The stereotypical distribution of TAR DNA-binding 43 protein (TDP-43) aggregates in frontotemporal lobar degeneration (FTLD-TDP) suggests that pathological TDP-43 spreads throughout the brain via ...cell-to-cell transmission and correlates with disease progression, but no in vivo experimental data support this hypothesis. We first develop a doxycycline-inducible cell line expressing GFP-tagged cytoplasmic TDP-43 protein (iGFP-NLSm) as a cell-based system to screen and identify seeding activity of human brain-derived pathological TDP-43 isolated from sporadic FTLD-TDP and familial cases with Granulin (FTLD-TDP-GRN) or C9orf72 repeat expansion mutations (FTLD-TDP-C9+). We demonstrate that intracerebral injections of biologically active pathogenic FTLD-TDP seeds into transgenic mice expressing cytoplasmic human TDP-43 (lines CamKIIa-hTDP-43
, rNLS8, and CamKIIa-208) and non-transgenic mice led to the induction of de-novo TDP-43 pathology. Moreover, TDP-43 pathology progressively spreads throughout the brain in a time-dependent manner via the neuroanatomic connectome. Our study suggests that the progression of FTLD-TDP reflects the templated cell-to-cell transneuronal spread of pathological TDP-43.
Integrin-mediated adhesion to the extracellular matrix involves a surprisingly large number of intracellular proteins, the integrin-associated proteins (IAPs), which are a fraction of the total ...integrin adhesome. In this review we discuss how genetic approaches have improved our understanding of how each IAP contributes to integrin function, especially in the context of building a functional organism during development. We then begin the process of assembling IAP roles together into an integrated mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Multiple sclerosis (MS) is a T cell-driven autoimmune disease that attacks the myelin of the central nervous system (CNS) and currently has no cure. MS etiology is linked to both the gut flora and ...external environmental factors but this connection is not well understood. One immune system regulator responsive to nonpathogenic external stimuli is the aryl hydrocarbon receptor (AHR). The AHR, which binds diverse molecules present in the environment in barrier tissues, is a therapeutic target for MS. However, AHR's precise function in T lymphocytes, the orchestrators of MS, has not been described. Here, we show that in a mouse model of MS, T cell-specific Ahr knockout leads to recovery driven by a decrease in T cell fitness. At the mechanistic level, we demonstrate that the absence of AHR changes the gut microenvironment composition to generate metabolites that impact T cell viability, such as bile salts and short chain fatty acids. Our study demonstrates a newly emerging role for AHR in mediating the interdependence between T lymphocytes and the microbiota, while simultaneously identifying new potential molecular targets for the treatment of MS and other autoimmune diseases.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Studies have shown an overlap of Aβ plaques, tau tangles, and α-synuclein (α-syn) pathologies in the brains of Alzheimer’s disease (AD) and Parkinson’s disease (PD) with dementia (PDD) patients, with ...increased pathological burden correlating with severity of cognitive and motor symptoms. Despite the observed co-pathology and concomitance of motor and cognitive phenotypes, the consequences of the primary amyloidogenic protein on the secondary pathologies remain poorly understood. To better define the relationship between α-syn and Aβ plaques, we injected α-syn preformed fibrils (α-syn mpffs) into mice with abundant Aβ plaques. Aβ deposits dramatically accelerated α-syn pathogenesis and spread throughout the brain. Remarkably, hyperphosphorylated tau (p-tau) was induced in α-syn mpff-injected 5xFAD mice. Finally, α-syn mpff-injected 5xFAD mice showed neuron loss that correlated with the progressive decline of cognitive and motor performance. Our findings suggest a “feed-forward” mechanism whereby Aβ plaques enhance endogenous α-syn seeding and spreading over time post-injection with mpffs.
•α-syn burden is associated with Aβ plaque load in the cortex of LBD patients•Aβ plaques potentiate α-syn spreading in 5xFAD mice•Aβ plaques establish a dynamic pre-misfolded pool of α-syn in dystrophic neurites•Aβ/α-syn co-pathology induces neurodegeneration and behavioral deficits
Bassil et al. describe a new model that shows how Aβ plaques in the brain can potentiate α-synuclein pathogenesis. The authors provide evidence that the interaction of both proteins in the brain lead to neurodegeneration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mutations in the GBA1 gene are the most common genetic risk factor for Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). GBA1 encodes the lysosomal lipid hydrolase glucocerebrosidase ...(GCase), and its activity has been linked to accumulation of α-synuclein. The current study systematically examines the relationship between GCase activity and both pathogenic and non-pathogenic forms of α-synuclein in primary hippocampal, cortical, and midbrain neuron and astrocyte cultures, as well as in transgenic mice and a non-transgenic mouse model of PD. We find that reduced GCase activity does not result in aggregation of α-synuclein. However, in the context of extant misfolded α-synuclein, GCase activity modulates neuronal susceptibility to pathology. Furthermore, this modulation does not depend on neuron type but rather is driven by the level of pathological α-synuclein seeds. This study has implications for understanding how GBA1 mutations influence PD pathogenesis and provides a platform for testing novel therapeutics.
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•GCase inhibition does not lead to α-synuclein aggregation in cell or animal models•Reducing GCase activity enhances pre-existing α-synuclein aggregation•GCase modulation of α-synuclein aggregation does not depend on neuron type•GCase activity enhances α-synuclein pathology when pathological seeds are low
Henderson et al. use cell and animal models of Parkinson’s disease to show that reducing glucocerebrosidase activity leads to an enhancement of pre-existing α-synuclein pathology that does not depend on neuron type, reconciling experimental biology with human epidemiology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Archaeal cell biology is an emerging field expected to identify fundamental cellular processes, help resolve the deep evolutionary history of cellular life, and contribute new components and ...functions in biotechnology and synthetic biology. To facilitate these, we have developed plasmid vectors that allow convenient cloning and production of proteins and fusion proteins with flexible, rigid, or semi-rigid linkers in the model archaeon
. For protein subcellular localization studies using fluorescent protein (FP) tags, we created vectors incorporating a range of codon-optimized fluorescent proteins for N- or C-terminal tagging, including GFP, mNeonGreen, mCherry, YPet, mTurquoise2 and mScarlet-I. Obtaining functional fusion proteins can be challenging with proteins involved in multiple interactions, mainly due to steric interference. We demonstrated the use of the new vector system to screen for improved function in cytoskeletal protein FP fusions, and identified FtsZ1-FPs that are functional in cell division and CetZ1-FPs that are functional in motility and rod cell development. Both the type of linker and the type of FP influenced the functionality of the resulting fusions. The vector design also facilitates convenient cloning and tandem expression of two genes or fusion genes, controlled by a modified tryptophan-inducible promoter, and we demonstrated its use for dual-colour imaging of tagged proteins in
cells. These tools should promote further development and applications of archaeal molecular and cellular biology and biotechnology.
Abstract We describe, for the first time, the use of cellular plastic compressed collagen as a substrate for human limbal epithelial cell expansion and stratification. The characteristics of expanded ...limbal epithelial cells on either acellular collagen constructs or those containing human limbal fibroblasts were compared to a human central cornea control. After compression, human fibroblasts in collagen constructs remained viable and limbal epithelial cells were successfully expanded on the surface. After airlifting, a multilayered epithelium formed with epithelial cell morphology very similar to that of cells in the central cornea. Immunochemical staining revealed expression of basement membrane proteins and differentiated epithelial cell markers found in native central cornea. Ultrastructural analysis revealed cells on collagen constructs had many features similar to central cornea, including polygonal, tightly opposed surface epithelial cells with microvilli and numerous desmosomes at cell–cell junctions. Taken together, these data demonstrate that plastic compressed collagen constructs can form the basis of a biomimetic tissue model for in vitro testing and could potentially provide a suitable alternative to amniotic membrane as a substrate for limbal epithelial cell transplantation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
α-Synuclein (α-syn) and tau aggregates are the neuropathological hallmarks of Parkinson's disease (PD) and Alzheimer's disease (AD), respectively, although both pathologies co-occur in patients with ...these diseases, suggesting possible crosstalk between them. To elucidate the interactions of pathological α-syn and tau, we sought to model these interactions. We show that increased accumulation of tau aggregates occur following simultaneous introduction of α-syn mousepreformed fibrils (mpffs) and AD lysate-derived tau seeds (AD-tau) both in vitro and in vivo. Interestingly, the absence of endogenous mouse α-syn in mice reduces the accumulation and spreading of tau, while the absence of tau did not affect the seeding or spreading capacity of α-syn. These in vivo results are consistent with our in vitro data wherein the presence of tau has no synergistic effects on α-syn. Our results point to the important role of α-syn as a modulator of tau pathology burden and spreading in the brains of AD, PDD, and DLB patients.
Tubulin superfamily (TSF) proteins are widespread, and are known for their multifaceted roles as cytoskeletal proteins underpinning many basic cellular functions, including morphogenesis, division, ...and motility. In eukaryotes, tubulin assembles into microtubules, a major component of the dynamic cytoskeletal network of fibres, whereas the bacterial homolog FtsZ assembles the division ring at midcell. The functions of the lesser-known archaeal TSF proteins are beginning to be identified and show surprising diversity, including homologs of tubulin and FtsZ as well as a third archaea-specific family, CetZ, implicated in the regulation of cell shape and possibly other unknown functions. In this study, we define sequence and structural characteristics of the CetZ family and CetZ1 and CetZ2 subfamilies, identify CetZ groups and diversity amongst archaea, and identify potential functional relationships through analysis of the genomic neighbourhoods of
genes. We identified at least three subfamilies of orthologous CetZ proteins in the archaeal class Halobacteria, including CetZ1 and CetZ2 as well as a novel uncharacterized subfamily. CetZ1 and CetZ2 were correlated to one another as well as to cell shape and motility phenotypes across diverse Halobacteria. Among other known CetZ clusters in orders Archaeoglobales, Methanomicrobiales, Methanosarcinales, and Thermococcales, an additional uncharacterized group from Archaeoglobales and Methanomicrobiales is affiliated strongly with Halobacteria CetZs, suggesting that they originated via horizontal transfer. Subgroups of Halobacteria CetZ2 and Thermococcales CetZ genes were found adjacent to different type IV pili regulons, suggesting potential utilization of CetZs by type IV systems. More broadly conserved
gene neighbourhoods include nucleotide and cofactor biosynthesis (e.g., F
) and predicted cell surface sugar epimerase genes. These findings imply that CetZ subfamilies are involved in multiple functions linked to the cell surface, biosynthesis, and motility.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Some microbes display pleomorphism, showing variable cell shapes in a single culture, whereas others differentiate to adapt to changed environmental conditions. The pleomorphic archaeon
commonly ...forms discoid-shaped ('plate') cells in culture, but may also be present as rods, and can develop into motile rods in soft agar, or longer filaments in certain biofilms. Here we report improvement of
growth in both semi-defined and complex media by supplementing with eight trace element micronutrients. With these supplemented media, transient development of plate cells into uniformly shaped rods was clearly observed during the early log phase of growth; cells then reverted to plates for the late log and stationary phases. In media prepared with high-purity water and reagents, without supplemental trace elements, rods and other complex elongated morphologies ('pleomorphic rods') were observed at all growth stages of the culture; the highly elongated cells sometimes displayed a substantial tubule at one or less frequently both poles, as well as unusual tapered and highly curved forms. Polar tubules were observed forming by initial mid-cell narrowing or tubulation, causing a dumbbell-like shape, followed by cell division towards one end. Formation of the uniform early log-phase rods, as well as the pleomorphic rods and tubules were dependent on the function of the tubulin-like cytoskeletal protein, CetZ1. Our results reveal the remarkable morphological plasticity of
cells in response to multiple culture conditions, and should facilitate the use of this species in further studies of archaeal biology.
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