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Articles 1 - 10 of 10

Full-Text Articles in Molecular Biology

Loss Of The Cone-Enriched Caspase-7 Does Not Affect Secondary Cone Death In Retinitis Pigmentosa, Aditya Venkatesh, Shun-Yun Cheng, Claudio Punzo Dec 2017

Loss Of The Cone-Enriched Caspase-7 Does Not Affect Secondary Cone Death In Retinitis Pigmentosa, Aditya Venkatesh, Shun-Yun Cheng, Claudio Punzo

University of Massachusetts Medical School Faculty Publications

Purpose: The apoptotic mechanisms responsible for secondary cone death in retinitis pigmentosa (RP) remain largely unknown. The cone-enriched apoptotic protease caspase-7 (Casp7) is thought to be triggered by endoplasmic reticulum (ER) stress and plays a pivotal role in mice deficient in the cone cyclic nucleotide-gated channels, a deficiency that causes achromatopsia in humans and in mice with autosomal dominant rhodopsin mutations, in particular the T17M mutation. Thus, we tested in two mouse models of RP whether the cone-enriched Casp7 plays a role during secondary cone death.

Methods: Casp7 knockout mice were crossed to two different RP mouse models with significantly ...


Hepatic Dysfunction Caused By Consumption Of A High-Fat Diet, Anthony R. Soltis, Norman J. Kennedy, Xiaofeng Xin, Feng Zhou, Scott B. Ficarro, Yoon Sing Yap, Bryan J. Matthews, Douglas A. Lauffenburger, Forest M. White, Jarrod A. Marto, Roger J. Davis, Ernest Fraenkel Dec 2017

Hepatic Dysfunction Caused By Consumption Of A High-Fat Diet, Anthony R. Soltis, Norman J. Kennedy, Xiaofeng Xin, Feng Zhou, Scott B. Ficarro, Yoon Sing Yap, Bryan J. Matthews, Douglas A. Lauffenburger, Forest M. White, Jarrod A. Marto, Roger J. Davis, Ernest Fraenkel

University of Massachusetts Medical School Faculty Publications

Obesity is a major human health crisis that promotes insulin resistance and, ultimately, type 2 diabetes. The molecular mechanisms that mediate this response occur across many highly complex biological regulatory levels that are incompletely understood. Here, we present a comprehensive molecular systems biology study of hepatic responses to high-fat feeding in mice. We interrogated diet-induced epigenomic, transcriptomic, proteomic, and metabolomic alterations using high-throughput omic methods and used a network modeling approach to integrate these diverse molecular signals. Our model indicated that disruption of hepatic architecture and enhanced hepatocyte apoptosis are among the numerous biological processes that contribute to early liver ...


Fluorescence Polarization Control For On-Off Switching Of Single Molecules At Cryogenic Temperatures, Christiaan Hulleman, Maximiliaan Huisman, Robert Moerland, David Grünwald, Sjoerd Stallinga, Bernd Rieger Oct 2017

Fluorescence Polarization Control For On-Off Switching Of Single Molecules At Cryogenic Temperatures, Christiaan Hulleman, Maximiliaan Huisman, Robert Moerland, David Grünwald, Sjoerd Stallinga, Bernd Rieger

University of Massachusetts Medical School Faculty Publications

Light microscopy allowing sub-diffraction limited resolution has been among the fastest developing techniques at the interface of biology, chemistry and physics. Intriguingly no theoretical limit exists on how far the underlying measurement uncertainty can be lowered. In particular data fusion of large amounts of images can reduce the measurement error to match the resolution of structural methods like cryo-electron microscopy. Fluorescence, although reliant on a reporter molecule and therefore not the first choice to obtain ultra resolution structures, brings highly specific labeling of molecules in a large assemble to the table and inherently allows the detection of multiple colors, which ...


A Synthetic Biology Approach To Probing Nucleosome Symmetry, Yuichi Ichikawa, Yuanyuan Chen, Vineeta Bajaj, Caitlin M. Connolly, Hsin-Jung Chou, Upasna Sharma, Hsiuyi V. Chen, Daniel N. Bolon, Oliver J. Rando, Paul D. Kaufman Sep 2017

A Synthetic Biology Approach To Probing Nucleosome Symmetry, Yuichi Ichikawa, Yuanyuan Chen, Vineeta Bajaj, Caitlin M. Connolly, Hsin-Jung Chou, Upasna Sharma, Hsiuyi V. Chen, Daniel N. Bolon, Oliver J. Rando, Paul D. Kaufman

University of Massachusetts Medical School Faculty Publications

The repeating subunit of chromatin, the nucleosome, includes two copies of each of the four core histones, and several recent studies have reported that asymmetrically modified nucleosomes occur at regulatory elements in vivo. To probe the mechanisms by which histone modifications are read out, we designed an obligate pair of H3 heterodimers, termed H3X and H3Y, which we validated genetically and biochemically. Comparing the effects of asymmetric histone tail point mutants with those of symmetric double mutants revealed that a single methylated H3K36 per nucleosome was sufficient to silence cryptic transcription in vivo. We also demonstrate the utility of this ...


Fundamental Limits On Dynamic Inference From Single Cell Snapshots, Caleb Weinreb, Samuel Wolock, Betsabeh K. Tusi, Merav Socolovsky, Allon M. Klein Aug 2017

Fundamental Limits On Dynamic Inference From Single Cell Snapshots, Caleb Weinreb, Samuel Wolock, Betsabeh K. Tusi, Merav Socolovsky, Allon M. Klein

University of Massachusetts Medical School Faculty Publications

Single cell expression profiling reveals the molecular states of individual cells with unprecedented detail. However, because these methods destroy cells in the process of analysis, they cannot measure how gene expression changes over time. But some information on dynamics is present in the data: the continuum of molecular states in the population can reflect the trajectory of a typical cell. Many methods for extracting single cell dynamics from population data have been proposed. However, all such attempts face a common limitation: for any measured distribution of cell states, there are multiple dynamics that could give rise to it, and by ...


Heterogeneity And Intrinsic Variation In Spatial Genome Organization, Elizabeth Finn, Gianluca Pegoraro, Hugo B. Brandao, Anne-Laure Valton, Marlies E. Oomen, Job Dekker, Leonid Mirny, Tom Misteli Aug 2017

Heterogeneity And Intrinsic Variation In Spatial Genome Organization, Elizabeth Finn, Gianluca Pegoraro, Hugo B. Brandao, Anne-Laure Valton, Marlies E. Oomen, Job Dekker, Leonid Mirny, Tom Misteli

University of Massachusetts Medical School Faculty Publications

The genome is hierarchically organized in 3D space and its architecture is altered in differentiation, development and disease. Some of the general principles that determine global 3D genome organization have been established. However, the extent and nature of cell-to-cell and cell-intrinsic variability in genome architecture are poorly characterized. Here, we systematically probe the heterogeneity in genome organization in human fibroblasts by combining high-resolution Hi-C datasets and high-throughput genome imaging. Optical mapping of several hundred genome interaction pairs at the single cell level demonstrates low steady-state frequencies of colocalization in the population and independent behavior of individual alleles in single nuclei ...


Ki-67 Contributes To Normal Cell Cycle Progression And Inactive X Heterochromatin In P21 Checkpoint-Proficient Human Cells, Xiaoming Sun, Aizhan Bizhanova, Timothy D. Matheson, Jun Yu, Lihua Julie Zhu, Paul D. Kaufman May 2017

Ki-67 Contributes To Normal Cell Cycle Progression And Inactive X Heterochromatin In P21 Checkpoint-Proficient Human Cells, Xiaoming Sun, Aizhan Bizhanova, Timothy D. Matheson, Jun Yu, Lihua Julie Zhu, Paul D. Kaufman

University of Massachusetts Medical School Faculty Publications

Ki-67 protein is widely used as a tumor proliferation marker. However, whether Ki-67 affects cell cycle progression has been controversial. Here, we demonstrate that depletion of Ki-67 in human hTERT-RPE1, WI-38, IMR90, hTERT-BJ cell lines and primary fibroblast cells slowed entry into S phase and coordinately downregulated genes related to DNA replication. Some gene expression changes were partially relieved in Ki-67-depleted hTERT-RPE1 cells by co-depletion of the Rb checkpoint protein, but more thorough suppression of the transcriptional and cell cycle defects was observed upon depletion of cell cycle inhibitor p21. Notably, induction of p21 upon depletion of Ki-67 was a ...


Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer Apr 2017

Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer

University of Massachusetts Medical School Faculty Publications

Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 A. This structure not only visualizes the active ...


The 4d Nucleome Project, Job Dekker, Andrew S. Belmont, Mitchell Guttman, Victor O. Leshyk, John T. Lis, Stavros Lomvardas, Leonid A. Mirny, Clodagh C. O'Shea, Peter J. Park, Bing Ren, Joan C. Ritland Politz, Jay Shendure, Sheng Zong Jan 2017

The 4d Nucleome Project, Job Dekker, Andrew S. Belmont, Mitchell Guttman, Victor O. Leshyk, John T. Lis, Stavros Lomvardas, Leonid A. Mirny, Clodagh C. O'Shea, Peter J. Park, Bing Ren, Joan C. Ritland Politz, Jay Shendure, Sheng Zong

University of Massachusetts Medical School Faculty Publications

The spatial organization of the genome and its dynamics contribute to gene expression and cellular function in normal development as well as in disease. Although we are increasingly well equipped to determine a genome's sequence and linear chromatin composition, studying the three-dimensional organization of the genome with high spatial and temporal resolution remains challenging. The 4D Nucleome Network aims to develop and apply approaches to map the structure and dynamics of the human and mouse genomes in space and time with the long term goal of gaining deeper mechanistic understanding of how the nucleus is organized. The project will ...


Targeted Degradation Of Ctcf Decouples Local Insulation Of Chromosome Domains From Higher-Order Genomic Compartmentalization, Elphege P. Nora, Anton Goloborodko, Anne-Laure Valton, Johan H. Gibcus, Alec Uebersohn, Nezar Abdennur, Job Dekker, Leonid A. Mirny, Benoit Bruneau Jan 2017

Targeted Degradation Of Ctcf Decouples Local Insulation Of Chromosome Domains From Higher-Order Genomic Compartmentalization, Elphege P. Nora, Anton Goloborodko, Anne-Laure Valton, Johan H. Gibcus, Alec Uebersohn, Nezar Abdennur, Job Dekker, Leonid A. Mirny, Benoit Bruneau

University of Massachusetts Medical School Faculty Publications

The molecular mechanisms underlying folding of mammalian chromosomes remain poorly understood. The transcription factor CTCF is a candidate regulator of chromosomal structure. Using the auxin-inducible degron system in mouse embryonic stem cells, we show that CTCF is absolutely and dose-dependently required for looping between CTCF target sites and segmental organization into topologically associating domains (TADs). Restoring CTCF reinstates proper architecture on altered chromosomes, indicating a powerful instructive function for CTCF in chromatin folding, and CTCF remains essential for TAD organization in non-dividing cells. Surprisingly, active and inactive genome compartments remain properly segregated upon CTCF depletion, revealing that compartmentalization of mammalian ...