SYTL3 (synaptotagmin-like 3) functions as a Rab effector protein involved in vesicle trafficking and exocytosis, with particular relevance to neuronal migration and immune cell function. In neurodevelopment, SYTL3 acts as a regulator of cortical neuronal migration, where knockout accelerates migration through modulation of matrix metalloproteinases and affects presynaptic neurotransmitter release in human embryonic stem cell-derived neurons 1. The protein plays a critical role in exocytosis pathways, as demonstrated in bladder cancer where SYTL3 functions as a Rab27b effector to mediate bacterial exocytosis, with knockdown reducing BCG elimination from cells and enhancing therapeutic efficacy 2. SYTL3 also shows distinct expression patterns in immune cells, particularly in cardiac sarcoidosis where SYTL3+ macrophages are scattered throughout granulomas and exhibit mTOR pathway activation associated with proliferation 3. Additionally, SYTL3 expression is upregulated in response to IL-23 inhibition therapy in psoriatic patients 4 and has been associated with cancer cell secretome alterations in renal cell carcinoma 5. These findings collectively indicate SYTL3's multifaceted role in vesicle trafficking, neuronal development, immune responses, and disease pathogenesis.