Biology subjects

Pfeiffer, A.

Publications and source records attributed to Pfeiffer, A..

6 recordsLinked to original sources

bioRxiv2023

Atlas of fetal metabolism during mid-to-late gestation and diabetic pregnancy

Mounting evidence supports an instructive role for metabolism in stem cell fate decisions. However, much is yet unknown about how fetal metabolism changes during mammalian development and how altered maternal metabolism shapes fetal metabolism. Here, we present a descriptive atlas of in vivo fetal murine metabolism during mid-to-late gestation in normal and diabetic pregnancy. Using 13C-glucose and LC-MS, we profiled the metabolism of fetal brains, hearts, livers, and placentas harvested from pregnant dams between embryonic days (E)10.5 and 18.5. Comparative analysis of our large metabolomics dataset revealed metabolic features specific to fetal tissues developed under a hyperglycemic environment as well as metabolic signatures that may denote developmental transitions during euglycemic development. We observed sorbitol accumulation in fetal tissues and altered neurotransmitter levels in fetal brains isolated from dams with maternal hyperglycemia. Tracing 13C-glucose revealed disparate nutrient sourcing in fetuses depending on maternal glycemic states. Regardless of glycemic state, histidine-derived metabolites accumulated during late development in fetal tissues and maternal plasma. Our rich dataset presents a comprehensive overview of in vivo fetal tissue metabolism and alterations occurring as a result of maternal hyperglycemia.

cell biology↗

bioRxiv2022

Identification of novel antiviral drug candidates using an optimized SARS-CoV-2 phenotypic screening platform

Reliable, easy-to-handle phenotypic screening platforms are needed for the identification of anti-SARS-CoV-2 compounds. Here, we present caspase 3/7 activity as a read-out for monitoring the replication of SARS-CoV-2 isolates from different variants, including a remdesivir-resistant strain, and of other coronaviruses in a broad range of cell culture models, independently of cytopathogenic effect formation. Compared to other cell culture models, the Caco-2 subline Caco-2-F03 displayed superior performance, as it possesses a stable SARS-CoV-2 susceptible phenotype and does not produce false-positive hits due to drug-induced phospholipidosis. A proof-of-concept screen of 1796 kinase inhibitors identified known and novel antiviral drug candidates including inhibitors of PHGDH, CLK-1, and CSF1R. The activity of the PHGDH inhibitor NCT-503 was further increased in combination with the HK2 inhibitor 2-deoxy-D-glucose, which is in clinical development for COVID-19. In conclusion, caspase 3/7 activity detection in SARS-CoV-2-infected Caco-2F03 cells provides a simple phenotypic high-throughput screening platform for SARS-CoV-2 drug candidates that reduces false positive hits.

pharmacology and toxicology↗

bioRxiv2022

TOR acts as metabolic gatekeeper for auxin-dependent lateral root initiation in Arabidopsis thaliana

Plants post-embryonic organogenesis requires matching the available metabolic resources to the developmental programs. The root system is determined by the formation of lateral roots (LR), which in Arabidopsis thaliana entails the auxin-induced activation of founder cells located in the pericycle. While the allocation of sugars to roots influences root branching, how sugar availability is sensed for auxin-triggered formation of LRs remains unknown. Here, we combine metabolic profiling with cell-specific genetic interference to show that LR formation is an important sink for carbohydrate accompanied by a switch to glycolysis. We show that the target-of-rapamycin (TOR) kinase is locally activated in the pericycle and the founder cells and that both chemical and genetic inhibition of TOR kinase lead to a block of LR initiation. TOR marginally affects the auxin-induced transcriptional response of the pericycle but modulates the translation of ARF19, ARF7 and LBD16, three key targets of auxin signalling. These data place TOR as a gatekeeper for post-embryonic LR formation that integrates local auxin-dependent pathways with systemic metabolic signals, modulating the translation of auxin induced gene expression.

plant biology↗

bioRxiv2021

TOR kinase controls shoot development by translational regulation of cytokinin catabolic enzymes

Plants continuously adjust their developmental program including organ initiation and growth in accordance with endogenous and environmental signals. This plasticity requires that a diversity of signaling pathways acts in concert to modulate stem cell activity. We have shown previously that the TOR kinase network integrates metabolic- and light signals and controls expression of WUSCHEL, a transcriptional master regulator of stem cells in the shoot apical meristem. However, the mechanism linking TOR activity with the WUSCHEL promoter remained unresolved. Here we demonstrate that TOR regulates the accumulation of trans-zeatin, the cytokinin species mainly responsible for shoot development. Importantly, we identify translational repression of RNAs encoding cytokinin degrading CYTOKININ OXIDASES/DEHYDROGENASE enzymes by TOR as an underlying mechanism. Employing this system, plants can quickly adjust stem cell activity and developmental programs in response to changes in their environment.

plant biology↗

bioRxiv2021

GDAP1 loss of function inhibits the mitochondrial pyruvate dehydrogenase complex by altering the actin cytoskeleton

Charcot-Marie-Tooth (CMT) disease 4A is an autosomal-recessive polyneuropathy caused by mutations of ganglioside-induced differentiation-associated protein 1 (GDAP1), a putative glutathione transferase, which affects mitochondrial shape and alters cellular Ca2+ homeostasis. Here, we identify the underlying mechanism. We found that patient-derived motoneurons and GDAP1 knockdown SH-SY5Y cells display two phenotypes: more tubular mitochondria and a metabolism characterized by glutamine dependence and fewer cytosolic lipid droplets. GDAP1 interacts with the actin-depolymerizing protein Cofilin-1 in a redoxdependent manner, suggesting a role for actin signaling. Consistently, GDAP1 loss causes less F-actin close to mitochondria, which restricts mitochondrial localization of the fission factor dynamin-related protein 1, instigating tubularity. Changes in the actin cytoskeleton also disrupt mitochondria-ER contact sites. This results in lower mitochondrial Ca2+ levels and inhibition of the pyruvate dehydrogenase complex, explaining the metabolic changes upon GDAP1 loss of function. Together, these findings reconcile GDAP1-associated phenotypes and implicate disrupted actin signaling in CMT4A pathophysiology.

neuroscience↗

bioRxiv2019

Role for Merlin/NF2 in transcription elongation through interaction with the PAF complex

The PAF complex (PAFC) coordinates transcription elongation and mRNA processing events and its CDC73/parafibromin subunit functions as a tumour suppressor. The NF2/Merlin tumour suppressor functions at the cell cortex and nucleus and is a key mediator of contact inhibition. Here we provide a direct link between nuclear Merlin and transcription elongation controlled by cell-cell adhesion. Merlin interacts with the PAFC in a cell density-dependent manner and tumour-derived inactivating mutations in both Merlin and CDC73 mutually disrupt their interaction. Growth suppression by Merlin requires CDC73 and Merlin regulates PAFC association with chromatin in a subset of genes. We also identify by CDC73 affinity-proteomics a role for FAT cadherins in regulating the Merlin-PAFC interaction. Our results suggest that in addition to its function within the Hippo pathway, nuclear Merlin is part of a tumour suppressor network which coordinates postinitiation steps of the transcription cycle of genes mediating in contact inhibition.

cancer biology↗