winged eye Induces Transdetermination of Drosophila Imaginal Disc by Acting in Concert with a Histone Methyltransferase, Su(var)3-9

Abstract

Drosophila imaginal disc cells exhibit a remarkable ability to convert cell fates in response to various perturbations, a phenomenon called transdetermination (TD). We previously identified winged eye (wge) as a factor that induces eye-to-wing TD upon overexpression in eye imaginal discs, but the molecular mechanisms underlying TD have remained largely unclear. Here, we found that wge induces various histone modifications and enhances the methylation of Lys9 on histone H3 (H3K9), a feature of heterochromatin. A histone methyltransferase, Su(var)3-9, is required for wge-mediated H3K9 methylation and eye-to-wing TD. Su(var)3-9 is also required for classical wound-induced TD but not for normal development, suggesting its involvement in several types of imaginal disc TDs. Transcriptome analysis revealed that wge represses eye identity genes independently of Su(var)3-9 and activates TD-related genes by acting together with Su(var)3-9. These findings provide new insights into diverse types of chromatin regulation at progressive steps of cell-fate conversions.

Nuclear Lamin is required for Winged Eye‐mediated transdetermination of Drosophila imaginal disc

“…Among these WiPs, we focus on Lam in this report, because there is increasing evidence that nuclear lamina proteins govern spatial genome organization in cell fate decisions (Kohwi et al., ; Poleshko et al., ; Solovei et al., ; Wen et al., ). Furthermore, we recently observed that Wge recombinant protein binds to Lam protein in vitro (Masuko et al., ). However, it is still not clear whether Wge interacts with Lam in vivo or what is the function of Lam in the TD process.…”

“…We then carried out mass‐spectrometric analysis of other WiPs detected as bands on SDS–PAGE (Figure a), and listed candidate WiPs (Supporting Information Table S1). It is interesting that the list included some heterochromatin regulators (Linker histone H1 [His1], Modulo and Lam), because our previous reports showed that wge affects the heterochromatin‐formation and heterochromatin‐related histone modifications (Masuko et al., ; Ozawa et al., ). His1 binds to linker DNA between nucleosomes and functions in gene silencing (Lu et al., ); Modulo is classified as a suppressor of position effect variegation (PEV) (Perrin et al., ), which involves establishment/maintenance of heterochromatin structure (Elgin & Reuter, ); Lam is a major component of the nuclear lamina on the inner nuclear membrane, and functions to regulate heterochromatin organization (Burke & Stewart, ; Van Steensel & Belmont, ).…”

“…Notably, a group of disc cells can acquire different disc identity instead of the original one during regeneration, a phenomenon called transdetermination (TD) (Hadorn, ; Worley et al., ). For example, the cells of the eye disc could transdetermine into cells with wing identity, and consequently, an ectopic wing would form in the adult eye region (eye‐to‐wing TD; Katsuyama et al., ; Masuko et al., ; Zhu, Ordway, Weber, Buddika, & Kumar, ). Drosophila’ s powerful genetics enables the study of imaginal disc TD to address fundamental features of cell fate plasticity.…”

“…We have studied genetically induced TD using the GAL4/UAS system (Kurata, Go, Artavanis‐Tsakonas, & Gehring, ) and previously found that over‐expression of Winged Eye (Wge) under the control of an eye disc‐specific GAL4 driver ( eyeless ‐GAL4) induced eye‐to‐wing TD (Katsuyama et al., ). We demonstrated that Wge is a heterochromatin‐related protein (Ozawa et al., ), and over‐expression of Wge induces ectopic expression of vestigial (a master regulator of wing identity) in the eye disc via heterochromatin‐related histone modifications (Masuko et al., ), but we are still far from a comprehensive understanding of the complex TD process.…”

Red‐Shifted Fluorogenic Substrate for Detection of lacZ‐Positive Cells in Living Tissue with Single‐Cell Resolution

“…Additionally,SDS-PAGEanalysis of the reaction solution revealed that activated SPiDER-Red-bGal was bound to surrounding protein (BSA) (Figure 1d). [12] In order to confirm the applicability of SPiDER-Red-bGal for live imaging of such lacZr eporters,a sw ell as compatibility with GFP markers,weperformed ex vivo imaging of cultured live tissues of Drosophila melanogaster. This could be accomplished by our observation that disconnection of the p-conjugation is the key to trapping the fluorescent hydrolysis product inside the cells of interest, which is probably due to the appropriate generation rate and reactivity of aquinone methide intermediate.…”