Formation Of Protrusions Research Articles

Cytosolic S100A8/A9 promotes Ca2+ supply at LFA-1 adhesion clusters during neutrophil recruitment.

S100A8/A9 is an endogenous alarmin secreted by myeloid cells during many acute and chronic inflammatory disorders. Despite increasing evidence of the proinflammatory effects of extracellular S100A8/A9, little is known about its intracellular function. Here, we show that cytosolic S100A8/A9 is indispensable for neutrophil post-arrest modifications during outside-in signaling under flow conditions in vitro and neutrophil recruitment in vivo, independent of its extracellular functions. Mechanistically, genetic deletion of S100A9 in mice caused dysregulated Ca2+ signatures in activated neutrophils resulting in reduced Ca2+ availability at the formed LFA-1/F-actin clusters with defective β2 integrin outside-in signaling during post-arrest modifications. Consequently, we observed impaired cytoskeletal rearrangement, cell polarization, and spreading, as well as cell protrusion formation in S100a9-/- compared to wildtype (WT) neutrophils, making S100a9-/- cells more susceptible to detach under flow, thereby preventing efficient neutrophil recruitment and extravasation into inflamed tissue.

Coaxial air-blast exfoliation breakup of a quasi-solid paste jet

A series of novel phenomena emerges when the coaxial airflow rapidly blows over the quasi-solid paste jet surface, leading to the direct solid-like exfoliation breakup of protrusions on the side face and the liquid-like tensile breakup on the end face. The experimental findings unequivocally demonstrate that the vertical protrusion formation on the side face under high gas velocity serves as a precursor to the subsequent exfoliation breakup, while the tensile breakup is a consequence of axial elongation of the protrusions at the junction between the side and end faces. A crucial step in interpreting the exfoliation breakup is to discern the individual force competition at the jet interface. As gas velocity increases, the radial shear force maintains stronger than the axial drag force and becomes the dominant factor. After the formation of protrusions, the airflow component directly impacts the upper surface of the protrusion in a vertical manner and causes it to fracture similar to the cutting off of a rod-shaped solid. During tensile breakup, the protrusions on the end face develop into liquid threads, which rotate and elongate under axial airflow drag and reflux, ultimately leading to the breakup. Mathematical force models are established to elucidate this intriguing phenomenon observed in the experiments. This study of quasi-solid pastes in airflow will expand the new understanding of the interaction between gas, liquid, and solid states.

Microtubule-Rab5 mutual-influential system screening based on gene-regulatory networks map in Rab5 RNAi eye-degeneration model

Rabs are involved in neuronal development and protrusion formation. Existing studies support the notion that manipulation or mutation of Rab genes could lead to functional changes in neurons. However, whether Rabs gene-manipulation induced Drosophila eye-degeneration remains unknown. By down-regulating Rab5, but not Rab7, we first constructed a compound eye injury model in Drosophila. As the distribution, content, and even maturation of Rab5-positive endosomes are influenced by cytoskeletal proteins, like actin or tubulin-related proteins, the existence of a bidirectional regulatory relationship between Rab5 and the cytoskeleton remains unclear and worth researching. Through complete transcriptome sequencing combined immunofluorescence testing, we confirmed that down-regulation of Rab5 affected the increase of α-Tub84B (alternatively named TubA84B) but not γ-tubulin. Based on Weighted Gene Co-Expression Network Analysis (WGCNA) and multi-tissue screening verification, this study proposes that the apoptosis-related factors–Rab5–TubA84B have conserved regulatory functions with cooperative expression. Gene manipulation confirmed that apoptotic factors, especially rpr, strongly regulate Rab5, and may ultimately influence microtubule structure through complex routes, including the Rab5 variance and the intracellular configuration ratio of α-Tubulin to Glyceraldehyde-3-phosphate dehydrogenase.

Glycocalyx-induced formation of membrane tubes.

In many cells, the existence of glycocalyx, a thick layer of polymer meshwork comprising proteins and complex sugar chains coating the outside of the cell membrane, regulates the formation of membrane tubes. Here, we propose a theoretical model that combines polymer physics theory and the Canham-Helfrich membrane theory to study the formation of cylindrical tubular protrusions induced by the glycocalyx. Our findings indicate that glycocalyx plays an important role in the formation of membrane tubes. We find that there exists critical grafting density and length of polymer that triggers the formation of membrane tubes, and the glycocalyx-induced tube formation is facilitated when combined with actin forces, line tension, and spontaneous curvature. Our theoretical model has implications for understanding how biological membranes may form tubular structures.

An allosteric inhibitor of RhoGAP class-IX myosins suppresses the metastatic features of cancer cells

Aberrant Ras homologous (Rho) GTPase signalling is a major driver of cancer metastasis, and GTPase-activating proteins (GAPs), the negative regulators of RhoGTPases, are considered promising targets for suppressing metastasis, yet drug discovery efforts have remained elusive. Here, we report the identification and characterization of adhibin, a synthetic allosteric inhibitor of RhoGAP class-IX myosins that abrogates ATPase and motor function, suppressing RhoGTPase-mediated modes of cancer cell metastasis. In human and murine adenocarcinoma and melanoma cell models, including three-dimensional spheroid cultures, we reveal anti-migratory and anti-adhesive properties of adhibin that originate from local disturbances in RhoA/ROCK-regulated signalling, affecting actin-dynamics and actomyosin-based cell-contractility. Adhibin blocks membrane protrusion formation, disturbs remodelling of cell-matrix adhesions, affects contractile ring formation, and disrupts epithelial junction stability; processes severely impairing single/collective cell migration and cytokinesis. Combined with the non-toxic, non-pathological signatures of adhibin validated in organoids, mouse and Drosophila models, this mechanism of action provides the basis for developing anti-metastatic cancer therapies.

Critical role of Babesia bovis spherical body protein 3 in ridge formation on infected red blood cells.

Babesia bovis, an apicomplexan intraerythrocytic protozoan parasite, causes serious economic loss to cattle industries around the world. Infection with this parasite leads to accumulation of infected red blood cells (iRBCs) in the brain microvasculature that results in severe clinical complications known as cerebral babesiosis. Throughout its growth within iRBCs, the parasite exports various proteins to the iRBCs that lead to the formation of protrusions known as "ridges" on the surface of iRBCs, which serve as sites for cytoadhesion to endothelial cells. Spherical body proteins (SBPs; proteins secreted from spherical bodies, which are organelles specific to Piroplasmida) are exported into iRBCs, and four proteins (SBP1-4) have been reported to date. In this study, we elucidated the function of SBP3 using an inducible gene knockdown (KD) system. Localization of SBP3 was assessed by immunofluorescence assay, and only partial colocalization was detected between SBP3 and SBP4 inside the iRBCs. In contrast, colocalization was observed with VESA-1, which is a major parasite ligand responsible for the cytoadhesion. Immunoelectron microscopy confirmed localization of SBP3 at the ridges. SBP3 KD was performed using the glmS system, and effective KD was confirmed by Western blotting, immunofluorescence assay, and RNA-seq analysis. The SBP3 KD parasites showed severe growth defect suggesting its importance for parasite survival in the iRBCs. VESA-1 on the surface of iRBCs was scarcely detected in SBP3 KD parasites, whereas SBP4 was still detected in the iRBCs. Moreover, abolition of ridges on the iRBCs and reduction of iRBCs cytoadhesion to the bovine brain endothelial cells were observed in SBP3 KD parasites. Immunoprecipitation followed by mass spectrometry analysis detected the host Band 3 multiprotein complex, suggesting an association of SBP3 with iRBC cytoskeleton proteins. Taken together, this study revealed the vital role of SBP3 in ridge formation and its significance in the pathogenesis of cerebral babesiosis.

A physical model for M1-mediated influenza A virus assembly

Influenza A virus particles assemble at the plasma membrane of infected cells. During assembly all components of the virus come together in a coordinated manner to deform the membrane into a protrusion eventually forming a new, membrane-enveloped virus. Here, we integrate recent molecular insights of this process, particularly concerning the structure of the matrix protein 1 (M1), within a theoretical framework describing the mechanics of virus assembly. Our model describes M1 polymerization and membrane protrusion formation, explaining why it is efficient for M1 to form long strands assembling into helices in filamentous virions. Eventually, we find how the architecture of M1 helices is controlled by physical properties of viral proteins and the host cell membrane. Finally, by considering the growth force and speed of viral filaments, we propose that the helical geometry of M1 strands might have evolved to optimize for fast and efficient virus assembly and growth.

Spatiotemporal coordination of actin regulators generates invasive protrusions in cell-cell fusion.

Invasive membrane protrusions play a central role in a variety of cellular processes. Unlike filopodia, invasive protrusions are mechanically stiff and propelled by branched actin polymerization. However, how branched actin filaments are organized to create finger-like invasive protrusions is unclear. Here, by examining the mammalian fusogenic synapse, where invasive protrusions are generated to promote cell membrane juxtaposition and fusion, we have uncovered the mechanism underlying invasive protrusion formation. We show that two nucleation-promoting factors for the Arp2/3 complex, WAVE and N-WASP, exhibit different localization patterns in the protrusions. Whereas WAVE is closely associated with the plasma membrane at the leading edge of the protrusive structures, N-WASP is enriched with WIP along the actin bundles in the shafts of the protrusions. During protrusion initiation and growth, the Arp2/3 complex nucleates branched actin filaments to generate low-density actin clouds in which the large GTPase dynamin organizes the new branched actin filaments into bundles, followed by actin-bundle stabilization by WIP, the latter functioning as an actin-bundling protein. Disruption of any of these components results in defective protrusions and failed myoblast fusion in cultured cells and mouse embryos. Together, our study has revealed the intricate spatiotemporal coordination between two nucleation-promoting factors and two actin-bundling proteins in building invasive protrusions at the mammalian fusogenic synapse and has general implications in understanding invasive protrusion formation in cellular processes beyond cell-cell fusion.

High‐Temperature Oxidation Response of 444 Ferritic Stainless Steel in a Synthetic Automotive Exhaust Gas

The high‐temperature oxidation behavior of 444 ferritic stainless steel has been studied in cyclic oxidation experiments using synthetic automotive exhaust gas atmospheres at 950 and 1050 °C. The weight gain per unit area of the 444 ferritic stainless steel following oxidation at 950 °C for 100 h iss 85.7% lower than recorded at 1050 °C. The oxide scale at both temperatures consisted of Fe–Cr and Mn–Cr spinels in the outer layer and Cr2O3 in the inner layer. Nodule formation and spallation of the oxide scale are identified as the main causes of breakaway oxidation. The depth of the internal oxides gradually increases with the oxidation time. The nucleation and growth of internal SiO2 result in the formation of metal protrusions, which are eventually consumed in the formation of a SiO2 layer. The SiO2 layer is formed at the interface between the oxide scale and the substrate at 1050 °C. The nucleation and growth of internal SiO2, in combination with lateral growth of SiO2 at the Cr2O3 layer/substrate interface contributed to the formation of the SiO2 layer.

Dennd2c Negatively Controls Multinucleation and Differentiation in Osteoclasts by Regulating Actin Polymerization and Protrusion Formation.

Osteoclasts are bone-resorbing multinucleated giant cells formed by the fusion of monocyte/macrophage lineages. Various small GTPases are involved in the multinucleation and differentiation of osteoclasts. However, the roles of small GTPases regulatory molecules in osteoclast differentiation remain unclear. In the present study, we examined the role of Dennd2c, a putative guanine nucleotide exchange factor for Rab GTPases, in osteoclast differentiation. Knockdown of Dennd2c promoted osteoclast differentiation, resorption, and expression of osteoclast markers. Morphologically, Dennd2c knockdown induced the formation of larger osteoclasts with several protrusions. In contrast, overexpression of Dennd2c inhibited the multinucleation and differentiation of osteoclasts, bone resorption, and the expression of osteoclast markers. Dennd2c-overexpressing macrophages exhibited spindle-shaped mononuclear cells and long thin protrusions. Treatment of Dennd2c-overexpressing cells with the Cdc42 inhibitor ML-141 or the Rac1 inhibitor 6-thio-GTP prevented protrusion formation. Moreover, treatment of Dennd2c-overexpressing cells with the actin polymerization inhibitor latrunculin B restored multinucleated and TRAP-positive osteoclast formation. These results indicate that Dennd2c negatively regulates osteoclast differentiation and multinucleation by modulating protrusion formation in macrophages.

Autophagy Regulator Rufy 4 Promotes Osteoclastic Bone Resorption by Orchestrating Cytoskeletal Organization via Its RUN Domain.

Rufy4, a protein belonging to the RUN and FYVE domain-containing protein family, participates in various cellular processes such as autophagy and intracellular trafficking. However, its role in osteoclast-mediated bone resorption remains uncertain. In this study, we investigated the expression and role of the Rufy4 gene in osteoclasts using small interfering RNA (siRNA) transfection and gene overexpression systems. Our findings revealed a significant increase in Rufy4 expression during osteoclast differentiation. Silencing Rufy4 enhanced osteoclast differentiation, intracellular cathepsin K levels, and formation of axial protrusive structures but suppressed bone resorption. Conversely, overexpressing wild-type Rufy4 in osteoclasts hindered differentiation while promoting podosome formation and bone resorption. Similarly, overexpression of a Rufy4 variant lacking the RUN domain mimics the effects of Rufy4 knockdown, significantly increasing intracellular cathepsin K levels, promoting osteoclastogenesis, and elongated axial protrusions formation, yet inhibiting bone resorption. These findings indicate that Rufy4 plays a critical role in osteoclast differentiation and bone resorption by regulating the cytoskeletal organization through its RUN domain. Our study provides new insights into the molecular mechanisms governing osteoclast activity and underscores Rufy4's potential as a novel therapeutic target for bone disorders characterized by excessive bone resorption.

Branched actin polymerization drives invasive protrusion formation to promote myoblast fusion during skeletal muscle regeneration.

Skeletal muscle regeneration is a multistep process involving the activation, proliferation, differentiation, and fusion of muscle stem cells, known as satellite cells. The fusion of satellite cell-derived mononucleated muscle cells (SCMs) is indispensable for the generation of multinucleated, contractile myofibers during muscle repair. However, the molecular and cellular mechanisms underlying SCM fusion during muscle regeneration remain poorly understood. In this study, we uncovered an essential role for branched actin polymerization in SCM fusion. Using conditional knockouts of the Arp2/3 complex and its actin nucleation-promoting factors, N-WASP and WAVE, we demonstrated that branched actin polymerization is required for the SCM fusion, but not for satellite cell proliferation, differentiation, and migration. We showed that the N-WASP and WAVE complexes have partially redundant functions in regulating SCM fusion. Furthermore, we showed that branched actin polymerization is essential for generating invasive protrusions at the fusogenic synapses in SCMs. Taken together, our study has identified new components of the myoblast fusion machinery in skeletal muscle regeneration and demonstrated a critical role for branched actin-propelled invasive protrusions in this process.

Actomyosin forces in cell migration: Moving beyond cell body retraction.

In textbook illustrations of migrating cells, actomyosin contractility is typically depicted as the contraction force necessary for cell body retraction. This dogma has been transformed by the molecular clutch model, which acknowledges that actomyosin traction forces also generate and transmit biomechanical signals at the leading edge, enabling cells to sense and shape their migratory path in mechanically complex environments. To fulfill these complementary functions, the actomyosin system assembles a gradient of contractile energy along the front-rear axis of migratory cells. Here, we highlight the hierarchic assembly and self-regulatory network structure of the actomyosin system and explain how the kinetics of different nonmuscle myosin II (NM II) paralogs synergize during contractile force generation. Our aim is to emphasize how protrusion formation, cell adhesion, contraction, and retraction are spatiotemporally integrated during different modes of migration, including chemotaxis and durotaxis. Finally, we hypothesize how different NM II paralogs might tune aspects of migration in vivo, highlighting future research directions.

Tao and Rap2l ensure proper Misshapen activation and levels during Drosophila border cell migration.

Collective cell migration is fundamental in development, wound healing, and metastasis. During Drosophila oogenesis, border cells (BCs) migrate collectively inside the egg chamber, controlled by the Ste20-like kinase Misshapen (Msn). Msn coordinates the restriction of protrusion formation and contractile forces within the cluster. Here, we demonstrate that Tao acts as an upstream activator of Msn in BCs. Depleting Tao significantly impedes BC migration, producing a phenotype similar to Msn loss of function. Furthermore, we show that the localization of Msn relies on its citron homology (CNH) domain, which interacts with the small GTPase Rap2l. Rap2l promotes the trafficking of Msn to the endolysosomal pathway. Depleting Rap2l elevates Msn levels by reducing its trafficking into late endosomes and increases overall contractility. These data suggest that Tao promotes Msn activation, while global Msn protein levels are controlled via Rap2l and the endolysosomal degradation pathway. Thus, two mechanisms ensure appropriate Msn levels and activation in BCs.

Visualizing multimerization of plasticity-related gene 5 at the plasma membrane using FLIM-FRET.

Plasticity-related gene (PRG) 5 is a vertebrate specific membrane protein, that belongs to the family of lipid-phosphate phosphatases (LPPs). It is prominently expressed in neurons and is involved in cellular processes such as growth-cone guidance and spine formation. At a functional level, PRG5 induces filopodia in non-neuronal cell lines, as well as the formation of plasma membrane protrusions in primary cortical and hippocampal neurons. Overexpression of PRG5 in immature neurons leads to the induction of spine-like structures, and regulates spine density and morphology in mature neurons. Understanding spine formation is pivotal, as spine abnormalities are associated with numerous neurological disorders. Although the importance of PRG5 in neuronal function is evident, the precise mechanisms as to how exactly it induces membrane protrusions and orchestrates cellular processes remain unresolved. Here we used in vitro biochemical assays to demonstrate that in HEK293T cells a large fraction of PRG5 can be found in homo dimers and lager multimers. By using Fluorescence Lifetime Imaging (FLIM) to quantify Förster Resonance Energy Transfer (FRET), we were able to visualize and quantify the specific localization of PRG5 multimers in living HEK293T cells and in fixed immature primary hippocampal neurons. Here, we provide the first evidence that PRG5 multimers are specifically localized in non-neuronal filopodia, as well as in neuronal spine-like structures. Our findings indicate a potential functional role for PRG5 multimerization, which might be required for interaction with extracellular matrix molecules or for maintaining the stability of membrane protrusions.

PIP5K-Ras bistability initiates plasma membrane symmetry breaking to regulate cell polarity and migration.

Symmetry breaking, polarity establishment, and spontaneous cell protrusion formation are fundamental but poorly explained cell behaviors. Here, we demonstrate that a biochemical network, where the mutually inhibitory localization of PIP5K and Ras activities plays a central role, governs these processes. First, in resting cells devoid of cytoskeletal activity, PIP5K is uniformly elevated on the plasma membrane, while Ras activity remains minimal. Symmetry is broken by spontaneous local displacements of PIP5K, coupled with simultaneous activations of Ras and downstream signaling events, including PI3K activation. Second, knockout of PIP5K dramatically increases both the incidence and size of Ras-PI3K activation patches, accompanied by branched F-actin assembly. This leads to enhanced cortical wave formation, increased protrusive activity, and a shift in migration mode. Third, high inducible overexpression of PIP5K virtually eliminates Ras-PI3K signaling, cytoskeletal activity, and cell migration, while acute recruitment of cytosolic PIP5K to the membrane induces contraction and blebs in cancer cells. These arrested phenotypes are reversed by reducing myosin II activity, indicating myosin's involvement in the PIP5K-Ras-centered regulatory network. Remarkably, low inducible overexpression of PIP5K unexpectedly facilitates polarity establishment, highlighting PIP5K as a highly sensitive master regulator of these processes. Simulations of a computational model combining an excitable system, cytoskeletal loops, and dynamic partitioning of PIP5K recreates the experimental observations. Taken together, our results reveal that a bistable, mutually exclusive localization of PIP5K and active Ras on the plasma membrane triggers the initial symmetry breaking. Coupled actomyosin reduction and increased actin polymerization lead to intermittently extended protrusions and, with feedback from the cytoskeleton, self-organizing, complementary gradients of PIP5K versus Ras steepen, raising the threshold of the networks at the rear and lowering it at the front to generate polarity for cell migration.

The host GTPase Dynamin 2 modulates apical junction structure to control cell-to-cell spread of Listeria monocytogenes.

The food-borne pathogen Listeria monocytogenes uses actin-based motility to generate plasma membrane protrusions that mediate the spread of bacteria between host cells. In polarized epithelial cells, efficient protrusion formation by L. monocytogenes requires the secreted bacterial protein InlC, which binds to a carboxyl-terminal Src homology 3 (SH3) domain in the human scaffolding protein Tuba. This interaction antagonizes Tuba, thereby diminishing cortical tension at the apical junctional complex and enhancing L. monocytogenes protrusion formation and spread. Tuba contains five SH3 domains apart from the domain that interacts with InlC. Here, we show that human GTPase Dynamin 2 associates with two SH3 domains in the amino-terminus of Tuba and acts together with this scaffolding protein to control the spread of L. monocytogenes. Genetic or pharmacological inhibition of Dynamin 2 or knockdown of Tuba each restored normal protrusion formation and spread to a bacterial strain deleted for the inlC gene (∆inlC). Dynamin 2 localized to apical junctions in uninfected human cells and protrusions in cells infected with L. monocytogenes. Localization of Dynamin 2 to junctions and protrusions depended on Tuba. Knockdown of Dynamin 2 or Tuba diminished junctional linearity, indicating a role for these proteins in controlling cortical tension. Infection with L. monocytogenes induced InlC-dependent displacement of Dynamin 2 from junctions, suggesting a possible mechanism of antagonism of this GTPase. Collectively, our results show that Dynamin 2 cooperates with Tuba to promote intercellular tension that restricts the spread of ∆inlC Listeria. By expressing InlC, wild-type L. monocytogenes overcomes this restriction.

FSH induces apoptosis in follicular granulosa cells of Tianzhu white yak and regulates the expression of Fas/FasL mRNA.

The Tianzhu white yak, a globally rare species, holds immense value as a source for yak materials. While the Fas/FasL pathway is pivotal in granulosa cells apoptosis, its precise molecular workings remain enigmatic. This study endeavours to decipher the role of follicle-stimulating hormone (FSH) in suppressing ovarian granulosa cells (GC) apoptosis in the Tianzhu white yak. Utilizing advanced cell culture techniques, we employed the MTT method, flow cytometry, fluorescence labelling and RT-PCR to investigate the apoptotic effects of FSH on yak GCs. Our results reveal that FSH's inhibitory effect on GC apoptosis follows a normal distribution pattern, peaking at an FSH concentration of 100 ng/mL with an apoptosis inhibition rate of 89.31%. When serum was withdrawn, an FSH concentration of 2 × 106 ng/mL reduced apoptosis by 72.84%. Annexin V-FITC staining revealed membrane invaginations, bubble and protrusion formation on the cell surface, and alterations in membrane structure and cell morphology. Flow cytometry analysis further demonstrated that FSH administration prior to early granulosa cell apoptosis had a more profound effect than during gradual apoptosis, both showing a suppressive effect on early follicular granulosa cell apoptosis. A transcription-level analysis conducted 3 h prior to serum withdrawal, with the addition of 100 ng/mL FSH, revealed intricate regulations in the expression of Fas/FasL. Notably, we observed a gradual increase in FasL expression over time, yet the presence of FSH effectively down-regulated FasL expression to baseline levels, without notable changes in Fas expression. Immunocytochemical analysis further confirmed the presence of both Fas and FasL on the cell membrane, nucleus and cytoplasm, with varying intensities depending on the duration of FSH treatment. Our findings suggest that FSH may suppress the apoptotic pathway in follicular primarily by down-regulating FasL expression, indicating that Fas-regulated mitochondrial pathways play a more prominent role compared to death receptor pathways. This study offers a fresh perspective on the mechanism underlying follicular atresia in Tianzhu white yaks and lays a solid theoretical foundation for the expansion of this endangered species' population.

Atomic-level quantum well degradation of GaN-based laser diodes investigated by atom probe tomography

Gallium nitride (GaN)- based lasers are extensively employed in display, lighting, and communication applications due to their visible laser emission. Despite notable advancements in their performance and reliability, sustained device functionality over extended periods remains a challenge. Among the diverse mechanisms contributing to degradation, the deterioration of quantum wells poses a persistent obstacle. In this study, we investigated the atomic-level degradation of quantum wells within GaN-based laser diodes utilizing atom probe microscopy. Our analysis revealed a substantial increase in indium fluctuation, accompanied by the formation of indium protrusions at the quantum well interfaces, which provides a credible explanation for the observed increase in FWHM (full width at half maximum) of the spontaneous spectra of lasers following prolonged operation. Additionally, magnesium analysis yielded no evidence of diffusion into the quantum well region. Combined with prior studies, we attribute the degradation of quantum wells primarily to the formation of indium-related non-radiative recombination centers.

De novo lipid synthesis and polarized prenylation drive cell invasion through basement membrane.

To breach the basement membrane, cells in development and cancer use large, transient, specialized lipid-rich membrane protrusions. Using live imaging, endogenous protein tagging, and cell-specific RNAi during Caenorhabditis elegans anchor cell (AC) invasion, we demonstrate that the lipogenic SREBP transcription factor SBP-1 drives the expression of the fatty acid synthesis enzymes POD-2 and FASN-1 prior to invasion. We show that phospholipid-producing LPIN-1 and sphingomyelin synthase SMS-1, which use fatty acids as substrates, produce lysosome stores that build the AC's invasive protrusion, and that SMS-1 also promotes protrusion localization of the lipid raft partitioning ZMP-1 matrix metalloproteinase. Finally, we discover that HMG-CoA reductase HMGR-1, which generates isoprenoids for prenylation, localizes to the ER and enriches in peroxisomes at the AC invasive front, and that the final transmembrane prenylation enzyme, ICMT-1, localizes to endoplasmic reticulum exit sites that dynamically polarize to deliver prenylated GTPases for protrusion formation. Together, these results reveal a collaboration between lipogenesis and a polarized lipid prenylation system that drives invasive protrusion formation.