Neugebauer, K. A. | bioRxiv Science

bioRxiv2025

Dolutegravir Developmental Toxicity is Mitigated by Magnesium and Folate in Zebrafish Embryos

Integrase-strand-transfer inhibitors have transformed HIV therapy, yet the widely prescribed drug dolutegravir (DTG) has been linked to developmental toxicity and its teratogenic mechanism remains uncertain. Here we use zebrafish to dissect DTG toxicity during early vertebrate development. DTG exposure from 2-4 h post-fertilization (hpf) to 24 hpf produced high mortality and abnormal morphology; co-treatment with folic acid or 5-methyltetrahydrofolate partially restored normal morphology, whereas calcium had no effect. Strikingly, supplementation with magnesium (Mg) rescued DTG-exposed embryos almost as effectively as folate, implicating magnesium availability in protection. In competitive binding assays, Mg increased binding of folate to purified folate receptor (FOLR1) by 30% in the presence of DTG. Maternal-zygotic zebrafish folr1 mutant embryos contained significantly less endogenous folate than wild-type embryos yet displayed marked hypersensitivity to DTG that could not be mitigated by folate supplementation. Critically, magnesium supplementation partially rescued DTG toxicity in folr1 mutants, indicating a Folr1-independent component and placing the free DTG vs Mg-bound DTG balance upstream of folate transport. These results support a model in which free DTG antagonizes FOLR1, and Mg modifies DTG developmental toxicity by both FOLR1 dependent and independent processes. Our work identifies magnesium status as a modifiable determinant of DTG teratogenicity and provides a proof-of-concept zebrafish model that could be adapted for rapid in vivo screening of integrase inhibitors for developmental phenotypes.

developmental biology↗

bioRxiv2022

Bile acid-CoA:amino acid N-acyltransferase gene knockout alters early life development, the gut microbiome and reveals unusual bile acid conjugates in mice

Bile acids are steroid detergents in bile that contribute to fat absorption, cell signaling and microbiome interactions in mammals. The final step in their synthesis is amino acid conjugation with either glycine or taurine to a cholic acid or chenodeoxycholic acid backbone in the liver by the enzyme bile acid-CoA:amino acid N-acyltransferase (BAAT). Here, we describe the microbial, chemical, and physiological consequences of BAAT gene deletion in mice. BAAT-/- mice were underweight after weaning but quickly exhibited catch-up growth. At 3-weeks-of-age, KO animals had increased phospholipid excretion and decreased subcutaneous fat pad mass, glycogen staining in hepatocytes and vitamin A stores in the liver, but these phenotypes were less marked in adulthood. Their bile acid (BA) pool was highly altered throughout the 8-weeks of life but was not completely devoid of conjugated BAs. These animals had 27-fold lower amounts of taurine-conjugated BAs than wildtype in their liver, but similar concentrations of glycine-conjugated BAs and higher microbially-conjugated BAs. The BA pool in BAAT-/- was enriched in a variety of unusual bile acids that were putatively sourced from cysteamine conjugation with subsequent oxidation and methylation of the sulfur group to mimic taurine. KO mice also had an altered microbiome, but most strongly in the first 3-weeks, indicating bile acid conjugation is important for proper microbiome development during the postnatal period. Finally, antibiotic treatment increased taurine, glycine, and the unusually conjugated BAs in BAAT-/- animals, indicating the microbiome was not the likely source of the conjugation. Instead, BA conjugation in KO animals was likely derived from the peroxisomal acyltransferases ACNAT1 and ACNAT2, which are duplications of BAAT in the mouse genome, but inactivated in humans. This study demonstrates that BA conjugation is important for early life development in mice and is facilitated by other host or microbial enzymes besides BAAT in a manner that results in molecular mimics of taurine that may rescue pathological phenotypes.

microbiology↗