Project description:We have used microarray technology to identify the transcriptional targets of Rho subfamily GTPases. This analysis indicated that murine fibroblasts transformed by these proteins show similar transcriptomal profiles. Functional annotation of the regulated genes indicate that Rho subfamily GTPases target a wide spectrum of biological functions, although loci encoding proteins linked to proliferation and DNA synthesis/transcription are up-regulated preferentially. Rho proteins promote four main networks of interacting proteins nucleated around E2F, c-Jun, c-Myc, and p53. Of those, E2F, c-Jun and c-Myc are essential for the maintenance of cell transformation. Inhibition of Rock, one of the main Rho GTPase targets, leads to small changes in the transcriptome of Rho-transformed cells. Rock inhibition decreases c-myc gene expression without affecting the E2F and c-Jun pathways. Loss-of-function studies demonstrate that c-Myc is important for the blockage of cell-contact inhibition rather than for promoting the proliferation of Rho-transformed cells. However, c-Myc overexpression does not bypass the inhibition of cell transformation induced by Rock blockage, indicating that c-Myc is essential, but not sufficient, for Rock-dependent transformation. These results reveal the complexity of the genetic program orchestrated by the Rho subfamily and pinpoint protein networks that mediate different aspects of the malignant phenotype of Rho-transformed cells Keywords: Rho/Rac GTPases, microarray, oncogenesis, proliferation, gene expression, transcription, Rock, c-Myc
Project description:Rho family small GTPases serve as molecular switches in the regulation of diverse cellular functions including actin cytoskeleton remodeling, cell migration, gene transcription, and cell proliferation. Importantly, Rho overexpression is frequently seen in many carcinomas. However, published studies have almost invariably utilized immortal or tumorigenic cell lines to study Rho GTPase functions and there are no studies on the potential of Rho small GTPase to overcome senescence checkpoints and induce preneoplastic transformation of human mammary epithelial cells (hMECs). We found that ectopic expression of wild-type RhoA as well as a constitutively-active RhoA mutant (G14V) in primary hMEC strains led to their immortalization and preneoplastic transformation. Significantly, RhoA-T37A mutant, known to be incapable of interacting with many well known Rho-effectors ,was also capable of immortalizing hMECs.Our results demonstrate that RhoA can induce the preneoplastic transformation of hMECs by altering multiple pathways linked cellular transformation and breast cancer. Through microarray analysis, we want to identify genes and pathways linked to RhoA induced hMECs immortalization. Experiment Overall Design: 4 samples, in triplicate analyses per sample.
Project description:We have used microarray technology to identify the transcriptional targets of Rho subfamily GTPases. This analysis indicated that murine fibroblasts transformed by these proteins show similar transcriptomal profiles. Functional annotation of the regulated genes indicate that Rho subfamily GTPases target a wide spectrum of biological functions, although loci encoding proteins linked to proliferation and DNA synthesis/transcription are up-regulated preferentially. Rho proteins promote four main networks of interacting proteins nucleated around E2F, c-Jun, c-Myc, and p53. Of those, E2F, c-Jun and c-Myc are essential for the maintenance of cell transformation. Inhibition of Rock, one of the main Rho GTPase targets, leads to small changes in the transcriptome of Rho-transformed cells. Rock inhibition decreases c-myc gene expression without affecting the E2F and c-Jun pathways. Loss-of-function studies demonstrate that c-Myc is important for the blockage of cell-contact inhibition rather than for promoting the proliferation of Rho-transformed cells. However, c-Myc overexpression does not bypass the inhibition of cell transformation induced by Rock blockage, indicating that c-Myc is essential, but not sufficient, for Rock-dependent transformation. These results reveal the complexity of the genetic program orchestrated by the Rho subfamily and pinpoint protein networks that mediate different aspects of the malignant phenotype of Rho-transformed cells Experiment Overall Design: In order to generate the cell clones used in this study, we took advantage of the oncogenic properties of the constitutively active versions (Q63L mutants) of Rho subfamily proteins when overexpressed in rodent fibroblasts (Schuebel et al., 1998). Based on this property, we transfected NIH3T3 cells with plasmids encoding the indicated versions of Rho subfamily proteins to obtain foci of transformed cells. Selected foci were picked, pooled, and used for the subsequent microarray experiments. Experiment Overall Design: To avoid the activation of genetic programs related to serum withdrawal or contact inhibition that may confound the detection of Rho-specific transcriptomal changes (Coller et al., 2006), we cultured the chosen cell lines and the parental NIH3T3 cells in the presence of serum and maintained them at confluency levels lower than 70% prior to RNA extraction. In addition, we isolated total RNAs from eight (in the case of NIH3T3 cells), seven (in the case of RhoAQ63L-transformed cells) and six (in the case of RhoBQ63L- and RhoCQ63L-transformed cells) independent cell cultures in order to make it possible a robust statistical treatment of the data obtained. Experiment Overall Design: three 10-cm diameter plates containing exponentially growing cultures of IMB11-1P (expressing RhoAQ63L) IMB11-2P (expressing RhoBQ63L), or IMB11-3P (expressing RhoCQ63L) cells were washed with PBS and their total cellular RNAs isolated using the RNeasy kit (Qiagen) according to the supplierâs specifications. The quantity and quality of the total RNAs obtained was determined using 6000 Nano Chips (Agilent Technologies). Total RNA samples (4 ug) were then processed for hybridization on MGU75Av2 microarrays (Affymetrix) using standard Affymetrix protocols at the CIC Genomics and Proteomics Facility (www.cicancer.org). Normalization, filtering and analysis of the raw data obtained from the microarrays was carried out with the Bioconductor software (www.bioconductor.com) using de ReadAffy package and the RMA application. The RMA algorithm was selected over the standard Affymetrix software because it provides a better precision in signal detection to achieve adequate normalization of multiple microarray hybridizations, especially in cases of low levels of gene expression (Bolstad et al., 2004; Gautier et al., 2004; Gentleman et al., 2004; Parrish & Spencer, 2004). We considered a gene to be differentially expressed when exhibiting a signal ⥠100 and met the following criteria: in the case of the characterization of the transcriptome of Rho-transformed cells, we regarded a gene as common to all GTPases when: i) It showed a fold change ⥠1.5 in at least two of the cell lines used. ii) The fold change in the third cell line was ⥠1.0 and displayed a similar variation trend when compared to the other two cell lines (i.e., similar up-regulation or down-modulation in the three cell lines). iii) The fold change values in the three cell lines had always P values ⤠0.01. We regarded a gene as common to only two GTPases when: i) It showed a fold change ⥠1.5 in two the cell lines with P values ⤠0.01. ii) The fold change in the third cell line was non-existent or, alternatively, had P values ⥠0.01. We considered a gene as uniquely-regulated by a GTPase when: i) The fold change in the expression levels of is transcript in the cell line transformed by that GTPase was ⥠1.5 with P value ⤠0.01. ii) The fold change, if any, obtained in the other cell lines had P values ⥠0.01. Statistical analyses were performed using F-statistics.
Project description:Engrams are considered to be substrates for memory storage, and the functional dysregulation of the engrams leads to cognition impairment.However, the cellular basis for these maladaptive changes lead to the forgetting of memories remains unclear. Here we found that the expression of autophagy protein 7 (Atg7) mRNA was dramatically upregulated in aged DG engrams, and led to the forgetting of contextual fear memory and the activation of surrounding microglia.To determine mechanism by which autophagy in DG engrams activates the surrounding microglia, mice were co-injected AAV-RAM-Cre either with AAV-Dio-Atg7-Flag or AAV-Dio- EYFP in dorsal dentate gyrus to overexpress ATG7 in the DG memory engrams. Microglia were separated using magnetic-activated cell sorting and subjected to RNA-Seq in dorsal hippocampus .Bioinformatics analysis shown overexpression of Atg7 in dorsal DG memory engrams caused an increase in the expression of Tlr2 in the surrounding microglia.Depletion of Toll-like receptor 2/4 (TLR2/4) in DG microglia prohibited excessive microglial activation and synapse elimination induced by the overexpression of ATG7 in DG engrams, and thus prevented forgetting. Furthermore, the expression of Rac1, a Rho-GTPases which regulates active forgetting in both fly and mice, was upregulated in aged engrams. Optogentic activation of Rac1 in DG engrams promoted the autophagy of the engrams, the activation of microglia, and the forgetting of fear memory. Invention of the Atg7 expression and microglia activation attenuated forgetting induced by activation of Rac1 in DG engrams. Together, our findings revealed autophagy-dependent synapse elimination of DG engrams by microglia as a novel forgetting mechanism.
Project description:Rho family small GTPases serve as molecular switches in the regulation of diverse cellular functions including actin cytoskeleton remodeling, cell migration, gene transcription, and cell proliferation. Importantly, Rho overexpression is frequently seen in many carcinomas. However, published studies have almost invariably utilized immortal or tumorigenic cell lines to study Rho GTPase functions and there are no studies on the potential of Rho small GTPase to overcome senescence checkpoints and induce preneoplastic transformation of human mammary epithelial cells (hMECs). We found that ectopic expression of wild-type RhoA as well as a constitutively-active RhoA mutant (G14V) in primary hMEC strains led to their immortalization and preneoplastic transformation. Significantly, RhoA-T37A mutant, known to be incapable of interacting with many well known Rho-effectors ,was also capable of immortalizing hMECs.Our results demonstrate that RhoA can induce the preneoplastic transformation of hMECs by altering multiple pathways linked cellular transformation and breast cancer. Through microarray analysis, we want to identify genes and pathways linked to RhoA induced hMECs immortalization.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:RHO subfamily of small GTPases comprise highly conserved family members RHOA, RHOB, and RHOC which cycle between GTP-bound 'active' and GDP-bound 'inactive' states. In the active form, RHO proteins interact with a variety of downstream effector proteins, controlling their activity and function. Many of the RHO subfamily effector proteins such as ROCK, PKN, and mDIA, are key regulators of actin cytoskeleton and cell motility. To identify novel effector proteins for RHOA,we carried out a GST-pulldown from heavy or light SILAC labelled HeLa cells using GST tagged GTP-bound RHOA, or GST alone control, as bait. Pulldowns were performed in duplicates with switched labellings. Specific interactors were destinguished from the background on the basis of SILAC Heavy to Light ratios between GST-RHOA and GST alone pulldowns.