A new paper from the groups of Jan Münch and James Shorter in the prestigious journal eLife reveals that CLR01 can not only break semen-related amyloid and reduce HIV infection, but also that CLR01 destroys membrane of the virus itself and therefore can act as a highly effective microbicide against AIDS and other viral diseases, including herpes and hepatitis C.
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The study by Danny Segal‘s group at Tel Aviv University was featured in the Spotlight of the American Chemical Society journal Chemical Research in Toxicology.
We don’t usually think of cancer as a disease related to amyloid or to protein aggregation. In cancer, the control systems that dictate the cell life cycle are lost and cells begin to proliferate out of control. A key element in the control system is the “tumor suppressor” protein, p53. p53 has been described as “the guardian of the genome” because it protects genes from mutation. However, the gene encoding p53 can be mutated itself, leading to formation of a dysfunctional protein, loss of control, and cancer.
An interesting recent discovery is that a sub-group of the mutations lead to protein aggregation, similar to what happens in amyloidoses, such as Alzheimer’s or Parkinson’s diseases. This finding is highly important because p53 acts as a homotetramer (a protein complex made of four identical subunits) and to be functional, each one of the four subunits has to have the correct structure. If just one is mutated, the complex falls apart. Because our genome has two copies of each gene, if a structure-altering mutation occurs in one of the copies and that mutation leads to a dysfunctional protein, 50% of the protein produced will be dysfunctional. But when four intact copies are needed for the protein to function and one copy of the gene is mutated, only 1/16, or 6.25%, of the tetramers will be normal and functional.
The problem with amyloid formation is that the normal protein tends to co-aggregate with the bad one, reducing the percentage of available normal protein even more. And if that is not bad enough, protein “cousins” of p53, called p63 and p73, also co-aggregate with the mutant protein, reducing the cells ability to control its processes even more. Moreover, the aggregates can be transmitted to other cells and induce abnormal aggregation in them, a possible mechanism for the propagation of cancer.
In addition to the loss of control, the rogue protein aggregates themselves are cytotoxic, similarly to protein aggregates in other amyloidoses. This is where the molecular tweezer, CLR01, might help. CLR01 is known to alter the formation of the toxic aggregates and facilitate their degradation by the body’s clearance mechanisms. Can it do that with mutant p53? Facilitate clearance of the mutant protein and possibly release the good protein? To begin to answer these questions, the team of Dr. Danny Segal at Tel Aviv University examined the effect of CLR01 on two prevalent mutant forms of p53 in a series of biophysical and biochemical tests. They found that CLR01 stabilized intermediate-size aggregates of the mutant proteins. Thus, the transition from small oligomers to the intermediate-size aggregates was accelerated, but further aggregation was inhibited when the mutant proteins interacted with CLR01.
These observations led to an important question: are the intermediate aggregates still toxic to cells? When the researchers added the aggregates of mutant p53 itself, without CLR01, to cultured cells, the cells died, but when they added the mixture of mutant p53 with CLR01, the molecular tweezer protected the cells and they survived. These findings suggest that CLR01 may be helpful in cases of cancer caused by p53 mutations because it may help prevent both the formation of toxic protein aggregates and the co-aggregation of healthy protein with the mutated form.
The study was published in the American Chemical Society journal Biochemistry.
Diabetes is known as a disease of uncontrolled blood-sugar levels because the body does not produce enough insulin, or the insulin that is produced is not used effectively by the body. Most people are not aware that type-2 diabetes is also the most prevalent amyloidosis. In type-2 diabetes, a small protein called Islet Amyloid PolyPeptide (IAPP) forms toxic aggregates that kill the insulin-producing beta cells in the pancreas.
A new study now shows that the molecular tweezer, CLR01, prevents the aggregation of IAPP and its toxicity towards pancreatic cells. The study, which is published in the American Chemical Society (ACS) journal ACS Chemical Biology, shows how CLR01 binds to IAPP, changes its structure, and prevents its aggregation. The study also shows that the blood levels of CLR01 needed for therapeutic effect can be achieved without causing safety concerns.
The new study was led by Gal Bitan‘s group at UCLA in collaboration with Thomas Schrader and Frank Klärner, University of Duisburg-Essen, Elsa Sanches-Garcia, Max-Planck-Institut für Kohlenforschung in Mülheim, and Chunyu Wang, Rensselaer Polytechnic Institute.
New compounds could offer therapy for multitude of diseases
March 29, 2015
Federation of American Societies for Experimental Biology (FASEB)
An international team of more than 18 research groups has demonstrated that the compounds they developed can safely prevent harmful protein aggregation in preliminary tests using animals. The findings raise hope that a new class of drugs may be on the horizon for the more than 30 diseases and conditions that involve protein aggregation, including diabetes, cancer, spinal cord injury, Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS).
Proteins are necessary for almost every cellular process. However, when cell machinery doesn’t clear out old proteins, they can clump, or aggregate, into toxic plaques that lead to disease.
“Diseases caused by protein aggregation affect millions of people around the world,” said Gal Bitan, Ph.D., associate professor of neurology at the David Geffen School of Medicine at the University of California — Los Angeles, who will present the team’s latest work at the American Society for Biochemistry and Molecular Biology (ASBMB) Annual Meeting during Experimental Biology 2015. “We hope that the new compounds will provide therapy for diseases caused by protein aggregation, many of which have no treatment at all.”
The researchers call the compounds that they developed molecular tweezers because of the way they wrap around the lysine amino acid chains that make up most proteins. The compounds are unique in their ability to attack only aggregated proteins, leaving healthy proteins alone.
To develop a new drug, researchers typically screen large libraries of compounds to find ones that affect a protein involved in a disease. Bitan’s team used a fundamentally different approach to develop the molecular tweezers.
“We looked at the molecular and atomic interactions of proteins to understand what leads to their abnormal clumping,” Bitan said. “Then, we developed a tailored solution. So unlike many other drugs, we understand how and why our drug works.”
The team is in the process of testing multiple versions of the tweezers, each with a slightly different molecular makeup. For CLR01, one of the most promising versions, the researchers have demonstrated therapeutic benefits in two rodent models of Alzheimer’s disease, two fish and one mouse model of Parkinson’s disease, a fish model of spinal cord injury and a mouse model of familial amyloidotic polyneuropathy, a rare disease in which protein aggregation affects the nervous system, heart and kidneys.
“Our data suggest that CLR01, or a derivative thereof, may become a drug for a number of diseases that involve protein aggregation,” Bitan said. “We also found a high safety window for CLR01.”
In one of the safety tests, mice receiving a daily CLR01 dose 250 times higher than the therapeutic dose for one month showed no behavioral or physiological signs of distress or damage. In fact, blood cholesterol in the mice dropped by 40 percent, a possible positive side effect of CLR01.
The researchers continue to study CLR01 in animal models of various diseases and are working to secure funding for more animal studies. The researchers are also making improvements that would allow CLR01 to be administered in a pill or capsule rather than requiring an injection.
During his presentation, Bitan will also discuss the evolutionary basis for protein aggregation.
Gal Bitan will present the findings during the Experimental Biology 2015 meeting on Sunday, March 29 at the Protein Aggregation and Amyloid Diseases poster session in Exhibit Halls A & B and on Wednesday, April 1 at the Targeting Disorder with Small Molecules symposium in the Boston Convention and Exhibition Center.
The above story is based on materials provided by Federation of American Societies for Experimental Biology (FASEB). Note: Materials may be edited for content and length.