DECODING AUTOPHAGOSOMES: A CLUE TO PARKINSON'S, HUNTINGTON'S, DEMENTIA

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 27, 2011.

         A paper centered on autophagy, the catabolic process by which a cell degrades its intercytoplasmic components transported in double-membraned autophagosomes by the action of its lysosomal machinery, may have implications in understanding the development of many neurodegenerative diseases, including Huntington’s disease, Parkinson’s disease, and dementia. Research from the Rubinsztein lab at the Cambridge Institute for Medical Research had previously demonstrated autophagy as an important regulator of the levels of proteins and pathogens prone to aggregation which in turn play a role in the development of these and potentially other diseases. In fact, apart from regulation of numerous physiological and pathological processes, and innate and acquired immunity, it is hypothesized that autophagosome function may play a role in cancer, infectious diseases, and ageing.

         Preautophagosomal structures stemming from the plasma membrane and other cellular sites form phagophores which in turn elongate and undergo fusion to become autophagosomes. However, the mechanism which governs the maturation of preautophagosomes to fully formed autophagosomes is largely unknown. A recent study from the same group at the Cambridge Institute for Medical Research entitled “Autophagosome Precursor Maturation Requires Homotypic Fusion” attempted to shed some light on the mechanism. More than 30 autophagy related proteins (Atg) have been previously shown to play some role in regulating autophagy. In this study, researchers were able to reveal that Atg16L1 precursors underwent homotypic fusion in order to form mature autophagosomes. This increases the size of the vesicles which appears to enhance acquisition of LC3, a key autophagosome protein, and maturation into autophagosomes. Furthermore, they were able to determine through a combination of colocalization analysis, knockdown experiments, live cell imaging, in vitro fusion assay, HCS and Image J methods etc., that the homotypic fusion of Atg16L1 precursors is dependant on the SNARE protein VAMP7 together with partner SNARE proteins including syntaxin 7, syntaxin 8, and Vti1b.

         By understanding new steps in the formation of autophagosomes, researchers have given insight and possible new therapeutic direction to the management of the many diseases and conditions for which autophagy plays a role.

REFERENCE:

Moreau K., Ravikumar B., Renna M., Puri C, and Rubinsztein D. C. Autophagosome precursor maturation requires homotypic fusion. 2011. Cell (146): 303-317.

ANXIETY: POSSIBLE TARGET FOR TREATMENT IDENTIFIED

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 25, 2011.

 British Baptist preacher Charles Haddon Spurgeon said of anxiety, “Anxiety does not empty tomorrow of its sorrows, but only empties today of its strengths.” Fear, which can be defined as an emotional response to a perceived treat, differs from anxiety in that anxiety can often occur without an identifiable triggering stimulus.          Anxiety is defined as having both psychological and physiological constituents and is characterized by “somatic, emotional, cognitive, and behavioral components.” Researchers from Queen’s University, Kingston, Ontario, have come one step closer in identifying a new method for regulating anxiety.

         Prior to the study, it was understood that neuropeptide Y (NPY) is one of the most abundant chemicals in the mammalian brain and that NPY counteracts the responses to acute threat in animal models. It was also known that intracerebroventricular (i.c.v) administration of NPY is anxiolytic (anxiety reducing). However, less had been known about the particular contributions of the area of the brain known as the lateral septum as relates to NPY-regulated anxiety reduction. NPY-like-immunoreactivity is highly expressed in the lateral septum.

         The study lead by Dr. Natalie L. Trent, of the Queen’s University’s Centre for Neuroscience Studies, was designed to investigate the effects of NPY infusions into the lateral septum across a range of anxiety related behaviors and to examine the effects of antagonizing NPY Y1 receptors on anxiety responses. 

         Rats were tested in three paradigms. The first is called the plus-maze test, in which it was found that NPY infusion into the lateral septum had no effects on the anxiety equitable behaviors as determined by the test. Furthermore, introduction of both NPY and Y1 antagonist (BIBO 3304) yielded the same result. A second test called the novelty-induced suppression of feeding test, found that rats were significantly quicker in initiating snack consumption following their first infusion of NPY, indicating a reduction in anxiety. This anxiolysis was attenuated when NPY and Y1 antagonist were co-infused into the lateral septum. The third test, called the shock-probe burying test showed that rats spent less time burying an electrified probe, a marker of reduced anxiety, after being infused with NPY. However, in this case, the Y1 antagonist did not attenuate anxiolysis. The results were enough to conclude that activation of NPY receptors in the lateral septum reduced anxiety-related responses, albeit in a test specific manner. This observation makes investigating the potential role of other NPY receptors (Y2 and/or Y5) in anxiolysis of particular interest.

         The researchers hope that the finding will lead to more selective treatment options for anxiety disorders.

REFERENCE:

Trent N. L., Menard J. L. Infusions of neuropeptide Y into the lateral septum reduce anxiety-related behaviors in the rat. Pharmacology, Biochemistry, and Behavior. 2011 (99): 580-590.

WHERE NO BONE HAS GONE BEFORE: SUBSTANCE P MEDIATES HETEROTROPIC OSSIFICATION

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 23, 2011.

            In the field of Developmental Biology one of the most fundamental principles is that of contextual determination, i.e. a cell goes along it’s particular lineage to become what it is destined to become based on a number of complex contextual factors. A condition known as Heterotopic Ossification (HO) in which patients have incurred soft tissue damage leading to the formation of extraskeletal bone is a common and serious reflection of the contextual principle. Although researchers have had advances in understanding the genetics of HO, the cellular and molecular triggers of HO have long remained unclear. That is, until recently when researchers from Northwestern University Feinberg School of Medicine and the Perelman School of Medicine at the University of Pennsylvania have managed to shed some light on the molecular mechanism of HO.

            In a previous study researchers were able to conclude that all forms of HO had something in common; the requirement of an inflammatory trigger. However, acknowledging that inflammation triggers are regulated by multiple cytokines (small cell signaling molecules that are secreted by the glial cells of the nervous system) and multiple complex neuro-endocrine controls, they conceded that identifying specific regulatory loci (specific gene or DNA sequences) that control these inflammatory triggers was difficult. Researchers were able to deduce that a pro-inflammatory neuropeptide known as Substance P (SP) was present in active areas of bone regeneration following a fracture.  Moreover, the receptor for SP had been found on cells and tissues associated with bone tissue formation and degradation. SP had also been shown to mediate immune modulation and injury-induced mobilization of CD29⁺, a cell involved in HO formation.

In this study, researchers lead by Lixin Kan studied the role of SP in patients with multiple forms of HO including sporadic, post-traumatic, neurologically associated HO, and fibrodysplasia ossificans progressiva or FOP (the genetic form of HO). They were able to show that SP expression intensified in early sporadic HO and FOP lesions. Moreover they were able to show that blocking SP prevented HO in these cases. Additionally, they were able to determine that cells that robustly express the SP receptor are required to mediate BMP-dependant (bone morphogenic protein) HO.

These results allowed researchers to determine that SP is seemingly critical in HO induction, and they go on to suggest that blocking SP or SP mediated HO pathways can be a potentially viable therapeutic approach in preventing HO.

REFERENCE: Lixin Kan, Vitali Y Lounev, Robert J Pignolo, Lishu Duan, Yijie Liu, Stuart R Stock, Tammy L McGuire, Bao Lu, Norma P Gerard, Eileen M Shore, Frederick S Kaplan, and John A Kessler. Substance P signaling mediates BMP dependent heterotopic ossification. Journal of Cellular Biochemistry, 2011.

NEW LUNG CANCER GENE: THE POWER OF MOUSE MODELS IN UNDERSTANDING HUMAN DISEASE

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 20, 2011.

                Cancer research faces many obstacles, the least of which is the sheer number of mechanisms by which cancer can arise and proliferate. Because of this and other factors, including the argument that cancer is evolutionarily conserved, it is hard to say with absolute certainty that a singular “cure for cancer” is a feasible goal. However, intuitively it seems that having an understanding of individual cancers and specific targets for treatment would be a more realistic and beneficial outlook. Alison Dooley of the David H. Koch Institute for Cancer Research at MIT is the lead author of a paper entitled “Nuclear Factor I/B is an oncogene in small cell lung cancer” that was published in the July 15 edition of Genes and Development. In the paper it is revealed that researchers have pinpointed a gene which apparently drives the progression of small cell lung cancer (SCLC).

            SCLC is an aggressive cancer accounting for about 15% of lung cancer cases and is often only diagnosed after it has metastasized. SCLC kills over 90% of patients within half a decade of being diagnosed. Previously, SCLC had been poorly characterized at the genomic level. Dr. Dooley and her team used a previously designed mouse model in which the tumor suppressor genes, Trp53 and Rb1, were conditionally deleted to identify genetic alterations that occur during SCLC progression.

            Using multiple techniques to identify genetic alterations in SCLC tumors and metastases, researchers were able to show that although the majority of the genome was surprisingly unaltered from normal cells, there were several high-level focal amplifications and deletions in tumor specimens. Nuclear factor I/B (NFIB) was found to represent a newly identified amplified gene in SCLC tumor cell expression profiles. Researchers were then able to confirm that NFIB amplifications were also seen in human SCLC.

            Knocking out NFIB in human SCLC tumors, researchers were also able to demonstrate that “NFIB is integral to human SCLC cell line viability and/or proliferation, likely depending on the NFIB levels or the cellular context of each individual tumor.” Researchers went further to demonstrate through analyses (transformations, arrays, gene set enrichment analysis) that NFIB seems to have oncogenic (cancer causing) properties.

            Dr. Dooley and her team point out that using a mouse model allowed for tumors to be initiated by defined genetic events and the disease progresses in the absence of smoking induced passenger mutations that could occur in studying the cancer type in humans. They also point out that a wealth of tumor and metastasis samples could be collected from mouse models at different stages giving more insight into the dynamic properties of genetic expression as relates to SCLC. They suggest that future efforts to identify point mutations in mouse SCLC models in conjunction with cross-species analyses would serve to prioritize the daunting number of meaningful mutations being expressed in human SCLC. It is conceivable that this approach would be beneficial in other types of cancers as well.

REFERENCE:

Dooley A. et al. Nuclear Factor I/B is an oncogene in small cell lung cancer. Genes and Development, 2011: (25) 1470-1475.

AUTOIMMUNE DISEASES AND PEANUT ALLERGIES: BORROWED APPROACH

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 18, 2011.

Arguably the man most synonymous with intelligence in the western world, Albert Einstein, said “The process of scientific discovery is, in effect, a continual flight from wonder”. In the process of inquisition scientists revisit questions, integrating novel approaches and fresh perspectives. In an article published in the journal Current Allergy and Asthma Reports entitled ‘Immunological Similarities between Selected Autoimmune Diseases and Peanut Allergy: Possible New Therapeutics Approach’, authors Michael A. Matucci and Stephen C. Dreskin decided to look at peanut allergies from the vantage point that tolerance to foods represents the normal state just as tolerance to self-proteins represents a normal state. Using this idea as the foundation to explore peanut allergies, they compared similar immunological abnormalities arising from both peanut allergies and several autoimmune diseases and suggest that understanding these similarities may lead to new therapeutic approaches for the treatment of several food allergies.

The authors stated that four ideas stimulated the article. The first idea is that patients who carry the peanut allergy exhibit elevated IgG; a type of antibody; levels compared to non-allergic control patients. This is also seen in patients with some autoimmune diseases. The second idea is that published works point to the fact that several links between autoimmunity and allergies. The third idea comes from the fact that research in both allergy and autoimmunity is focused on the regulation of T and B cells; the major cells of the adaptive immune response; by regulatory T cells. For the final inspirational idea the authors suggest that the “you are what you eat” proposal points to a greater similarity between food allergy and autoimmunity than is currently understood.

The authors used the example of autoimmune thyroidosis to highlight the similarity. Elevated IgG comparable to what is seen in patients with peanut allergies were seen in patients with autoimmune thyroidosis. It is currently thought that the disease is caused by abnormal suppressor T Cell function. The authors point out that while production of IgE; another immunoglobulin; is an absolute necessity in allergic diseases, IgG’s role is underappreciated.

Noticing the similarities, the authors decided to ask themselves whether current methods of treating autoimmune diseases, specifically immunomodulatory approaches, could be applicable to the treatment of peanut and ultimately other food allergies. They singled out Rituximab, an antibody initially developed to treat follicular lymphoma by targeting certain B-cells, as having potential for application to the treatment of food allergies. The drug has been shown useful in the treatment of several autoimmune diseases including rheumatoid arthritis, autoimmune hemolytic anemia, and systemic lupus erythematosus. In their conclusion they stated that plasma cell directed therapies may become greater targeted and clinically more viable in the future. They expect that a role for B-cell targeted therapies may someday be used alone or in concert with other approaches for the treatment of severe food allergies.

REFERENCE:                                                                                                                                          

Martucci M. A., and Dreskin S. C. Immuno Immunological Similarities between Selected Autoimmune Diseases and Peanut Allergy: Possible New Therapeutics Approach.  . Current allergy Asthma Reports, 2011, 11: 334-339.

BIOLOGY OF MUSIC: THE EARTH HAS MUSIC FOR THOSE WHO LISTEN

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. June 12, 2011.

               In William Shakespeare’s play, Twelfth Night, he is famously quoted as having written “If music be the food of love, play on; give me excess of it, that, surfeiting, the appetite may so sicken and die.” Biologists and philosophers have wondered for as long as there has been biology and philosophy, just how deeply intertwined is music in the very nature and success of life. Charles Darwin, the father of modern evolutionary theory, believed that it is in the process of sexual selection, that the origin of music lay. In commenting on the struggle of males for females as part of the greater goal of natural selection, Darwin says “These struggles are generally decided by the law of battle, but in the case of birds, apparently, by the charms of their song, by the beauty of the power of courtship, as in the dancing rock-thrush of Guiana.”

                David Rothenberg, professor of philosophy and music at the New Jersey Institute of Technology, is a great believer that one can use a musical vantage point to attempt to explain the vast beauty and diversity of nature. In particular he marvels at the commonality between the precise choreography of Australia’s lyrebird, flawless and beautiful, and the humpback whale, mysterious and awesome. Rothenberg remarks, “Why should whales and birds, two animals so different from each other, makes sounds that somehow seem related?”  In fact, if you were to speed up a whale’s song, the similarities to a complex bird song that you would observe is nothing short of remarkable. Rothenberg contends that humans may not be able to explain the beauty and profusion in the songs of species as different as lyrebirds and humpbacks, but that evolution has conserved them for some reason.

                In the Journal Lancelet, Claudius Conrad wrote an essay entitled, “Music for healing: from magic to medicine.” Depictions as far back as 4000BCE, he explains, illustrate harp-playing priests and musicians hinting at early contextual use of music for healing. While work remains to be done in understanding just how exactly music related to positive medical outcomes in yet unexplained ways, music is currently used to overcome some of the “anonymity and deindividuation of the clinical environment.”

                A culture without a musical compartment is yet to be identified. Mothers soothe their babies with a melodious “motherese” singsong; a quality that Dean Falk of the School for Advanced Research in Santa Fe, New Mexico, notes is unique to humans. Falk proposes that these singsongs are common across the human spectrum, higher in pitch and slower than adult speech, and are imperative to mother-child bonding.

                Robin Dunbar, a psychologist of Oxford University, investigates the musical role in bond strengthening in small groups of hominids. He proposes that the evolution of music occurred because the grooming practices of primates were impractical in human society, with groups becoming much larger. Dunbar and his group were able to find a remarkable connection between people who moved their bodies to music and those who merely listened, elevated thresholds for pain due to elevated levels of endorphin release.

                The mysteries and complexities of music and its role in our lives, everyday and over large time scales in an evolutionary sense, are far from understood. One can’t help but think; maybe it is better that way. Marvel as a part of our everyday existence, the wonder and the unknown, may just be music’s biggest gift to us.

REFERENCES:

Rothenberg D. Singing Nature’s Tune. USA Today, November 2010, 58-59.

Kivy P. Charles Darwin on Music. Journal of the American Musicological Society. 1959, 12(1): 42.

Zimmer C. The Brain: Is music for wooing, mothering, bonding, or is it just “auditory cheesecake”. Discover Magazine. December 2010.

Conrad C. Music for healing: from magic to medicine. The Lancelet, December 2010, 376 (9757): 1980-1981.

ALCOHOL: BEAUTY IN THE EYE OF THE BEERHOLDER

By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. June 09, 2011.

               

              Alcohol has in some way affected every individual, directly or indirectly, socially or religiously, positively or negatively, at one point or another in our lives. Whatever your beliefs about alcohol and its use or misuse, it is undeniable that alcohol is surrounded by many tales and equally as many truths. Despite its widespread social permeation, alcohol still retains the allure of mystery, especially to eager to grow up adolescents.

                In a study published in the Journal Addictive Behaviors entitled “Making Sense of alcohol experiences, young adolescents’ accounts of alcohol-related critical incidents”, Joris J. Van Hoof and his team decided to explore the implications of alcohol use in the life of young adolescents in the Netherlands. Researchers decided to look closely at the consequences, parental roles, and adolescent evaluations of alcohol use and incidents stemming from alcohol use.

                Researchers conducted 45 interviews using the ‘critical incident technique’ or CIT; a technique used in research to observe and inherently attempt to evaluate human behavior, in this case adolescents between 15 and 16; through methodically defined criteria.  Of the incidents recalled, researchers were able to find that the most prevalent consequence was that of ‘becoming ill’. This was seen in 19% of recollected alcohol related incidents, followed by ‘doing strange things’ seen in 16% of recollections, ‘interpersonal conflicts’ in 12%, ‘accidents or injuries’ in 11% and finally, ‘making contact more easily’ was recollected in 10% of incidents. Furthermore, parents were only aware of incidents in their entirety in about half the total number of cases.

                Perhaps the most important finding of the study was that whilst participants were clearly able to link the negative consequences of alcohol consumption to their personal experience or being witness to someone else’s negative experience, it was unlikely that they were deterred from intentions to consume alcohol again, or consume less alcohol. In fact, interview participants tended to label negative consequences as overall positive experiences in their accounts.

                Researchers believe that these findings point out two important observations in adolescent alcohol consumption. Firstly, it is complex in nature and a greater understanding of the roles of parents and the information being provided to adolescents is needed. Secondly, the study points towards the failure of the ‘scary story’ approach to prevention of alcohol consumption in teens and young adults. They contend that this approach may have the opposite effect and instead of deterring, encourage the early consumption of alcohol. Efforts in controlling availability and encouraging parental involvement seem to more likely offer a solution to the problem.

REFERENCE: Van Hoof J J V, Van den Boom S, and De Jong M D T. Making sense of alcohol experiences: young adolescents’ accounts of alcohol-related critical incidents. Addictive Behaviors, 36: 849-854; 2011.