Fig. S1.

Growth arrest induces cfTERRA production in LCLs. (A) Northern blot showing total cellular TERRA levels in LCLs grown in 15% or 0.5% serum for 24 h. (B) Northern blot showing total cellular TERRA or exosome fraction for cfTERRA in EREB LCLs with or without estradiol treatment required for EBV EBNA2 expression and cell proliferation. (C) Comparison of two exosomes isolation methods to purify cfTERRA complex. Exosomes were isolated from equal volume of LCL culture medium (10 mL) by either ultracentrifugation or exosomes isolation kit (Invitrogen). RNAs were isolated from 80% of recovered exosomes and analyzed for cfTERRA by Northern blotting. The remaining exosomes (20%) were assayed by Western blotting with CD63 antibody. (D) Comparison of the recovery of cfTERRA complex by filters with different molecular weight cutoff. Equal amount of exsomes was loaded on the centrifugal filters with either 50- or 100-kDa cutoff. RNA were isolated from either flow through (FT) or retention (RE), and analyzed for cfTERRA by Northern blotting. Proteins of each fraction were TCA precipitated and assayed by Western blotting with CD63 antibody. (E) qRT-PCR for quantification of subtelomere containing TERRA levels in 1 µg of total RNA from LCL cells and exosomes. The subtelomere containing TERRA levels were determine using ∆CT method relative to cellular internal control GAPDH. The distances of the primers to specific telomere track were indicated below.