Glucagon-like peptide 1 receptor agonists (GLP-1RAs) are widely prescribed to treat obesity and related diseases such as diabetes, cardiovascular disease, and sleep apnea. The remarkable success of GLP-1RAs in treating these diseases has been tempered by the dramatic loss of muscle mass and function associated with the treatment. Our lab has previously demonstrated the capacity of microbial-derived exerkines (MDEs) pipecolic acid and succinate (PAS) to ameliorate losses of skeletal muscle size and function during disuse atrophy. In the current study, we treated diet-induced obesity (DIO) mice with vehicle (VEH), semaglutide (SEM), or semaglutide and PAS (SEM+PAS) for one week during high fat diet and assessed body composition and skeletal muscle phenotype and function. Treatment with PAS protects against SEM-induced losses in lean mass and rescues skeletal muscle cross-sectional area and function. These findings demonstrate the therapeutic potential of MDEs in protecting against GLP-1RA-induced losses in skeletal muscle size and function. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction: Sleep apnea (SA) is recognized as an independent risk factor for development of hypertension (HTN) and chronic kidney disease (CKD). Epidemiological studies show HTN and CKD risk is lower in pre-menopausal women vs. men but increases after transition to menopause. Our lab has previously shown that estrogen loss in female rats via ovariectomy (OVX) combined with exposure to chronic intermittent hypoxia (CIH, an experimental model of SA) results in increased mean arterial pressure (MAP) and reductions in renal blood flow (RBF) and tissue oxygenation (PO 2 ). Other labs have shown that specific activation of the g-protein coupled estrogen receptor (GPER) attenuates increases in arterial pressure associated with OVX. Hypothesis: We hypothesized that activation of GPER with a selective agonist (G1) would attenuate previously observed increases in MAP and decreases in RBF and PO 2 in OVX females conditioned with CIH. Methods: Adult female Sprague Dawley rats were randomized to OVX/sham groups and then further randomized to CIH or AIR conditioning for 14 days while receiving treatment with G1 via osmotic mini pumps. MAP was measured non-invasively using tail cuff plethysmography and invasively using an indwelling arterial pressure catheter. RBF and PO 2 were measured under light isoflurane anesthesia (1.5-2% in air) under normoxic and hypoxic conditions. Data was analyzed using ANOVA w/ Sidak Holm Multiple Comparison Tests. Results: No significant differences were observed in MAP, RBF, or PO 2 between sham air and sham CIH groups, whereas MAP was higher and RBF and PO 2 lower in OVX-CIH vs. OVX groups. In the OVX-CIH-G1 group MAP was significantly lower and RBF and PO 2 were significantly higher (p< 0.05) relative to OVX-CIH. Conclusion: Our results suggest that ovarian hormone loss combined with CIH has a deleterious effect on regulation of MAP, RBF, and PO 2 that is attenuated by G1, suggesting an avenue for treatment of HTN and CKD in post-menopausal women with SA. Supported by a grant from the Iowa Osteopathic Education Research Fund (IOER #122205, #062503) and the DMU Mentored Student Research Program. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Purine cyclic nucleotide monophosphates (cAMP and cGMP) are well-studied second messenger signals. More recently, non-canonical pyrimidine cyclic nucleotides monophosphates (cUMP and cCMP) have been discovered and shown to play essential second messenger signaling roles, sensing infectious and/or inflammatory stimuli and triggering innate immune responses. Similarly, cyclic-di-nucleotide monophosphates (c-di-NMPs) have been resolved, and they too serve as signaling molecules linked to innate immunity. More specifically, the cyclic GMP-AMP synthase(s) (i.e., cGAS) senses cytosolic DNA, which leads to production of 2’3’-cGAMP that activates the transmembrane protein stimulator of interferon no-genes, or STING, inducing the production of type I interferons. The 2’-5’-oligoadenylate family of proteins sense double stranded RNA and produce c-di-AMP, which activates the RNase L leading to degradation of viral RNA. At present, the molecular diversity of c-di-NMPs present within mammalian cells is poorly understood. Here, we tested the hypothesis that lung microvascular endothelial cells possess diverse c-di-NMPs under basal conditions. To test this hypothesis, c-di-NMPs were extracted from flash frozen cell pellets using a 2:2:1 H 2 O/MeOH/ACN protocol, followed by analysis on an Agilent 1200 Series HPLC coupled to a Thermo Q Exactive Plus mass spectrometer and a HILICON iHILIC-Fusion (P) (2.1 x 150mm) column using a 3.0 µL injection volume for each. One full positive ionization scan from 200–800 m/z was performed at 17,500 resolution, followed by targeted MS2 scans of cGAMP (675.1045 m/z), c-di-AMP (659.1123 m/z), c-di-GMP (691.1021 m/z), and c-di-UMP (613.0578 m/z), and one full negative ionization scan from 200–800 m/z. Detection and peak analysis of c-di-NMPs were performed using Thermo XCalibur software. Pulmonary microvascular endothelial cells possessed detectable levels of cGAMP (~0.05 nmol/106 cells) and c-di-AMP (~0.05 nmol/106 cells) under basal conditions. We also detected c-di-GMP at similar basal concentrations (~0.03 nmol/106 cells). cAMP and cGMP were measured from the same samples; cNMPs were present at higher concentrations, where cAMP was ~2 nmol/106 cells and cGMP was ~0.2 nmol/106 cells. Thus, the c-di-NMPs were present at concentrations representing ~2% of the cAMP abundance and at ~20% of the cGMP levels. Remarkably, we detected the presence of c-di-UMP at a similar concentration range (~0.035 nmol/106 cells). c-di-UMP has not been previously described in any mammalian cell. The basal c-di-UMP concentrations were ~35% of cUMP levels. We next tested whether infection with exoenzyme Y competent P. aeruginosa impacts c-di-NMP abundance. Infection increased cGMP, cUMP, and to a lesser extent, cCMP, inside the cell and cGMP and cUMP outside the cell, due to activity of the promiscuous nucleotidyl cyclase exoenzyme Y. Whereas the intracellular concentrations of c-di-AMP and cGAMP were unchanged following infection, c-di-GMP levels were increased and c-di-UMP concentrations decreased to nearly undetectable levels. It is unclear whether c-di-UMP can be released from endothelial cells during infection and accumulate in the extracellular space, similar to cGMP and cUMP. Thus, we report the presence of the novel c-di-UMP in endothelium, and determine that intracellular concentrations of c-di-UMP and c-di-GMP are responsive to bacterial infection. Studies are ongoing to better understand the role of c-di-NMPs, and especially c-di-UMP, in endothelial innate immunity. Supported by HL140182, HL167997, and HL148069. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

In addition to neuronal tissue, Alzheimer’s disease (AD) influences the function of peripheral tissues such as skeletal muscle. Recent work suggests the presence of AD pathology limits the responsiveness of young muscles to exercise. However, the extent that AD pathology influences the responsiveness of aged muscle to acute exercise is also unknown. Thus, the purpose of this study was to assess transcriptional changes in aged muscle subjected to acute exercise in the presence of AD pathology. The tibialis anterior (TA) of 20-month-old female 3xTg-AD (model of AD) and B6129F1 wild-type (WT) mice was subjected to a bout of unilateral, electrically evoked, eccentric contractions to mimic resistance exercise. The contralateral TA served as the internal control muscle. Muscles were harvested 4 hours post-contractions. RNA was isolated and subjected to RNA sequencing. Pathway analysis on differentially expressed genes (DEGs) with a >0.5-fold change was performed using DAVID software. Absolute and normalized TA masses (normalized to tibia length) were lower in aged 3xTg-AD mice compared to age-matched WT values. There were 1,309 DEGs (505 upregulated & 804 downregulated) in the non-contracted TA of 3xTg-AD mice compared to the non-contracted TA in WT mice, corresponding to pathways associated with growth regulation, substrate metabolism, inflammation, and structural remodeling. Contractions altered 338 DEGs in WT muscle and 990 DEGs in 3xTg-AD muscle, with only 192 DEGs shared between genotypes. In WT mice, contraction-sensitive DEGs were enriched into pathways related to structural remodeling, extracellular matrix interactions, inflammation, and substrate metabolism. In contrast, contraction-sensitive DEGs in 3xTg-AD mice were mainly enriched into pathways related to inflammation, with others associated with cell survival/growth, and cytoskeletal organization. Those contraction-sensitive DEGs shared by both groups were enriched into pathways related to cytoskeletal organization, growth regulation, inflammation, and cell–cell interactions. Overall, these findings show AD pathology and high force contractions in the presence of AD pathology alter similar gene programs. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Background: In the United States over 10% of all neonates are born premature (less than 37 weeks gestational age) and many face complications, such as necrotizing enterocolitis (NEC). NEC is the most deadly gastrointestinal disease in preterm neonates with up to 50% mortality. Survivors face life-long complications. NEC is a multifactorial disease caused by 1) intestinal immaturity, including a poorly developed physical barrier between luminal contents and the rest of the body; 2) an exaggerated immune response; and 3) intestinal dysbiosis, which together can result in irreparable damage to the intestine. Since there is no cure for NEC, prevention is the best strategy. Enhancing our understanding of intestinal epithelial cell (IEC) barrier regulation during early development will provide novel therapeutic targets to prevent NEC. Published evidence indicates roles for the RNA-binding protein insulin-like growth factor 2 mRNA binding protein 1 (IMP1) in intestinal development, barrier function, and intestinal repair. Sequencing data from the inflamed tissue of a NEC patient indicates that IMP1 is down-regulated relative to uninflamed tissue. Notably, roles for IMP1 in NEC are not defined. Emerging evidence suggests that mucus complexity, governed by enzymes such as Qsox1, impacts intestinal barrier function and inflammation susceptibility. This study aimed to define the role of IMP1 in NEC pathogenesis using a model of NEC-like intestinal injury in mice with IEC-specific Imp1 overexpression or Imp1 loss. Hypothesis: IMP1 expression is protective in a mouse model of NEC-like intestinal injury. Methods: All studies are OHSU IACUC-approved. This study used: wild-type (WT, control), Imp1 IEC-knockout ( VillinCre;Imp1 fl/fl ; Imp1 Δ IEC ), and Imp1 IEC-overexpression ( VillinCre;lslFLAG-Imp1 OE ; Imp1 IEC-OE ) mice. At post-natal day 4 mice of both sexes were randomly assigned to control or NEC groups. The control mice remained with the dam. NEC was induced with the well-established experimental NEC-like intestinal injury model. Mice were separated from the dam and maintained for 72 hours in an incubator. Pups were gavage-fed NEC formula (mixture of infant formula, puppy replacer, 1:10 dilution of bacteria derived from a premature infant with NEC, and 2.5 ug/g body weight of lipopolysaccharide) every 3 hours from 7am-10pm. Twice daily the pups were exposed to hypoxia (5% oxygen). After 72 hours, tissue was collected for histology, gene, and protein expression analyses. Survival was assessed with Kaplan-Meier curves. Total RNA sequencing was performed using the NovaSeq S4. The mucus and tissue barrier were evaluated by immunofluorescence staining for mucin 2, mucus lectins, occludin, and E-cadherin. Statistical analyses were performed using 2-way ANOVA with Tukey’s test for multiple comparisons and the Mantel-Cox log-rank test for survival analysis. Results: The NEC model induces pneumatosis, histological damage, and a significant up-regulation of inflammatory cytokine gene expression Lcn2 and Il1 b in all three genotypes, p <0.05, n=5-15. Despite damage, Imp1 IEC-OE mice survive 2-times better than WT or Imp1 Δ IEC mice (survival for WT: 27.8%, n=36; Imp1 Δ IEC : 31.6%, n=19; Imp1 IEC-OE : 60%, n=10 mice, p<0.05). RNA-sequencing data indicates that Imp1 IEC-OE mice significantly up-regulate expression of the disulfide catalyst Qsox1 (In NEC: WT: 1077 ± 94.6, Imp1 Δ IEC : 1017 ± 12.75, Imp1 IEC-OE : 1446 ± 45.73, p=0.003 vs WT and p=0.002 vs Imp1 Δ IEC ). Conclusion: Our data suggest that Imp1 expression enhances survival in a mouse model of NEC and promotes expression of a disulfide catalyst Qsox1, which may promote mucus maturation and protect the neonatal small intestine. NIH K01DK129401, R01HD097367, the Gerber Foundation, the OHSU Knight Cancer Institute This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Glomeruli number and glomerular volume are indicators of kidney health and chronic kidney disease (CKD) progression. Low nephron number is predictive of the development of CKD, and increased glomerular volume is associated with hyperfiltration and hypertension. Accurate estimates of glomeruli number are necessary for relating whole body GFR to single nephron GFR (SNGFR) which is an important parameter for mathematical modeling of transport along the nephron. In addition, previous studies had observed larger volumes and greater SNGFR in juxtamedullary glomeruli compared to cortical glomeruli. To enable routine estimation of cortical glomerular density and the size of cortical and juxtamedullary glomeruli, we optimized a cost- and time-effective method for labeling and imaging glomeruli in mouse models. Mice were injected with Alexa fluor 647 conjugated wheat germ agglutinin (WGA-647; 0.5 mg) intracardially. After 4 minutes circulation time, kidneys were perfusion fixed and harvested. Kidneys were sectioned at the midline at 600 µm up to 999 µm and cleared with ethyl cinnamate. Cross sections were imaged on Leica Sp8 with either 10x or 25x objective and 15 µm z-step size. This method enabled visualization of perfused glomerular capillaries and kidney vasculature. The cortical region was identified based on autofluorescence (488 nm laser). Individual glomeruli were identified and counted by automated 3D segmentation in Python. The diameters of individual glomeruli were measured in higher magnification images using Leica LAS X software. Juxtamedullary glomeruli were identified as those within the inner third of the cortex, nearest the medulla. On average, juxtamedullary glomeruli had larger diameters compared to cortical glomeruli. However, the extent of WGA-647 perfusion within individual glomeruli varied along the interlobular vessels. Including heparin (500 U/L) in the WGA-647 injection resulted in better filling or perfusion of glomeruli, especially in the superficial cortex, and as a result the estimated average glomerular diameter increased. In future, this methodology will be applied to compare cortical glomerular density and average glomerular volume in male and female mice and in genetic kidney disease models. National Institutes of Health T32 DK007052, R01 DK125049, U54 DK137329 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction: Skeletal muscle regeneration is an energy-demanding process that relies on mitochondria to generate ATP. While healthy skeletal muscle fibers have organized interfibrillar mitochondrial networks organizing architecture segregated into columns along the Z-line of the myofiber, regenerating fibers exhibits altered mitochondrial networks that span several sarcomeres. Despite links between muscle regeneration and altered mitochondrial dynamics and biogenesis, the role of specific cells in remodeling these networks remains unclear. Because muscle stem cells (MuSCs) play a critical role in muscle regeneration, we explored the relationship between MuSCs and mitochondria in regenerating muscle fibers. Methods: To induce muscle regeneration, we used the hindlimb ischemia mouse model of peripheral artery disease (PAD) and the mdx mouse model of Duchenne’s muscular dystrophy (DMD). Furthermore, transgenic reporter mice such as Pax7-tdTomato, H2B-EGFP, and mitoDendra2 were used to mark MuSCs, track nuclei, and label mitochondria, respectively. Fluorescently labeled MuSCs were also transplanted into BaCl 2 -injured muscle to elucidate their behavior and interactions throughout muscle regeneration. Immunofluorescence, single fiber staining, and biochemical assays from harvested muscles were performed for data analysis. Results: Following injury, a significant increase in the number of endogenous MuSCs was observed 7 days post-injury compared to contralateral control, while a dramatic increase in the fusion of MuSCs into myofibers was noted at days 14 and 28. Interestingly, all fused myofibers at days 14 and 28 displayed central nucleation, a hallmark of regeneration that fusion of the MuSC is critical for myofiber regeneration. Primary MuSCs from H2B-EGFP reporter mice were isolated and transplanted into the injured muscle to determine the origin of the centrally located myonuclei. In myofibers where the transplanted MuSCs had fused, centrally located myonuclei were GFP + , indicating their origin from MuSCs. Surprisingly, regenerating muscle fibers isolated from the mitoDendra2 mouse model exhibited high densities of mitochondrial content near the centrally located myonuclei. To evaluate whether MuSCs contribute to producing these central myonuclei near mitochondria, primary MuSCs isolated from mitoDendra2 reporter mice were transplanted into mdx mice. Fused myofibers indeed exhibited high Dendra2 + mitochondrial density between central nuclei along with a restoration of the mitochondrial network. Finally, we also observed a change in myogenic potential and mitochondrial respiration after transplanting MuSCs that have been preconditioned to enhance mitochondrial biogenesis. SIGNIFICANCE RELEVANCE: Overall, these data indicate that MuSC-derived myonuclei synthesize new mitochondria to generate the bioenergetics for myofiber regeneration after muscle injury. This relationship between MuSCs and myofiber mitochondria provides a basis for MuSC-derived mitochondrial transplantation as a therapeutic approach for muscular diseases associated with mitochondrial dysfunction. Acknowledgements: This work was supported by the NIH R01AR080169, R01AG072309, VA Merit Award I02RX005009 (to YCJ) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

objective: WDR77, a component of 20S PRMT5 containing a methyltransferase complex, can modify certain arginines in several splicosome Sm proteins and histones to dimethylarginine, which may play a role in transcriptional regulation. Studies have shown that the expression level of WDR77 plays a role in many systemic cancers such as non-small cell lung cancer, prostate cancer and ovarian cancer, and is positively correlated with poor prognosis of most cancers. However, WDR77 has not been studied in detail in glioma, and its biological significance in glioma has not been fully clarified. This study focused on glioma and explored the characterization and prognostic value of WDR77 in glioma, aiming to explore the role of WDR77 in glioma and its feasibility as a potential prognostic factor, so as to guide the clinical treatment of glioma in order to improve the prognosis of patients. Methods: In this study, the role of WDR77 in glioma and its feasibility as a potential prognostic factor were studied by bioinformatics analysis. In this study, transcriptome gene expression profiles and clinical data of 1018 glioma patients were collected from the Chinese glioma Genome Atlas Database (CGGA). The target gene WDR77 was selected from the candidate genes after four-layer analysis filtering (including survival analysis filtering, independent prognostic analysis filtering, ROC curve filtering and clinical correlation analysis filtering). Differential expression analysis, survival analysis, independent prognosis analysis, ROC curve analysis and clinical correlation analysis of the target gene WDR77 were performed to explore the feasibility of WDR77 as a potential prognostic factor for glioma. Then, immunoinfiltration analysis, co-expression analysis and GSEA analysis of the target gene WDR77 were performed to explore the role and mechanism of WDR77 in glioma. Results: WDR77 is significantly overexpressed in gliomas, which is associated with poor prognosis in gliomas (including GBM and LGG), and leads to shorter overall survival in LGG patients (HR =2.8, P =8.9 e-08). WDR77 was an independent prognostic factor for glioma (HR=2.110; 95%CI=1.700 – 2.618; P <0.001), WDR77 had good prognostic accuracy (AUC values for 1-year, 3-year, and 5-year overall survival were 0.710, 0.761, and 0.799, respectively). WDR77 was positively correlated with regulatory pathways such as regulatory T cell differentiation and macrophage differentiation, and with immune cell infiltration such as CD4 + T cells (r=0.523, P =8.78e-35) and macrophages (r=0.509, P =1.36e-32). Conclusion: WDR77 is a novel molecular marker that can be used as an independent prognostic factor for human glioma, and the high expression of WDR77 suggests a poor prognosis for glioma. WDR77 may be a potential immunotherapeutic target for human glioma, and WDR77 affects the occurrence and development of glioma through multiple molecular pathways. National Clinical Key Specialty Project Foundation ; Shanxi Scholarship Council of China;Lvliang City high-level scientific and technological talents development project This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

The Special Master’s Program at Georgetown University Medical Center (GUMC SMP) is a one year academic enhancement MS program that prepares students for future success in medical school. Its curriculum covers about half of the material in the first year basic science curriculum of Georgetown’s School of Medicine, supplemented with complementary graduate courses. GUMC SMP students attend the relevant basic science lectures with first year medical students (M1), are assessed by completing the same multiple choice questions used for their M1 counterparts and are graded against the M1 average to determine grades for corresponding SMP medical courses. In 2015, a second campus, the Georgetown Downtown SMP (GTDT), was opened that follows the same curriculum, but with all material delivered in a fully “flipped” manner. The GTDT students' average undergraduate GPA and MCAT scores are not different from the GUMC SMP students, whereas the average GPAs of SMP students are significantly lower than GPAs of their M1 peers (3.2 vs 3.7 in M1 class). The GTDT students review the lecture capture (LC) recordings of medical (or graduate) lectures on their own time and attend 2-4 hrs of class time four days per week during which the GTDT instructor provides active learning sessions to reinforce the material. The current research expands on our earlier findings, by evaluating the GTDT cohort performance in six medical physiology exams and three medical gross anatomy (GA) exams over the past five years compared to GUMC SMP peers and M1 students. Using the Student’s t test with the Bonferroni correction for multiple comparisons, significance level was designated at p<0.05. Our results indicate that the GTDT students continued to outperform their GUMC SMP counterparts in all exams, reaching statistical significance in three out of six medical physiology exams and three out of three medical GA exams. The GTDT students also had higher average scores than their peer M1 students on five out of six medical physiology exams, reaching significance in three out of the six M1 exams. GTDT averages were higher than M1 students on GA exams, but differences did not reach statistical significance. The higher GTDT performance is most likely attributable to the students being actively engaged in flipped learning in all classroom sessions. Additionally, GTDT students’ responses to anonymous polling showed that they felt the active learning exercises were beneficial to their overall learning and their long-term retention of the material. Overall, our results continue to validate the successful use of the active learning environment in medical education, confirm its successful use in the GTDT program, and suggest that the flipped learning modality results in overall better learning outcomes in a rigorous medical curriculum. Georgetown University This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.