A VPS33B CRISPR knockout study: In vitro evidence of an adhesion defect.

VPS33B is a ubiquitously expressed regulator of vesicular membrane fusion and protein sorting involved in a broad range of cellular functions from organelle biogenesis to the establishment of apicobasal polarity. Loss-of-function mutations in VPS33B cause arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome, a rare autosomal recessive disorder with multi-organ involvement, including a characteristic proximal tubular dysfunction in the kidney. While VPS33B has been studied in several cell types, its role in proximal tubular epithelial cells remains poorly understood. To investigate its function, a proximal tubular cell line (RPTEC-TERT1) was CRISPR-edited to generate VPS33B knockout (KO) cells. These cells were characterised using brightfield imaging, immunostaining, RNA sequencing, and cell detachment assays, revealing a distinct 'peeling' phenotype and altered adhesion properties. Transcriptional profiling indicated changes in genes linked to cell adhesion. Together, these findings offer preliminary evidence that loss of VPS33B impairs cell-matrix attachment and reveal the first insights into the role of VPS33B within proximal tubular epithelial cells.