SOX4 and RELA Function as Transcriptional Partners to Regulate the Expression of TNF- Responsive Genes in Fibroblast-Like Synoviocytes

SOX4 belongs to the group C of the SOX transcription factor family. It is a critical mediator of tumor necrosis factor alpha (TNF)-induced transformation of fibroblast-like s-ynoviocytes (FLS) in arthritis. In this study we investigated the genome wide association between the DNA binding and transcriptional activities of SOX4 and the NF-kappaB signaling transcription factor RELA/p65 downstream of TNF signaling. We used ChIP-seq assays in mouse FLS to compare the global DNA binding profiles of SOX4 and RELA. RNA-seq of TNF-induced wildtype and SoxC-knockout FLS was used to identify the SOX4-dependent and independent aspects of the TNF-regulated transcriptome. We found that SOX4 and RELA physically interact with each other on the chromatin. Interestingly, ChIP-seq assays revealed that 70.4% of SOX4 peak summits were within 50bp of the RELA peak summits suggesting that both proteins bind in close-proximity on regulatory sequences, enabling them to co-operatively regulate gene expression. By integrating the ChIP-seq results with RNA-seq from SoxC-knockout FLS we identified a set of TNF-responsive genes that are targets of the RELA-SOX4 transcriptional complex. These TNF-responsive and RELA-SOX4-depenedent genes included inflammation mediators, histone remodeling enzymes and components of the AP-1 signaling pathway. We also identified an autoregulatory mode of SoxC gene expression that involves a TNF-mediated switch from RELA binding to SOX4 binding in the 3' UTR of Sox4 and Sox11 genes. In conclusion, our results show that SOX4 and RELA together orchestrate a multimodal regulation of gene expression downstream of TNF signaling. Their interdependent activities play a pivotal role in the transformation of FLS in arthritis and in the inflammatory pathology of diverse tissues where RELA and SOX4 are co-expressed.

Human Adult Fibroblast-like Synoviocytes and Articular Chondrocytes Exhibit Prominent Overlap in Their Transcriptomic Signatures

Objectives

Fibroblast‐like synoviocytes (FLS) and articular chondrocytes (AC) derive from a common pool of embryonic precursor cells. They are currently believed to engage in largely distinct differentiation programs to build synovium and articular cartilage and maintain healthy tissues throughout life. We tested this hypothesis by deeply characterizing and comparing their transcriptomic attributes.

Methods

We profiled the transcriptomes of freshly isolated AC, synovium, primary FLS, and dermal fibroblasts from healthy adult humans using bulk RNA sequencing assays and downloaded published single‐cell RNA sequencing data from freshly isolated human FLS. We integrated all data to define cell‐specific signatures and validated findings with quantitative reverse transcription PCR of human samples and RNA hybridization of mouse joint sections.

Results

We identified 212 AC and 168 FLS markers on the basis of exclusive or enriched expression in either cell and 294 AC/FLS markers on the basis of similar expression in both cells. AC markers included joint‐specific and pan‐cartilaginous genes. FLS and AC/FLS markers featured 37 and 55 joint‐specific genes, respectively, and 131 and 239 pan‐fibroblastic genes, respectively. These signatures included many previously unrecognized markers with potentially important joint‐specific roles. AC/FLS markers overlapped in their expression patterns among all FLS and AC subpopulations, suggesting that they fulfill joint‐specific properties in all, rather than in discrete, AC and FLS subpopulations.

Conclusion

This study broadens knowledge and identifies a prominent overlap of the human adult AC and FLS transcriptomic signatures. It also provides data resources to help further decipher mechanisms underlying joint homeostasis and degeneration and to improve the quality control of tissues engineered for regenerative treatments.

Interleukin 9 alterations linked to alzheimer disease in african americans

OBJECTIVE

Compared to older Caucasians, older African Americans have higher risks of developing Alzheimer disease (AD) and lower cerebrospinal fluid (CSF) tau biomarker levels. It is not known whether tau-related differences begin earlier in life or whether race modifies other AD-related biomarkers such as inflammatory proteins.

METHODS

We performed multiplex cytokine analysis in a healthy middle-aged cohort with family history of AD (n = 68) and an older cohort (n = 125) with normal cognition (NC), mild cognitive impairment, or AD dementia. After determining baseline interleukin (IL)-9 level and AD-associated IL-9 change to differ according to race, we performed immunohistochemical analysis for proteins mechanistically linked to IL-9 in brains of African Americans and Caucasians (n = 38), and analyzed postmortem IL-9-related gene expression profiles in the publicly available Mount Sinai cohort (26 African Americans and 180 Caucasians).

RESULTS

Compared to Caucasians with NC, African Americans with NC had lower CSF tau, p-Tau181 , and IL-9 levels in both living cohorts. Conversely, AD was only correlated with increased CSF IL-9 levels in African Americans but not Caucasians. Immunohistochemical analysis revealed perivascular, neuronal, and glial cells immunoreactive to IL-9, and quantitative analysis in independent US cohorts showed AD to correlate with molecular changes (upstream differentiation marker and downstream effector cell marker) of IL-9 upregulation only in African Americans but not Caucasians.

INTERPRETATION

Baseline and AD-associated IL-9 differences between African Americans and Caucasians point to distinct molecular phenotypes for AD according to ancestry. Genetic and nongenetic factors need to be considered in future AD research involving unique populations. ANN NEUROL 2019;86:407-418.

Cerebral Amyloid Angiopathy: Similarity in African-Americans and Caucasians with Alzheimer's Disease

Cerebral amyloid angiopathy (CAA) of the Aβ type is variably present in the brains of patients with Alzheimer's disease (AD). CAA contributes to cognitive decline and increases the risk of lobar hemorrhage; because both AD-typical dementia and lobar hemorrhage are more common in African-Americans than in Caucasians, we postulated that African-Americans with AD might be particularly susceptible to CAA. To test this hypothesis, we analyzed CAA histopathologically in the large vessels and capillaries of autopsy-derived frontal, temporal, parietal, and occipital cortical samples from African-Americans (n = 18) and Caucasians (n = 19) with end-stage AD. In the combined cohort of 37 subjects, 22% of the subjects had severe CAA in large vessels, and 11% had severe CAA in capillaries. However, the prevalence and histopathologic characteristics of CAA were similar in the African-Americans and Caucasians. This conclusion was substantiated in an independent sample from the National Alzheimer's Coordinating Center database, in which the degree of CAA was comparable in 1,554 Caucasians and 68 African-Americans with end-stage AD. These findings support a growing consensus that the fundamental histopathologic features of AD are largely impartial to the race of the afflicted.

CSF Cytokines in Aging, Multiple Sclerosis, and Dementia

Inflammation is a common process involved in aging, multiple sclerosis (MS), and age-related neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), but there is limited evidence for the effects of aging on inflammation in the central nervous system. We collected cerebrospinal fluid (CSF) from 105 healthy control subjects representing a wide age range (23–86), and analyzed levels of cytokines associated innate immunity (TNF-α) and different T-helper subtypes: interferon–gamma induced protein 10 (IP-10) for Th1, interleukin-10 (IL-10) for Th2, and interleukin 8 (IL-8/CXCL8) for Th17. We show that CSF levels of TNF-α, IP-10, and IL-8 all increased linearly with age, but levels of IL-10 demonstrated a U-shaped relationship with age. We further found greater age-related increases in TNF-α, IL-10, and IL-8 relative to increases in IP-10 levels, consistent with a shift from Th1 to other inflammatory phenotypes. Finally, when we analyzed the same four cytokines in people with neurological disorders, we found that MS and AD, but not PD or dementia with Lewy bodies, further accentuated the age-related shift from Th1- to non-Th1-related cytokines. We propose that CSF cytokine levels represent powerful surrogates of brain inflammation and aging, and some, but not all, neurological disorders accelerate the shift away from Th1 phenotypes.

Non-beta-amyloid/tau cerebrospinal fluid markers inform staging and progression in Alzheimer's disease

Background

Alzheimer’s disease (AD) is a complex neurodegenerative disorder characterized by neuropathologic changes involving beta-amyloid (Aβ), tau, neuronal loss, and other associated biological events. While levels of cerebrospinal fluid (CSF) Aβ and tau peptides have enhanced the antemortem detection of AD-specific changes, these two markers poorly reflect the severity of cognitive and functional deficits in people with altered Aβ and tau levels. While multiple previous studies identified non-Aβ, non-tau proteins as candidate neurodegenerative markers to inform the A/T/N biomarker scheme of AD, few have advanced beyond association with clinical AD diagnosis. Here we analyzed nine promising neurodegenerative markers in a three-centered cohort using independent assays to identify candidates most likely to complement Aβ and tau in the A/T/N framework.

Methods

CSF samples from 125 subjects recruited at the three centers were exchanged such that each of the nine previously identified biomarkers can be measured at one of the three centers. Subjects were classified according to cognitive status and CSF AD biomarker profiles as having normal cognition and normal CSF (n = 31), normal cognition and CSF consistent with AD (n = 13), mild cognitive impairment and normal CSF (n = 13), mild cognitive impairment with CSF consistent with AD (n = 23), AD dementia (n = 32; CSF consistent with AD), and other non-AD dementia (n = 13; CSF not consistent with AD).

Results

Three biomarkers were identified to differ among the AD stages, including neurofilament light chain (NfL; p < 0.001), fatty acid binding protein 3 (Fabp3; p < 0.001), and interleukin (IL)-10 (p = 0.033). Increased NfL levels were most strongly associated with the dementia stage of AD, but increased Fabp3 levels were more sensitive to milder AD stages and correlated with both CSF tau markers. IL-10 levels did not correlate with tau biomarkers, but were associated with rates of longitudinal cognitive decline in mild cognitive impairment due to AD (p = 0.006). Prefreezing centrifugation did not influence measured CSF biomarker levels.

Conclusion

CSF proteins associated with AD clinical stages and progression can complement Aβ and tau markers to inform neurodegeneration. A validated panel inclusive of multiple biomarker features (etiology, stage, progression) can improve AD phenotyping along the A/T/N framework.

The Homeobox Genes of Caenorhabditis elegans and Insights into Their Spatio-Temporal Expression Dynamics during Embryogenesis

Homeobox genes play crucial roles for the development of multicellular eukaryotes. We have generated a revised list of all homeobox genes for Caenorhabditis elegans and provide a nomenclature for the previously unnamed ones. We show that, out of 103 homeobox genes, 70 are co-orthologous to human homeobox genes. 14 are highly divergent, lacking an obvious ortholog even in other Caenorhabditis species. One of these homeobox genes encodes 12 homeodomains, while three other highly divergent homeobox genes encode a novel type of double homeodomain, termed HOCHOB. To understand how transcription factors regulate cell fate during development, precise spatio-temporal expression data need to be obtained. Using a new imaging framework that we developed, Endrov, we have generated spatio-temporal expression profiles during embryogenesis of over 60 homeobox genes, as well as a number of other developmental control genes using GFP reporters. We used dynamic feedback during recording to automatically adjust the camera exposure time in order to increase the dynamic range beyond the limitations of the camera. We have applied the new framework to examine homeobox gene expression patterns and provide an analysis of these patterns. The methods we developed to analyze and quantify expression data are not only suitable for C. elegans, but can be applied to other model systems or even to tissue culture systems.

The transcription factor Grainy head and the steroid hormone ecdysone cooperate during differentiation of the skin of Drosophila melanogaster

The arthropod epidermis is an epithelium that deposits the apical cuticle, which is a stratified extracellular matrix (ECM) protecting the animal against pathogens, preventing dehydration and also serving as an exoskeleton. Differentiation of the cuticle conceivably implies coordinated production, secretion and localization of its components. The underlying molecular mechanisms are poorly explored. In this work, we show that the transcription factor Grainy head and the steroid hormone ecdysone drive the production of two partially overlapping sets of cuticle factors. Nevertheless, Grainy head is needed to modulate the expression of ecdysone signalling factors; the significance of this cross-talk is yet unclear. In addition, we found that ecdysone signalling negatively regulates its own impact. In conclusion, our findings suggest that at least two independently triggered pathways have evolved in parallel to cooperatively ensure the stereotypic implementation of the cuticle. As Grainy head is also essential for epithelial differentiation in vertebrates, we speculate that it acts to decode the ancient skin programme common to all animals. Full differentiation of the skin necessitates a second, complementing taxon-specific programme that requires its own decoder, which is represented by ecdysone in arthropods, whereas the vertebrate specific one remains to be identified.

Effects of benzoylphenylurea on chitin synthesis and orientation in the cuticle of the Drosophila larva

Chitin is an essential constituent of the insect exoskeleton, the cuticle, which is an extracellular matrix (ECM) covering the animal. It is produced by the glycosyltransferase chitin synthase at the apical plasma membrane of epidermal and tracheal cells. To fulfil its role in cuticle elasticity and stiffness it associates with proteins, thereby adopting a stereotypic arrangement of helicoidally stacked sheets, which run parallel to the surface of the animal. One approach to understand the mechanisms of chitin synthesis and organisation is to dissect these processes genetically. However, since only a few genes coding for factors involved in chitin synthesis and organisation have been identified to date using the model arthropod Drosophila melanogaster insight arising from mutant analysis is rather limited. To collect new data on the role of chitin during insect cuticle differentiation, we have analysed the effects of chitin synthesis inhibitors on Drosophila embryogenesis. For this purpose, we have chosen the benzoylphenylurea diflubenzuron and lufenuron that are widely used as insect growth regulators. Our data allow mainly two important conclusions. First, correct organisation of chitin seems to directly depend on the amount of chitin synthesised. Second, chitin synthesis and organisation are cell-autonomous processes as insecticide-treated larvae display a mosaic of cuticle defects. As benzoylphenylurea are used not only as insecticides but also as anti-diabetic drugs, the study of their impact on Drosophila cuticle differentiation may be fruitful for understanding their mode of action on a cellular pathway that is seemingly conserved between vertebrates and invertebrates.