Biology subjects

Michael, J.

Publications and source records attributed to Michael, J..

4 recordsLinked to original sources

bioRxiv2026

A pyoverdine-type metallophore is required for lanthanide-dependent growth in Pseudomonas putida

Lanthanides (Ln) are recently discovered cofactors for alcohol metabolism in a growing number of bacteria, including the soil-dwelling bacterium Pseudomonas putida, yet the mechanisms for Ln uptake are poorly defined. Here, we discovered that the non-ribosomal peptide synthase biosynthetic gene cluster, pvdLIJD, was essential to Ln-dependent growth in P. putida. Pyoverdine G4R and its precursor ferribactin were identified as pvdLIJD gene products with La-responsive abundances, and both chelated La as well as iron. Deletion of the putative pyoverdine outer membrane transport system encoded by fpvA and exbBD:tonB were strongly linked to Ln-dependent growth in a concentration-dependent manner. Global transcriptomes were remodeled in response to La, but weak evidence of transcriptional pvdLIJD regulation and no evidence of discernment between La provided as chloride versus oxide were observed. Overall, this work establishes pyoverdines as metallophores involved in La uptake, re-framing them from strictly iron-scavenging siderophores to dual-purpose metallophores with Ln-binding activity.

microbiology↗

bioRxiv2024

Ketone Body Metabolism is Not Required for Improvement of Heart Failure by Ketogenic Diet in Mice

Failing hearts increasingly metabolize ketone bodies, and enhancing ketosis improves heart failure (HF) remodeling. Circulating ketones are elevated by fasting/starvation, which is mimicked with a high-fat, low-carbohydrate "ketogenic diet" (KD). While speculated that KD improves HF through increased ketone oxidation, some evidence suggests KD paradoxically downregulates cardiac ketone oxidation despite increased ketone delivery. We sought to clarify the significance of cardiac ketone metabolism during KD in HF. Mice were subjected to transverse aortic constriction with apical myocardial infarction (TAC-MI) and fed either low-fat (LF) control or KD. Cardiac-specific mitochondrial pyruvate carrier 2 (csMPC2-/-) mice were used as a second model of heart failure. In both mice, feeding a KD improved HF, determined by echocardiography, heart weights, and gene expression analyses. Although KD increases plasma ketone bodies, gene expression for ketone metabolic genes is decreased in the hearts of KD-fed mice. Cardiac-specific {beta}-hydroxybutyrate dehydrogenase 1 (csBDH1-/-), the first enzyme in ketone catabolism, mice were also studied and crossed with the csMPC2-/-mice to create double knockout (DKO) mice. These mice were aged to 16 weeks and switched to LF or KD, and KD was able to completely normalize the hearts of both csMPC2-/- and DKO mice, suggesting that ketone metabolism is unnecessary for improving heart failure with ketogenic diet. These studies were then repeated, and mice injected with U-13C-{beta}-hydroxybutyrate to evaluate ketone metabolism. KD feeding significantly decreased the enrichment of the TCA cycle from ketone body carbons, as did the BDH1-deletion in DKO mice. Gene expression and respirometry suggests that KD instead increases cardiac fat oxidation. In conclusion, these results suggest that ketogenic diet decreases cardiac ketone metabolism and does not require ketone metabolism to improve heart failure.

physiology↗

bioRxiv2020

Improved bioavailability of montelukast through a novel oral mucoadhesive film in humans and mice

The leukotriene receptor antagonist Montelukast (MTK) is an approved medication for the treatment of asthma and allergic rhinitis. The existing marketed tablet forms of MTK exhibit inconsistent uptake and bioavailability, which partially explains the presence of a significant proportion of MTK low- and non-responders in the population. Besides that, tablets are suboptimal formulations for patients suffering of dysphagia, for example seen in COVID-19 patients or in patients with neurodegenerative diseases such as Alzheimers Disease. The increasing interest in repurposing of MTK for the treatment of such patients and the need for an improved bioavailability triggered us to reformulate MTK. The aim was to develop a mucoadhesive MTK film with a good safety and improved pharmacological, i.e. improved bioavailability, profile in humans as well as in a mouse model of Alzheimers Disease. We tested dissolution of the mucoadhesive film containing MTK in saliva buffer and assessed pharmacoexposure and -kinetics after acute and chronic oral application in mice. Furthermore, we performed a Phase I safety / bioavailability / pharmacokinetic analysis in healthy volunteers. The latter included a comparison with the marketed tablet form as well as a quantitative analysis of the MTK levels in the cerebrospinal fluid. The novel MTK film demonstrated significantly improved bioavailability compared to the marketed tablet in the clinical phase 1a study in healthy humans. Furthermore, there were measurable amounts of MTK present in the cerebrospinal fluid (CSF) at the 3.0 and 7.0 hour time points post drug administration in humans. In mice, MTK was detected in serum and CSF after acute and chronic exposure in a dose-dependent manner. The developed mucoadhesive film of MTK represents a promising alternative for the tablet delivery. The oral film might lower the non-responder rate in patients with asthma and might be an interesting product for repurposing of MTK in other diseases. As we demonstrate BBB penetrance in a preclinical model as well as in a clinical study, the oral film of MTK might find its use as a therapeutic for acute and chronic neurodegenerative diseases such as dementias and stroke.

pharmacology and toxicology↗

bioRxiv2020

SATB2 induction of a neural crest mesenchyme-like program drives invasion and drug resistance in melanoma

Recent genomic and scRNA-seq analyses of melanoma identified common transcriptional states correlating with invasion or drug resistance, but failed to find recurrent drivers of metastasis. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:BRAFV600E;tp53-/- model, in which malignant progression is characterized by minimal genetic evolution. We undertook an overexpression-screen of 80 epigenetic/transcriptional regulators and found neural crest-mesenchyme developmental regulator SATB2 to accelerate aggressive melanoma development. Its overexpression induces invadopodia formation and invasion in zebrafish tumors and human melanoma cell lines. SATB2 binds and activates neural crest-regulators, including pdgfab and snai2. The transcriptional program induced by SATB2 overlaps with known MITFlowAXLhlgh and AQP1+NGFR1high drug resistant states and functionally drives enhanced tumor propagation and resistance to Vemurafenib in vivo. Here we show that melanoma transcriptional rewiring by SATB2 to a neural crest mesenchyme-like program can drive invasion and drug resistance in endogenous tumors.

cancer biology↗