SYGL-1 and LST-1 link niche signaling to PUF RNA repression for stem cell maintenance in Caenorhabditis elegans
Fig 6
SYGL-1 and LST-1 repress gld-1 expression post-transcriptionally in GSC pool.
(A) Schematic of gld-1(q361), a missense allele with a null phenotype [45] that generates mRNA and protein normally [30]. The smFISH probe set spanned the locus. See text for details. (B-E) GLD-1(q361) protein in distal gonads, stained with α-GLD-1 (green) and DAPI (cyan). Genotypes are: (B) gld-2(q497) gld-1(q361); (C) sygl-1(q828) gld-2(q497) gld-1(q361); (D) lst-1(ok814) gld-2(q497) gld-1(q361); (E) lst-1(ok814) sygl-1(q828) gld-2(q497) gld-1(q361). (F) Quantitation of GLD-1(q361). α-GLD-1 intensities in 0–20 μm (1-~5 gcd) from the distal end were averaged and plotted. Box plot conventions as in Fig 2F, genotypes as in Fig 6B–6E. Asterisks indicate a statistically significant difference by 1-way Welch’s ANOVA with Games Howell post hoc test. ** p<0.001, * p< 0.05. Number of gonads examined: Control, n = 23; sygl-1, n = 26; lst-1, n = 24; lst-1 sygl-1, n = 38. (G-J) gld-1(q361) transcripts in distal gonads, probed using smFISH (white) and DAPI (cyan). Genotypes as in Fig 6B–6E. All gonads (100%) had mRNA distributions as shown: control, n = 32; sygl-1, n = 35; lst-1, n = 41; lst-1 sygl-1, n = 38. (K and L) Pink arrows, nascent transcripts in nucleus. Yellow arrowheads, mature mRNAs in cytoplasm. Top, gld-1 RNA; bottom, RNA merged with DAPI. (K) Magnifications from boxed areas in (G). In the presence of wild-type sygl-1 and lst-1, distal germ cells possess nuclear transcripts, but little cytoplasmic mRNA, whereas proximal germ cells have both. (L) Magnifications from boxed areas in (J). Without sygl-1 and lst-1, both distal and proximal germ cells contain nuclear and cytoplasmic gld-1 transcripts. See S8 Fig for confirmation of gld-1 probe specificity. All images are maximum intensity z-projections, except (K) and (L) show a single z-slice. Conventions as in Fig 1E–1J; scale bar is 20 μm in all images, except 2 μm in (K) and (L). n, number of gonadal arms.