Hepatocyte nuclear factor 4α mediated quinolinate phosphoribosylltransferase (QPRT) expression in the kidney facilitates resilience against acute kidney injury.

Nicotinamide adenine dinucleotide (NAD+) levels decline in experimental models of acute kidney injury (AKI). Attenuated enzymatic conversion of tryptophan to NAD+ in tubular epithelium may contribute to adverse cellular and physiological outcomes. Mechanisms underlying defense of tryptophan-dependent NAD+ production are incompletely understood. Here we show that regulation of a bottleneck enzyme in this pathway, quinolinate phosphoribosyltransferase (QPRT) may contribute to kidney resilience. Expression of QPRT declined in two unrelated models of AKI. Haploinsufficient mice developed worse outcomes compared to littermate controls whereas novel, conditional gain-of-function mice were protected from injury. Applying these findings, we then identified hepatocyte nuclear factor 4 alpha (HNF4α) as a candidate transcription factor regulating QPRT expression downstream of the mitochondrial biogenesis regulator and NAD+ biosynthesis inducer PPARgamma coactivator-1-alpha (PGC1α). This was verified by chromatin immunoprecipitation. A PGC1α - HNF4α -QPRT axis controlled NAD+ levels across cellular compartments and modulated cellular ATP. These results propose that tryptophan-dependent NAD+ biosynthesis via QPRT and induced by HNF4α may be a critical determinant of kidney resilience to noxious stressors.

Hypoxia-inducible factor 1 signaling drives placental aging and can provoke preterm labor.

Most cases of preterm labor have unknown cause, and the burden of preterm birth is immense. Placental aging has been proposed to promote labor onset, but specific mechanisms remain elusive. We report findings stemming from unbiased transcriptomic analysis of mouse placenta, which revealed that hypoxia-inducible factor 1 (HIF-1) stabilization is a hallmark of advanced gestational timepoints, accompanied by mitochondrial dysregulation and cellular senescence; we detected similar effects in aging human placenta. In parallel in primary mouse trophoblasts and human choriocarcinoma cells, we modeled HIF-1 induction and demonstrated resultant mitochondrial dysfunction and cellular senescence. Transcriptomic analysis revealed that HIF-1 stabilization recapitulated gene signatures observed in aged placenta. Further, conditioned media from trophoblasts following HIF-1 induction promoted contractility in immortalized uterine myocytes, suggesting a mechanism by which the aging placenta may drive the transition from uterine quiescence to contractility at the onset of labor. Finally, pharmacological induction of HIF-1 via intraperitoneal administration of dimethyloxalyl glycine (DMOG) to pregnant mice caused preterm labor. These results provide clear evidence for placental aging in normal pregnancy, and demonstrate how HIF-1 signaling in late gestation may be a causal determinant of the mitochondrial dysfunction and senescence observed within the trophoblast as well as a trigger for uterine contraction.

Adaptation of an Obstetric Anesthesia Service for the Severe Acute Respiratory Syndrome Coronavirus-2 Pandemic: Description of Checklists, Workflows, and Development Tools.

BACKGROUND: Care of the pregnant patient during the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic presents many challenges, including creating parallel workflows for infected and noninfected patients, minimizing waste of materials, and ensuring that clinicians can seamlessly transition between types of anesthesia. The exponential community spread of disease limited the time for development and training. METHODS: The goals of our workflow and process development were to maximize safety for staff and patients, minimize the risk of contamination, and reduce the waste of unused supplies and materials. We used a cyclical improvement system and the plus/delta debriefing method to rapidly develop workflows consisting of sequential checklists and procedure-specific packs. RESULTS: We designed independent workflows for labor analgesia, neuraxial anesthesia for cesarean delivery, conversion of labor analgesia to cesarean anesthesia, and general anesthesia. In addition, we created procedure-specific material packs to optimize supplies and prevent wastage. Finally, we generated sequential checklists to allow staff to perform standard operating procedures without extensive training. CONCLUSIONS: Collectively, these workflows and tools allowed our staff to urgently care for patients in high-risk situations without prior experience. Over time, we refined the workflows using a cyclical improvement system. We present our checklists and workflows as well as the system we used for their development, so that others may use them to their benefit.

Placenta accreta spectrum: biomarker discovery using plasma proteomics.

BACKGROUND: Many cases of placenta accreta spectrum are not diagnosed antenatally, despite identified risk factors and improved imaging methods. Identification of plasma protein biomarkers could further improve the antenatal diagnosis of placenta accreta spectrum . OBJECTIVE: The purpose of this study was to determine if women with placenta accreta spectrum have a distinct plasma protein profile compared with control subjects. STUDY DESIGN: We obtained plasma samples before delivery from 16 participants with placenta accreta spectrum and 10 control subjects with similar gestational ages (35.1 vs 35.5 weeks gestation, respectively). We analyzed plasma samples with an aptamer-based proteomics platform for alterations in 1305 unique proteins. Heat maps of the most differentially expressed proteins (T test, P<.01) were generated with matrix visualization and analysis software. Principal component analysis was performed with the use of all 1305 proteins and the top 21 dysregulated proteins. We then confirmed dysregulated proteins using enzyme-linked immunosorbent assay and report significant differences between placenta accreta spectrum and control cases (Wilcoxon-rank sum test, P<.05). RESULTS: Many of the top 50 proteins that significantly dysregulated in participants with placenta accreta spectrum were inflammatory cytokines, factors that regulate vascular remodeling, and extracellular matrix proteins that regulate invasion. Placenta accreta spectrum, with the use of the top 21 proteins, distinctly separated the placenta accreta spectrum cases from control cases (P<.01). Using enzyme-linked immunosorbent assay, we confirmed 4 proteins that were dysregulated in placenta accreta spectrum compared with control cases: median antithrombin III concentrations (240.4 vs 150.3 mg/mL; P=.002), median plasminogen activator inhibitor 1 concentrations (4.1 vs 7.1 ng/mL; P<.001), soluble Tie2 (13.5 vs 10.4 ng/mL; P=.02), soluble vascular endothelial growth factor receptor 2 (9.0 vs 5.9 ng/mL; P=.003). CONCLUSION: Participants with placenta accreta spectrum had a unique and distinct plasma protein signature.

A workshop on leadership for MD/PhD students.

Success in academic medicine requires scientific and clinical aptitude and the ability to lead a team effectively. Although combined MD/PhD training programs invest considerably in the former, they often do not provide structured educational opportunities in leadership, especially as applied to investigative medicine. To fill a critical knowledge gap in physician-scientist training, the Vanderbilt Medical Scientist Training Program (MSTP) developed a biennial two-day workshop in investigative leadership. MSTP students worked in partnership with content experts to develop a case-based curriculum and deliver the material. In its initial three offerings in 2006, 2008, and 2010, the workshop was judged by MSTP student attendees to be highly effective. The Vanderbilt MSTP Leadership Workshop offers a blueprint for collaborative student-faculty interactions in curriculum design and a new educational modality for physician-scientist training.

KCNE4 juxtamembrane region is required for interaction with calmodulin and for functional suppression of KCNQ1.

Voltage-gated potassium (K(V)) channels, such as KCNQ1 (K(V)7.1), are modulated by accessory subunits and regulated by intracellular second messengers. Accessory subunits belonging to the KCNE family exert diverse functional effects on KCNQ1, have been implicated in the pathogenesis of various genetic disorders of heart rhythm, and contribute to transducing intracellular signaling events into changes in K(V) channel activity. We investigated the interactions between calmodulin (CaM), the ubiquitous Ca(2+)-transducing protein that binds and confers Ca(2+) sensitivity to the biophysical properties of KCNQ1, and KCNE4. These studies were motivated by the observed similarities between the suppression of KCNQ1 function by pharmacological disruption of KCNQ1-CaM interactions and the effects of KCNE4 co-expression on the channel. We determined that KCNE4, but not KCNE1, can biochemically interact with CaM and that this interaction is Ca(2+)-dependent and requires a tetraleucine motif in the juxtamembrane region of the KCNE4 C terminus. Furthermore, disruption of the KCNE4-CaM interaction either by mutagenesis of the tetraleucine motif or by acute Ca(2+) chelation impairs the ability of KCNE4 to inhibit KCNQ1. Our findings have potential relevance to KCNQ1 regulation both by KCNE accessory subunits and by an important intracellular signaling molecule.