and release signaling molecules to regulate synaptic transmission. Their dysfunctions impair synaptic functions and are implicated in neuropsychiatric disorders. Increasing evidence indicates that astrocytes are diverse and they have distinct features and functions in different circuits. However, selectively targeting and controlling astrocytes in a circuit-specific manner is technically challenging. Recently we constructed a series of anterograde transneuronal viral vectors based on the yellow fever vaccine YFV-17D. These YFV-17D derivatives express fluorescent proteins almost exclusively in neurons. However, we find that YFV-17D carrying DNA recombinase Cre infect astrocytes associated with the traced neuronal pathways and express Cre to turn on reporter genes. The targeting of astrocytes is at a whole-brain level but specific to the neuronal circuits traced. Therefore, YFV-17D vectors carrying DNA recombinases provide tools for selectively and genetically targeting pathway-specific astrocytes. This new technology will also allow us to reveal the roles of astrocytes in specific neuronal circuits in normal brain functions and diseases.

neuroscience↗

bioRxiv2020

Listeria monocytogenes personalized cancer vaccines drive therapeutic immune responses to cancer derived neoantigens

BackgroundRecent advances in the field of cancer immunotherapy have identified CD8+ T cell responses against tumor-specific mutations as a key driver of tumor regression and overall survival. ADXS-NEO is a personalized Listeria monocytogenes (Lm)-based immunotherapy designed to target a patients mutation-derived tumor-specific neoantigens. The objective of this study is to demonstrate the feasibility of using the ADXS-NEO platform to target tumor-specific point mutations and control tumor growth by generating neoantigen-specific T cell responses using a pre-clinical mouse tumor model. MethodsWhole-exome sequencing of the MC38 mouse tumor cell line identified 2870 unique non-synonymous mutations. The netMHCcons algorithm was used to predict 137 potential neoantigens. We validated 20 immunogenic neoantigens either by peptide immunization followed by ELISPOT or by the presence of CD8+ T cells recognizing the neoantigen peptide following checkpoint inhibitor treatment. Two ADXS-NEO vectors were constructed; Lm20, targeting 20 validated immunogenic neoantigens, and Lm19, targeting most of the non-validated NSMs. ResultsBoth Lm19 & Lm20 significantly slowed tumor growth in C57BL/6 mice compared to control. An accumulation of ADXS-NEO-specific TILs was observed in tumor bearing mice treated with either Lm19 or Lm20. Examination of the tumor microenvironment in Lm19 or Lm20 treated mice revealed a decrease in the frequency and absolute number of Tregs, TAMs, MDSCs, and PD1high exhausted CD8+ T cells as well as an increase in the frequency and absolute number of effector CD8+ T cells, relative to control. ConclusionADXS-NEO is a potent immunotherapy capable of driving immune responses against tumor-specific mutations and leading to tumor control in mice.

immunology↗

bioRxiv2018

Hexokinase: A central player in the synergism of high-intensity intermittent exercise and every-other-day intermittent fasting regimen on energy metabolism adaptations

Visceral lipid accumulation, organ hypertrophy and a reduction in skeletal muscle strength are all signs associated with the severity of obesity related disease. Intermittent fasting (IF) and high-intensity intermittent exercise (HIIE) are natural strategies that, individually, can prevent and ameliorate obesity along with metabolic syndrome and its associated diseases. However, the combinatorial effect of IF and HIIF on energetic metabolism is currently not well understood. We hypothesized that their combination could have a potential for more than strictly additive benefits. Here, we show that two months of every-other-day intermittent fasting regimen combined with a high-intensity intermittent exercise protocol (IF/HIIE) produce a synergetic effect, preventing fat accumulation, enhancing physical performance and optimizing energy production. The IF/HIIE group presented increased glucose uptake, lower levels of serum insulin and a global activation of hexokinases in skeletal muscle, heart and liver comparing to control, IF and HIIE groups. IF/HIIE synergism led to activation of the FoF1 ATP synthase and promoted a more oxidative profile of mitochondria in observed skeletal muscle. Additionally, high-resolution respirometry of muscle fibers showed that animals in the IF/HIIE group presented characteristics suggestive of augmented mitochondrial mass and efficiency. Finally, an important reduction in serum oxidative stress markers were observed in IF/HIIE group. These findings provide new insights for the implementation of non-pharmaceutical strategies to prevent/treat metabolic syndrome and associated diseases.

biochemistry↗