Biology subjects

Giedt, M. S.

Publications and source records attributed to Giedt, M. S..

5 recordsLinked to original sources

bioRxiv2026

Prostaglandins regulate the nucleoskeleton during Drosophila border cell migration

The nucleoskeleton, which is comprised of Lamin A (stiffer), Lamin B, and Lamin interacting proteins, including Emerin, controls nuclear stiffness. Nuclear stiffness regulates 3D single cell migration, but its roles in collective cell migration remain unclear. To define the roles of the nucleoskeleton during collective migration we use Drosophila border cell migration. During migration the nucleoskeleton remodels. Throughout migration, Lamin A is predominantly in the nucleoskeleton of the polar cells, whereas Emerin is progressively reduced in the nucleoskeletons of both the border and polar cells, and Lamin B increases in the border cell nucleoskeleton. Further, the border cell nucleoskeleton is polarized; Lamin B is enriched in the front of the cluster while Emerin is enriched in the back. These nucleoskeletal changes require prostaglandin (PG) signaling. When PG signaling is lost, border cell migration is delayed, Lamin A and Emerin are prevalent within the border cell nucleoskeletons throughout migration and nucleoskeletal polarity is lost. Further, overexpression of Lamin A R237P in the border cells delays migration. These data reveal that border cell cluster nucleoskeletal remodeling requires PG signaling and support that this remodeling facilitates invasive, collective migration. Similar PG regulation of the nucleoskeleton likely promotes collective migration across organisms and contexts. Significance StatementO_LINucleoskeletal remodeling is critical for 3D single cell migration, but its roles in collective migration are poorly understood. C_LIO_LIDuring Drosophila border cell migration, the nucleoskeleton remodels and exhibits polarity that suggests the nuclei are softer in the front and stiffer in the back of the cluster. PG signaling is required for these nucleoskeletal changes and on-time border cell migration. Overexpression of Lamin A R237P in the border cells impairs migration. C_LIO_LIThese results demonstrate for the first time that nucleoskeletal remodeling occurs during an in vivo, collective cell migration and identify PG signaling as a novel regulator of the nucleoskeleton. C_LI

cell biology↗

bioRxiv2026

ATGL-mediated lipid droplet lipolysis promotes collective migration in Drosophila

While lipid droplets (LDs), dynamic organelles central to lipid and energy homeostasis, are implicated in cancer cell migration, their roles during collective cell migration remain unknown. We use Drosophila border cell migration as an in vivo model of invasive, collective cell migration to dissect the roles of LDs and the conserved LD lipase, Adipose Triglyceride Lipase (ATGL). Border cell LDs undergo dynamic changes and decrease in volume by the end of migration. Loss of ATGL increases LD volume, whereas border cell overexpression depletes LDs. Loss, border cell knockdown or overexpression of ATGL delays migration and blocks delamination. Further, loss of ATGL disrupts border cell mitochondria - it alters morphology, reduces membrane potential and increases reactive oxygen species. These results demonstrate that tight regulation of lipid mobilization from LDs, including for energy production, drives delamination and collective migration. Our findings not only have the potential to inform how cancer cells exploit LDs to promote their invasive behaviors but also highlight the crucial role of LDs in migration during development, hinting at their broader significance in diverse migratory contexts.

cell biology↗

bioRxiv2025

The lipid droplet protein Jabba promotes actin remodeling downstream of prostaglandin signaling during Drosophila oogenesis

Growing evidence supports that lipid droplets (LDs) are critical for producing high-quality oocytes. However, the functions of LDs during oocyte development remain largely unknown. Using Drosophila oogenesis as a model, we previously discovered the LD-associated Adipose Triglyceride Lipase (ATGL) promotes actin remodeling necessary for oocyte development by providing the substrate for producing lipid signals termed prostaglandins (PGs). Here we find that Jabba, a LD-associated protein best known for its role in anchoring other proteins to LDs, also promotes PG-dependent actin remodeling. Overexpression of Jabba results in thickened cortical actin and excessive actin bundles, whereas loss of Jabba results in cortical actin breakdown and severely defective actin bundle formation. We find that Jabba regulates actin remodeling independently of ATGL but in conjunction with PG signaling. These data support that there are two PG signaling pathways that promote actin remodeling: one PG pathway that is dependent on ATGL and the other requires Jabba. Overexpression of Jabba rescues the actin defects when PG signaling is lost. Together these data lead to the model that PGs produced independently of ATGL positively regulate Jabba to promote actin remodeling necessary for follicle morphogenesis and the production of a fertilization competent oocyte. Significance statementO_LIAcross organisms, lipid droplets accumulate during oocyte development and are implicated in fertility. The functions of lipid droplets during oogenesis are poorly understood. C_LIO_LIThe authors use the genetic tools and well-characterized process of Drosophila oogenesis to reveal that Jabba, a lipid droplet anchoring protein, is a new downstream effector of prostaglandin signaling and promotes actin remodeling necessary for producing a fertilization competent oocyte. C_LIO_LIThe results extend prior studies connecting lipid droplet proteins, prostaglandins, and actin remodeling, providing insight into how these critical conserved factors contribute to high-quality oocytes. C_LI

cell biology↗

bioRxiv2024

Lipid droplet protein Perilipin 2 is critical for the regulation of insulin secretion through beta cell lipophagy and glucagon expression in pancreatic islets

Knockdown (KD) of lipid droplet (LD) protein perilipin 2 (PLIN2) in beta cells impairs glucose-stimulated insulin secretion (GSIS) and mitochondrial function. Here, we addressed a pathway responsible for compromised mitochondrial integrity in PLIN2 KD beta cells. In PLIN2 KD human islets, mitochondria were fragmented in beta cells but not in alpha cells. Glucagon but not insulin level was elevated. While the formation of early LDs followed by fluorescent fatty acids (FA) analog Bodipy C12 (C12) was preserved, C12 accumulated in mitochondria over time in PLIN2 KD INS-1 cells. A lysosomal acid lipase inhibitor Lali2 prevented C12 transfer to mitochondria, mitochondrial fragmentation, and the impairment of GSIS. Direct interactions between LD-lysosome and lysosome-mitochondria were increased in PLIN2 KD INS-1 cells. Thus, FA released from LDs by microlipophagy cause mitochondrial changes and impair GSIS in PLIN2 KD beta cells. Interestingly, glucolipotoxic condition (GLT) caused C12 accumulation and mitochondrial fragmentation similar to PLIN2 KD in beta cells. Moreover, Lali2 reversed mitochondrial fragmentation and improved GSIS in human islets under GLT. In summary, PLIN2 regulates microlipophagy to prevent excess FA flux to mitochondria in beta cells. This pathway also contributes to GSIS impairment when LD pool expands under nutrient load in beta cells.

molecular biology↗

bioRxiv2021

Lipid droplets regulate actin remodeling via prostaglandin signaling during Drosophila oogenesis

A key factor controlling oocyte quality and fertility is lipids. Even though lipid droplets (LDs) are crucial regulators of lipid metabolism, their roles in fertility are poorly understood. During Drosophila oogenesis, LD accumulation in nurse cells coincides with dynamic actin remodeling necessary for late-stage follicle morphogenesis and fertility. Loss of the LD-associated Adipose Triglyceride Lipase (ATGL) disrupts both actin bundle formation and cortical actin integrity, an unusual phenotype also seen when Pxt, the enzyme responsible for prostaglandin (PG) synthesis, is missing. Dominant genetic interactions and PG treatment of follicles in vitro reveal that ATGL and Pxt act in the same pathway to regulate actin remodeling, with ATGL upstream of Pxt. Further, lipidomic analysis detects arachidonic acid (AA) containing triglycerides in ovaries. Because AA is the substrate for Pxt, we propose that ATGL releases AA from LDs to drive PG synthesis necessary for follicle development. We also find that exogenous AA is toxic to follicles in vitro, and LDs modulate this toxicity. This leads to the model that LDs both sequester AA to limit toxicity, and release AA via ATGL to drive PG production. We speculate that the same pathways are conserved across organisms to regulate oocyte development and promote fertility.

cell biology↗