Fig 2: qRT-PCR certification on control and degenerative meniscus and the selection of potential osteoarthritis (OA) biomarkers in meniscus. (A) Hematoxylin–eosin staining and arthroscopy of the meniscus from normal and degenerative OA meniscus. (B) Relative expression levels of selected differentially expressed microRNAs (DEMs) in normal versus degenerative meniscus. U6 was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001. (C) Relative expression levels of selected differentially expressed circRNA (DECs) in normal versus degenerative meniscus. GAPDH was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001. (D) Relative expression levels of selected differentially expressed lncRNAs (DELs) in normal versus degenerative meniscus. GAPDH was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001. (E) Relative expression patterns of lncRNA LOC107986251hsa_circ_0018069 in normal versus degenerative meniscus. GAPDH was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001. (F) Relative expression patterns of hsa_circ_0018069 in normal versus degenerative meniscus. GAPDH was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001. (G) The scatter plots of differentially expressed mRNAs between normal and degenerative menisci. (H) The Venn diagram of single-cell sequence data of normal meniscus versus degenerative meniscus, whole-transcriptome sequence data of control versus IL-1ßstimulated OA degenerative meniscus, and RNA sequence data of normal meniscus versus OA degenerative meniscus. (I) qRT-PCR confirmation of the screening mRNA (LCN2, RAB27B, PRDM1, and SERPINB2). GAPDH was used as the internal reference gene for qRT-PCR relative expression. Error bars reveal the standard deviation or the standard error of the data. The statistical methods are described above. *p < 0.05, **p < 0.01, ***p < 0.001.

Fig 3: ANXA2 secretion pathway is regulated by RAB8A and RAB27A. (a) Cells with RAB8A, RAB27A, RAB27B knockdown and control knockdown were cultured with or without 500 U/ml IFN-? for 24 h. Cells were then fixed, permeabilized and stained for ANXA2 (blue), LC3 (red) and CD63 (green). The colocalization of ANXA2, LC3 and CD63 was observed by confocal microscopy. Scale bar: 10 µm (2 µm in insets). (b) Line tracing analysis of fluorescence signal from image in (a) of RAB8A, RAB27A, RAB27B knockdown and control knockdown cells after IFN-? stimulation is shown. (c) RAB8A, RAB27A, RAB27B knockdown and control knockdown cells were cultured with or without 500 U/ml IFN-? for 48 h. ANXA2, calnexin and a-tubulin from cultured supernatant and total cell lysate were analyzed by western blotting.

Fig 4: Rab27a and Rab27b have opposite effects in mice. (A) In vivo, Rab27a siRNA was injected into the mouse dorsal skin once every 3 days for a total of three times, and the hair and dorsal tissue of the mice were harvested after 16 days. Rab27b siRNA was injected into the mouse dorsal skin once every 3 days for a total of three times, and the hair and dorsal tissue were harvested after 14 days. (B–D) Knockdown of Rab27a inhibited telogen-to-anagen transition evidenced by hair weight and the number of hair follicles compared with the control. (E–G) In contrast, knockdown of Rab27b promoted telogen-to-anagen transition evidenced by hair weight and the number of hair follicles compared with the control. Ctr; control, si; siRNA. Black arrows indicate the day of siRNA injection. Red arrows indicate that samples were harvested that day. Scale bars indicate 200 µm (B). * p < 0.05, ** p < 0.01, using Student’s t test. n = 4 per group. Three independent experiments were conducted. All error bars indicate S.E.M.

Fig 5: Proposed model for the role of LINC00511 in the regulation of exosome secretion and invadopodia formation, which further facilitating invadopodia membrane extension and extracellular matrix degradation/invasion. LINC00511 induces RAB27B expression and localization to MVBs to drive their anterograde transport, and also induce VAMP7-SNAP23 complex formation to promote exosome secretion, and further promote invadopodia mature and cell invasion. EE, early endosome. MVB, multivesicular body