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Falabregue, M.

Publications and source records attributed to Falabregue, M..

2 recordsLinked to original sources

A dWDR45 knock-out Drosophila model to decipher the role of autophagy in BPAN

Beta-propeller protein-associated neurodegeneration (BPAN) is a rare neurological disorder characterized by severe cognitive and motor impairments. BPAN is caused by de novo pathogenic variants in the WDR45 gene on the X chromosome. WDR45 gene encodes the protein WDR45/WIPI4, a known regulator of autophagy. A defective autophagy has been observed in cellular models of BPAN disease and is associated with neurological dysfunctions in wdr45 knockout (KO) mice. However, it remains unclear whether the autophagic defect directly contributes to all WDR45 loss-induced phenotypes or whether other WDR45-dependent cellular functions are involved. To investigate this, we generated a CRISPR/Cas9-mediated KO of CG11975 (dwdr45 KO), the Drosophila homolog of WDR45. Our analysis revealed that dwdr45 KO flies display BPAN-like phenotypes, including impaired locomotor function, seizure-like behavior, autophagy dysregulation and iron dyshomeostasis. Additionally, dwdr45 KO flies exhibit shortened lifespan compared to control flies. These findings demonstrate that dwdr45 KO fly is a relevant in-vivo model for investigating the key cellular and molecular mechanisms underlying BPAN-associated phenotypes. Here we showed that induction of autophagy in dwdr45 KO flies improved both the shortened lifespan and the seizure-like behavior, but did not restore locomotor function. This suggests that defective autophagy contributes to some, but not all, aspects of the phenotypes resulting from loss of dWdr45 function.

cell biology↗

Serotonin regulates hepcidin expression via a gut-liver axis

Iron is essential to key biological processes of all living organisms. Proper iron levels must be maintained to meet biological needs and prevent toxicity. Given the central role played by the hormone hepcidin in systemic iron homeostasis, extensive research has sought to identify regulators of its expression. Diverse evidence shows the gut to be an essential sensor and regulator of iron homeostasis, independently of other known hepcidin regulators, including bone marrow signals. Here we identify gut-derived serotonin as a key physiological factor in hepcidin regulation. In response to hypoxia, serotonin synthesized and secreted by enterochromaffin cells can act beyond the gut to repress hepcidin expression in the liver, through a 5-HT2B receptor-dependent pathway. Bone marrow transplant experiments clearly indicate the gut is responsible for hepcidin repression. This regulatory system appears to be conserved in humans: a significant negative correlation exists between hepcidin and serotonin levels in the serum of healthy individuals. Our findings imply hepcidin regulation by serotonin is a physiological process, and modulation of the gut serotonergic system may have broad therapeutic implications.

physiology↗