Transposon Dysregulation Modulates dWnt4 Signaling to Control Germline Stem Cell Differentiation in Drosophila
Fig 1
dWnt4 is required for cystoblast differentiation.
(A) A schematic of the Drosophila female germarium present at the anterior-most end of each ovariole. Stem cells (blue) are attached to the cap cells (light green). The stem cells divide to give rise to the cystoblast (blue) that turns on expression of Bam, and is referred to as the differentiating cystoblast (green). The cystoblast then undergoes four incomplete mitotic divisions to give rise to a 16-cell cyst (blue). The germline is surrounded by the somatic niche composed of the terminal filament (red), cap cells (light green) and escort cells (grey). (B) Microarray analysis of dSETDB1 mutants compared to bam mutants showing that transposons (blue) are upregulated and dWnt4 (green) is downregulated. (C-F) Wild type, dWnt4 heterozygotes and dWnt4 mutants stained with 1B1 (red) and Vasa (green) showing an accumulation of >3 undifferentiated cells in dWnt4 mutants (white line). (G) Quantification of the number of single cell spectrosomes in wild type (n = 50), dWnt4 heterozygotes dWnt4EMS23 (n = 90), dWnt4C1 (n = 40) and dWnt4 mutants (n = 90) showing a significant difference. (H-I2) dWnt4 heterozygote and dWnt4 mutant stained with pMad (red) (white asterisk), BamC (green), and Vasa (blue) showing that dWnt4 mutants accumulate pMad and Bam negative cells (white line). pMad is shown in H1 and I1, BamC is shown in H2 and I2. (J) Quantification of number of pMad and Bam negative cells in dWnt4 heterozygote (n = 22) and dWnt4 mutants (n = 24) showing a significant increase in dWnt4 mutants. (K-L) dWnt4 heterozygote and dWnt4 mutants carrying a hs-bam transgene stained with 1B1 (red) and Vasa (green) showing differentiating cysts marked by fusomes (red) post heat shock (white arrow). (M-N) dWnt4 heterozygote and dWnt4, dSETDB1 trans-heterozygote stained with 1B1 (red) and Vasa (green) showing an accumulation of >3 undifferentiated single cells (white line) in the trans-heterozygote.