The tumor suppressor, vitamin D3 up-regulated protein 1 (VDUP1), functions downstream of REPO during Drosophila gliogenesis

Abstract

The tumor suppressor, vitamin D(3) up-regulated protein 1 (VDUP1), regulates cell cycle progression by suppressing AP-1-dependent transcription. Loss of VDUP1 activity is associated with tumorigenesis but little is known about VDUP1 regulatory controls or developmental roles. Here we show that the Drosophila homolog of human VDUP1 (dVDUP1) is expressed throughout the nervous system at all stages of development, the first in vivo analysis of VDUP1 expression patterns in the brain. During neurogenesis dVDUP1 expression is transiently down-regulated coincident with neuroblast delamination. Subsequent to expression of the neuronal marker elav, dVDUP1 is up-regulated to varying degrees in developing neurons. In contrast, dVDUP1 expression is both robust and sustained during gliogenesis, and the cis-regulatory region of the dvdup1 gene contains consensus binding sites for the glial fate gene reversed polarity (repo). Expression of dVDUP1 in presumptive glia is lost in embryos deficient for the glial fate genes glial cells missing (gcm) and repo. Conversely, ectopic expression of gcm or repo was sufficient to induce dVDUP1 expression in the nervous system. Taken together, these data suggest a novel role for the dVDUP1 tumor suppressor during nervous system development as a regulatory target for REPO during gliogenesis.

Expression and regulation of vitamin D3 upregulated protein 1 (VDUP1) is conserved in mammalian and insect brain

“…3B). The 50-kDa band corresponds to the molecular weight for VDUP1 predicted from the amino acid sequence; the higher molecular weight VDUP1 isoform (55 kDa) has been previously observed and arises from posttranslational modification (Mandalaywala et al, 2008). Anti-VDUP1 C-18 and D-15 immunoreactivity was eliminated by preincubation of the diluted antisera with appropriate blocking peptides (Fig.…”

“…The C-18 antibody was generated using a synthetic peptide (DSPIFMYAPEF) mapping to amino acids 360 -370 of the human VDUP1 C-terminus; the D-15 antibody was generated using a synthetic peptide (DLNIPDTPEAPPCYMDVIPE) mapping to amino acids 321-340 of the C-terminus of human VDUP1. On Western blots of rat brain, both C-18 and D-15 VDUP1 antisera recognized the expected (50 kDa) band and a higher molecular weight isoform (55 kDa) previously reported (Mandalaywala et al, 2008) to arise from posttranslational modification of VDUP1. Staining was eliminated when diluted antisera was preincubated with 5 g/mL blocking peptides.…”

“…VDUP1 expression during Drosophila embryonic and larval nervous system development was previously shown to be required for gliogenesis (Mandalaywala et al, 2008), although postdevelopmental roles and expression patterns were not characterized. In an effort to better understand VDUP1's role within the nervous system, VDUP1 expression patterns were analyzed in adult Drosophila brain.…”

“…In an effort to better understand VDUP1's role within the nervous system, VDUP1 expression patterns were analyzed in adult Drosophila brain. The JY2 mouse monoclonal anti-VDUP1 antibody used in these experiments was validated previously, which included the absence of immunoreactivity in embryos with a dvdup1 deletion (Mandalaywala et al, 2008). While representative sections of selected regions are shown for these studies, the entire brain was surveyedthe data summarize major trends and features of VDUP1 expression.…”

“…1, 2). During embryonic and larval development, VDUP1 is expressed in a majority of glia, where it is required for gliogenesis (Mandalaywala et al, 2008). To determine if glial ex- pression of VDUP1 was maintained postdevelopmentally, we examined adult brains of both wildtype (yw) flies and the gliogenic mutant reversed-polarity (repo 1 ) for coexpression of VDUP1 with glial markers (Fig.…”