The Serine Protease Homolog, Scarface, Is Sensitive to Nutrient Availability and Modulates the Development of the <i>Drosophila</i> Blood–Brain Barrier

The adaptable transcriptional response to changes in food availability not only ensures animal survival but also lets embryonic development progress. Interestingly, the CNS is preferentially protected from periods of malnutrition, a phenomenon known as “brain sparing.” However, mechanisms that mediate this remain poorly understood. To get better understanding this, we used Drosophila melanogaster model, analyzing neural stem cells (neuroblasts) and glia blood–brain barrier (BBB) larvae both sexes during nutrient restriction using targeted DamID. We found differentially expressed genes neuroblasts BBB, although effect deficiency was primarily observed BBB. characterized function nutritional sensitive gene serine protease homolog, scarface (scaf). Scaf subperineurial BBB nutrition. Tissue-specific knockdown scaf increases endoreplication proliferation perineurial barrier. Furthermore, neuroblast diminished on glia. reexpression able enhance brain growth animals starvation. Finally, show loss sensitivity drugs adulthood, suggesting physiological impairment. propose integrates status modulate balance between neurogenesis preserving proper equilibrium size brain. SIGNIFICANCE STATEMENT Drosophila separates open circulatory system. are acting physical segregation tissues participate regulation metabolism development. Here analyze deprivation larval development, condition which protective switched Our findings reduces while promoting stem, assuring balanced Thus, Scarface would link nutrition with coordinating