Non-cell Autonomous Effects Research Articles

THE COMBINATION OF DUVELISIB AND ROMIDEPSIN (DR) IS HIGHLY ACTIVE AGAINST RELAPSED/REFRACTORY PERIPHERAL T‐CELL LYMPHOMA WITH LOW RATES OF TRANSAMINITIS: FINAL RESULTS

Introduction: Standard therapies for most relapsed/refractory (R/R) T-cell lymphomas (TCL) have overall response rates (ORR) of 25%-35%. Phosphoinositide-3-kinase (PI3K) δ and γ isoforms can promote tumor cell autonomous and nonautonomous effects in TCL. Initial studies of the PI3K-δ/γ inhibitor duvelisib (D) in R/R TCL showed an ORR of 50% and CR of 19%, but also a 40% rate of grade (Gr) 3/4 ALT elevation at the MTD of 75 mg BID (Horwitz et al Blood 2018). Based on preclinical data, we initiated a phase I study of D with either romidepsin (R) or bortezomib. Based on efficacy and safety, Arm A (DR) was expanded to further describe safety and subtype-specific efficacy. Methods: 66 patients were treated on Arm A, with 59 at the MTD of D 75mg BID + R 10 mg/m2 on days 1, 8, 15 of a 28 day cycle with prophylaxis against VZV and PJP. Response was assessed q2 cycles x 3 then q3 cycles. 10 patients received 1 cycle (Lead In) of D 75 mg BID alone prior to combination DR. Patients proceeding to transplant were censored. Results: 55 patients with PTCL and 11 with CTCL were treated (Table 1). No DLTs were seen in the phase 1 on Arm A so dose level 3 (D 75 + R 10) was deemed the MTD. At the MTD, 50/59 (85%) had AEs Gr 3-4 (no Gr 5) possibly related to study drug. AEs ≥Gr 3 in ≥10% of pt were: neutropenia (36%), diarrhea (15%), increased ALT/AST (14%), thrombocytopenia (10%), and infection (10%). 5 patients (9%) had ≥Gr 3 rash. 12 had any Gr oropharyngeal/esophageal candidiasis; 2 Gr3. In 10 patients who began on D-only Lead In, 4 (40%) had ≥Gr 3 ALT/AST and 3/10 had ≥Gr 3 diarrhea. By contrast, only 4 /49 (8%) who got R + D in cycle 1 had Gr 3-4 ALT/AST (p = .022) and 6/49 had ≥Gr 3 diarrhea (p = .170). 64/66 patients were evaluable for response. ORR was 55% (35/64) and CR was 34% (22/64). In PTCL, ORR was 58% (31/53) and CR was 42% (22/53). In CTCL, ORR was 36% (4/11), all PR. Response by histology is in Table 1. Of responders, 15/35 (43%) proceeded to allo-SCT with curative intent, after a median of 4 cycles. Median PFS was 6.9 m (PTCL) and 5.5 m (CTCL) and median DOR was 8.1 m. 4 subjects had CR to single agent D on Lead-in and did not proceed to DR; 2/4 went to SCT and 1/4 remains on D at 42m. Conclusion: DR is highly active in R/R PTCL. Adding Romidepsin to Duvelisib 75 mg BID is safe and reduces Gr 3-4 transaminitis compared to Duvelisib at the same dose. The high rates of CR and frequent bridging to allotransplant support the value of DR for patients with R/R PTCL. The research was funded by Verastem/SecuraBio for this clinical trial Keywords: Aggressive T-cell non-Hodgkin lymphoma, Chemotherapy, Combination Therapies Conflicts of interests pertinent to the abstract S. M. Horwitz Consultant or advisory role: Acrotech Biopharma, ADC Therapeutics, Astex, C4 Therapeutics, Celgene, Janssen, Kura Oncology, Kyowa Hakko Kirin, Myeloid Therapeutics, ONO Pharmaceuticals, Seattle Genetics, Shoreline Bio, Takeda, Trillium Therapeutics, Tubulis, Verastem, SecuraBio, and Vividion Therapeutics. Honoraria: Takeda Research funding: ADC Therapeutics, Affimed, Aileron, Celgene, Daiichi Sankyo, Forty Seven, Inc., Kyowa Hakko Kirin, Millennium/Takeda, Seattle Genetics, Trillium Therapeutics, and Verastem/SecuraBio A. J. Moskowitz Consultant or advisory role: Imbrium Therapeutics L.P, Janpix Ltd., Merck, Seattle Genetics, and Takeda Research funding: ADC Therapeutics, Miragen, Seattle Genetics, Merck, Bristol-Myers Squibb, and Incyte N. Mehta-Shah Consultant or advisory role: Kiowa Hakka Kirin, Karyopharm Therapeutics, C4 Therapeutics, Daiichi Sankyo, Ono Pharmaceuticals, SecuraBio Research funding: Bristol Myers Squibb, Celgene, Verastem, Innate Pharmaceuticals, Corvus Pharmaceuticals, Genentech/Roche D. C. Fisher Consultant or advisory role: Verastem A. Kumar Consultant or advisory role: Celgene, Kite Pharmaceuticals Research funding: Abbvie Pharmaceuticals, Adaptive Biotechnologies, Pharmacyclics, Seattle Genetics, Astra Zeneca – Steering Committee for MCL Registry A. Dogan Consultant or advisory role: Corvus Pharmaceuticals, Physicians’ Education Resource, Seattle Genetics, Takeda, Roche, EUSAPharma, PeerView Research funding: Roche and Takeda D. Weinstock Consultant or advisory role: Secura Pharma Research funding: Verastem

Caenorhabditis elegans junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin.

The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole Caenorhabditis elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 colocalizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68 RyR calcium channel, and is required for animal movement. In neurons, JPH-1 colocalizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in the soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell nonautonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and with unc-68 for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68 is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.

APOE2 mitigates disease-related phenotypes in an isogenic hiPSC-based model of Alzheimer\u2019s disease

Genome-wide association studies (GWAS) have identified polymorphism in the Apolipoprotein E gene (APOE) to be the most prominent risk factor for Alzheimer’s disease (AD). Compared to individuals homozygous for the APOE3 variant, individuals with the APOE4 variant have a significantly elevated risk of AD. On the other hand, longitudinal studies have shown that the presence of the APOE2 variant reduces the lifetime risk of developing AD by 40 percent. While there has been significant research that has identified the risk-inducing effects of APOE4, the underlying mechanisms by which APOE2 influences AD onset and progression have not been extensively explored. In this study, we utilize an isogenic human induced pluripotent stem cell (hiPSC)-based system to demonstrate that conversion of APOE3 to APOE2 greatly reduced the production of amyloid-beta (Aβ) peptides in hiPSC-derived neural cultures. Mechanistically, analysis of pure populations of neurons and astrocytes derived from these neural cultures revealed that mitigating effects of APOE2 are mediated by cell autonomous and non-autonomous effects. In particular, we demonstrated the reduction in Aβ is potentially driven by a mechanism related to non-amyloidogenic processing of amyloid precursor protein (APP), suggesting a gain of the protective function of the APOE2 variant. Together, this study provides insights into the risk-modifying effects associated with the APOE2 allele and establishes a platform to probe the mechanisms by which APOE2 enhances neuroprotection against AD.

Restoration of SIRT3 gene expression by airway delivery resolves age-associated persistent lung fibrosis in mice.

Aging is a risk factor for progressive fibrotic disorders involving diverse organ systems, including the lung. Idiopathic pulmonary fibrosis, an age-associated degenerative lung disorder, is characterized by persistence of apoptosis-resistant myofibroblasts. In this report, we demonstrate that sirtuin-3 (SIRT3), a mitochondrial deacetylase, is downregulated in lungs of IPF human subjects and in mice subjected to lung injury. Over-expression of the SIRT3 cDNA via airway delivery restored capacity for fibrosis resolution in aged mice, in association with activation of the forkhead box transcription factor, FoxO3a, in fibroblasts, upregulation of pro-apoptotic members of the Bcl-2 family, and recovery of apoptosis susceptibility. While transforming growth factor-β1 reduced levels of SIRT3 and FoxO3a in lung fibroblasts, cell non-autonomous effects involving macrophage secreted products were necessary for SIRT3-mediated activation of FoxO3a. Together, these findings reveal a novel role of SIRT3 in pro-resolution macrophage functions that restore susceptibility to apoptosis in fibroblasts via a FoxO3a-dependent mechanism.

Genetically Defined, Syngeneic Organoid Platform for Developing Combination Therapies for Ovarian Cancer.

The paucity of genetically informed, immunocompetent tumor models impedes evaluation of conventional, targeted, and immune therapies. By engineering mouse fallopian tube epithelial organoids using lentiviral gene transduction and/or CRISPR/Cas9 mutagenesis, we generated multiple high-grade serous tubo-ovarian cancer (HGSC) models exhibiting mutational combinations seen in patients with HGSC. Detailed analysis of homologous recombination (HR)-proficient (Trp53-/-;Ccne1OE;Akt2OE;KrasOE ), HR-deficient (Trp53-/-;Brca1-/-;MycOE ), and unclassified (Trp53-/-;Pten-/-;Nf1-/- ) organoids revealed differences in in vitro properties (proliferation, differentiation, and "secretome"), copy-number aberrations, and tumorigenicity. Tumorigenic organoids had variable sensitivity to HGSC chemotherapeutics, and evoked distinct immune microenvironments that could be modulated by neutralizing organoid-produced chemokines/cytokines. These findings enabled development of a chemotherapy/immunotherapy regimen that yielded durable, T cell-dependent responses in Trp53-/-;Ccne1OE;Akt2OE;Kras HGSC; in contrast, Trp53-/-;Pten-/-;Nf1-/- tumors failed to respond. Mouse and human HGSC models showed genotype-dependent similarities in chemosensitivity, secretome, and immune microenvironment. Genotype-informed, syngeneic organoid models could provide a platform for the rapid evaluation of tumor biology and therapeutics. SIGNIFICANCE: The lack of genetically informed, diverse, immunocompetent models poses a major barrier to therapeutic development for many malignancies. Using engineered fallopian tube organoids to study the cell-autonomous and cell-nonautonomous effects of specific combinations of mutations found in HGSC, we suggest an effective combination treatment for the currently intractable CCNE1-amplified subgroup.This article is highlighted in the In This Issue feature, p. 211.

Deciphering the Mechanisms of COVID-19 Induced Anosmia

SARS-CoV-2 infects less than 1% of cells in the human body, yet it can cause severe damage in a variety of organs. Thus, deciphering the non-cell autonomous effects of SARS-CoV-2 infection is imperative for understanding the cellular and molecular disruption it elicits. Neurological and cognitive defects are among the least understood symptoms of COVID-19 patients, with olfactory dysfunction being their most common sensory deficit. Here, we show that both in humans and hamsters SARS-CoV-2 infection causes widespread downregulation of olfactory receptors (OR) and of their signaling components. This non-cell autonomous effect coincides with a dramatic reorganization of the neuronal nuclear architecture, which results in dissipation of genomic OR compartments and elimination of genomic contact domains genomewide. Our data provide a novel mechanism by which SARS-CoV-2 infection alters the cellular morphology and the transcriptome of cells it cannot infect, providing insight to its systemic effects in the nervous system and beyond.Funding Information: NIDCD 3R01DC018744-01S1 (SL, JO) National Institutes of Health grant, 4D Nucleome Consortium U01DA052783 (SL) Howard Hughes Medical Institute Faculty Scholar Award (SL), Zegar Family Foundation (SL).Ethics Approval Statement: The study was approved by the ethics and Institutional Review Board of Columbia University Medical Center (IRB AAAT0689, AAAS7370). LVG Golden Syrian hamsters (Mesocricetus auratus) were treated in compliance with the rules and regulations of IACUC under protocol number PROTO202000113-20-0743.

Selection-driven tumor evolution with public goods leads to patterns of clonal expansion consistent with neutral growth.

SummaryCancers are the result of eco-evolutionary processes fueled by heritable phenotypic diversification and driven by environmentally dependent selection. Space represents a key growth-limiting ecological resource, the ability to explore this resource is likely under strong selection. Using agent-based modeling, we explored the interplay between phenotypic strategies centered on gaining access to new space through cell-extrinsic degradation of extracellular matrix barriers and the exploitation of this resource through maximizing cell proliferation. While cell proliferation is a cell-intrinsic property, newly accessed space represents a public good, which can benefit both producers and non-producers. We found that this interplay results in ecological succession, enabling emergence of large, heterogeneous, and highly proliferative populations. Even though in our simulations both remodeling and proliferation strategies were under strong positive selection, their interplay led to sub-clonal architecture that could be interpreted as evidence for neutral evolution, warranting cautious interpretation of inferences from sequencing of cancer genomes.

Analysis of Clonal Evolution of AML Using Simultaneous Single-Cell DNA/RNA Analysis

Background Acute myeloid leukemia (AML) was defined by an increase of immature myeloid cells, or blasts that exceed ≥20% in bone marrow or peripheral blood. Many lines of evidence suggest that the development of AML is shaped by clonal evolution through multiple rounds of positive selection driven by newly acquired mutations, ultimately leading to an increased blast count. This process has been analyzed in detail in the case of progression from myelodysplastic syndromes (MDS) to secondary AML (sAML), which is invariably accompanied by expansion of cells that acquired new driver alterations, generating clonal substructures in many cases (Walter et al. NEJM. 2012, Makishima et al. Nat. Genet. 2015). However, it has not been fully elucidated how these newly acquired mutations contribute to increased blast cells that define AML. Results In order to understand how driver mutations contribute to the phenotype of blasts, we first focused on the driver mutations that have known to be enriched in sAML, including those in IDH1/2, NPM1, FLT3,NRAS, KRAS, PTPN11, CBL and WT1, and compared BM blast count (BC) and mutant cell fraction (MCF) of each driver mutation in 27 cases with sAML. Compared with BC, IDH1- or IDH2-mutated cells exhibited a larger MCF in most cases, suggesting that newly acquired IDH1/2 mutations contribute clonal expansion but only a part of the expanded cells undergo differentiation block and the remaining cells can differentiate into mature cells. Of interest, we observed lower MCFs than BC in approximately half of the cases with signaling pathway mutations, including FLT3 and RAS pathway (NRAS, KRAS, PTPN11 and CBL) mutations, in which MCFs for signaling pathway mutation accounted for less than 2/3 of BC, which was also observed in de novo AML cases. In fact, signaling pathway mutations in two representative cases were confirmed to account only for 30.4% and 3.4% of blast cells, using ddPCR of the blast cells collected as the CD45dim SSClow fraction, which were confirmed to show a blast morphology. These results suggest a possibility that the presence of mutant cells might affect the phenotype of the surrounding unmutated cells. Thus, to investigate the mechanism of such non-cell autonomous effects of mutations on blast cell morphology, we developed an advanced single-cell sequencing platform that enables simultaneous measurements of both mutations and gene expression profiles at a single-cell level and applied this to the analysis of immature (CD34+ Lin-) BM cells from 2 sAML cases with multiple RAS pathway mutations showing disproportionately small MCF compared to BC, in which gene expression of mutated and unmutated cells were evaluated separately. The same BM faction in 13 healthy donors was also analyzed as normal control. In single-cell mutation analysis, multiple RAS pathway mutations in both cases represented independent clones. As expected, cells carrying each RAS pathway mutation at sAML showed an immature myeloid phenotype. However, most of the cells, even carrying MDS mutations alone, also exhibited an immature myeloid phenotype similar to the RAS pathway mutated cells, although the latter cells showed upregulated RAS signaling compared with the former cells. Cells solely carrying MDS mutations in MDS phase showed multi-lineage differentiation, which was no longer observed in those cells in sAML phase. This was in contrast to another case who acquired MYC amplification on sAML progression, where nearly all cells having MYC-amplification showed an immature myeloid phenotype, whereas the remaining MDS clones lacking MYC-amplification retained multilineage differentiation even at the sAML phase. These results suggest that RAS mutants might have a non-cell autonomous effect on the surrounding cells including those hematopoietic cells lacking those mutations and other stromal cells, preventing their differentiation to mature cells, although we cannot exclude another possibility that altered BM microenvironment could influence the phenotype of both mutated and unmutated cells. Conclusions Although an acquisition of new mutations is essential for the progression of MDS to sAML, our results suggest that the blast cell phenotype may not solely be determined by cell-intrinsic effects of such mutations, but non-cell autonomous effects of mutated cells (and possibly also of an altered BM microenvironment) may have a role in increased blast count and therefore AML progression. Disclosures Inagaki: Sumitomo Dainippon Pharma Co., Ltd.: Current Employment. Nakagawa:Sumitomo Dainippon Pharma Co., Ltd.: Research Funding. Ogawa:KAN Research Institute, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai Co., Ltd.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Asahi Genomics Co., Ltd.: Current equity holder in private company; Otsuka Pharmaceutical Co., Ltd.: Research Funding; Chordia Therapeutics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Lung Myofibroblasts Promote Macrophage Profibrotic Activity through Lactate-induced Histone Lactylation.

Augmented glycolysis due to metabolic reprogramming in lung myofibroblasts is critical to their profibrotic phenotype. The primary glycolysis byproduct, lactate, is also secreted into the extracellular milieu, together with which myofibroblasts and macrophages form a spatially restricted site usually described as fibrotic niche. Therefore, we hypothesized that myofibroblast glycolysis might have a non-cell autonomous effect through lactate regulating the pathogenic phenotype of alveolar macrophages. Here, we demonstrated that there was a markedly increased lactate in the conditioned media of TGF-β1 (transforming growth factor-β1)-induced lung myofibroblasts and in the BAL fluids (BALFs) from mice with TGF-β1- or bleomycin-induced lung fibrosis. Importantly, the media and BALFs promoted profibrotic mediator expression in macrophages. Mechanistically, lactate induced histone lactylation in the promoters of the profibrotic genes in macrophages, consistent with the upregulation of this epigenetic modification in these cells in the fibrotic lungs. The lactate inductions of the histone lactylation and profibrotic gene expression were mediated by p300, as evidenced by their diminished concentrations in p300-knockdown macrophages. Collectively, our study establishes that in addition to protein, lipid, and nucleic acid molecules, a metabolite can also mediate intercellular regulations in the setting of lung fibrosis. Our findings shed new light on the mechanism underlying the key contribution of myofibroblast glycolysis to the pathogenesis of lung fibrosis.

MAPK activity dynamics regulate non-cell autonomous effects of oncogene expression.

A large fraction of human cancers contain genetic alterations within the Mitogen Activated Protein Kinase (MAPK) signaling network that promote unpredictable phenotypes. Previous studies have shown that the temporal patterns of MAPK activity (i.e. signaling dynamics) differentially regulate cell behavior. However, the role of signaling dynamics in mediating the effects of cancer driving mutations has not been systematically explored. Here, we show that oncogene expression leads to either pulsatile or sustained ERK activity that correlate with opposing cellular behaviors (i.e. proliferation vs. cell cycle arrest, respectively). Moreover, sustained-but not pulsatile-ERK activity triggers ERK activity waves in unperturbed neighboring cells that depend on the membrane metalloprotease ADAM17 and EGFR activity. Interestingly, the ADAM17-EGFR signaling axis coordinates neighboring cell migration toward oncogenic cells and is required for oncogenic cell extrusion. Overall, our data suggests that the temporal patterns of MAPK activity differentially regulate cell autonomous and non-cell autonomous effects of oncogene expression.

Non-cell autonomous effect of neuronal nicotinamide phosphoribosyl transferase on the function of neuromuscular junctions.

Non-cell autonomous effect of neuronal nicotinamide phosphoribosyl transferase on the function of neuromuscular junctions.

Abstract A13: Yap activity in bile ducts, but not in hepatocytes, is required for normal liver regeneration

Abstract The Hippo-pathway effectors Yap/Taz are assumed to be master regulators of organ regeneration. In the mouse liver, loss of Yap indeed affects the regeneration potential of hepatocytes. However, we found that this is not due to a requirement for Yap in hepatocytes to drive proliferation and regeneration, but is rather due to non-cell autonomous effects of the bile duct defects that develop in the absence of Yap. Developmental deletion of Yap and Taz in liver progenitors, which develop into hepatocytes and bile epithelial cells (BECs), impaired liver regeneration after toxin-induced injury. However, hepatocyte-specific deletion of Yap/Taz in adult mice revealed that Yap/Taz are dispensable in hepatocytes for liver regeneration. In contrast, deletion of Yap/Taz in mature BECs recapitulated the liver regeneration defects that were observed after knockout in liver progenitor cells. Notably, loss of Yap/Taz in BECs impaired bile duct integrity over time, induced a cholestatic liver phenotype, and increased apoptosis in wild-type hepatocytes after toxic liver injury. Our data show that Yap and Taz are required to maintain bile duct integrity, which is essential to maintain the regenerative capacity of adult hepatocytes. Citation Format: Elisabeth Verboven, Ivan M. Moya, Georg Halder. Yap activity in bile ducts, but not in hepatocytes, is required for normal liver regeneration [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr A13.

OTX2 Non-Cell Autonomous Activity Regulates Inner Retinal Function.

OTX2 is a homeoprotein transcription factor expressed in photoreceptors and bipolar cells in the retina. OTX2, like many other homeoproteins, transfers between cells and exerts non-cell autonomous effects such as promoting the survival of retinal ganglion cells that do not express the protein. Here we used a genetic approach to target extracellular OTX2 in the retina by conditional expression of a secreted single-chain anti-OTX2 antibody. Compared with control mice, the expression of this antibody by parvalbumin-expressing neurons in the retina is followed by a reduction in visual acuity in 1-month-old mice with no alteration of the retinal structure or cell type number or aspect. The a-waves and b-waves measured by electroretinogram were also indistinguishable from those of control mice, suggesting no functional deficit of photoreceptors and bipolar cells. Mice expressing the OTX2-neutralizing antibody did show a significant doubling in the flicker amplitude and a reduction in oscillatory potential, consistent with a change in inner retinal function. Our results show that interfering in vivo with OTX2 non-cell autonomous activity in the postnatal retina leads to an alteration in inner retinal cell functions and causes a deficit in visual acuity.

Knockout of reactive astrocyte activating factors slows disease progression in an ALS mouse model

Reactive astrocytes have been implicated in the pathogenesis of neurodegenerative diseases, including a non-cell autonomous effect on motor neuron survival in ALS. We previously defined a mechanism by which microglia release three factors, IL-1α, TNFα, and C1q, to induce neurotoxic astrocytes. Here we report that knocking out these three factors markedly extends survival in the SOD1G93A ALS mouse model, providing evidence for gliosis as a potential ALS therapeutic target.

Influences of circulatory factors on intervertebral disc aging phenotype.

Whether disc aging is influenced by factors beyond its local environment is an important unresolved question. Here we performed heterochronic parabiosis in mice to study the effects of circulating factors in young and old blood on age-associated intervertebral disc degeneration. Compared to young isochronic pairs (Y-Y), young mice paired with old mice (Y-O) showed significant increases in levels of disc MMP-13 and ADAMTS4, aggrecan fragmentation, and histologic tissue degeneration, but negligible changes in cellular senescence markers (p16INK4a, p21Cip1). Compared to old isochronic pairs (O-O), old mice paired with young mice (O-Y) exhibited a significant decrease in expression of cellular senescence markers (p16, p21, p53), but only marginal decreases in the levels of disc MMP-13 and ADAMTS4, aggrecan fragmentation, and histologic degeneration. Thus, exposing old mice to young blood circulation greatly suppressed disc cellular senescence, but only slightly decreased disc matrix imbalance and degeneration. Conversely, exposing young mice to old blood accelerated their disc matrix imbalance and tissue degeneration, with little effects on disc cellular senescence. Thus, non-cell autonomous effects of circulating factors on disc cellular senescence and matrix homeostasis are complex and suggest that disc matrix homeostasis is modulated by systemic factors and not solely through local disc cellular senescence.

Mutant TDP-43 Expression Triggers TDP-43 Pathology and Cell Autonomous Effects on Primary Astrocytes: Implications for Non-cell Autonomous Pathology in ALS.

Motor neuron degeneration in amyotrophic lateral sclerosis (ALS) caused by mutations in superoxide dismutase 1 (SOD1) is partly non-cell autonomous, involving cellular dysfunction of astrocytes. Whether non-cell autonomous effects occur in other forms of ALS, such as TAR DNA binding protein 43 (TDP-43)-related disease, remains unclear. Here, we characterised the impact of mutant TDP-43 expression on primary astrocytes derived from transgenic TDP-43A315T mice. Mutant TDP-43 astrocytes revealed evidence for TDP-43 pathology, shown by cytoplasmic TDP-43 inclusions and accumulation in insoluble cell fractions which was exacerbated by proteasomal inhibition. L-glutamate uptake, measured using an [3H]D-aspartate assay, was impaired in mutant TDP-43 astrocytes, while ATP accumulation was abnormal, suggesting mutant TDP-43 induced astrocytic dysfunction. Astrocyte activation coupled with spinal and cortical motor neuron loss in transgenic TDP-43A315T mice could imply non-cell autonomous effects of astrocytes in vivo. These data demonstrate mutant TDP-43-mediated cell autonomous effects on astrocytes that may contribute to motor neuron pathology in ALS.

MON-LB130 Glucocorticoid Receptor Signaling and Stress in the Developing Mammalian Germline

While the consequences of stress on organs such as the heart and immune system have long been established, it has only recently been shown in mice that stress experienced during pregnancy can cause molecular and behavioral changes in the exposed fetus, and even their offspring. The transmission of such phenotypes across generations implies that fetal germ cells can sense and maintain epigenetic memories of stress experienced in the womb. However, how the fetal germ cells within the developing embryo detect and respond to these stress signals is unknown. In response to stress, the major circulating hormone released is cortisol, which is the ligand for the nuclear hormone receptor known as the glucocorticoid receptor (GR). GR induces highly cell type-specific transcriptional changes in many cell types, although its function in germ cells has yet to be explored. Our preliminary studies have shown, for the first time, the robust expression and dynamic localization of GR in fetal germ cells, suggesting its activity during a crucial window of epigenetic reprogramming in male and female germ cell development. Fetal germ cells naturally undergo genome-wide demethylation of somatic and parental imprints, which leads to the de-repression of transposons that are normally silenced by methylation at their promoters. If not properly re-silenced, these transposons will generate large numbers of DNA double strand breaks during transposition, posing a serious risk to germline integrity. When GR was genetically deleted from all cells of the mouse body, we discovered elevated expression of the retrotransposon, Line1 (L1), specifically in the developing germ cells. Surprisingly, mice with a conditional deletion of GR specifically in germ cells were unable to phenocopy the full body knockout, implying that GR-mediated repression of L1 in fetal germ cells is a non-cell autonomous effect. Rather, conditional deletion of GR from the surrounding somatic cells (e.g. granulosa cells of the ovary) demonstrated increased germ cell L1 expression, strongly suggesting that GR signaling through the somatic niche is indirectly regulating L1 expression in neighboring germ cells. We therefore hypothesize that GR signaling from the somatic cell niche is functioning to indirectly suppress L1 expression within the developing fetal germ cells, which holds broad implications for how stress signals mediated by GR signaling can influence germline integrity and thus the health of future generations.

Myosin heavy chain-embryonic regulates skeletal muscle differentiation during mammalian development.

Myosin heavy chain-embryonic (MyHC-emb) is a skeletal muscle-specific contractile protein expressed during muscle development. Mutations in MYH3, the gene encoding MyHC-emb, lead to Freeman-Sheldon and Sheldon-Hall congenital contracture syndromes. Here, we characterize the role of MyHC-emb during mammalian development using targeted mouse alleles. Germline loss of MyHC-emb leads to neonatal and postnatal alterations in muscle fiber size, fiber number, fiber type and misregulation of genes involved in muscle differentiation. Deletion of Myh3 during embryonic myogenesis leads to the depletion of the myogenic progenitor cell pool and an increase in the myoblast pool, whereas fetal myogenesis-specific deletion of Myh3 causes the depletion of both myogenic progenitor and myoblast pools. We reveal that the non-cell-autonomous effect of MyHC-emb on myogenic progenitors and myoblasts is mediated by the fibroblast growth factor (FGF) signaling pathway, and exogenous FGF rescues the myogenic differentiation defects upon loss of MyHC-emb function in vitro Adult Myh3 null mice exhibit scoliosis, a characteristic phenotype exhibited by individuals with Freeman-Sheldon and Sheldon-Hall congenital contracture syndrome. Thus, we have identified MyHC-emb as a crucial myogenic regulator during development, performing dual cell-autonomous and non-cell-autonomous functions.This article has an associated 'The people behind the papers' interview.

American Society for Bone and Mineral Research‐Orthopaedic Research Society Joint Task Force Report on Cell‐Based Therapies – Secondary Publication

Cell-based therapies, defined here as the delivery of cells in vivo to treat disease, have recently gained increasing public attention as a potentially promising approach to restore structure and function to musculoskeletal tissues. Although cell-based therapy has the potential to improve the treatment of disorders of the musculoskeletal system, there is also the possibility of misuse and misrepresentation of the efficacy of such treatments. The medical literature contains anecdotal reports and research studies, along with web-based marketing and patient testimonials supporting cell-based therapy. Both the American Society for Bone and Mineral Research (ASBMR) and the Orthopaedic Research Society (ORS) are committed to ensuring that the potential of cell-based therapies is realized through rigorous, reproducible, and clinically meaningful scientific discovery. The two organizations convened a multidisciplinary and international Task Force composed of physicians, surgeons, and scientists who are recognized experts in the development and use of cell-based therapies. The Task Force was charged with defining the state-of-the art in cell-based therapies and identifying the gaps in knowledge and methodologies that should guide the research agenda. The efforts of this Task Force are designed to provide researchers and clinicians with a better understanding of the current state of the science and research needed to advance the study and use of cell-based therapies for skeletal tissues. The design and implementation of rigorous, thorough protocols will be critical to leveraging these innovative treatments and optimizing clinical and functional patient outcomes. In addition to providing specific recommendations and ethical considerations for preclinical and clinical investigations, this report concludes with an outline to address knowledge gaps in how to determine the cell autonomous and nonautonomous effects of a donor population used for bone regeneration. © 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:485-502, 2020.

Glial Cells-The Strategic Targets in Amyotrophic Lateral Sclerosis Treatment.

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease, which is characterized by the degeneration of motor neurons in the motor cortex and the spinal cord and subsequently by muscle atrophy. To date, numerous gene mutations have been linked to both sporadic and familial ALS, but the effort of many experimental groups to develop a suitable therapy has not, as of yet, proven successful. The original focus was on the degenerating motor neurons, when researchers tried to understand the pathological mechanisms that cause their slow death. However, it was soon discovered that ALS is a complicated and diverse pathology, where not only neurons, but also other cell types, play a crucial role via the so-called non-cell autonomous effect, which strongly deteriorates neuronal conditions. Subsequently, variable glia-based in vitro and in vivo models of ALS were established and used for brand-new experimental and clinical approaches. Such a shift towards glia soon bore its fruit in the form of several clinical studies, which more or less successfully tried to ward the unfavourable prognosis of ALS progression off. In this review, we aimed to summarize current knowledge regarding the involvement of each glial cell type in the progression of ALS, currently available treatments, and to provide an overview of diverse clinical trials covering pharmacological approaches, gene, and cell therapies.