Protein form and function

Scientists have long theorized that the way in which the roughly three meters of DNA in a human cell is packaged to fit within a nuclear space just six microns wide, affects gene expression. Now, Whitehead Institute researchers present the first evidence that DNA structure does indeed have such effects—in this case finding a link between chromosome structure and the expression and repression of key genes.

Cells rely on the mechanistic target of rapamycin complex 1 (mTORC1) pathway—which senses the availability of nutrients—to coordinate their growth with existing environmental conditions. The lab of Whitehead Member David Sabatini has identified a family of proteins that negatively regulate the branch upstream of mTORC1 that senses amino acids, the building blocks of proteins.

Long associated with enabling the proliferation of cancer cells, the ancient cellular survival response regulated by Heat-Shock Factor 1 (HSF1) can also turn neighboring cells in their environment into co-conspirators that support malignant progression and metastasis.

The lab of Whitehead Member Terry Orr-Weaver has conducted perhaps the most comprehensive look yet at changes in translation and protein synthesis during a developmental change, using the oocyte-to-embryo transition in Drosophila as a model system. One of the insights from this research is that a surprisingly large number of mRNAs that are translationally regulated.

Mitochondria, long known as “cellular power plants” for their generation of the key energy source adenosine triphosphate (ATP), are essential for proper cellular functions. Mitochondrial defects are often observed in a variety of diseases, including cancer, Alzheimer’s disease, and Parkinson’s disease, and are the hallmarks of a number of untreatable genetic mitochondrial disorders whose manifestations range from muscle weakness to organ failure. Whitehead Institute scientists have identified a protein whose inhibition could hold the key to alleviating suffering caused by such disorders.

A team of researchers from Harvard Medical School and Whitehead Institute report that, at least in the case of one variety of cavefish, one agent of evolutionary change is the heat shock protein known as HSP90.

The most common fungal pathogen in humans, Candida albicans, rarely develops resistance to the antifungal drug amphotericin B (AmB).  This has been puzzling as the drug has been in clinical use for over 50 years. Whitehead Institute scientists have now discovered why.  The genetic mutations that enable certain strains of C. albicans to resist AmB simultaneously render it highly susceptible to environmental stressors and disarm its virulence factors.

Using a discovery platform whose components range from yeast cells to human stem cells, Whitehead Institute scientists have identified a novel Parkinson’s disease drug target and a compound capable of repairing neurons derived from Parkinson’s patients.

By directly altering the gene coding for the prion protein (PrP), Whitehead Institute researchers have created mouse models of two neurodegenerative prion diseases, each of which manifests in different regions of the brain.  These new models for fatal familial insomnia (FFI) and Creutzfeldt-Jakob disease (CJD) accurately reflect the distinct patterns of destruction caused by the these diseases in humans.  Remarkably, as different as each disease is, they both spontaneously generate infectious prions.

For more than 125 years, scientists have been peering through microscopes, carefully watching cells divide. Until now, however, none has actually seen how cells manage to divide precisely into two equally-sized daughter cells during mitosis. Such perfect division depends on the position of the mitotic spindle (chromosomes, microtubules, and spindle poles) within the cell, and it’s now clear that human cells employ two specific mechanisms during the portion of division known as anaphase to correct mitotic spindle positioning.