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Category: biotech/medical – Page 2,185

Missing protein in brain causes behaviors mirroring autism

Scientists at Rutgers University-Newark have discovered that when a key protein needed to generate new brain cells during prenatal and early childhood development is missing, part of the brain goes haywire—causing an imbalance in its circuitry that can lead to long-term cognitive and movement behaviors characteristic of autism spectrum disorder.

“During , there is a coordinated series of events that have to occur at the right time and the right place in order to establish the appropriate number of cells with the right connections,” said Juan Pablo Zanin, Rutgers-Newark research associate and lead author on a paper published in the Journal of Neuroscience.” Each of these steps is carefully regulated and if any of these steps are not regulated correctly, this can impact behavior.”

Zanin has been working with Wilma Friedman, professor of cellular neurobiology in the Department of Biological Sciences, studying the p75NTR —needed to regulate —to determine its exact function in brain development, gain a better understanding of how this genetic mutation could cause to die off and discover whether there is a genetic link to autism or like Alzheimer’s.

The connection between ribosomes and telomeres in plants

Findings from a recent research project, conducted by a Marshall University scientist and assistant professor in the Marshall University College of Science, with researchers in Texas, was recently published in the December issue of the prestigious online journal, Nature Communications.

Dr. Eugene Shakirov is studying the connection between ribosomes and telomeres in plants. Telomeres are the physical ends of chromosomes and they shorten with age in most cells. Accelerated shortening of telomeres is linked to age-related diseases and overly long telomeres are often linked to cancer.

Telomere length varies between individuals at birth and is known to predetermine cellular lifespan, but the genes establishing length variations are largely unknown. The research being done by Shakirov, along with collaborators at the University of Texas at Austin, Texas A&M University, HudsonAlpha Institute for Biology and the Kazan Federal University in Russia focused on the study of the genetic and epigenetic causes of natural telomere length variation in Arabidopsis thaliana, a small flowering plant.

Nanoparticles deliver ‘suicide gene’ therapy to pediatric brain tumors growing in mice

Johns Hopkins researchers report that a type of biodegradable, lab-engineered nanoparticle they fashioned can successfully deliver a “suicide gene” to pediatric brain tumor cells implanted in the brains of mice. The poly(beta-amino ester) nanoparticles, known as PBAEs, were part of a treatment that also used a drug to kill the cells and prolong the test animals’ survival.

In their study, described in a report published January 2020 in the journal Nanomedicine: Nanotechnology, Biology and Medicine, the researchers caution that for safety and biological reasons, it is unlikely that the herpes simplex virus type I thymidine kinase (HSVtk)—which makes tumor cells more sensitive to the lethal effects of the anti-viral drug ganciclovir—could be the exact therapy used to treat human medulloblastoma and atypical teratoid/rhabdoid tumors (AT/RT) in children.

So-called “suicide ” have been studied and used in cancer treatments for more than 25 years. The HSVtk gene makes an enzyme that helps restore the function of natural tumor suppression.

PES1 is a critical component of telomerase assembly and regulates cellular senescence

Telomerase defers the onset of telomere shortening and cellular senescence by adding telomeric repeat DNA to chromosome ends, and its activation contributes to carcinogenesis. Telomerase minimally consists of the telomerase reverse transcriptase (TERT) and the telomerase RNA (TR). However, how telomerase assembles is largely unknown. Here, we demonstrate that PES1 (Pescadillo), a protein overexpressed in many cancers, forms a complex with TERT and TR through direct interaction with TERT, regulating telomerase activity, telomere length maintenance, and senescence. PES1 does not interact with the previously reported telomerase components Reptin, Pontin, p23, and Hsp90. PES1 facilitates telomerase assembly by promoting direct interaction between TERT and TR without affecting TERT and TR levels. PES1 expression correlates positively with telomerase activity and negatively with senescence in patients with breast cancer. Thus, we identify a previously unknown telomerase complex, and targeting PES1 may open a new avenue for cancer therapy.

Telomerase is a ribonucleoprotein (RNP) enzyme that adds telomeric repeat DNA to chromosome ends (1–3). This prevents progressive shortening of telomeres caused by the failure of the DNA replication machinery to duplicate the very end of each chromosome. Once telomeres are shortened to a certain length, cells enter replicative senescence or, alternatively, undergo apoptosis, a major tumor-suppressive mechanism. Telomerase, which is required for de novo telomeric repeat DNA synthesis and telomere maintenance, is expressed in approximately 90% of cancer cells but undetectable in the majority of normal somatic cells (4–6). Thus, telomerase is thought to be a relevant factor in distinguishing cancer cells from normal cells and has become a target for cancer therapy.

Telomerase is minimally composed of the telomerase reverse transcriptase (TERT) and the telomerase RNA (TR). Studies have shown in vitro assembly of active telomerase by combining the purified RNA component with the TERT synthesized in rabbit reticulocyte extract (7–9). A few accessory proteins have been identified to associate with the active telomerase RNP complex. The molecular chaperones p23 and Hsp90 bind to human TERT (hTERT), and chemical inhibition of Hsp90 decreases telomerase activity (10, 11). However, determining whether Hsp90 is required for active telomerase assembly is difficult because chemical inhibition of a key chaperone in human cells potentially has pleiotropic and indirect effects. Assembly of human TR (hTR) and hTERT into catalytically active telomerase is facilitated by the adenosine triphosphatases Reptin and Pontin (12). Pontin knockdown (KD) reduces telomerase activity and hTR levels.

Dendritic action potentials and computation in human layer 2/3 cortical neurons

A new unique signal discovered within the brain might be what makes us human:

https://science.sciencemag.org/content/367/6473/83

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A special developmental program in the human brain drives the disproportionate thickening of cortical layer 2/3. This suggests that the expansion of layer 2/3, along with its numerous neurons and their large dendrites, may contribute to what makes us human. Gidon et al. thus investigated the dendritic physiology of layer 2/3 pyramidal neurons in slices taken from surgically resected brain tissue in epilepsy patients. Dual somatodendritic recordings revealed previously unknown classes of action potentials in the dendrites of these neurons, which make their activity far more complex than has been previously thought. These action potentials allow single neurons to solve two long-standing computational problems in neuroscience that were considered to require multilayer neural networks.

Science, this issue p. 83

The active electrical properties of dendrites shape neuronal input and output and are fundamental to brain function. However, our knowledge of active dendrites has been almost entirely acquired from studies of rodents. In this work, we investigated the dendrites of layer 2 and 3 (L2/3) pyramidal neurons of the human cerebral cortex ex vivo. In these neurons, we discovered a class of calcium-mediated dendritic action potentials (dCaAPs) whose waveform and effects on neuronal output have not been previously described. In contrast to typical all-or-none action potentials, dCaAPs were graded; their amplitudes were maximal for threshold-level stimuli but dampened for stronger stimuli. These dCaAPs enabled the dendrites of individual human neocortical pyramidal neurons to classify linearly nonseparable inputs—a computation conventionally thought to require multilayered networks.

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Remembering Stephen Hawking on his 78th birthday: A legacy of humanity

Stephen Hawking passed away on 14 March 2018. His work changed literally everything we know about the cosmos and our place in it. But his greatest contribution to our species wasn’t his theories on black holes or how quickly the universe was expanding, it was his humanity.

Professor Hawking was born on 8 January 1942. He would have been 78 years old today – a bit older than ‘boomer’ age, his generation was called the “Silent” one. In his early twenties he was diagnosed with Lou Gehrig’s disease (ALS). Eventually he became paralyzed and could only speak with the assistance a computer-generated audio device.