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Program in Molecular Medicine Publications and Presentations

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Articles 1 - 14 of 14

Full-Text Articles in Molecular Biology

A Microrna Family Exerts Maternal Control On Sex Determination In C. Elegans, Katherine Mcjunkin, Victor R. Ambros Feb 2017

A Microrna Family Exerts Maternal Control On Sex Determination In C. Elegans, Katherine Mcjunkin, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

Gene expression in early animal embryogenesis is in large part controlled post-transcriptionally. Maternally contributed microRNAs may therefore play important roles in early development. We elucidated a major biological role of the nematode mir-35 family of maternally contributed essential microRNAs. We show that this microRNA family regulates the sex determination pathway at multiple levels, acting both upstream of and downstream from her-1 to prevent aberrantly activated male developmental programs in hermaphrodite embryos. Both of the predicted target genes that act downstream from the mir-35 family in this process, suppressor-26 (sup-26) and NHL (NCL-1, HT2A, and LIN-41 repeat) domain-containing-2 (nhl-2), encode RNA-binding ...


Staufen Negatively Modulates Microrna Activity In Caenorhabditis Elegans, Zhiji Ren, Isana Veksler-Lublinsky, David Morrissey, Victor R. Ambros Feb 2016

Staufen Negatively Modulates Microrna Activity In Caenorhabditis Elegans, Zhiji Ren, Isana Veksler-Lublinsky, David Morrissey, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

The double-stranded RNA-binding protein Staufen has been implicated in various post-transcriptional gene regulatory processes. Here we demonstrate that the Caenorhabditis elegans homolog of Staufen, STAU-1, functionally interacts with microRNAs. Loss-of-function mutations of stau-1 significantly suppress phenotypes of let-7 family microRNA mutants, a hypomorphic allele of dicer and a lsy-6 microRNA partial loss-of-function mutant. Furthermore, STAU-1 modulates the activity of lin-14, a target of lin-4 and let-7 family microRNAs, and this modulation is abolished when the 3' untranslated region of lin-14 is removed. Deep sequencing of small RNA cDNA libraries reveals no dramatic change in the levels of microRNAs, or other ...


Tenomodulin Promotes Human Adipocyte Differentiation And Beneficial Visceral Adipose Tissue Expansion, Ozlem Senol-Cosar, Rachel J. Roth Flach, Marina Distefano, Anil K. Chawla, Sarah M. Nicoloro, Juerg R. Straubhaar, Olga T. Hardy, Hye Lim Noh, Jason K. Kim, Martin Wabitsch, Philipp E. Scherer, Michael P. Czech Feb 2016

Tenomodulin Promotes Human Adipocyte Differentiation And Beneficial Visceral Adipose Tissue Expansion, Ozlem Senol-Cosar, Rachel J. Roth Flach, Marina Distefano, Anil K. Chawla, Sarah M. Nicoloro, Juerg R. Straubhaar, Olga T. Hardy, Hye Lim Noh, Jason K. Kim, Martin Wabitsch, Philipp E. Scherer, Michael P. Czech

Program in Molecular Medicine Publications and Presentations

Proper regulation of energy storage in adipose tissue is crucial for maintaining insulin sensitivity and molecules contributing to this process have not been fully revealed. Here we show that type II transmembrane protein tenomodulin (TNMD) is upregulated in adipose tissue of insulin-resistant versus insulin-sensitive individuals, who were matched for body mass index (BMI). TNMD expression increases in human preadipocytes during differentiation, whereas silencing TNMD blocks adipogenesis. Upon high-fat diet feeding, transgenic mice overexpressing Tnmd develop increased epididymal white adipose tissue (eWAT) mass, and preadipocytes derived from Tnmd transgenic mice display greater proliferation, consistent with elevated adipogenesis. In Tnmd transgenic mice ...


Caenorhabditis Elegans Alg-1 Antimorphic Mutations Uncover Functions For Argonaute In Microrna Guide Strand Selection And Passenger Strand Disposal, Anna Y. Zinovyeva, Isana Veksler-Lublinsky, Ajay A. Vashisht, James A. Wohlschlegel, Victor R. Ambros Sep 2015

Caenorhabditis Elegans Alg-1 Antimorphic Mutations Uncover Functions For Argonaute In Microrna Guide Strand Selection And Passenger Strand Disposal, Anna Y. Zinovyeva, Isana Veksler-Lublinsky, Ajay A. Vashisht, James A. Wohlschlegel, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

MicroRNAs are regulators of gene expression whose functions are critical for normal development and physiology. We have previously characterized mutations in a Caenorhabditis elegans microRNA-specific Argonaute ALG-1 (Argonaute-like gene) that are antimorphic [alg-1(anti)]. alg-1(anti) mutants have dramatically stronger microRNA-related phenotypes than animals with a complete loss of ALG-1. ALG-1(anti) miRISC (microRNA induced silencing complex) fails to undergo a functional transition from microRNA processing to target repression. To better understand this transition, we characterized the small RNA and protein populations associated with ALG-1(anti) complexes in vivo. We extensively characterized proteins associated with wild-type and mutant ALG-1 and ...


Highly Selective In Vivo Labeling Of Subcutaneous White Adipocyte Precursors With Prx1-Cre, Joan Sanchez-Gurmaches, Wen-Yu Hsiao, David A. Guertin Apr 2015

Highly Selective In Vivo Labeling Of Subcutaneous White Adipocyte Precursors With Prx1-Cre, Joan Sanchez-Gurmaches, Wen-Yu Hsiao, David A. Guertin

Program in Molecular Medicine Publications and Presentations

The origins of individual fat depots are not well understood, and thus, the availability of tools useful for studying depot-specific adipose tissue development and function is limited. Cre drivers that selectively target only brown adipocyte, subcutaneous white adipocyte, or visceral white adipocyte precursors would have significant value because they could be used to selectively study individual depots without impacting the adipocyte precursors or intrinsic metabolic properties of the other depots. Here, we show that the majority of the precursor and mature subcutaneous white adipocytes in adult C57Bl/6 mice are labeled by Prx1-Cre. In sharp contrast, few to no brown ...


The Ino80 Complex Prevents Invasion Of Euchromatin Into Silent Chromatin, Yong Xue, Christopher Van, Suman K. Pradhan, Trent Su, Jason Gehrke, Benjamin G. Kuryan, Tasuku Kitada, Ajay Vashisht, Nancy Tran, James Wohlschlegel, Craig L. Peterson, Siavash K. Kurdistani, Michael F. Carey Feb 2015

The Ino80 Complex Prevents Invasion Of Euchromatin Into Silent Chromatin, Yong Xue, Christopher Van, Suman K. Pradhan, Trent Su, Jason Gehrke, Benjamin G. Kuryan, Tasuku Kitada, Ajay Vashisht, Nancy Tran, James Wohlschlegel, Craig L. Peterson, Siavash K. Kurdistani, Michael F. Carey

Program in Molecular Medicine Publications and Presentations

Here we show that the Ino80 chromatin remodeling complex (Ino80C) directly prevents euchromatin from invading transcriptionally silent chromatin within intergenic regions and at the border of euchromatin and heterochromatin. Deletion of Ino80C subunits leads to increased H3K79 methylation and noncoding RNA polymerase II (Pol II) transcription centered at the Ino80C-binding sites. The effect of Ino80C is direct, as it blocks H3K79 methylation by Dot1 in vitro. Heterochromatin stimulates the binding of Ino80C in vitro and in vivo. Our data reveal that Ino80C serves as a general silencing complex that restricts transcription to gene units in euchromatin.


Ciliary Proteins Bbs8 And Ift20 Promote Planar Cell Polarity In The Cochlea, Helen L. May-Simera, Ronald S. Petralia, Mireille Montcouquiol, Ya-Xian Wang, Katherine B. Szarama, Yun Liu, Weichun Lin, Michael R. Deans, Gregory J. Pazour, Matthew W. Kelley Feb 2015

Ciliary Proteins Bbs8 And Ift20 Promote Planar Cell Polarity In The Cochlea, Helen L. May-Simera, Ronald S. Petralia, Mireille Montcouquiol, Ya-Xian Wang, Katherine B. Szarama, Yun Liu, Weichun Lin, Michael R. Deans, Gregory J. Pazour, Matthew W. Kelley

Program in Molecular Medicine Publications and Presentations

Primary cilia have been implicated in the generation of planar cell polarity (PCP). However, variations in the severity of polarity defects in different cilia mutants, coupled with recent demonstrations of non-cilia-related actions of some cilia genes, make it difficult to determine the basis of these polarity defects. To address this issue, we evaluated PCP defects in cochlea from a selection of mice with mutations in cilia-related genes. Results indicated notable PCP defects, including mis-oriented hair cell stereociliary bundles, in Bbs8 and Ift20 single mutants that are more severe than in other cilia gene knockouts. In addition, deletion of either Bbs8 ...


The Embryonic Mir-35 Family Of Micrornas Promotes Multiple Aspects Of Fecundity In Caenorhabditis Elegans, Katherine Mcjunkin, Victor R. Ambros Jul 2014

The Embryonic Mir-35 Family Of Micrornas Promotes Multiple Aspects Of Fecundity In Caenorhabditis Elegans, Katherine Mcjunkin, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

MicroRNAs guide many aspects of development in all metazoan species. Frequently, microRNAs are expressed during a specific developmental stage to perform a temporally defined function. The C. elegans mir-35-42 microRNAs are expressed abundantly in oocytes and early embryos and are essential for embryonic development. Here, we show that these embryonic microRNAs surprisingly also function to control the number of progeny produced by adult hermaphrodites. Using a temperature-sensitive mir-35-42 family mutant (a deletion of the mir-35-41 cluster), we demonstrate three distinct defects in hermaphrodite fecundity. At permissive temperatures, a mild sperm defect partially reduces hermaphrodite fecundity. At restrictive temperatures, somatic gonad ...


Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros Apr 2014

Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

microRNAs function in diverse developmental and physiological processes by regulating target gene expression at the post-transcriptional level. ALG-1 is one of two Caenorhabditis elegans Argonautes (ALG-1 and ALG-2) that together are essential for microRNA biogenesis and function. Here, we report the identification of novel antimorphic (anti) alleles of ALG-1 as suppressors of lin-28(lf) precocious developmental phenotypes. The alg-1(anti) mutations broadly impair the function of many microRNAs and cause dosage-dependent phenotypes that are more severe than the complete loss of ALG-1. ALG-1(anti) mutant proteins are competent for promoting Dicer cleavage of microRNA precursors and for associating with and ...


Hdac6 Regulates Tip60-P400 Function In Stem Cells, Poshen B. Chen, Jui-Hung Hung, Taylor L. Hickman, Andrew H. Coles, James F. Carey, Zhiping Weng, Feixia Chu, Thomas G. Fazzio Dec 2013

Hdac6 Regulates Tip60-P400 Function In Stem Cells, Poshen B. Chen, Jui-Hung Hung, Taylor L. Hickman, Andrew H. Coles, James F. Carey, Zhiping Weng, Feixia Chu, Thomas G. Fazzio

Program in Molecular Medicine Publications and Presentations

In embryonic stem cells (ESCs), the Tip60 histone acetyltransferase activates genes required for proliferation and silences genes that promote differentiation. Here we show that the class II histone deacetylase Hdac6 co-purifies with Tip60-p400 complex from ESCs. Hdac6 is necessary for regulation of most Tip60-p400 target genes, particularly those repressed by the complex. Unlike differentiated cells, where Hdac6 is mainly cytoplasmic, Hdac6 is largely nuclear in ESCs, neural stem cells (NSCs), and some cancer cell lines, and interacts with Tip60-p400 in each. Hdac6 localizes to promoters bound by Tip60-p400 in ESCs, binding downstream of transcription start sites. Surprisingly, Hdac6 does not ...


Victor Ambros: The Broad Scope Of Micrornas. Interview By Caitlin Sedwick, Victor R. Ambros May 2013

Victor Ambros: The Broad Scope Of Micrornas. Interview By Caitlin Sedwick, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

Interview with Victor Ambros, who studies how microRNAs impact development.


Effect Of Life History On Microrna Expression During C. Elegans Development, Xantha Karp, Molly Hammell, Maria C. Ow, Victor R. Ambros Apr 2011

Effect Of Life History On Microrna Expression During C. Elegans Development, Xantha Karp, Molly Hammell, Maria C. Ow, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

Animals have evolved mechanisms to ensure the robustness of developmental outcomes to changing environments. MicroRNA expression may contribute to developmental robustness because microRNAs are key post-transcriptional regulators of developmental gene expression and can affect the expression of multiple target genes. Caenorhabditis elegans provides an excellent model to study developmental responses to environmental conditions. In favorable environments, C. elegans larvae develop rapidly and continuously through four larval stages. In contrast, in unfavorable conditions, larval development may be interrupted at either of two diapause stages: The L1 diapause occurs when embryos hatch in the absence of food, and the dauer diapause occurs ...


A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros Nov 2009

A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

Animal development is remarkably robust; cell fates are specified with spatial and temporal precision despite physiological and environmental contingencies. Favorable conditions cause Caenorhabditis elegans to develop rapidly through four larval stages (L1-L4) to the reproductive adult. In unfavorable conditions, L2 larvae can enter the developmentally quiescent, stress-resistant dauer larva stage, enabling them to survive for prolonged periods before completing development. A specific progression of cell division and differentiation events occurs with fidelity during the larval stages, regardless of whether an animal undergoes continuous or dauer-interrupted development. The temporal patterning of developmental events is controlled by the heterochronic genes, whose products ...


Drosophila Let-7 Microrna Is Required For Remodeling Of The Neuromusculature During Metamorphosis, Nicholas S. Sokol, Peizhang Xu, Yuh-Nung Jan, Victor R. Ambros Jun 2008

Drosophila Let-7 Microrna Is Required For Remodeling Of The Neuromusculature During Metamorphosis, Nicholas S. Sokol, Peizhang Xu, Yuh-Nung Jan, Victor R. Ambros

Program in Molecular Medicine Publications and Presentations

The Drosophila let-7-Complex (let-7-C) is a polycistronic locus encoding three ancient microRNAs: let-7, miR-100, and fly lin-4 (miR-125). We find that the let-7-C locus is principally expressed in the pupal and adult neuromusculature. let-7-C knockout flies appear normal externally but display defects in adult behaviors (e.g., flight, motility, and fertility) as well as clear juvenile features in their neuromusculature. We find that the function of let-7-C to ensure the appropriate remodeling of the abdominal neuromusculature during the larval-to-adult transition is carried out predominantly by let-7 alone. This heterochronic role of let-7 is likely just one of the ways in ...