Karen Ashe | |
---|---|
Born | circa 1955 [1] United States |
Occupation | Neuroscientist |
Years active | 1981–present |
Known for | Alzheimer's disease research |
Karen K. Hsiao Ashe is a professor at the Department of Neurology and Neuroscience at the University of Minnesota (UMN) Medical School, where she holds the Edmund Wallace and Anne Marie Tulloch Chairs in Neurology and Neuroscience. [2] She is the founding director of the N. Bud Grossman Center for Memory Research and Care, [2] [3] and her specific research interest is memory loss resulting from Alzheimer's disease and related dementias. [2] [1] Her research has included the development of an animal model of Alzheimer's. [1] [4]
In July 2022, concerns were raised that certain images in a 2006 Nature paper [5] co-authored by Ashe and her postdoctoral student Sylvain Lesné were manipulated. [6] In May 2023, the Star Tribune reported that Ashe was using new techniques to re-do the work reported in the 2006 Nature study, this time without Lesné, and that she stated "it's my responsibility to establish the truth of what we've published". [7] The new article was published in March 2024. [8] The 2006 article was retracted in June 2024; all of the original authors except Lesné agreed with the retraction. [9] [10]
Ashe's parents came to the United States from China in 1943 to pursue PhDs, before settling in the Minneapolis–Saint Paul area. Her father, C.C. Hsiao, taught aerospace engineering at the University of Minnesota, and her mother, Joyce, was a biochemist. [1] [11] She has three younger siblings. [1]
Attending the St. Paul Academy and Summit School in the 1970s, Ashe's interest in the brain began in primary school, where she excelled in math, along with music. [1] She obtained her undergraduate degree at Harvard University [2] in 1975 in chemistry and physics, [12] starting as a sophomore at the age of 17. [1] She went on to earn her PhD in brain and cognitive sciences at MIT in 1981 and her MD from Harvard in 1982. [12] [1]
Ashe's husband, James, is a neurologist; she has three children (two sons and a daughter). [1]
Between 1986 and 1989, she was a post-doctoral fellow at the University of California, San Francisco where she researched prion diseases and published with Stanley Prusiner. [2] [1] [12] In 1989, she was the first author on a paper published in Nature , entitled "Linkage of a prion protein missense variant to Gerstmann‑Sträussler syndrome", describing the discovery of a mutation linked to a neurodegenerative disease. [13] She was the first author on a paper published in 1990 in Science, entitled "Spontaneous neurodegeneration in transgenic mice with mutant prion protein", describing the creation of a transgenic mouse modeling a neurodegenerative disease. [14] According to the Minneapolis Star Tribune , she helped prove Prusiner's theory that prions cause neurodegenerative diseases. [1] Prusiner recognized her contribution towards the Nobel Prize he won for that work, [1] saying that Karen Hsiao "discovered a mutation in the PrP gene that caused familial disease and reproduced the disease in transgenic mice". [15]
Ashe joined the University of Minnesota Medical School in 1992 as an assistant professor of neurology. [1] She has also worked with the Minneapolis Veterans Affairs Health Care System. [1] She was the founding director of the N. Bud Grossman Center for Memory Research and Care. [2] [3] [16] As of 2022, she has received over $28 million in grants from the U.S. National Institutes of Health. [17]
The Minneapolis Star Tribune described Ashe as a "distinguished professor considered by many to be on the short list for a Nobel Prize for her work". [18]
In 1996—early in her career at UMN—Ashe was the first author on a paper published in Science, entitled "Correlative memory deficits, Aβ elevation, and amyloid plaques in transgenic mice", [19] describing a mouse model of Alzheimer's disease, which furthered her rising star as a scientist; the mice are used in research around the world, and students and scientists "come from all over the world to work with her", according to the Star Tribune. [1] In 2006, three of her research papers made a list of the eighteen papers that had contributed the most to Alzheimer's research. [20]
Ashe is a co-author on a 2006 paper published in Nature (retracted in 2024 [10] ), entitled "A specific amyloid-β protein assembly in the brain impairs memory". [6] [5] The paper describes the Aβ*56 oligomer (known as amyloid beta star 56 and Aβ*56) correlating with memory loss in mice prior to the appearance of amyloid plaques. According to a Science article, in 2022 the paper was the fifth-highest cited paper in Alzheimer's research, with approximately 2,300 other articles citing it. [6] The Guardian says the paper was "highly influential" and calls it "one of the most cited pieces of Alzheimer's disease research in the last two decades", writing that it has "dominated the field" of research. [21] The Daily Telegraph states that the "seminal research paper" led to increased drug research funding worldwide. [22] The paper was discussed at the Alzheimer Research Forum as a "star is born". [6] [23]
In 2015, Ashe was a co-author on a paper entitled "Quaternary structure defines a large class of amyloid-beta oligomers neutralized by sequestration", which defines two forms of Aβ based on quaternary structure, type 1 and type 2, that have different effects on memory function in mice. [24] Type 1 is dispersed in the brain and associated with impaired memory. Type 2 is entrapped in amyloid plaques and does not impair memory. [24] [25] In 2020, she published a review summarizing this work, entitled "The biogenesis and biology of amyloid β oligomers in the brain". [25]
In July 2022, concerns were raised by Matthew Schrag, a Vanderbilt University neuroscientist, [18] that certain images in the 2006 Nature paper were manipulated [6] in the paper co-authored by Ashe's postdoctoral Sylvain Lesné, whom she hired in 2002. [6] [26] These concerns were published in an article in Science authored by Charles Piller which questioned the association between the Aβ*56 protein and dementia symptoms. [6] Ashe stated in July 2022 via email that "it is devastating to discover that a colleague may have misled me and the scientific community [... it is also] distressing that a major scientific journal has blatantly misrepresented the implications of my work." [17] [Note 1] Ashe has stated that the edited images, which she agrees "should not have occurred", [27] do not change the conclusions of the paper. [28] No image inconsistencies have been found in other work published by Ashe without Lesné as a co-author. [6]
UMN is investigating the reports [21] as of May 2023. [29] The editors of Nature responded with a July 14, 2022 note stating they were aware of and investigating the concerns raised, that a "further editorial response [would] follow as soon as possible", and that "readers are advised to use caution when using results reported therein". [5] [17] The NIH, where Schrag lodged the whistleblower report, is also investigating the matter. [22] Retraction Watch states that Ashe co-authored with Lesné other disputed papers, and that the authors in the disputed work do not overlap except for two from UMN Department of Neuroscience. [30]
In May 2023, the Star Tribune reported that Ashe was using new techniques to re-do the work reported in the 2006 Nature study, this time without Lesné, and that she stated "it's my responsibility to establish the truth of what we've published". [29] Ashe's new article was published in March 2024 in the journal iScience. [8]
In May 2024, Ashe announced that the 2006 publication would be retracted because Nature would not print a correction. [10] According to Retraction Watch, this makes it the most highly cited paper ever retracted. [10] Piller reported in Science that Ashe "and colleagues claim to confirm the findings of the 2006 paper", and Ashe states that "the manipulated images did not affect the study conclusions". [10] All of the original authors except Lesné agreed to the June 2024 retraction; [9] other researchers dispute the strength of conclusions in the new, re-worked study. [10]
Ashe was awarded the Metlife Foundation Award for Medical Research in Alzheimer's Disease in 2005. [31] Ashe also earned the Potamkin Prize in 2006 for her Alzheimer's research, [32] [33] shortly after the publication of the 2006 Nature paper. [6]
In 2009, Ashe was elected to the National Academy of Medicine for her achievements in medicine. [34]
A prion is a misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death. Prions are responsible for prion diseases, known as transmissible spongiform encephalopathies (TSEs), which are fatal and transmissible neurodegenerative diseases affecting both humans and animals. These proteins can misfold sporadically, due to genetic mutations, or by exposure to an already misfolded protein, leading to an abnormal three-dimensional structure that can propagate misfolding in other proteins.
Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure and ability to be stained by particular dyes, such as Congo red. In the human body, amyloids have been linked to the development of various diseases. Pathogenic amyloids form when previously healthy proteins lose their normal structure and physiological functions (misfolding) and form fibrous deposits within and around cells. These protein misfolding and deposition processes disrupt the healthy function of tissues and organs.
Amyloid beta denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid-beta precursor protein (APP), which is cleaved by beta secretase and gamma secretase to yield Aβ in a cholesterol-dependent process and substrate presentation. Both neurons and oligodendrocytes produce and release Aβ in the brain, contributing to formation of amyloid plaques. Aβ molecules can aggregate to form flexible soluble oligomers which may exist in several forms. It is now believed that certain misfolded oligomers can induce other Aβ molecules to also take the misfolded oligomeric form, leading to a chain reaction akin to a prion infection. The oligomers are toxic to nerve cells. The other protein implicated in Alzheimer's disease, tau protein, also forms such prion-like misfolded oligomers, and there is some evidence that misfolded Aβ can induce tau to misfold.
Amyloid-beta precursor protein (APP) is an integral membrane protein expressed in many tissues and concentrated in the synapses of neurons. It functions as a cell surface receptor and has been implicated as a regulator of synapse formation, neural plasticity, antimicrobial activity, and iron export. It is coded for by the gene APP and regulated by substrate presentation. APP is best known as the precursor molecule whose proteolysis generates amyloid beta (Aβ), a polypeptide containing 37 to 49 amino acid residues, whose amyloid fibrillar form is the primary component of amyloid plaques found in the brains of Alzheimer's disease patients.
Amyloid plaques are extracellular deposits of the amyloid beta (Aβ) protein mainly in the grey matter of the brain. Degenerative neuronal elements and an abundance of microglia and astrocytes can be associated with amyloid plaques. Some plaques occur in the brain as a result of aging, but large numbers of plaques and neurofibrillary tangles are characteristic features of Alzheimer's disease. The plaques are highly variable in shape and size; in tissue sections immunostained for Aβ, they comprise a log-normal size distribution curve, with an average plaque area of 400-450 square micrometers (μm2). The smallest plaques, which often consist of diffuse deposits of Aβ, are particularly numerous. Plaques form when Aβ misfolds and aggregates into oligomers and longer polymers, the latter of which are characteristic of amyloid.
The major prion protein (PrP) is encoded in the human body by the PRNP gene also known as CD230. Expression of the protein is most predominant in the nervous system but occurs in many other tissues throughout the body.
The biochemistry of Alzheimer's disease, the most common cause of dementia, is not yet very well understood. Alzheimer's disease (AD) has been identified as a proteopathy: a protein misfolding disease due to the accumulation of abnormally folded amyloid beta (Aβ) protein in the brain. Amyloid beta is a short peptide that is an abnormal proteolytic byproduct of the transmembrane protein amyloid-beta precursor protein (APP), whose function is unclear but thought to be involved in neuronal development. The presenilins are components of proteolytic complex involved in APP processing and degradation.
In medicine, proteinopathy, or proteopathy, protein conformational disorder, or protein misfolding disease, is a class of diseases in which certain proteins become structurally abnormal, and thereby disrupt the function of cells, tissues and organs of the body. Often the proteins fail to fold into their normal configuration; in this misfolded state, the proteins can become toxic in some way or they can lose their normal function. The proteinopathies include such diseases as Creutzfeldt–Jakob disease and other prion diseases, Alzheimer's disease, Parkinson's disease, amyloidosis, multiple system atrophy, and a wide range of other disorders. The term proteopathy was first proposed in 2000 by Lary Walker and Harry LeVine.
HEPPS (EPPS) is a buffering agent used in biology and biochemistry. The pKa of HEPPS is 8.00. It is ones of Good's buffers.
Solanezumab is a monoclonal antibody being investigated by Eli Lilly as a neuroprotector for patients with Alzheimer's disease. The drug originally attracted extensive media coverage proclaiming it a breakthrough, but it has failed to show promise in Phase III trials.
Rudolph Emile 'Rudy' Tanzi a professor of Neurology at Harvard University, vice-chair of neurology, director of the Genetics and Aging Research Unit, and co-director of the Henry and Allison McCance Center for Brain Health at Massachusetts General Hospital (MGH).
p3 peptide also known as amyloid β- peptide (Aβ)17–40/42 is the peptide resulting from the α- and γ-secretase cleavage from the amyloid precursor protein (APP). It is known to be the major constituent of diffuse plaques observed in Alzheimer's disease (AD) brains and pre-amyloid plaques in people affected by Down syndrome. However, p3 peptide's role in these diseases is not truly known yet.
Karen Elizabeth Keitley Duff is a British scientist known for her work on Alzheimer's disease. Her most notable work focused on the development and characterization of mouse models of Alzheimer's disease amyloid deposition. She became Centre Director of the UK Dementia Research Institute's hub at University College London in spring 2020.
The ion channel hypothesis of Alzheimer's disease (AD), also known as the channel hypothesis or the amyloid beta ion channel hypothesis, is a more recent variant of the amyloid hypothesis of AD, which identifies amyloid beta (Aβ) as the underlying cause of neurotoxicity seen in AD. While the traditional formulation of the amyloid hypothesis pinpoints insoluble, fibrillar aggregates of Aβ as the basis of disruption of calcium ion homeostasis and subsequent apoptosis in AD, the ion channel hypothesis in 1993 introduced the possibility of an ion-channel-forming oligomer of soluble, non-fibrillar Aβ as the cytotoxic species allowing unregulated calcium influx into neurons in AD.
YoungSoo Kim is a South Korean chemist. Kim is an associate professor in Department of Pharmacy at Yonsei University.
Early long-term potentiation (E-LTP) is the first phase of long-term potentiation (LTP), a well-studied form of synaptic plasticity, and consists of an increase in synaptic strength. LTP could be produced by repetitive stimulation of the presynaptic terminals, and it is believed to play a role in memory function in the hippocampus, amygdala and other cortical brain structures in mammals.
Mathias Jucker is a Swiss neuroscientist, Professor, and a Director at the Hertie Institute for Clinical Brain Research of the University of Tübingen. He is also a group leader at the German Center for Neurodegenerative Diseases in Tübingen. Jucker is known for his research on the basic biologic mechanisms underlying brain aging and Alzheimer's disease.
Lary Walker is an American neuroscientist and researcher at Emory University in Atlanta, Georgia. He is Associate Director of the Goizueta Alzheimer's Disease Research Center at Emory, and he is known for his research on the role of abnormal proteins in the causation of Alzheimer's disease.
Dennis J. Selkoe is an American physician (neurologist) known for his research into the molecular basis of Alzheimer's disease. In 1985 he became Co-Director of the Center for Neurological Diseases and from 1990, Vincent and Stella Coates Professor of Neurological Diseases at Harvard Medical School. He is also a Fellow of the AAAS and a member of the National Academy of Medicine.
Sylvain E. Lesné is a French neuroscientist and associate professor at the Department of Neuroscience at the University of Minnesota (UMN) Medical School, known for his research into Alzheimer's disease. He is the primary author of a controversial 2006 Nature paper, "A specific amyloid-β protein assembly in the brain impairs memory". Lesné's work in the 2006 publication and others has been investigated since June 2022 on charges that he manipulated images to inflate the role of Aβ*56 in Alzheimer's. Retracted in 2024, the paper was foundational in the hypothesis that one specific toxic oligomer of the amyloid beta protein, known as Aβ*56, caused memory impairment in Alzheimer's, aligned with the prevailing amyloid hypothesis.