Snail transcription factor is up-regulated in several cancers and associated with increased tumor migration and invasion via induction of epithelial-to-mesenchymal transition (EMT). MAPK (ERK1/2) ...signaling regulates cellular processes including cell motility, adhesion, and invasion. We investigated the regulation of ERK1/2 by Snail in breast cancer cells. ERK1/2 activity (p-ERK) was higher in breast cancer patient tissue as compared to normal tissue. Snail and p-ERK were increased in several breast cancer cell lines as compared to normal mammary epithelial cells. Snail knockdown in MDA-MB-231 and T47-D breast cancer cells decreased or re-localized p-ERK from the nuclear compartment to the cytoplasm. Snail overexpression in MCF-7 breast cancer cells induced EMT, increased cell migration, decreased cell adhesion and also increased tumorigenicity. Snail induced nuclear translocation of p-ERK, and the activation of its subcellular downstream effector, Elk-1. Inhibiting MAPK activity with UO126 or knockdown of ERK2 isoform with siRNA in MCF-7 Snail cells reverted EMT induced by Snail as shown by decreased Snail and vimentin expression, decreased cell migration and increased cell adhesion. Overall, our data suggest that ERK2 isoform activation by Snail in aggressive breast cancer cells leads to EMT associated with increased cell migration and decreased cell adhesion. This regulation is enhanced by positive feedback regulation of Snail by ERK2. Therefore, therapeutic targeting of ERK2 isoform may be beneficial for breast cancer.
The RNA exosome is an evolutionarily conserved, ribonuclease complex that is critical for both processing and degradation of a variety of RNAs. Cofactors that associate with the RNA exosome likely ...dictate substrate specificity for this complex. Recently, mutations in genes encoding both structural subunits of the RNA exosome and its cofactors have been linked to human disease. Mutations in the RNA exosome genes
and
cause pontocerebellar hypoplasia type 1b (PCH1b) and type 1c (PCH1c), respectively, which are similar autosomal-recessive, neurodegenerative diseases. Mutations in the RNA exosome gene
cause a distinct syndrome with various tissue-specific phenotypes including retinitis pigmentosa and mild intellectual disability. Mutations in genes that encode RNA exosome cofactors also cause tissue-specific diseases with complex phenotypes. How mutations in these genes give rise to distinct, tissue-specific diseases is not clear. In this review, we discuss the role of the RNA exosome complex and its cofactors in human disease, consider the amino acid changes that have been implicated in disease, and speculate on the mechanisms by which exosome gene mutations could underlie dysfunction and disease.
Highly conserved Inhibitors of DNA-Binding (ID1–ID4) genes encode multi-functional proteins whose transcriptional activity is based on dominant negative inhibition of basic helix–loop–helix (bHLH) ...transcription factors. Initial animal models indicated a degree of compensatory overlap between ID genes such that deletion of multiple ID genes was required to generate easily recognizable phenotypes. More recently, new model systems have revealed alterations in mice harboring deletions in single ID genes suggesting complex gene and tissue specific functions for members of the ID gene family. Because ID genes are highly expressed during development and their function is associated with a primitive, proliferative cellular phenotype there has been significant interest in understanding their potential roles in neoplasia. Indeed, numerous studies indicate an oncogenic function for ID1, ID2 and ID3. In contrast, the inhibitor of differentiation 4 (ID4) presents a paradigm shift in context of well-established role of ID1, ID2 and ID3 in development and cancer. Apart from some degree of functional redundancy such as HLH dependent interactions with bHLH protein E2A, many of the functions of ID4 are distinct from ID1, ID2 and ID3: ID4 proteins a) regulate distinct developmental processes and tissue expression in the adult, b) promote stem cell survival, differentiation and/or timing of differentiation, c) epigenetic inactivation/loss of expression in several advanced stage cancers and d) increased expression in some cancers such as those arising in the breast and ovary. Thus, in spite of sharing the conserved HLH domain, ID4 defies the established model of ID protein function and expression. The underlying molecular mechanism responsible for the unique role of ID4 as compared to other ID proteins still remains largely un-explored. This review will focus on the current understanding of ID4 in context of development and cancer.
The RNA exosome is an evolutionarily-conserved ribonuclease complex critically important for precise processing and/or complete degradation of a variety of cellular RNAs. The recent discovery that ...mutations in genes encoding structural RNA exosome subunits cause tissue-specific diseases makes defining the role of this complex within specific tissues critically important. Mutations in the RNA exosome component 3 (EXOSC3) gene cause Pontocerebellar Hypoplasia Type 1b (PCH1b), an autosomal recessive neurologic disorder. The majority of disease-linked mutations are missense mutations that alter evolutionarily-conserved regions of EXOSC3. The tissue-specific defects caused by these amino acid changes in EXOSC3 are challenging to understand based on current models of RNA exosome function with only limited analysis of the complex in any multicellular model in vivo. The goal of this study is to provide insight into how mutations in EXOSC3 impact the function of the RNA exosome. To assess the tissue-specific roles and requirements for the Drosophila ortholog of EXOSC3 termed Rrp40, we utilized tissue-specific RNAi drivers. Depletion of Rrp40 in different tissues reveals a general requirement for Rrp40 in the development of many tissues including the brain, but also highlight an age-dependent requirement for Rrp40 in neurons. To assess the functional consequences of the specific amino acid substitutions in EXOSC3 that cause PCH1b, we used CRISPR/Cas9 gene editing technology to generate flies that model this RNA exosome-linked disease. These flies show reduced viability; however, the surviving animals exhibit a spectrum of behavioral and morphological phenotypes. RNA-seq analysis of these Drosophila Rrp40 mutants reveals increases in the steady-state levels of specific mRNAs and ncRNAs, some of which are central to neuronal function. In particular, Arc1 mRNA, which encodes a key regulator of synaptic plasticity, is increased in the Drosophila Rrp40 mutants. Taken together, this study defines a requirement for the RNA exosome in specific tissues/cell types and provides insight into how defects in RNA exosome function caused by specific amino acid substitutions that occur in PCH1b can contribute to neuronal dysfunction.
The Drosophila polyadenosine RNA binding protein Nab2, which is orthologous to a human protein lost in a form of inherited intellectual disability, controls adult locomotion, axon projection, ...dendritic arborization, and memory through a largely undefined set of target RNAs. Here, we show a specific role for Nab2 in regulating splicing of ~150 exons/introns in the head transcriptome and focus on retention of a male-specific exon in the sex determination factor Sex-lethal (Sxl) that is enriched in female neurons. Previous studies have revealed that this splicing event is regulated in females by N6-methyladenosine (m6A) modification by the Mettl3 complex. At a molecular level, Nab2 associates with Sxl pre-mRNA in neurons and limits Sxl m6A methylation at specific sites. In parallel, reducing expression of the Mettl3, Mettl3 complex components, or the m6A reader Ythdc1 rescues mutant phenotypes in Nab2 flies. Overall, these data identify Nab2 as an inhibitor of m6A methylation and imply significant overlap between Nab2 and Mettl3 regulated RNAs in neuronal tissue.
Abstract
Working with multiple mentors is a critical way for students to expand their network, gain opportunities, and better prepare for future scholastic or professional ventures. However, students ...from underrepresented groups (UR) are less likely to be mentored or have access to mentors, particularly in science, technology, engineering, and mathematics (STEM) fields. We developed and implemented a workshop, to provide the necessary foundation for students to be better prepared for establishing future mentorships throughout graduate and professional school. Faculty well-versed in the area of effective mentorship from multiple universities developed and delivered a 1.5-hour workshop to address the roles of a mentor, especially when it comes to UR students, and how students may effectively work with multiple mentors. This workshop was delivered to a group of students from, the Historically Black College and University (HBCU), Winston-Salem State University, and a pre/post-10-point Likert scale-based survey was administered where 1 represented strongly disagree and 10 was strongly agree. The questions used in this seminar were newly designed by the authors as program evaluations. We analyzed the raw data with nonparametric tests for comparison within paired samples. Wilcoxon matched-pairs and signed-rank tests showed statistically significant growth in student self-ratings related to the workshop learning objectives. The ‘How to Handle More than One Mentor to Achieve Excellence’ workshop was well-received as a component of pregraduate and preprofessional training. Incorporating workshops like this may increase student preparedness around developing and cultivating healthy mentorship relationships throughout STEM training.
This contribution reports the outcome of a workshop focused on increasing student preparedness around developing and cultivating healthy mentorship relationships throughout STEM training.
Experimental evolution with
has been used extensively for decades to study aging and longevity. In recent years, the addition of DNA and RNA sequencing to this framework has allowed researchers to ...leverage the statistical power inherent to experimental evolution to study the genetic basis of longevity itself. Here, we incorporated metabolomic data into to this framework to generate even deeper insights into the physiological and genetic mechanisms underlying longevity differences in three groups of experimentally evolved
populations with different aging and longevity patterns. Our metabolomic analysis found that aging alters mitochondrial metabolism through increased consumption of NAD
and increased usage of the TCA cycle. Combining our genomic and metabolomic data produced a list of biologically relevant candidate genes. Among these candidates, we found significant enrichment for genes and pathways associated with neurological development and function, and carbohydrate metabolism. While we do not explicitly find enrichment for aging canonical genes, neurological dysregulation and carbohydrate metabolism are both known to be associated with accelerated aging and reduced longevity. Taken together, our results provide plausible genetic mechanisms for what might be driving longevity differences in this experimental system. More broadly, our findings demonstrate the value of combining multiple types of omic data with experimental evolution when attempting to dissect mechanisms underlying complex and highly polygenic traits such as aging.
Deregulation of tumor suppressor genes is associated with tumorigenesis and the development of cancer. In prostate cancer, ID4 is epigenetically silenced and acts as a tumor suppressor. In normal ...prostate epithelial cells, ID4 collaborates with androgen receptor (AR) and p53 to exert its tumor suppressor activity. Previous studies have shown that ID4 promotes tumor suppressive function of AR whereas loss of ID4 results in tumor promoter activity of AR. Previous study from our lab showed that ectopic ID4 expression in DU145 attenuates proliferation and promotes AR expression suggesting that ID4 dependent AR activity is tumor suppressive. In this study, we examined the effect of ectopic expression of ID4 on highly malignant prostate cancer cell, PC3. Here we show that stable overexpression of ID4 in PC3 cells leads to increased apoptosis and decreased cell proliferation and migration. In addition, in vivo studies showed a decrease in tumor size and volume of ID4 overexpressing PC3 cells, in nude mice. At the molecular level, these changes were associated with increased androgen receptor (AR), p21, and AR dependent FKBP51 expression. At the mechanistic level, ID4 may regulate the expression or function of AR through specific but yet unknown AR co-regulators that may determine the final outcome of AR function.
•ID4 expression induces AR expression in PC3 cells, which generally lack AR.•ID4 expression increased apoptosis and decreased cell proliferation and invasion.•Overexpression of ID4 reduces tumor growth of subcutaneous xenografts in vivo.•ID4 induces p21 and FKBP51 expression- co-factors of AR tumor suppressor activity.
Abstract
The success of mentoring derives from active and respectful listening and the willingness to learn and accept opportunities for personal growth. This shapes every trainee and their destined ...path in science, technology, engineering, and mathematics (STEM). The act of cultivating rapport, asking, and pondering meaningful questions, and receiving constructive feedback are critical to support a productive mentoring relationship. Successful mentoring in STEM can be established and allow mentees, especially underrepresented minorities (URMs), to flourish in an environment where they feel welcomed and supported. However, mentees from underrepresented groups often experience inadequate mentoring due to a mentor's lack of awareness, poor trainings themselves, or lack of understanding of the mentee’s hardships. It is important for mentors and mentees to work together to promote diversity, equity, and inclusion (DEI) in STEM education through creativity, authenticity, and networking. We analyzed data obtained from students who attended a recent workshop that are interested in going to graduate school. Our results show that despite low initial expectations for the workshop, many students were satisfied in the knowledge they gleaned. The future and role of diversity in STEM within these underrepresented groups lies in community support and an important role that they can play in the lives of others through DEI initiatives and throughout their careers all of which involves positive mentoring.
Notably, underrepresented minorities (URM) trainees often experience inadequate mentoring due to their mentor’s inexperience with URM groups, poor mentorship training, or a lack of understanding of their mentee’s journey.
Abstract
Despite an increase in programming to promote persons excluded by their ethnicity or race (PEER) scholars, minorities remain underrepresented in many STEM programs. The academic pipeline is ...largely leaky for underrepresented minority (URM) scholars due to a lack of effective mentorship. Many URM students experience microaggressions and discrimination from their mentors due to a lack of quality mentorship training. In this workshop, we provide a framework to show trainees what effective mentoring looks like. Mentees, especially URM trainees, can flourish in effective mentoring environments where they feel welcomed and can comfortably develop new ideas without feeling threatened by external factors. Effective mentoring environments provide motivational support, empathy, cultural competency, and training. This workshop explains facets of effective mentoring to students, as well as highlights to URM trainees why mentors can serve as valuable resources.
The authors provide a framework for how to be an effective mentor to URM trainees; this workshop helps to establish mentees, especially URM trainees, to have a more effective mentoring environment where they feel welcomed and can comfortably develop new ideas without feeling threatened by external factors.
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