Age-dependent changes in metabolism can manifest as cellular lipid accumulation, but how this accumulation is regulated or impacts longevity is poorly understood. We find that Saccharomyces cerevisiae accumulate lipid droplets (LDs) during aging. We also find that overexpressing BNA2, the first Biosynthesis of NAD + (kynurenine) pathway gene, reduces LD accumulation during aging and extends lifespan. Mechanistically, this LD accumulation during aging is not linked to NAD + levels, but is anti-correlated with metabolites of the shikimate and aromatic amino acid biosynthesis (SA) pathways (upstream of BNA2), which produce tryptophan (the Bna2p substrate). We provide evidence that over-expressed BNA2 skews glycolytic flux from LDs towards the SA-BNA pathways, effectively reducing LDs. Importantly, we find that accumulation of LDs does not shorten lifespan, but does protect aged cells against stress. Our findings reveal how lipid accumulation impacts longevity, and how aging cell metabolism can be rewired to modulate lipid accumulation independently from longevity.

Pavarotti, the Drosophila MKLP1 orthologue, is a kinesin-like protein that works with Tumbleweed (MgcRacGAP) as the centralspindlin complex. This complex is essential for cytokinesis, where it helps to organize the contractile actomyosin ring at the equator of dividing cells by activating the RhoGEF Pebble. Actomyosin rings also function as the driving force during cell wound repair. We previously showed that Tumbleweed and Pebble are required for the cell wound repair process. Here, we show that Pavarotti also functions during wound repair and confirm that while Pavarotti, Tumbleweed, and Pebble are all used during this cellular repair, each has a unique localization pattern and knockdown phenotype, demonstrating centralspindlin-independent functions. Surprisingly, we find that the classically microtubule-associated Pavarotti binds directly to actin in vitro and in vivo and has a noncanonical role directly regulating actin dynamics. Finally, we demonstrate that this actin regulation by Pavarotti is not specific to cellular wound repair but is also used in normal development.

36Pavarotti, the Drosophila MKLP1 ortholog, is a kinesin-like protein that with Tumbleweed 37 (MgcRacGAP) works together as the centralspindlin complex. This complex is essential for 38 cytokinesis where it helps to organize the contractile actomyosin ring at the equator of dividing 39 cells by activating the RhoGEF Pebble. Actomyosin rings also function as the driving force 40 during cell wound repair. We previously showed that Tumbleweed and Pebble are required for 41 the cell wound repair process. Here, we show that Pavarotti also functions during wound repair 42 and confirm that while Pavarotti, Tumbleweed, and Pebble are utilized during this cellular repair, 43 it is not as the conserved centralspindlin complex. Surprisingly, in vitro and in vivo work show 44 that the classically microtubule-associated Pavarotti binds directly to actin and has a non-45 canonical role directly regulating actin dynamics. We show that Pavarotti also works 46 independently from Tumbleweed in several actin-related processes during the normal 47 48 49 Nakamura et al.