Crumbs interacts with Xpd for nuclear division control in Drosophila

Abstract

Crumbs (Crb) family proteins are crucial for cell polarity. Recent studies indicate that they are also involved in growth regulation and cancer. However, it is not well-understood how Crb participates in mitotic processes. Here, we report that Drosophila Crb is critically involved in nuclear division by interacting with Xeroderma pigmentosum D (XPD). A novel gene named galla-1 was identified from a genetic screen for crb modifiers. Galla-1 protein shows homology to MIP18, a subunit of the mitotic spindle-associated MMS19-XPD complex. Loss-of-function galla-1 mutants show abnormal chromosome segregation, defective centrosome positions and branched spindles during nuclear division in early embryos. Embryos with loss-of-function or overexpression of crb show similar mitotic defects and genetic interaction with galla-1. Both Galla-1 and Crb proteins show overlapping localization with spindle microtubules during nuclear division. Galla-1 physically interacts with the intracellular domain of Crb. Interestingly, Galla-1 shows little binding to the Drosophila homolog of XPD, but a related protein Galla-2 binds both Crb and Xpd. Loss-of-function galla-2 mutants show similar mitotic defects as galla-1 and strong genetic interaction with crb. Xpd can form a physical complex with Crb. In imaginal disc, Crb overexpression causes tissue overgrowth as well as DNA damages marked by H2Av phosphorylation. These phenotypes are suppressed by reduction of Xpd. Taken together, this study identifies a novel Crb-Galla-Xpd complex and its function for proper chromosome segregation during nuclear division, implicating a potential link between Crb and Xpd-related genome instability.

Plasmodium falciparum XPD translocates in 5′ to 3′ direction, is expressed throughout the blood stages, and interacts with p44

“…First, during cell division, the transcription process is restricted and the transcription factors move out of chromatin (Akoulitchev and Reinberg 1998;Long et al 1998). Secondly, XPD is known to interact with mitosis-associated proteins (like Crb, galla, MMS19, MAT1) and is crucial for normal progression of cell division (Cameroni et al 2010;Ito et al 2010;Yeom et al 2014).…”

Nucleotide Excision Repair and Transcriptional Regulation: TFIIH and Beyond

“…XPB and XPD were first defined as DNA repair factors before being demonstrated as parts of TFIIH (1, [33][34][35]. XPD is also found in the MMS19-MIP18-XPD (MMXD) and Crumbs-Galla-XPD (CGX) complexes, which are both implicated in chromosome segregation (36,37). Such multitasking capabilities of TFIIH could help to coordinate different cellular processes.…”

“…In association with Crumbs (Crb) and Galla, XPD has also been found in a CGX complex, which is required for proper chromosome segregation during nuclear division in early Drosophila embryos (37). Crb, which recruits XPD and promotes the binding between Galla and XPD, is involved in retinal morphogenesis during postembryonic development (134,135).…”

TFIIH localization is highly dynamic during zygotic genome activation in Drosophila, and its depletion causes catastrophic mitosis

“…However, XPD has been demonstrated to be a component of the MMXD complex, which is involved in chromosome segregation in human cells; thus, XPD depletion produces catastrophic mitosis (Ito et al, 2010). Furthermore, in Drosophila, XPD physically and genetically interacts with Galla, the fly homologue of a component of the human MMXD complex, which when defective also causes catastrophic mitosis during early embryonic nuclear division (Yeom et al, 2014). Therefore, the general transcription factor TFIIH is involved in at least three fundamental cellular processes: transcription, DNA repair and cell cycle regulation.…”