Rab7 regulates primary cilia disassembly through cilia excision.

The primary cilium is a sensory organelle that protrudes from the cell surface. Primary cilia undergo dynamic transitions between assembly and disassembly to exert their function in cell signaling. In this study, we identify the small GTPase Rab7 as a novel regulator of cilia disassembly. Depletion of Rab7 potently induced spontaneous ciliogenesis in proliferating cells and promoted cilia elongation during quiescence. Moreover, Rab7 performs an essential role in cilia disassembly; knockdown of Rab7 blocked serum-induced ciliary resorption, and active Rab7 was required for this process. Further, we demonstrate that Rab7 depletion significantly suppresses cilia tip excision, referred to as cilia ectocytosis, which has been identified as required for cilia disassembly. Mechanically, the failure of F-actin polymerization at the site of excision of cilia tips caused suppression of cilia ectocytosis on Rab7 depletion. Overall, our results suggest a novel function for Rab7 in regulating cilia ectocytosis and cilia disassembly via control of intraciliary F-actin polymerization.

Diffusion-weighted imaging volume and diffusion-weighted imaging volume growth in acute stroke: associations with fluid-attenuated inversion recovery hyperintensities-diffusion-weighted imaging mismatch and functional outcome.

PURPOSE: This study assessed the association between diffusion-weighted imaging (DWI) volume and fluid-attenuated inversion recovery vascular hyperintensity (FVH)-DWI mismatch, functional outcome in patients with acute stroke patients receiving endovascular therapy, as well as the value of DWI volume in predicting functional outcome with stroke patients. METHODS: In 38 stroke patients who received endovascular therapy, FVH-DWI mismatch, DWI volume on admission, DWI volume on follow-up, DWI volume growth, the functional outcome at 3 months [modified Rankin scale (mRS)], and other clinical data were collected. Statistical analysis was performed to compare the associations with the above variables and predict functional outcome after stroke. RESULTS: Compared with no FVH-DWI mismatch group (n = 15), FVH-DWI mismatch group (n = 23) had a smaller DWI volume on admission (t = -2.980; P = 0.008), smaller DWI volume on follow-up (t = -2.911; P = 0.009), lower DWI volume growth (t = -2.328; P = 0.031). The 3-month outcome (1.87 ± 0.92) in patients with FVH-DWI mismatch was better than that (2.93 ± 1.62) of patients with no FVH-DWI mismatch (t = -2.307; P = 0.032). Spearman's rank correlation analysis revealed that FVH-DWI mismatch (r = 0.327; P = 0.045), DWI volume on admission (r = 0.414; P = 0.010), DWI volume on follow-up (r = 0.486; P = 0.002), and DWI volume growth (r = 0.467; P = 0.003) were positively correlated with mRS at 3 months. ROC analysis showed when the optimal cutoff value of DWI volume on admission was 33.50, the sensitivity and specificity for predicting functional outcome was 60 and 95.65%, respectively. CONCLUSIONS: Evaluating DWI volume on admission, DWI volume on follow-up as well as DWI volume growth comprehensively may be useful in predicting the functional outcome of acute stroke patients after thrombectomy.