Biology subjects

Klotz, J.

Publications and source records attributed to Klotz, J..

6 recordsLinked to original sources

bioRxiv2025

A mutation in the transmembrane domain of Adenylate cyclase 3 impairs enzymatic function to cause sex-specific depression- and anxiety-like behaviors and food seeking in a rat model

We have previously demonstrated that a transmembrane domain mutation in Adenylate cyclase 3 (Adcy3) causes increased adiposity and negative emotion-like behaviors in a rat model. We set out to replicate and expand upon our previous study by conducting comprehensive behavioral testing, and we also investigated the molecular changes that result from this mutation. Rats with a mutation in the second transmembrane helix of ADCY3 (Adcy3mut/mut) and wild-type rats were fed a high-fat diet for 12 weeks. We measured body weight, body composition, and depression-like and anxiety-like behaviors using the following tests: sucrose splash test, sucrose preference test, forced swim test, open field test, elevated plus maze, successive alleys test, and novelty-suppressed feeding. We also measured serum leptin levels, hypothalamic cyclic AMP (cAMP) production, and membrane fraction ADCY3 content. Adcy3mut/mut male and female rats had increased adiposity. Adcy3mut/mut males showed increased despair- and anxiety-like behaviors, food seeking, and higher leptin levels relative to wild-type males. Adcy3mut/mut females showed only mildly increased anxiety-like behaviors relative to wild-type females. Adcy3mut/mut rats of both sexes had decreased cAMP production in the hypothalamus, with no changes in ADCY3 content in the membrane fraction. We conclude that the transmembrane domain of ADCY3 plays a critical role regulating adiposity and behavior, as well as cAMP production. There were key differences between males and females for the observed phenotypes. This study supports the idea that Adcy3 contributes to emotion-like behaviors and potentially mental health disorders, and that the transmembrane domain of ADCY3 is important for protein function.

neuroscience↗

bioRxiv2024

Protein-coding mutation in Adcy3 increases adiposity and alters emotional behaviors sex-dependently in rats

1ObjectiveAdenylate cyclase 3 (Adcy3) has been linked to both obesity and major depressive disorder (MDD). Our lab identified a protein-coding variant in the 2nd transmembrane (TM) helix of Adcy3 in rats, and similar obesity variants have been identified in humans. The current study investigates the role of a TM variant in adiposity and behavior. MethodsWe used CRISPR-SpCas9 to mutate the TM domain of Adcy3 in WKY rats (Adcy3mut/mut). We also created a heterozygous knockout rat in the same strain (Adcy3+/-). Wild-type (WT), Adcy3+/-, and Adcy3mut/mut rats were fed a high-fat diet for 12 weeks. We measured body weight, fat mass, glucose tolerance, food intake, metabolism, emotion-like behaviors, and memory. ResultsAdcy3+/- and Adcy3mut/mut rats weighed more than WT rats due to increased fat mass. There were key sex differences: adiposity was driven by increased food intake in males but by decreased energy expenditure in females. Adcy3mut/mut males displayed increased passive coping and decreased memory while Adcy3mut/mut females displayed increased anxiety-like behavior. ConclusionsThese studies show that the ADCY3 TM domain plays a role in protein function, that Adcy3 may contribute to the relationship between obesity and MDD, and that sex influences the relationships between Adcy3, metabolism, and behavior. Study Importance QuestionsO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIAdcy3 has been linked to both obesity and depression in humans, with protein-coding variants in the transmembrane domain leading to increased obesity. Yet the underlying mechanisms are unknown, and it is unknown if the same Adcy3 variants can cause both obesity and depression. C_LIO_LIRodent Adcy3 knockout models show increased adiposity and altered emotional behaviors, but no rodent models have assessed the role of protein-coding variants in Adcy3. Very few studies have assessed sex differences. C_LI What are the new findings in your manuscript?O_LIThis is the first study to assess the role of a protein-coding variant in the transmembrane domain of Adcy3, showing increases in both obesity and emotion-like behaviors in a rat model. C_LIO_LIWe observed striking sex differences, where male and female rats had different factors driving their adiposity and different patterns of altered behavior. C_LI How might your results change the direction of research or the focus of clinical practice?O_LIUnderstanding the role of Adcy3 in obesity and MDD may lead to improved treatments for both diseases. C_LIO_LIImproving our understanding of the sex differences caused by the same Adcy3 mutation emphasizes the importance of studying both sexes and paves the way for personalized medicine approaches. C_LI

genetics↗

bioRxiv2023

Chronic Stress Increases Adiposity and Anxiety in Rats with Decreased Expression of Krtcap3

We previously identified Keratinocyte-associated protein 3, Krtcap3, as a novel adiposity gene but subsequently found that its impact on adiposity may depend on environmental stress. To more thoroughly understand the connection between Krtcap3, adiposity, and stress, we exposed wild-type (WT) and Krtcap3 knock-out (KO) rats to chronic stress then measured adiposity and behavioral outcomes. We found that KO rats displayed lower basal stress than WT rats under control conditions and exhibited the expected responses to chronic stress exposure. Specifically, stress-exposed KO rats gained more weight, consumed more food when socially isolated, and displayed more anxiety-like behaviors relative to control KO rats. Meanwhile, there were minimal differences between control and stressed WT rats. At study conclusion stress-exposed KO rats had increased corticosterone (CORT) relative to control KO rats with no differences between WT rats. In addition, KO rats, independent of prior stress exposure, had an increased CORT response to removal of their cage-mate (psychosocial stress), which was only seen in WT rats when exposed to chronic stress. Finally, we found differences in expression of the glucocorticoid receptor, Nr3c1, in the pituitary and colon between control and stress-exposed KO rats that were not present in WT rats. These data support that Krtcap3 expression affects stress response, potentially via interactions with Nr3c1, with downstream effects on adiposity and behavior. Future work is necessary to more thoroughly understand the role of Krtcap3 in the stress response.

molecular biology↗

bioRxiv2023

Changes in Environmental Stress over COVID-19 Pandemic Likely Contributed to Failure to Replicate Adiposity Phenotype Associated with Krtcap3

We previously identified Keratinocyte-associated protein 3, Krtcap3, as an obesity-related gene in female rats where a whole-body Krtcap3 knock-out (KO) led to increased adiposity compared to wild-type (WT) controls when fed a high-fat diet (HFD). We sought to replicate this work to better understand the function of Krtcap3 but were unable to reproduce the adiposity phenotype. In the current work, WT female rats ate more compared to WT in the prior study, with corresponding increases in body weight and fat mass, while there were no changes in these measures in KO females between the studies. The prior study was conducted before the COVID-19 pandemic, while the current study started after initial lock-down orders and was completed during the pandemic with a generally less stressful environment. We hypothesize that the environmental changes impacted stress levels and may explain the failure to replicate our results. Analysis of corticosterone (CORT) at euthanasia showed a significant study by genotype interaction where WT had significantly higher CORT relative to KO in Study 1, with no differences in Study 2. These data suggest that decreasing Krtcap3 expression may alter the environmental stress response to influence adiposity. We also found that KO rats in both studies, but not WT, experienced a dramatic increase in CORT after their cage mate was removed, suggesting a separate connection to social behavioral stress. Future work is necessary to confirm and elucidate the finer mechanisms of these relationships, but these data indicate the possibility of Krtcap3 as a novel stress gene.

molecular biology↗

bioRxiv2022

Genetic Disruption of System xc- Mediated Glutamate Release from Astrocytes Increases Negative-Outcome Behaviors While Preserving Basic Brain Function in Rat

The impact of CNS disorders is exacerbated by the difficulty in developing safe, effective glutamatergic therapeutics. Synaptic glutamate transmission is vital for neural physiology throughout the brain, which contributes to the vast therapeutic potential and safety risk of glutamatergic therapeutics. Here, we created a genetically modified rat (MSxc) to survey the range of brain functions impacted by the loss of glutamate release from astrocytes involving system xc- (Sxc). Eliminating Sxc activity was not lethal and did not alter growth patterns, activity states, novel object recognition or performance of other simple tasks. In contrast, MSxc rats differed from WT in Pavlovian Conditioned Approach and cocaine self-administration/reinstatement paradigms. Both WT and MSxc rats readily learned that a cue predicted food delivery during Pavlovian Conditioned Approach training. However, WT rats were more likely to approach the food tray (i.e., goal tracking) whereas MSxc rats were more likely to approach the food-predicted cue (i.e., sign tracking) even when this behavior was punished. In the self-administration/reinstatement paradigm, MSxc rats had higher levels of cocaine-primed drug seeking in the absence of altered extinction or cocaine self-administration. These data demonstrate that Sxc-mediated glutamate release from astrocytes regulates non-reinforced and negative-outcome behaviors without altering simple learning or other forms of basic brain function.

neuroscience↗

bioRxiv2022

Keratinocyte-Associated Protein 3 is a novel gene for adiposity with differential effects in males and females

ObjectiveDespite the obesity crisis in the United States, the underlying genetics are poorly understood. Our lab previously identified Keratinocyte-associated protein 3, Krtcap3, as a candidate gene for adiposity where increased expression of Krtcap3 correlated with decreased fat mass. Here we seek to confirm that Krtcap3 expression affects adiposity traits. MethodsWe developed an in vivo whole-body Krtcap3 knock-out (KO) rat model. Wild-type (WT) and KO rats were placed onto a high-fat or low-fat diet at six weeks of age and were maintained on diet for 13 weeks, followed by assessments of metabolic health. We hypothesized that Krtcap3-KO rats will have increased adiposity and a worsened metabolic phenotype relative to WT. ResultsWe found that KO male and female rats have significantly increased body weight versus WT. KO females ate more, had more fat mass, but were also more insulin sensitive than WT. Alternatively, KO males weighed more and were more insulin resistant than WT, with no differences in eating or fat mass. ConclusionsThis study validates Krtcap3 in body weight regulation and demonstrates sex-specific effects on food intake, adiposity, and insulin sensitivity. Future studies will investigate how Krtcap3 is acting and seek to better understand these sex differences. Study Importance QuestionsWhat is already known about this subject? O_LIOver 900 low-risk, common genetic variants for BMI have been identified, but these still only explain a fraction of the heritability and many of the underlying causal genes remain unknown C_LIO_LIKrtcap3 has been identified as a candidate gene for obesity in both rats and humans, but no verification or functional studies have been done C_LI What are the new findings in your manuscript? O_LIIdentified Krtcap3 as a novel gene that impacts feeding behavior and adiposity in female rats C_LIO_LIDetermined that Krtcap3 impacts insulin sensitivity differentially in male and female rats C_LI How might your results change the direction of research or the focus of clinical practice? O_LIThis work may lead to identification of new pathways that contribute to obesity without metabolic complications, which will advance understanding of the biology of obesity and potentially identify novel drug targets C_LIO_LIThis work highlights the need to investigate sex differences in the genetics of obesity C_LI

genetics↗