Try a new search

Format these results:

Searched for:

person:sanchi01

in-biosketch:yes

Total Results:

21


Whole-genome screen identifies diverse pathways that negatively regulate ciliogenesis

Failler, Marion; Giro-Perafita, Ariadna; Owa, Mikito; Srivastava, Shalini; Yun, Chi; Kahler, David J; Unutmaz, Derya; Esteva, Francisco J; Sánchez, Irma; Dynlacht, Brian D
We performed a high-throughput whole-genome RNAi screen to identify novel inhibitors of ciliogenesis in normal and basal breast cancer cells. Our screen uncovered a previously undisclosed, extensive network of genes linking integrin signaling and cellular adhesion to the extracellular matrix with inhibition of ciliation in both normal and cancer cells. Surprisingly, a cohort of genes encoding extracellular matrix (ECM) proteins was also identified. We characterized several ciliation inhibitory genes and showed that their silencing was accompanied by altered cytoskeletal organization and induction of ciliation, which restricts cell growth and migration in normal and breast cancer cells. Conversely, supplying an integrin ligand, vitronectin, to the ECM rescued the enhanced ciliation observed upon silencing this gene. Aberrant ciliation could also be suppressed through hyper-activation of the YAP/TAZ pathway, indicating a potential mechanistic basis for our findings. Our findings suggest an unanticipated reciprocal relationship between ciliation and cellular adhesion to the extracellular matrix and provide a resource that could vastly expand our understanding of controls involving "outside-in" and "inside-out" signaling that restrain cilium assembly.
PMID: 33206585
ISSN: 1939-4586
CID: 4672802

LncRNA RP11-19E11 is an E2F1 target required for proliferation and survival of basal breast cancer

Giro-Perafita, A; Luo, L; Khodadadi-Jamayran, A; Thompson, M; Akgol Oksuz, B; Tsirigos, A; Dynlacht, B D; Sánchez, I; Esteva, F J
Long non-coding RNAs (lncRNAs) play key roles in the regulation of breast cancer initiation and progression. LncRNAs are differentially expressed in breast cancer subtypes. Basal-like breast cancers are generally poorly differentiated tumors, are enriched in embryonic stem cell signatures, lack expression of estrogen receptor, progesterone receptor, and HER2 (triple-negative breast cancer), and show activation of proliferation-associated factors. We hypothesized that lncRNAs are key regulators of basal breast cancers. Using The Cancer Genome Atlas, we identified lncRNAs that are overexpressed in basal tumors compared to other breast cancer subtypes and expressed in at least 10% of patients. Remarkably, we identified lncRNAs whose expression correlated with patient prognosis. We then evaluated the function of a subset of lncRNA candidates in the oncogenic process in vitro. Here, we report the identification and characterization of the chromatin-associated lncRNA, RP11-19E11.1, which is upregulated in 40% of basal primary breast cancers. Gene set enrichment analysis in primary tumors and in cell lines uncovered a correlation between RP11-19E11.1 expression level and the E2F oncogenic pathway. We show that this lncRNA is chromatin-associated and an E2F1 target, and its expression is necessary for cancer cell proliferation and survival. Finally, we used lncRNA expression levels as a tool for drug discovery in vitro, identifying protein kinase C (PKC) as a potential therapeutic target for a subset of basal-like breast cancers. Our findings suggest that lncRNA overexpression is clinically relevant. Understanding deregulated lncRNA expression in basal-like breast cancer may lead to potential prognostic and therapeutic applications.
PMCID:6944689
PMID: 31934613
ISSN: 2374-4677
CID: 4264352

Prognostic role of elevated mir-24-3p in breast cancer and its association with the metastatic process

Khodadadi-Jamayran, Alireza; Akgol-Oksuz, Betul; Afanasyeva, Yelena; Heguy, Adriana; Thompson, Marae; Ray, Karina; Giro-Perafita, Ariadna; Sánchez, Irma; Wu, Xifeng; Tripathy, Debu; Zeleniuch-Jacquotte, Anne; Tsirigos, Aristotelis; Esteva, Francisco J
MicroRNAs have been shown to play important roles in breast cancer progression and can serve as biomarkers. To assess the prognostic role of a panel of miRNAs in breast cancer, we collected plasma prospectively at the time of initial diagnosis from 1,780 patients with stage I-III breast cancer prior to definitive treatment. We identified plasma from 115 patients who subsequently developed distant metastases and 115 patients without metastatic disease. Both groups were matched by: age at blood collection, year of blood collection, breast cancer subtype, and stage. The median follow up was 3.4 years (range, 1-9 years). We extracted RNA from plasma and analyzed the expression of 800 miRNAs using Nanostring technology. We then assessed the expression of miRNAs in primary and metastatic breast cancer samples from The Cancer Genome Atlas (TCGA). We found that, miR-24-3p was upregulated in patients with metastases, both in plasma and in breast cancer tissues. Patients whose primary tumors expressed high levels of miR-24-3p had a significantly lower survival rate compared to patients with low mir-24-3p levels in the TCGA cohort (n=1,024). RNA-Seq data of the samples with the highest miR-24-3p expression versus those with the lowest miR-24-3p in the TCGA cohort identified a specific gene expression signature for those tumors with high miR-24-3p. Possible target genes for miR-24-3p were predicted based on gene expression and binding site, and their effects on cancer pathways were evaluated. Cancer, breast cancer and proteoglycans were the top three pathways affected by miR-24-3p overexpression.
PMCID:5849180
PMID: 29560116
ISSN: 1949-2553
CID: 3000882

Gating Ciliary Transport

Sanchez, Irma; Dynlacht, Brian D
Cilia lack the ability to synthesize proteins and thus require dynamic transport. Reporting in this issue of Developmental Cell, Kanie et al. (2017) shed light on the mechanism of transport by implicating CEP19, which is associated with an autosomal-recessive obesity syndrome when mutated, in the triggering of intraflagellar transport.
PMID: 28697332
ISSN: 1878-1551
CID: 2630422

Rnf11 sequestration of Smurf2 on membranes antagonizes Smad7 down-regulation of TGFbeta signaling

Malonis, Ryan J; Fu, Wenxiang; Jelcic, Mark J; Thompson, Marae; Canter, Brian S; Tsikitis, Mary; Esteva, Francisco J; Sanchez, Irma
The activity of the E3 ligase, Smurf2, is antagonized by an intra-molecular, auto-inhibitory interaction between its C2 and Hect domains. Relief of Smurf2 auto-inhibition is induced by TGFbeta and is mediated by the inhibitory SMAD, Smad7. In a proteomic screen for endo-membrane interactants of the RING-domain E3 ligase, Rnf11, we identified Smurf2, among a cohort of Hect E3 ligases previously implicated in TGFbeta signaling. Reconstitution of the Smurf2/Rnf11 complex in vitro unexpectedly revealed robust Smurf2 E3 ligase activity, with biochemical properties previously restricted to the Smurf2/Smad7 complex. Using in vitro binding assays, we find that Rnf11 can directly compete with Smad7 for Smurf2 and that binding is mutually exclusive and dependent on a proline-rich domain. Moreover, we found that co-expression of Rnf11 and Smurf2 dramatically reduced Smurf2 ubiquitylation in the cell. This effect is strictly dependent on complex formation and sorting determinants that regulate the association of Rnf11 with membranes. Rnf11 is over-expressed in certain tumors, and, importantly, we find that depletion of this protein down-regulated gene expression of several TGFbeta-responsive genes, dampened cell proliferation, and dramatically reduced cell migration in response to TGFbeta. Our data suggest for the first time that choice of binding partners for Smurf2 can sustain or repress TGFbeta signaling and Rnf11 may promote TGFbeta-induced cell migration.
PMCID:5418044
PMID: 28292929
ISSN: 1083-351x
CID: 2544592

Cilium assembly and disassembly

Sanchez, Irma; Dynlacht, Brian David
The primary cilium is an antenna-like, immotile organelle present on most types of mammalian cells, which interprets extracellular signals that regulate growth and development. Although once considered a vestigial organelle, the primary cilium is now the focus of considerable interest. We now know that ciliary defects lead to a panoply of human diseases, termed ciliopathies, and the loss of this organelle may be an early signature event during oncogenic transformation. Ciliopathies include numerous seemingly unrelated developmental syndromes, with involvement of the retina, kidney, liver, pancreas, skeletal system and brain. Recent studies have begun to clarify the key mechanisms that link cilium assembly and disassembly to the cell cycle, and suggest new possibilities for therapeutic intervention.
PMCID:5079433
PMID: 27350441
ISSN: 1476-4679
CID: 2165552

Tethering of an E3 ligase by PCM1 regulates the abundance of centrosomal KIAA0586/Talpid3 and promotes ciliogenesis

Wang, Lei; Lee, Kwanwoo; Malonis, Ryan; Sanchez, Irma; Dynlacht, Brian D
To elucidate the role of centriolar satellites in ciliogenesis, we deleted the gene encoding the PCM1 protein, an integral component of satellites. PCM1 null human cells show marked defects in ciliogenesis, precipitated by the loss of specific proteins from satellites and their relocation to centrioles. We find that an amino-terminal domain of PCM1 can restore ciliogenesis and satellite localization of certain proteins, but not others, pinpointing unique roles for PCM1 and a group of satellite proteins in cilium assembly. Remarkably, we find that PCM1 is essential for tethering the E3 ligase, Mindbomb1 (Mib1), to satellites. In the absence of PCM1, Mib1 destabilizes Talpid3 through poly-ubiquitylation and suppresses cilium assembly. Loss of PCM1 blocks ciliogenesis by abrogating recruitment of ciliary vesicles associated with the Talpid3-binding protein, Rab8, which can be reversed by inactivating Mib1. Thus, PCM1 promotes ciliogenesis by tethering a key E3 ligase to satellites and restricting it from centrioles.
PMCID:4858382
PMID: 27146717
ISSN: 2050-084x
CID: 2100872

Cell biology: Short RNAs and shortness of breath [Comment]

Sanchez, Irma; Dynlacht, Brian D
PMCID:5079430
PMID: 24899299
ISSN: 0028-0836
CID: 1061982

Traf7, a MyoD1 transcriptional target, regulates nuclear factor-kappaB activity during myogenesis

Tsikitis, Mary; Acosta-Alvear, Diego; Blais, Alexandre; Campos, Eric I; Lane, William S; Sanchez, Irma; Dynlacht, Brian D
We have identified the E3 ligase Traf7 as a direct MyoD1 target and show that cell cycle exit-an early event in muscle differentiation-is linked to decreased Traf7 expression. Depletion of Traf7 accelerates myogenesis, in part through downregulation of nuclear factor-kappaB (NF-kappaB) activity. We used a proteomic screen to identify NEMO, the NF-kappaB essential modulator, as a Traf7-interacting protein. Finally, we show that ubiquitylation of NF-kappaB essential modulator is regulated exclusively by Traf7 activity in myoblasts. Our results suggest a new mechanism by which MyoD1 function is coupled to NF-kappaB activity through Traf7, regulating the balance between cell cycle progression and differentiation during myogenesis
PMCID:2999857
PMID: 20948544
ISSN: 1469-3178
CID: 114826

Cep76, a centrosomal protein that specifically restrains centriole reduplication

Tsang, William Y; Spektor, Alexander; Vijayakumar, Sangeetha; Bista, Bigyan R; Li, Ji; Sanchez, Irma; Duensing, Stefan; Dynlacht, Brian D
Centrosomes duplicate only once per cell cycle, but the controls that govern this process are largely unknown. We have identified Cep76, a centriolar protein that interacts with CP110. Cep76 is expressed at low levels in G1 and is induced in S and G2 phase, during which point centrioles have already commenced duplication. Interestingly, depletion of Cep76 drives the accumulation of centriolar intermediates in certain types of cancer cells. Enforced Cep76 expression specifically inhibits centriole amplification in cells undergoing multiple rounds of duplication without preventing the formation of extra procentrioles from a parental template. Furthermore, elevated levels of Cep76 do not affect normal centriole duplication. Thus, Cep76 helps limit duplication to once per cell cycle. Our findings also point to mechanistic differences between normal duplication and aberrant centriole amplification, as well as distinctions between diverse modes of amplification
PMCID:4062978
PMID: 19460342
ISSN: 1878-1551
CID: 99216