Welcome to Ehud Cohen's lab website!
Many human diseases emerge late in life. In the laboratory we study the mechanisms that link the aging process to late onset disorders that are associated with toxic protein aggregation at the molecular and cell biological levels. Practically we ask: what goes wrong with aging?
To address that question we use nematodes, cells and a variety of biochemical, cell biological, microscopic and in-vitro research techniques.
In this website you will be able to learn more about our scientific activity and the opportunities offered by the lab to conduct state of the art research.
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October 2017: PrP is secreted by vesicles from CsA-treated cells - Ieshita's manuscript has been accepted for publication at the FASEB journal!
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- The regulation of aging at the genetic, cell biological and organismal levels.
- Protein folding, aggregation and deposition within the single cell.
- Mechanisms and biological activities that link aging and toxic protein aggregation.
- Aging manipulation as a strategy to combat neurodegenerative disorders.
Aberrant protein aggregation is linked to the development of various late-onset human neurodegenerative disorders, such as Alzheimer and Parkinson diseases. Interestingly different neurodegenerative disorders share surprisingly similar temporal emergence patterns: familial, mutation-linked cases onset during the fifth decade of life while sporadic cases do not emerge earlier than the seventh decade. This common emergence pattern defines aging as the major risk factor for the development of these maladies. Why neurodegenerative disorders onset late in life and why distinct diseases share similar temporal patterns are principle enigmas that are studied in our laboratory. To explore the mechanistic links between aging and toxic protein aggregation we use the nematode Caenorhabditis elegans (C. elegns) and mammalian cell cultures. The Insulin/IGF signaling pathway (IIS) is a prominent aging and lifespan regulator. In C. elegans, IIS reduction results in slowed aging, extended lifespan and elevated stress resistance. Recently we discovered that IIS reduction can also protect worms from toxic aggregation of the human Alzheimer disease associated peptide, A. The IIS mediates this protection by regulating two opposing activities, disaggregation and protective hyper-aggregation. In the laboratory we study in details the mechanisms that link aging and toxic protein aggregation via the IIS and other aging regulating pathways. We also characterize the cell biological mechanisms that act to detoxify protein aggregates at the single cell level. Our long term goal is to develop therapies that will enable to maintain the activity of the mechanisms that protect the young organism from late-onset disorders through late stages of life aiming to promote healthy aging.
The Biological Systems
The major model organism used in the lab is the nematode C. elegans. These worms have remarkable advantages for the research of aging and toxic protein aggregation. C. elegans live very short life (wild-type worm lives on average only 19 days) yet, the known aging regulating pathways are highly conserved from worms to mammals. The worms are post-mitotic, just like neurons, and the lineage of each and every cell is known. It is relatively easy to create transgenic worms and to cross different strains. Biochemistry techniques are also applicable as worm can be easily homogenized to test protein content or perform protein-protein interaction assays. The worms are transparent, thus, immuno-fluorescence and the tracking of fluorescently tagged proteins are easy to perform. But most important is the ease to silence genes using RNAi. The expression of a target gene can be drastically reduced simply by feeding the nematodes with bacteria expressing the RNAi construct towards the target gene.
A worm carrying GFP tagged DAF-16.
Worm expressing RFP under gtr-1p and GFP under gcy-8p
Despite the overwhelming advantages of C. elegans as a model system, some research aspects such as protein trafficking need to be validated in mammalian system. In our laboratory we utilize mammalian cell cultures to support the observations obtained in the worms using various microscopic and biochemical techniques.
A cell containing an aggresome.
Modulation of Caveolae by Insulin/IGF-1 Signaling Regulates Aging of Caenorhabditis elegans
Roitenberg N†, Bejerano-Sagie M†, Boocholez H, Moll L, Carvalhal Marques F, Golodetzki L, Nevo Y, Elami T and Cohen E.
EMBO Reports (2018), In press
Here we report that in the nematode Caenorhabditis elegans, the IIS positively regulates the expression of caveolin-1 (cav-1), a gene which is primarily expressed in neurons of the adult worm and underlies the formation of caveolae, a subtype of lipid microdomains that serve as platforms for signaling complexes. Accordingly, IIS reduction lowers cav-1 expression and lessens the quantity of neuronal caveolae. Reduced cav-1 expression extends lifespan and mitigates toxic protein aggregation by modulating the expression of aging-regulating and signaling-promoting genes. Our findings define caveolae as aging-governing signaling centers.
Vesicle-mediated secretion of misfolded prion protein molecules from cyclosporin A-treated cells,
Pan, I, Roitenberg N and Cohen E.
FASEB J. 2018 Mar;32(3):1479-1492.
Do cells secret CsA-induced, misfolded PrP molecules? To address this we inhibited the activity of cyclophilins in cells that stably express PrP and examined whether aggregative PrP species are present in the media. We found that misfolded PrP molecules are secreted by vesicles that share key features with exosomes. Our results indicate that cells can adopt more than one strategy to get rid of unwanted, potentially hazardous PrP species.
Dubnikov T, Ben-Gedalya T, Reiner R, Hoepfner D, Cabral WA, Marini JC, Cohen E.
Journal of Cell Science Oct 1;129(19):3635-3647 (2016)
Where aggresome-resident PrP molecules originate from is the key question that we dealt with in this study. Using fluorescently-tagged PrP molecules that bear different localization signals and live imaging techniques we discovered that PrP has to pass through the ER in order to reach the aggresome. Surprisingly, the Golgi apparatus has no role in directing PrP to the aggresome but the GPI is needed for the molecule to reach this cellular compartment. This study indicates that the aggresome is a cytosolic component of an ER quality control mechanism.
The inhibition of IGF-1 signaling promotes proteostasis by enhancing protein aggregation and deposition
Moll L, Ben-Gedalya T, Reuveni H, Cohen E.
FASEB J. Apr;30(4):1656-69 (2016).
What are the biological outcomes of IGF-1 signaling inhibition by NT219 is the key question that we addressed in this study. We found that mammalian cells that were treated with NT219 enhanced the expression of folding chaperones and increased the aggregation and deposition of the prion protein (PrP). Surprisingly, the inhibition of IGF-1 signaling by NT219 reduced proteasome activity and the rate of autophagy. This work supports the notion that decreased activity of protein degradation machineries is not necessarily deleterious.
Alzheimer's Disease-Causing Proline Substitutions Lead to Presenilin 1 Aggregation and Malfunction
Ben-Gedalya T, Moll L, Bejerano-Sagie M, Frere S, Cabral WA, Friedmann-Morvinski D, Slutsky I, Burstyn-Cohen T, Marini JC and Cohen E.
The EMBO journal Nov 12;34(22):2820-39 (2015).
If aging-mediated negative regulation of folding chaperone activity enables neurodegenerative maladies to onset late in life, it is plausible that distinct maladies are develop due to the failure of the same cellular mechanism. To test this idea we compared neurodegeneration-linked mutational patterns in distinct proteins and discovered that the substitution of either proline in the motif P102XXP105 of the prion protein leads to the development of the familial prion disease GSS, while the replacement of P264 or of P267 in the sequence of presenilin 1 underlies familial Alzheimer's disease (fAD). Both mutated proteins misfold and form aggregates due the inability of the ER-resident chaperone cyclophilin B to assist their folding. Our study describes a new mechanism that initiates fAD in certain families and raises key questions regarding the different faces of this devastating disorder.
Differential Regulation of the Heat Shock Factor 1 and DAF-16 by Neuronal nhl-1 in the Nematode C. elegans.
Volovik Y, Moll L, Carvalhal Marques F, Maman M, Bejerano-Sagie M and Cohen E.
Cell Reports 24;9(6):2192-205 (2014).
We found that nhl-1 is a DAF-16 co-factor which is expressed in chemosensory neurons and differentially regulates the activation of DAF-16 and HSF-1 upon exposure to heat. The expression of nhl-1 is regulated by DAF-16 and it is required for the expression of some DAF-16 targets but not of others. The knockdown of nhl-1 has no effect on lifespan but it provides partial protection from proteotoxicity. Our discoveries support the notions that lifespan is separable from stress resistance and that the abolishment of the worm's ability to respond to heat stress protects from proteotoxicity.
The Nematode Caenorhabditis elegans: a Versatile Model for the Study of Proteotoxicity and Aging.
Volovik Y, Carvalhal Marques F and Cohen E.
Methods 1;68(3):458-64, (2014).
How to study proteotoxicity in model nematodes and what are the considerations that should be taken when designing a new strain that express an aggregative protein are explained in this technical review.
A novel inhibitor of the insulin/IGF signaling pathway protects from age-onset, neurodegeneration-linked proteotoxicity.
El-Ami T, Moll L, Carvalhal Marques F, Volovik Y, Reuveni H and Cohen E.
Aging Cell, 13(1):165-74 (2014).
In this article we report that NT219, a novel IGF1 signaling inhibitor, protects worms from toxic protein aggregation of two distinct neurodegeneration-linked, aggregative peptides, A and polyQ. In practice we believe that this is the first step towards the development of a therapy that will enable the treatment of various neurodenerative disorders through the manipulation of aging.
A neuronal GPCR is critical for the induction of the heat shock response in the nematode C. elegans.
Maman M, Carvalhal Marques F, Volovik Y, Dubnikov T, Bejerano-Sagie M and Cohen E.
The Journal of Neuroscience 33(14):6102-11, (2013).
How neurons regulate the heat shock response (HSR) in remote tissues is partially understood. In this project we used an RNAi-based directed screening technique to identify neuronal receptors that are required for HSR activation in other tissues and discovered that the knockdown of a gene that encodes a putative GPCR abolishes the worm's ability to respond to elevated temperatures. This GPCR, which we termed GPCR thermal receptor 1 (gtr-1), is expressed in chemosensory neurons and has no role in the regulation of lifespan. The finding that the knockdown of gtr-1 protected worms from toxic protein aggregation supports the emerging notion that the ability to respond to heat comes at the expense of proteostasis.
Temporal Requirements of Heat Shock Factor-1 for Longevity Assurance.
Volovik Y, Maman M, Dubnikov T, Bejerano-Sagie M, Joyce D, Kapernick E, Cohen E and Dillin A.
Aging Cell 11(3):491-9, (2012).
It was shown previously that in C. elegans IIS reduction extends lifespan exclusively during reproductive adulthood. Here we asked when during the worm's lifecycle HSF-1 executes its longevity functions and found that it has dual role as a lifespan determinant. It is foremost required during early development but also needed during reproductive and late adulthood for full longevity phenotype.
Quality control compartments coming of age.
Ben Gedalya T and Cohen E.
Traffic 13(5):635-42, (2012).
The accumulation of protein aggregates in cellular deposition sites is a common feature of late-onset neurodegenerative disorders. Typically, these cellular structures appear in late life stages even in individuals who carry disease-linked mutations. In this article we reviewed the recent developments in the field of toxic protein aggregation and deposition sites and proposed models to explain the mechanistic links between the aging process, proteotoxicity and these cellular structures.
Cyclosporin A-induced prion protein aggresomes are dynamic quality control cellular compartments.
Ben Gedalya T, Lyakhovetsky R, Yedidia Y, Bejerano-Sagie M, Kogan NM, Karpuj MV, Kaganovich D and Cohen E.
Journal of Cell Science 124 (11):1891-902 (2011).
Recently two types of aggregates containing inclusion bodies have been defined; a dynamic quality control structure which was termed JUNQ and a deposition site for terminally aggregated insoluble proteins which was called IPOD. We asked what the nature of PrP containing aggresomes is, are they dynamic structures or IPOD-like deposition sites. Using live imaging techniques we found that PrP aggresomes are dynamic, JUNQ-like compartments that attract molecular chaperones and proteasomes and enable the degradation of misfolded PrP species.
Temporal requirements for insulin/IGF-1 signaling for proteotoxicity protection.
Cohen E, Du D, Joyce D, Kapernick E, Volovik Y, Kelly JW, Dillin A.
Aging Cell 9(2): 126-34, (2010).
Can IIS reduction protect worms from A aggregation when applied late in life? We used conditional RNAi techniques to address that question and found that IIS reduction can protect form A after it can no longer extend lifespan. This surprising discovery strengthen the theme that IIS reduction has an anti neurodegeneration therapeutic potential.
Reduced IGF-1 signaling delays age-associated proteotoxicity in mice.
Cohen E, Paulsson JF, Blinder P, Burstyn-Cohen T, Du D, Estepa G, Adame A, Pham HM, Holzenberger M, Kelly JW, Masliah E, Dillin A.
Cell 139(6): 1157-69, (2009).
To address whether IGF signaling reduction can protect mammals from toxicity that stems from the expression and aggregation of the Alzheimer's disease associated, A peptide we crossed AD-model mice with long-lived animals that harbor only one copy of the IGF-1 receptor. Employing behavioral, microscopic, biochemical and in-vitro techniques we found that indeed, reducing IGF-1 signaling promote a notable protection towards A toxicity. These findings have possible clinical implications as they point to IGF-1 signaling reduction as a valid approach for the development of novel neurodegeneration treatments.
The insulin paradox: aging, proteotoxicity and neurodegeneration.
Cohen E and Dillin A.
Nat Rev Neuroscience 9(10): 759-767 (2008).
In this article we reviewed the current knowledge on the links between the aging process and toxic protein aggregation focusing on the Insulin/IGF signaling pathway. We also discussed possible explanations for the insulin paradox: how can insulin reduction lead to diabetes on one hand but extend lifespan and promote health benefits on the other?
Opposing activities protect against age-onset proteotoxicity.
Cohen E, Bieschke J, Perciavalle RM, Kelly JW, Dillin A.
Science 313(5793): 1604-1610, (2006).
Can aging alteration protect from toxic protein aggregation? In this study we utilized transgenic worms expressing the human Alzheimer disease-linked peptide A in their body wall muscles and developed a paralysis assay to measure the rate of toxicity associated with the aggregating peptide. Using various techniques we found that the aging process negatively regulates two opposing activities; disaggregation and protective hyper-aggregation that are regulated by the two downstream Insulin/IGF signaling transcription factors, DAF-16 and HSF-1 respectively. This paper is the basis for ongoing research in our laboratory and in other labs in the field.
Ieshita Pan, PhD
Deposition in aggresomes is one strategy to recycle misfolded PRP species, however this is not the only mechanism that is activated by cells upon exposure to CsA. Ieshita found that secretion of PrP species is induced upon the inhibition of cyclophilins by CsA. This work, which is accepted for publication at the FASEB journal, suggests that secretion of vesicles may be involved in the spreading of misfolded PrP molecules.
Tatyana (Taly) Dubnikov, MSc
Taly tested where PrP molecules that eventually deposited in the aggresome are originated from. She found that PrP must pass through the endoplasmic reticulum to reach the aggresome. This work, which was published at the Journal of Cell Science (2016), defined the aggresome as an ER-associated quality control compartment.
Lorna Moll, PhD
What roles are played by post-translational modifications in the regulation of aging was Lorna's main focus. She found that SUMOylation links the aging-regulating mechanisms downstream of the Insulin/IGF signaling cascade and the germ cells. Lorna made critical contributions to our assessment of the drug NT219.
Filipa Carvalhal Marques, PhD
Filipa was a joint student of HUJI and the University of Coimbra (Portugal). She was interested in the differential responses of the proteostasis network to dissimilar challenges. Now Filipa is a post-doctoral fellow at the Weizmann Institute.
Lital helped our research as a great technician. She is now a student at Tommer Ravid's lab (HUJI).
Yuli Volovik, PhD
Yuli's work was focused on exploring the functional roles the neuronal gene nhl-1 in the regulation and stress resistance and proteostasis. She discovered that while the knockdown of nhl-1 renders the worm heat-sensitive, it protects from proteotoxicity in the muscle. Yuli's work was published in Cell Reports in December 2014.
Tziona Ben-Gedalya, PhD
During her years as a postdoc in the lab, Tziona focused on studying the cell biology of protein aggregation. She discovered that PrP aggresomes are dynamic quality control compartments (JCS 2011) and that certain cases of familial Alzheimer's disease and of prion disoredrs share the same mechanism (The EMBO Journal, 2015). Since 2015 Tziona works at the Hadassah medical center.
Oswa helped our research by being an excellent technical assistant. Now she works as a pharmacist.
Tayir El-Ami, MD
Tayir was interested in the potential of IGF-1 inhibitors to protect worms and mammals from proteotoxicity. She discovered that NT219, a highly efficient IGF-1 signaling inhibitor, mitigates proteotoxicity of A-beta and polyQ. Her work was published in Aging Cell (2014).
Michal Bejerano-Sagie, PhD
Michal who was our lab manager for four years, moved to the USA in August of 2014. She was involved in several projects and had an invaluable contribution to the lab.
Moria Maman, MSc
Moria completed her MSc in the lab in January of 2013 with distinction. Her thesis was focused on the roles of gtr-1 in stress response and proteotoxicity. Her work was published at the Journal of Neuroscience in April 2013. Moria is now emplyed by a biotech company.
Naama Sheffer, MSc
While in the lab Naama worked on the link between the Insulin/IGF signaling cascade and the RNaseP complex in C. elegans. She graduated in October 2013.
Ludmila Golodetzki, MSc
Mila worked on memebrane rafts and their influence on the aging process of the nematode C. elegans. She completed her studies and graduated with distinction in September 2013.
Nitai Harari, MD/PhD student
Ehud Dahan, BSc
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Excellent students who are interested in joining the lab for either M.Sc or Ph.D studies as well as post-doctorate fellows are encouraged to contact Dr. Ehud Cohen (firstname.lastname@example.org
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