The differentiation/retrodifferentiation program of human U937 leukemia cells is accompanied by changes of VCP/p97
ABSTRACT: A possible functional role of VCP/p97 during differentiation of U937 cells was addressed by siRNA-targeting of VCP/p97. Functional changes in VCP-siRNA-transfected cells following phorbol ester-induced monocytic differentiation have been examind by DNA microarray analysis. Cells transfected with the non-targeting AllStars negative siRNA (Qiagen) served as a reference. Keywords: cellular modification design Overall design: Computed
Project description:A possible functional role of VCP/p97 during differentiation of U937 cells was addressed by siRNA-targeting of VCP/p97. Functional changes in VCP-siRNA-transfected cells following phorbol ester-induced monocytic differentiation have been examind by DNA microarray analysis. Cells transfected with the non-targeting AllStars negative siRNA (Qiagen) served as a reference. Computed
Project description:Study of the effects of the VCP knockdown. VCP (p97, yeast cdc48) is a hexameric AAA ATPase involved in various cellular functions including degradation of proteins by the ubiquitin-proteasome system. We examine the consequences of the reduction of VCP levels after RNAi of VCP in HeLa cells. We find ~30 transcripts upregulated in a sequence independent manner. Those transcripts encode proteins involved in endoplasmic reticulum stress, apoptosis, and amino acid starvation.
Project description:VCP is an evolutionary conserved ubiquitin-dependent ATPase that mediates the degradation of proteins through the ubiquitin-proteasome pathway. Despite the central role of VCP in the regulation of protein homeostasis, identity and nature of its cellular substrates remain poorly defined. Here, we combined chemical inhibition of VCP and quantitative ubiquitin remnant profiling to assess the effect of VCP inhibition on the ubiquitin-modified proteome and to probe the substrate spectrum of VCP in human cells. We demonstrate that inhibition of VCP perturbs cellular ubiquitylation and increases ubiquitylation of a different subset of proteins compared to proteasome inhibition. VCP inhibition globally upregulates K6-linked ubiquitylation that is dependent on the HECT-type ubiquitin E3 ligase HUWE1. We report ~450 putative VCP substrates, many of which function in nuclear processes, including gene expression, DNA repair and cell cycle. Moreover, we identify that VCP regulates the level and activity of the transcription factor c-Myc. Overall design: RNA profiling of U2OS cells in the response to VCP inhibition by NMS-873 (5 µM, 4 h) treatment
Project description:The goal of this study was to analyze differential gene expression 8 hr after treatment of CB-5083, a small molecule inhibitor of p97 (VCP), in HCT116 cells grown in culture. DMSO treated cells were compared to cells treated with 1uM CB-5083 after 8 hr.
Project description:The ubiquitin-directed AAA-ATPase VCP/p97 facilitates degradation of misfolded proteins in diverse cellular stress response pathways. Resolving the complexity of dynamic interactions with hosts of accessory proteins and substrates has therefore been a major challenge. Here, we used affinity-purification SWATH mass spectrometry (AP-SWATH) to identify proteins that specifically interact with a p97 substrate-trapping mutant, p97-E578Q. AP-SWATH identified differential interactions over a large detection range from abundant cofactors to pathway-specific partners and individual ligases such as RNF185 and MUL1 that were trapped in p97-E578Q complexes. In addition, we identified substrate candidates including the PP1 regulator CReP/PPP1R15B that dephosphorylates eIF2α and thus counteracts attenuation of translation by stress-kinases. We demonstrate here that p97 with its Ufd1-Npl4 adapter ensures rapid turnover and balanced levels of CReP in unperturbed cells. Moreover, we show that p97 is essential for the quantitative stress-induced degradation of CReP and, consequently, robust eIF2α phosphorylation to enforce the stress response. Thus, p97 not only facilitates bulk degradation of misfolded proteins upon stress, but also has an unanticipated function in directly modulating the integrated stress response at the level of signalling.
Project description:To allow exclusion of non-expressed genes from the hit identification process, microarray analyses of (i) Allstars transfected and Chikungunya (CHIKV) infected, (ii) Allstars transfected and non-infected, (iii) non-transfected and CHIKV infected and (iv) non-transfected and non-infected 293 cells were performed. Transfection was done by adding 4x10e5 293 cells (in complete DMEM medium) to a mixture of serum-free RPMI medium, HiperFect (Qiagen) and Allstars siRNAs (Qiagen, final siRNA concentration: 20 nM). Infection with CHIKV-GFP was performed 72 h p.t. at an MOI of ~3. Cells were lysed 18 h p.i. using Trizol (Invitrogen), followed by RNA isolation, that was subsequently subjected to microarray analysis. Overall design: Microarray experiments were performed as dual-color hybridizations on Agilent 4x44K human whole genome catalog arrays (Agilent-014850). To compensate for dye-specific effects, a dye-reversal color-swap was applied.
Project description:Inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD) is caused by mutations in the Valosin Containing Protein (VCP) gene on chromosome 9p12-13. To elucidate affected signaling transduction axes in IBMPFD, we determined expression profiles using microarray technology in quadriceps muscle from patients and unaffected relatives. Muscle from 10 individuals (7 affected, 3 unaffected first degree relatives) was obtained after informed consent for the muscle biopsy was obtained.
Project description:Nutrient deprivation triggers stringent response in bacteria, allowing rapid reallocation of resources from proliferation toward stress survival. Critical to this process is the accumulation of (p)ppGpp regulated by the RelA/SpoT homologues. While mammalian genomes encode MESH1—the homologue of the bacterial (p)ppGpp hydrolase SpoT, neither (p)ppGpp nor its synthetase has been identified in mammalian cells. Therefore, the function of MESH1 remains a mystery. Here, we report that genetic removal of MESH1 from human cell induce an extensive transcriptional response. The changes are distinct from the canonical unfolding protein response but strongly resemble the bacterial stringent response, which induce cell proliferation arrest, implicating MESH1 in a previously uncharacterized stress response in human cells. Overall design: human clear cell renal carcinoma cell line RCC4 were transfected by two independent siRNA targeting MESH1 (siMESH1-CDS, siMESH1-3UTR=siMESH1-7002) and compared to the control with non-targeting siRNA (siNT). siMESH1-CDS: GGGAAUCACUGACAUUGUG, D-031786-01, Dharmacon siMESH1-3'UTR (siMESH1-7002): CTGAAGGTCTCCTGCTAACTA, SI04167002, Qiagen non-targeting siRNA (siNT, AllStars Negative Control siRNA, SI03650318).
Project description:Motor neurons (MNs) and astrocytes (ACs) are implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), but their interaction and the sequence of molecular events leading to MN death remain unresolved. Herewe optimized directed differentiation of induced pluripotent stem cells (iPSCs) into highly enriched (>85%) functional populations of spinal cord MNs and ACs. We identifysignificantlyincreased cytoplasmic TDP-43 and ER stress as primary pathogenic events in patient-specific valosin-containing protein (VCP)-mutant MNs, with secondary mitochondrial dysfunction and oxidative stress. Cumulatively these cellular stresses result in synaptic pathology and cell death in VCP-mutant MNs. We additionallyidentify a cell-autonomous VCP-mutant AC survival phenotype, which is not attributable to the same molecular pathology occurring in VCP-mutant MNs. Finally, through iterative co-culture experiments, we uncover non-cell-autonomous effects of VCP-mutant ACs on both control and mutant MNs. This work elucidates molecular events and cellular interplay thatcould guide future therapeutic strategies in ALS. Overall design: Bulk RNA-seq at different timepoints throughout a 35-day differentiation protocol that converted iPSC cells to highly enriched motor neurons.
Project description:In this study we use a combination of mass spectrometry-based proteomics and biophysical studies to characterize the interaction of adaptors with VCP. Our results reveal that most VCP–adaptor interactions are characterized by exceptionally rapid dynamics that in some cases are modulated by the VCP inhibitor NMS873. These findings have significant implications for both the regulation of VCP function and the impact of VCP inhibition on different VCP–adaptor complexes.