bims-proarb 2022-10-02 papers

bims-proarb

Biomed News

on Proteostasis in aging and regenerative biology

Issue of 2022‒10‒02
nineteen papers selected by
Rich Giadone
Harvard University

Error-prone protein synthesis recapitulates early symptoms of Alzheimer disease in aging mice.
The unfolded protein response gene Ire1α is required for tissue renewal and normal differentiation in the mouse tongue and esophagus.
ER stress transforms random olfactory receptor choice into axon targeting precision.
The Role of Endoplasmic Reticulum Stress in Differentiation of Cells of Mesenchymal Origin.
Efficiency of Protein Renewal Is Limited by Feed Intake and Not by Protein Lifetime in Aging Caenorhabditis elegans.
Resveratrol Promotes LRSAM1 E3 Ubiquitin Ligase-Dependent Degradation of Misfolded Proteins Linked with Neurodegeneration.
Bmi1 suppresses protein synthesis and promotes proteostasis in hematopoietic stem cells.
TurnoveR: A Skyline External Tool for Analysis of Protein Turnover in Metabolic Labeling Studies.
A next-generation iPSC-derived forebrain organoid model of tauopathy with tau fibrils by AAV-mediated gene transfer.
Reprograming of proteasomal degradation by branched chain amino acid metabolism.
Single-cell analysis reveals transcriptomic reprogramming in aging primate entorhinal cortex and the relevance with Alzheimer's disease.
Autophagy Enhances Longevity of Induced Pluripotent Stem Cell-Derived Endothelium via mTOR-Independent ULK1 Kinase.
Priming mesenchymal stem cells with α-synuclein enhances neuroprotective properties through induction of autophagy in Parkinsonian models.
A nomenclature consensus for nervous system organoids and assembloids.
Building in vitro models of the brain to understand the role of APOE in Alzheimer's disease.
Proteomic features of skeletal muscle adaptation to resistance exercise training as a function of age.
Alzheimer's drug slows mental decline in trial - but is it a breakthrough?
Stress-triggered hematopoietic stem cell proliferation relies on PrimPol-mediated repriming.
Exploring the molecular mechanisms underlie the endoplasmic reticulum stress-mediated methylmercury-induced neuronal developmental damage.

Cell Rep. 2022 Sep 27. pii: S2211-1247(22)01274-8. [Epub ahead of print]40(13): 111433

Error-prone protein synthesis recapitulates early symptoms of Alzheimer disease in aging mice.

Margarita Brilkova, Martina Nigri, Harshitha Santhosh Kumar, James Moore, Matilde Mantovani, Claudia Keller, Amandine Grimm, Anne Eckert, Dimitri Shcherbakov, Rashid Akbergenov, Petra Seebeck, Stefanie D Krämer, David P Wolfer, Thomas C Gent, Erik C Böttger.

  Age-related neurodegenerative diseases (NDDs) are associated with the aggregation and propagation of specific pathogenic protein species (e.g., Aβ, α-synuclein). However, whether disruption of synaptic homeostasis results from protein misfolding per se rather than accumulation of a specific rogue protein is an unexplored question. Here, we show that error-prone translation, with its frequent outcome of random protein misfolding, is sufficient to recapitulate many early features of NDDs, including perturbed Ca2+ signaling, neuronal hyperexcitability, and mitochondrial dysfunction. Mice expressing the ribosomal ambiguity mutation Rps9 D95N exhibited disrupted synaptic homeostasis resulting in behavioral changes reminiscent of early Alzheimer disease (AD), such as learning and memory deficits, maladaptive emotional responses, epileptiform discharges, suppressed circadian rhythmicity, and sleep fragmentation, accompanied by hippocampal NPY expression and cerebral glucose hypometabolism. Collectively, our findings suggest that random protein misfolding may contribute to the pathogenesis of age-related NDDs, providing an alternative framework for understanding the initiation of AD.

Keywords:  Alzheimer; CP: Neuroscience; error-prone translation; neurodegenerative diseases; pathogenesis; protein misfolding; synaptic homeostasis

DOI:  https://doi.org/10.1016/j.celrep.2022.111433
Dev Biol. 2022 Sep 27. pii: S0012-1606(22)00180-4. [Epub ahead of print]

The unfolded protein response gene Ire1α is required for tissue renewal and normal differentiation in the mouse tongue and esophagus.

Fiona E Chalmers, Saie Mogre, Bipin Rimal, Jeongin Son, Andrew D Patterson, Douglas B Stairs, Adam B Glick.

  The IRE1α-XBP1s signaling branch of the unfolded protein response is a well-characterized survival pathway that allows cells to adapt to and resolve endoplasmic reticulum stress. Recent data has broadened our understanding of IRE1α-XBP1s signaling beyond a stress response and revealed a physiological mechanism required for the differentiation and maturation of a wide variety of cell types. Here we provide evidence that the IRE1α-XBP1s signaling pathway is required for the proliferation and maturation of basal keratinocytes in the mouse tongue and esophageal epithelium. Mice with conditional targeted deletion of either Ire1α or Xbp1 in keratin 14 expressing basal keratinocytes displayed severe thinning of the lingual and esophageal mucosa that rendered them unable to eat. In IRE1α null epithelium harvested at an earlier timepoint, genes regulating cell proliferation, cell-cell adhesion, and keratinization were significantly downregulated; indirect immunofluorescence revealed fewer proliferating basal keratinocytes, downregulation of E-cadherin, and thinning of the loricrin-positive granular and cornified layers. The number of Tp63-positive basal keratinocytes was reduced in the absence of IRE1α, and expression of the Wnt pathway transcription factor LEF1, which is required for the proliferation of lingual transit amplifying cells, was also significantly downregulated at the transcript and protein level. Together these results reveal an essential role for IRE1α-XBP1s in the maintenance of the stratified squamous epithelial tissue of the tongue and esophagus.

Keywords:  Differentiation; Endoplasmic reticulum stress; Keratinocytes; Stratified squamous epithelium; Unfolded protein response; Wnt pathway

DOI:  https://doi.org/10.1016/j.ydbio.2022.09.009
Cell. 2022 Sep 21. pii: S0092-8674(22)01120-5. [Epub ahead of print]

ER stress transforms random olfactory receptor choice into axon targeting precision.

Hani J Shayya, Jerome K Kahiapo, Rachel Duffié, Katherine S Lehmann, Lisa Bashkirova, Kevin Monahan, Ryan P Dalton, Joanna Gao, Song Jiao, Ira Schieren, Leonardo Belluscio, Stavros Lomvardas.

  Olfactory sensory neurons (OSNs) convert the stochastic choice of one of >1,000 olfactory receptor (OR) genes into precise and stereotyped axon targeting of OR-specific glomeruli in the olfactory bulb. Here, we show that the PERK arm of the unfolded protein response (UPR) regulates both the glomerular coalescence of like axons and the specificity of their projections. Subtle differences in OR protein sequences lead to distinct patterns of endoplasmic reticulum (ER) stress during OSN development, converting OR identity into distinct gene expression signatures. We identify the transcription factor Ddit3 as a key effector of PERK signaling that maps OR-dependent ER stress patterns to the transcriptional regulation of axon guidance and cell-adhesion genes, instructing targeting precision. Our results extend the known functions of the UPR from a quality-control pathway that protects cells from misfolded proteins to a sensor of cellular identity that interprets physiological states to direct axon wiring.

Keywords:  Ddit3; PERK; axon guidance; axon targeting; cell adhesion; extracellular barcodes; olfactory receptors; stochastic gene choice; transcriptional networks; unfolded protein response

DOI:  https://doi.org/10.1016/j.cell.2022.08.025
Biochemistry (Mosc). 2022 Sep;87(9): 916-931

The Role of Endoplasmic Reticulum Stress in Differentiation of Cells of Mesenchymal Origin.

Ekaterina Turishcheva, Mariya Vildanova, Galina Onishchenko, Elena Smirnova.

  Endoplasmic reticulum (ER) is a multifunctional membrane-enclosed organelle. One of the major ER functions is cotranslational transport and processing of secretory, lysosomal, and transmembrane proteins. Impaired protein processing caused by disturbances in the ER homeostasis results in the ER stress. Restoration of normal ER functioning requires activation of an adaptive mechanism involving cell response to misfolded proteins, the so-called unfolded protein response (UPR). Besides controlling protein folding, UPR plays a key role in other physiological processes, in particular, differentiation of cells of connective, muscle, epithelial, and neural tissues. Cell differentiation is induced by the physiological levels of ER stress, while excessive ER stress suppresses differentiation and can result in cell death. So far, it remains unknown whether UPR activation induces cell differentiation or if UPR is initiated by the upregulated synthesis of secretory proteins during cell differentiation. Cell differentiation is an important stage in the development of multicellular organisms and is tightly controlled. Suppression or excessive activation of this process can lead to the development of various pathologies in an organism. In particular, impairments in the differentiation of connective tissue cells can result in the development of fibrosis, obesity, and osteoporosis. Recently, special attention has been paid to fibrosis as one of the major complications of COVID-19. Therefore, studying the role of UPR in the activation of cell differentiation is of both theoretical and practical interest, as it might result in the identification of molecular targets for selective regulation of cell differentiation stages and as well as the potential to modulate the mechanisms involved in the development of various pathological states.

Keywords:  adipogenesis; cell differentiation; endoplasmic reticulum; endoplasmic reticulum stress; fibrosis; myofibroblasts; myogenesis; osteoblastogenesis; osteoclastogenesis; unfolded protein response

DOI:  https://doi.org/10.1134/S000629792209005X
J Proteome Res. 2022 Oct 01.

Efficiency of Protein Renewal Is Limited by Feed Intake and Not by Protein Lifetime in Aging Caenorhabditis elegans.

Jasmeet Kaur Khanijou, Zhuangli Yee, Manfred Raida, Jin Meng Lee, Evan Zhi En Tay, Jan Gruber, Thomas Walczyk.

  Protein turnover maintains the proteome's functional integrity. Here, protein turnover efficiency over time in wild-type Caenorhabditis elegans was assessed using inverse [15N]-pulse labeling up to 7 days after the egg-laying phase at 20 °C. Isotopic analysis of some abundant proteins was executed favoring data quality over quantity for mathematical modeling. Surprisingly, isotopic enrichment over time reached an upper limit showing an apparent cessation of protein renewal well before death, with protein fractions inaccessible to turnover ranging from 14 to 83%. For life span modulation, worms were raised at different temperatures after egg laying. Mathematical modeling of isotopic enrichment points either to a slowdown of protein turnover or to an increasing protein fraction resistant to turnover with time. Most notably, the estimated time points of protein turnover cessation from our mathematical model were highly correlated with the observed median life span. Thrashing and pumping rates over time were linearly correlated with isotopic enrichment, therefore linking protein/tracer intake to protein turnover rate and protein life span. If confirmed, life span extension is possible by optimizing protein turnover rate through modulating protein intake in C. elegans and possibly other organisms. While proteome maintenance benefits from a high protein turnover rate, protein turnover is fundamentally energy-intensive, where oxidative stress contributes to damage that it is supposed to repair.

Keywords:  15N stable isotope tracing; C. elegans; protein turnover; tracer kinetics

DOI:  https://doi.org/10.1021/acs.jproteome.2c00383
Cell Physiol Biochem. 2022 Sep 28. 56(5): 530-545

Resveratrol Promotes LRSAM1 E3 Ubiquitin Ligase-Dependent Degradation of Misfolded Proteins Linked with Neurodegeneration.

Ankur Rakesh Dubey, Ribhav Mishra, Naveen Sundaria, Yuvraj Anandrao Jagtap, Prashant Kumar, Sumit Kinger, Akash Choudhary, Hem Chandra Jha, Amit Prasad, Ravi Kumar Gutti, Amit Mishra.

  BACKGROUND/AIMS: Cells require regular maintenance of proteostasis. Synthesis of new polypeptides and elimination of damaged or old proteins is an uninterrupted mechanism essential for a healthy cellular environment. Impairment in the removal of misfolded proteins can disturb proteostasis; such toxic aggregation of misfolded proteins can act as a primary risk factor for neurodegenerative diseases and imperfect ageing. The critical challenge is to design effective protein quality control (PQC) based molecular tactics that could potentially eliminate aggregation-prone protein load from the cell. Still, targeting specific components of the PQC pathway for the suppression of proteotoxic insults retains several challenges. Earlier, we had observed that LRSAM1 promotes the degradation of aberrant proteins. Here, we examined the effect of resveratrol, a stilbenoid phytoalexin compound, treatment on LRSAM1 E3 ubiquitin ligase, involved in the spongiform neurodegeneration.METHODS: In this study, we reported induction of mRNA and protein levels of LRSAM1 in response to resveratrol treatment via RT-PCR, immunoblotting, and immunofluorescence analysis. The LRSAM1-mediated proteasomal-based clearance of misfolded proteins was also investigated via proteasome activity assays, immunoblotting and immunofluorescence analysis. The increased stability of LRSAM1 by resveratrol was demonstrated by cycloheximide chase analysis.
RESULTS: Here, we show that resveratrol treatment induces LRSAM1 E3 ubiquitin ligase expression levels. Further, our findings suggest that overexpression of LRSAM1 significantly elevates proteasome activities and improves the degradation of bona fide heat-denatured luciferase protein. Exposure of resveratrol not only slows down the turnover of LRSAM1 but also effectively degrades abnormal proteinaceous inclusions, which eventually promotes cell viability.
CONCLUSION: Our findings suggest that resveratrol facilitates LRSAM1 endogenous establishment, which consequently promotes the proteasome machinery for effective removal of intracellular accumulated misfolded or proteasomal-designated substrates. Altogether, our study proposes a promising molecular approach to specifically trigger PQC signaling for efficacious rejuvenation of defective proteostasis via activation of overburdened proteolytic machinery.

Keywords:  Resveratrol; LRSAM1; E3 Ubiquitin Ligase; Proteasome; Neurodegeneration

DOI:  https://doi.org/10.33594/000000574
Genes Dev. 2022 Sep 27.

Bmi1 suppresses protein synthesis and promotes proteostasis in hematopoietic stem cells.

Rebecca J Burgess, Zhiyu Zhao, Daisuke Nakada, Sean J Morrison.

  The polycomb complex component Bmi1 promotes the maintenance of stem cells in multiple postnatal tissues, partly by negatively regulating the expression of p16Ink4a and p19Arf, tumor suppressors associated with cellular senescence. However, deficiency for p16Ink4a and p19Arf only partially rescues the function of Bmi1-deficient stem cells. We conditionally deleted Bmi1 from adult hematopoietic cells and found that this slowly depleted hematopoietic stem cells (HSCs). Rather than inducing senescence, Bmi1 deficiency increased HSC division. The increased cell division was caused partly by increased Aristaless-related homeobox (ARX) transcription factor expression, which also increased ribosomal RNA expression. However, ARX deficiency did not rescue HSC depletion. Bmi1 deficiency also increased protein synthesis, protein aggregation, and protein ubiquitylation independent of its effects on cell division and p16Ink4a, p19Arf, and ARX expression. Bmi1 thus promotes HSC quiescence by negatively regulating ARX expression and promotes proteostasis by suppressing protein synthesis. This highlights a new connection between the regulation of stem cell maintenance and proteostasis.

Keywords:  polycomb; self-renewal; senescence; tissue regeneration; tumor suppressor

DOI:  https://doi.org/10.1101/gad.349917.122
J Proteome Res. 2022 Sep 27.

TurnoveR: A Skyline External Tool for Analysis of Protein Turnover in Metabolic Labeling Studies.

Nathan Basisty, Nicholas Shulman, Cameron Wehrfritz, Alexandra N Marsh, Samah Shah, Jacob Rose, Scott Ebert, Matthew Miller, Dao-Fu Dai, Peter S Rabinovitch, Christopher M Adams, Michael J MacCoss, Brendan MacLean, Birgit Schilling.

  In spite of its central role in biology and disease, protein turnover is a largely understudied aspect of most proteomic studies due to the complexity of computational workflows that analyze in vivo turnover rates. To address this need, we developed a new computational tool, TurnoveR, to accurately calculate protein turnover rates from mass spectrometric analysis of metabolic labeling experiments in Skyline, a free and open-source proteomics software platform. TurnoveR is a straightforward graphical interface that enables seamless integration of protein turnover analysis into a traditional proteomics workflow in Skyline, allowing users to take advantage of the advanced and flexible data visualization and curation features built into the software. The computational pipeline of TurnoveR performs critical steps to determine protein turnover rates, including isotopologue demultiplexing, precursor-pool correction, statistical analysis, and generation of data reports and visualizations. This workflow is compatible with many mass spectrometric platforms and recapitulates turnover rates and differential changes in turnover rates between treatment groups calculated in previous studies. We expect that the addition of TurnoveR to the widely used Skyline proteomics software will facilitate wider utilization of protein turnover analysis in highly relevant biological models, including aging, neurodegeneration, and skeletal muscle atrophy.

Keywords:  Skyline; aging; mass spectrometry; metabolic labeling; protein degradation; protein synthesis; protein turnover; proteostasis; quantitative proteomics; stable isotope labeling

DOI:  https://doi.org/10.1021/acs.jproteome.2c00173
Cell Rep Methods. 2022 Sep 19. 2(9): 100289

A next-generation iPSC-derived forebrain organoid model of tauopathy with tau fibrils by AAV-mediated gene transfer.

Hiroko Shimada, Yuta Sato, Takashi Sasaki, Aki Shimozawa, Kent Imaizumi, Tomoko Shindo, Sachiyo Miyao, Kosuke Kiyama, Takahiro Kondo, Shinsuke Shibata, Seiji Ishii, Junro Kuromitsu, Hirofumi Aoyagi, Daisuke Ito, Hideyuki Okano.

  It is known that the human cellular models of Alzheimer's disease (AD) and tauopathy can only recapitulate the very early stage of the disease. To overcome these limitations, we developed a technology to make forebrain organoids (FBOs) from feeder-free induced pluripotent stem cells (iPSC)s by regulating a FGF2 concentration and applied this method to generate FBOs from patients with familial AD (fAD FBOs). The obtained fAD FBOs recapitulated the amyloid-β pathology and increased tau phosphorylation but not tau aggregates. To fully induce the tau pathology, FBOs were injected with adeno-associated virus (AAV)-expressing P301L mutant tau. In these Tau-P301L FBOs, tau fibrils were observed in the neuronal cell body and neurites with immunoelectron microscopy, in addition to the sarkosyl-insoluble and thioflavin S-positive phospho-tau aggregates. Collectively, this model can be used as a platform for investigating pathogenetic mechanisms and evaluation of target molecules for drug discovery for tauopathy.

Keywords:  AAV; Alzheimer's disease; FGF2; brain organoids; feeder-free iPSCs; tau; tauopathy

DOI:  https://doi.org/10.1016/j.crmeth.2022.100289
Aging Cell. 2022 Sep 27. e13725

Reprograming of proteasomal degradation by branched chain amino acid metabolism.

Sonia Ravanelli, Qiaochu Li, Andrea Annibal, Aleksandra Trifunovic, Adam Antebi, Thorsten Hoppe.

  Branched-chain amino acid (BCAA) metabolism is a central hub for energy production and regulation of numerous physiological processes. Controversially, both increased and decreased levels of BCAAs are associated with longevity. Using genetics and multi-omics analyses in Caenorhabditis elegans, we identified adaptive regulation of the ubiquitin-proteasome system (UPS) in response to defective BCAA catabolic reactions after the initial transamination step. Worms with impaired BCAA metabolism show a slower turnover of a GFP-based proteasome substrate, which is suppressed by loss-of-function of the first BCAA catabolic enzyme, the branched-chain aminotransferase BCAT-1. The exogenous supply of BCAA-derived carboxylic acids, which are known to accumulate in the body fluid of patients with BCAA metabolic disorders, is sufficient to regulate the UPS. The link between BCAA intermediates and UPS function presented here sheds light on the unexplained role of BCAAs in the aging process and opens future possibilities for therapeutic interventions.

Keywords:   Caenorhabditis elegans ; aging; branched-chain amino acid; branched-chain aminotransferase; metabolism; proteasome; proteostasis; ubiquitin

DOI:  https://doi.org/10.1111/acel.13725
Aging Cell. 2022 Sep 27. e13723

Single-cell analysis reveals transcriptomic reprogramming in aging primate entorhinal cortex and the relevance with Alzheimer's disease.

Ming-Li Li, Shi-Hao Wu, Bo Song, Jing Yang, Li-Yuan Fan, Yang Yang, Yun-Chao Wang, Jing-Hua Yang, Yuming Xu.

  The entorhinal cortex is of great importance in cognition and memory, its dysfunction causes a variety of neurological diseases, particularly Alzheimer's disease (AD). Yet so far, research on entorhinal cortex is still limited. Here, we provided the first single-nucleus transcriptomic map of primate entorhinal cortex aging. Our result revealed that synapse signaling, neurogenesis, cellular homeostasis, and inflammation-related genes and pathways changed in a cell-type-specific manner with age. Moreover, among the 7 identified cell types, we highlighted the neuronal lineage that was most affected by aging. By integrating multiple datasets, we found entorhinal cortex aging was closely related to multiple neurodegenerative diseases, particularly for AD. The expression levels of APP and MAPT, which generate β-amyloid (Aβ) and neurofibrillary tangles, respectively, were increased in most aged entorhinal cortex cell types. In addition, we found that neuronal lineage in the aged entorhinal cortex is more prone to AD and identified a subpopulation of excitatory neurons that are most highly associated with AD. Altogether, this study provides a comprehensive cellular and molecular atlas of the primate entorhinal cortex at single-cell resolution and provides new insights into potential therapeutic targets against age-related neurodegenerative diseases.

Keywords:  aging; alzheimer’s disease; entorhinal cortex; primate; single cell

DOI:  https://doi.org/10.1111/acel.13723
Stem Cells Transl Med. 2022 Sep 29. pii: szac069. [Epub ahead of print]

Autophagy Enhances Longevity of Induced Pluripotent Stem Cell-Derived Endothelium via mTOR-Independent ULK1 Kinase.

Katherine E Hekman, Kyle M Koss, David Z Ivancic, Congcong He, Jason A Wertheim.

  Stem cells are enabling an improved understanding of the peripheral arterial disease, and patient-specific stem cell-derived endothelial cells (ECs) present major advantages as a therapeutic modality. However, applications of patient-specific induced pluripotent stem cell (iPSC)-derived ECs are limited by rapid loss of mature cellular function in culture. We hypothesized that changes in autophagy impact the phenotype and cellular proliferation of iPSC-ECs. Endothelial cells were differentiated from distinct induced pluripotent stem cell lines in 2D culture and purified for CD144 positive cells. Autophagy, mitochondrial morphology, and proliferation were characterized during differentiation and over serial passages in culture. We found that autophagy activity was stimulated during differentiation but stagnated in mature iPSC-ECs. Mitochondria remodeled through mitophagy during differentiation and demonstrated increasing membrane potential and mass through serial passages; however, these plateaued, coinciding with decreased proliferation. To evaluate for oxidative damage, iPSC-ECs were alternatively grown under hypoxic culture conditions; however, hypoxia only transiently improved the proliferation. Stimulating mTOR-independent ULK1-mediated autophagy with a plant derivative AMP kinase activator Rg2 significantly improved proliferative capacity of iPSC-ECs over multiple passages. Therefore, autophagy, a known mediator of longevity, played an active role in remodeling mitochondria during maturation from pluripotency to a terminally differentiated state. Autophagy failed to compensate for increasing mitochondrial mass over serial passages, which correlated with loss of proliferation in iPSC-ECs. Stimulating ULK1-kinase-driven autophagy conferred improved proliferation and longevity over multiple passages in culture. This represents a novel approach to overcoming a major barrier limiting the use of iPSC-ECs for clinical and research applications.

Keywords:  endothelial cell; mitochondria; rapamycin; senescence; tissue engineering; vascular tissue

DOI:  https://doi.org/10.1093/stcltm/szac069
Stem Cell Res Ther. 2022 Sep 24. 13(1): 483

Priming mesenchymal stem cells with α-synuclein enhances neuroprotective properties through induction of autophagy in Parkinsonian models.

Jin Young Shin, Dong-Yeol Kim, Jieun Lee, Yu Jin Shin, Yi Seul Kim, Phil Hyu Lee.

  BACKGROUND: Mesenchymal stem cells (MSCs) may be one of candidates for disease-modifying therapy in Parkinsonian diseases. As knowledge regarding the therapeutic properties of MSCs accumulates, some obstacles still remain to be overcome, especially, successful clinical translation requires the development of culture systems that mimic the natural MSC niche, while allowing clinical-scale cell expansion without compromising quality and function of the cells. In recent years, priming approaches using bioactive peptide or complement components have been investigated to enhance the therapeutic potential of MSCs.METHODS: We investigated an innovative priming strategy by conditioning the MSCs with α-synuclein (α-syn). To induce priming, MSCs were treated with different concentrations of α-syn and various time course. We evaluated whether α-syn enhances stemness properties of MSCs and priming MSCs with α-syn would modulate autophagy-related gene expression profiles.
RESULTS: Treatment of naïve MSCs with α-syn upregulated transcriptional factors responsible for regulation of stemness, which was associated with the elevated expression of genes involved in glycolysis and cell re-programming. Primed MSCs with α-syn enhanced the expression of autophagy-regulating miRNA, and exosomes derived from primed MSCs were packed with autophagy-associated miRNA. In α-syn-overexpressing neuronal cells, primed MSCs with α-syn enhanced neuronal viability relative to naïve MSCs, through the induction of autophagy and lysosome activity. Animal study using an α-syn-overexpressing mice showed that the pro-survival effect of MSCs on dopaminergic neurons was more prominent in primed MSC-treated mice compared with that in naïve MSC-treated mice.
CONCLUSIONS: The present data suggest that MSC priming with α-syn exerts neuroprotective effects through augmented stemness and possibly the enhancement of autophagy-mediated α-syn modulation in Parkinsonian models.

Keywords:  AMBRA1; Autophagy; Exosome miRNA; Mesenchymal stem cells; Parkinson’s disease; α-Synuclein

DOI:  https://doi.org/10.1186/s13287-022-03139-w
Nature. 2022 09;609(7929): 907-910

A nomenclature consensus for nervous system organoids and assembloids.

Sergiu P Pașca, Paola Arlotta, Helen S Bateup, J Gray Camp, Silvia Cappello, Fred H Gage, Jürgen A Knoblich, Arnold R Kriegstein, Madeline A Lancaster, Guo-Li Ming, Alysson R Muotri, In-Hyun Park, Orly Reiner, Hongjun Song, Lorenz Studer, Sally Temple, Giuseppe Testa, Barbara Treutlein, Flora M Vaccarino.

Self-organizing three-dimensional cellular models derived from human pluripotent stem cells or primary tissue have great potential to provide insights into how the human nervous system develops, what makes it unique and how disorders of the nervous system arise, progress and could be treated. Here, to facilitate progress and improve communication with the scientific community and the public, we clarify and provide a basic framework for the nomenclature of human multicellular models of nervous system development and disease, including organoids, assembloids and transplants.

DOI: https://doi.org/10.1038/s41586-022-05219-6
Life Sci Alliance. 2022 Nov;pii: e202201542. [Epub ahead of print]5(11):

Building in vitro models of the brain to understand the role of APOE in Alzheimer's disease.

Rebecca L Pinals, Li-Huei Tsai.

Alzheimer's disease (AD) is a devastating, complex, and incurable disease that represents an increasingly problematic global health issue. The etiology of sporadic AD that accounts for a vast majority of cases remains poorly understood, with no effective therapeutic interventions. Genetic studies have identified AD risk genes including the most prominent, APOE, of which the ɛ4 allele increases risk in a dose-dependent manner. A breakthrough discovery enabled the creation of human induced pluripotent stem cells (hiPSCs) that can be differentiated into various brain cell types, facilitating AD research in genetically human models. Herein, we provide a brief background on AD in the context of APOE susceptibility and feature work employing hiPSC-derived brain cell and tissue models to interrogate the contribution of APOE in driving AD pathology. Such models have delivered crucial insights into cellular mechanisms and cell type-specific roles underlying the perturbed biological functions that trigger pathogenic cascades and propagate neurodegeneration. Collectively, hiPSC-based models are envisioned to be an impactful platform for uncovering fundamental AD understanding, with high translational value toward AD drug discovery and testing.

DOI: https://doi.org/10.26508/lsa.202201542
Geroscience. 2022 Sep 26.

Proteomic features of skeletal muscle adaptation to resistance exercise training as a function of age.

Colleen S Deane, Bethan E Phillips, Craig R G Willis, Daniel J Wilkinson, Ken Smith, Nahoko Higashitani, John P Williams, Nathaniel J Szewczyk, Philip J Atherton, Atsushi Higashitani, Timothy Etheridge.

  Resistance exercise training (RET) can counteract negative features of muscle ageing but older age associates with reduced adaptive capacity to RET. Altered muscle protein networks likely contribute to ageing RET adaptation; therefore, associated proteome-wide responses warrant exploration. We employed quantitative sarcoplasmic proteomics to compare age-related proteome and phosphoproteome responses to RET. Thigh muscle biopsies were collected from eight young (25 ± 1.1 years) and eight older (67.5 ± 2.6 years) adults before and after 20 weeks supervised RET. Muscle sarcoplasmic fractions were pooled for each condition and analysed using Isobaric Tags for Relative and Absolute Quantification (iTRAQ) labelling, tandem mass spectrometry and network-based hub protein identification. Older adults displayed impaired RET-induced adaptations in whole-body lean mass, body fat percentage and thigh lean mass (P > 0.05). iTRAQ identified 73 differentially expressed proteins with age and/or RET. Despite possible proteomic stochasticity, RET improved ageing profiles for mitochondrial function and glucose metabolism (top hub; PYK (pyruvate kinase)) but failed to correct altered ageing expression of cytoskeletal proteins (top hub; YWHAZ (14-3-3 protein zeta/delta)). These ageing RET proteomic profiles were generally unchanged or oppositely regulated post-RET in younger muscle. Similarly, RET corrected expression of 10 phosphoproteins altered in ageing, but these responses were again different vs. younger adults. Older muscle is characterised by RET-induced metabolic protein profiles that, whilst not present in younger muscle, improve untrained age-related proteomic deficits. Combined with impaired cytoskeletal adhesion responses, these results provide a proteomic framework for understanding and optimising ageing muscle RET adaptation.

Keywords:  Ageing; Hub protein; Network analysis; Phosphoproteome; Proteomics

DOI:  https://doi.org/10.1007/s11357-022-00658-5
Nature. 2022 Sep 29.

Alzheimer's drug slows mental decline in trial - but is it a breakthrough?

McKenzie Prillaman.



Keywords:  Alzheimer's disease; Diseases; Drug discovery

DOI:  https://doi.org/10.1038/d41586-022-03081-0
Mol Cell. 2022 Sep 20. pii: S1097-2765(22)00898-X. [Epub ahead of print]

Stress-triggered hematopoietic stem cell proliferation relies on PrimPol-mediated repriming.

Kurt Jacobs, Cyril Doerdelmann, Jana Krietsch, Daniel González-Acosta, Nicolas Mathis, Saul Kushinsky, Estrella Guarino, Carmen Gómez-Escolar, Dolores Martinez, Jonas A Schmid, Peter J Leary, Raimundo Freire, Almudena R Ramiro, Christine M Eischen, Juan Mendez, Massimo Lopes.

  Stem cell division is linked to tumorigenesis by yet-elusive mechanisms. The hematopoietic system reacts to stress by triggering hematopoietic stem and progenitor cell (HSPC) proliferation, which can be accompanied by chromosomal breakage in activated hematopoietic stem cells (HSCs). However, whether these lesions persist in their downstream progeny and induce a canonical DNA damage response (DDR) remains unclear. Inducing HSPC proliferation by simulated viral infection, we report that the associated DNA damage is restricted to HSCs and that proliferating HSCs rewire their DDR upon endogenous and clastogen-induced damage. Combining transcriptomics, single-cell and single-molecule assays on murine bone marrow cells, we found accelerated fork progression in stimulated HSPCs, reflecting engagement of PrimPol-dependent repriming, at the expense of replication fork reversal. Ultimately, competitive bone marrow transplantation revealed the requirement of PrimPol for efficient HSC amplification and bone marrow reconstitution. Hence, fine-tuning replication fork plasticity is essential to support stem cell functionality upon proliferation stimuli.

Keywords:  DNA damage response; DNA replication; Primpol; bone marrow reconstitution; hematopoietic stem cells; induced proliferation; replication fork plasticity; repriming; stem cell division

DOI:  https://doi.org/10.1016/j.molcel.2022.09.009
Ecotoxicol Environ Saf. 2022 Sep 22. pii: S0147-6513(22)00939-3. [Epub ahead of print]245 114099

Exploring the molecular mechanisms underlie the endoplasmic reticulum stress-mediated methylmercury-induced neuronal developmental damage.

Jingjing Pan, Xiaoyang Li, Haihui Liu, Chen Wang, Si Xu, Bin Xu, Yu Deng, Tianyao Yang, Wei Liu.

  Methylmercury (MeHg) is a ubiquitous environmental pollutant, which can cross the placenta and blood brain barrier, thus affecting fetal growth and development. Although previous studies have demonstrated that MeHg induces endoplasmic reticulum (ER) stress in rat cerebral cortex and primary neurons, the role of ER stress in MeHg-induced neurodevelopmental toxicity remains unclear. Here, we used ICR pregnant mice and hippocampal neurons cells (HT22 cells) to investigate the molecular mechanism by which MeHg exposure during pregnancy affects neurodevelopment. We found that prenatal MeHg exposure caused developmental delay in offspring, accompanied with ER stress, cell apoptosis, cell cycle arrest and abnormal DNA methylation. Then, we used ER stress specific inhibitor 4-PBA and CHOP siRNA to investigate the role of ER stress on HT22 cells damage caused by MeHg. The results showed that 4-PBA pretreatment restored MeHg-induced axonal shortening and alleviated apoptosis, cell cycle arrest and DNA methylation. At the same time, the activation of CHOP/c-Jun/GADD45A signaling pathway was inhibited, and the interaction between CHOP and c-Jun was weakened. In addition, CHOP siRNA reduced the expression of c-Jun and GADD45A, and relieved DNA methylation levels to some extent. In summary, our study suggested that ER stress induced by MeHg mediated cell apoptosis and cell cycle arrest, and may affect DNA methylation through activation of CHOP/c-Jun/GADD45A signaling pathway, thus leading to neuronal damage.

Keywords:  CHOP; DNA methylation; Endoplasmic reticulum stress; Methylmercury; Neurodevelopment

DOI:  https://doi.org/10.1016/j.ecoenv.2022.114099