"The nucleus of each of your cells contains all the genetic information (the genome) necessary to build every type of cell and protein in your entire body.
Like a complex library in a tiny space 50 times smaller than the width of a human hair, genes are organized into precise regions in three dimensions.
In addition to the genome, the nucleus contains structures called
nuclear bodies that contain high concentrations of specific proteins and nucleic acids.
In addition to the genome, the nucleus contains structures called
The role of nuclear bodies, however, has been a mystery for nearly a century. A new study from the laboratory of Caltech's Mitch Guttman, professor of biology, shows that these nuclear bodies can act like miniature factories to enable efficient production of mRNA.
mRNA splicing is a fundamental part of the process that occurs when encoded DNA instructions are turned into a functional protein. After a gene is transcribed from DNA to RNA, extraneous sections (called introns) must be cut out, a process facilitated by splicing enzymes.
Caltech researchers examined a particular type of nuclear body, called the nuclear speckle, which contains high concentrations of splicing enzymes.
Guttman's team discovered that the genome physically shifts itself around so that highly transcribed genes are in close proximity to speckles, enabling more efficient splicing.
The paper describing the findings was published in the journal Nature on May 8. It is titled "Genome organization around nuclear speckles drives mRNA splicing efficiency."
For a decade, researchers in the Guttman laboratory have studied how the nucleus is spatially organized—the layout of the library, in other words.
mRNA splicing is a fundamental part of the process that occurs when encoded DNA instructions are turned into a functional protein. After a gene is transcribed from DNA to RNA, extraneous sections (called introns) must be cut out, a process facilitated by splicing enzymes.
Caltech researchers examined a particular type of nuclear body, called the nuclear speckle, which contains high concentrations of splicing enzymes.
Guttman's team discovered that the genome physically shifts itself around so that highly transcribed genes are in close proximity to speckles, enabling more efficient splicing.
The paper describing the findings was published in the journal Nature on May 8. It is titled "Genome organization around nuclear speckles drives mRNA splicing efficiency."
For a decade, researchers in the Guttman laboratory have studied how the nucleus is spatially organized—the layout of the library, in other words.
The 3D structures into which DNA is ordered make certain genes more or less accessible to the machinery that convert DNA into mRNA, and the new study shows that the physical structure of the genome links transcription with the process of splicing.
A muscle cell, for example,
A muscle cell, for example,
---will shift its genome around so that highly transcribed genes for muscle activity are in physical proximity to nuclear speckles, where high concentrations of splicing enzymes make RNA splicing particularly efficient.
A neuronal cell, on the other hand,
---will reorient its genome in space so that the genes necessary to produce cells specialized for neurological function are closer to the speckles."
Phys.org
