Cells maintain homeostasis not only through the well-known routes of vesicle-mediated trafficking but also via a subtle yet powerful set of non-vesicular mechanisms. These pathways enable material exchange and signaling without the use of membrane-bound vesicles, often providing speed, specificity, or capacity beyond what vesicular transport alone can achieve, such as adjusting lipid composition, bridging organelle membranes, sequestering key proteins, and coordinating signaling. In this dissertation we focus on two such mechanisms: firstly, lipid transfer at membrane contact sites, which governs the distribution of phospholipids and maintains membrane identity and flux; secondly, protein phase separation in p62 bodies, a process by which cells regulate autophagy-related cargo sequestration and stress-response signaling. Through these interrelated mechanisms, cells execute refined control of membrane composition and regulated degradation pathways to sustain internal equilibrium under changing conditions.Chapter 1 first provides a comprehensive review of tools to study lipid dynamics in cells, setting the foundation for innovative approaches in subsequent chapters. Chapter 2 introduces a novel application of a metabolic labeling strategy, RT-IMPACT, to track phospholipid movement from the plasma membrane (PM) to the endoplasmic reticulum (ER). Using PLD-mediated lipid generation and bioorthogonal tagging, we observed rapid, non-vesicular PM to ER traffic, dependent in part on extended synaptotagmins (E-Syts). Chapter 3 identifies SHKBP1, a Cullin-3 adaptor protein, as a novel negative regulator of p62 body formation. We found that SHKBP1 binds p62 and limits its oligomerization into phase-separated bodies, thereby preventing excessive sequestration of the ubiquitin ligase adaptor Keap1. In the absence of SHKBP1, Keap1 is sequestered in p62 bodies and unable to target Nrf2 for degradation, leading to elevated Nrf2 antioxidant signaling. This reveals a non-canonical, ubiquitin-independent role for SHKBP1 in autophagy regulation and cell signaling. Chapter 4 integrates these findings, highlighting their significance in the broader context of cellular organization. It discusses how membrane contact site lipid transfer and p62 body dynamics contribute to cellular homeostasis, and outlines future directions. Collectively, the dissertation advances our understanding of non-vesicular processes that organize lipids and proteins in cells, bridging gaps between membrane biology, autophagy, and stress signaling.