Similar Phenotype Research Articles

Rhizobial secretion of truncated exopolysaccharides severely impairs the Mesorhizobium-Lotus symbiosis.

The symbiosis between Mesorhizobium japonicum R7A and Lotus japonicus Gifu is an important model system for investigating the role of bacterial exopolysaccharides (EPS) in plant-microbe interactions. Previously we showed that R7A exoB mutants that are affected at an early stage of EPS synthesis and in lipopolysaccharide (LPS) synthesis induce effective nodules on L. japonicus Gifu after a delay, whereas exoU mutants affected in the biosynthesis of the EPS side chain induce small uninfected nodule primordia and are impaired in infection. The presence of a halo around the exoU mutant when grown on Calcofluor-containing media suggested the mutant secreted a truncated version of R7A EPS. A non-polar ΔexoA mutant defective in the addition of the first glucose residue to the EPS backbone was also severely impaired symbiotically. Here we used a suppressor screen to show that the severe symbiotic phenotype of the exoU mutant was due to secretion of an acetylated pentasaccharide, as both monomers and oligomers, by the same Wzx/Wzy system that transports wild-type exopolysaccharide. We also present evidence that the ΔexoA mutant secretes an oligosaccharide by the same transport system, contributing to its symbiotic phenotype. In contrast, ΔexoYF, and polar exoA and exoL mutants have a similar phenotype to exoB mutants, forming effective nodules after a delay. These studies provide substantial evidence that secreted incompatible EPS is perceived by the plant leading to abrogation of the infection process.

The Tree Shrew Model of Parkinson Disease: A Cost-Effective Alternative to Nonhuman Primate Models

The surge in demand for experimental monkeys has led to a rapid increase in their costs. Consequently, there is a growing need for a cost-effective model of Parkinson disease (PD) that exhibits all core clinical and pathologic phenotypes. Evolutionarily, tree shrews (Tupaia belangeri) are closer to primates in comparison with rodents and could be an ideal species for modeling PD. To develop a tree shrew PD model, we used the 1-methyl-4-phenylpyridinium (MPP+), a metabolite derived from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, to induce lesions in dopaminergic neurons of the unilateral substantia nigra. The induced tree shrew model consistently exhibited and maintained all classic clinical manifestations of PD for a 5-month period. The symptoms included bradykinesia, rest tremor, and postural instability, and ∼50% individuals showed apomorphine-induced rotations, a classic phenotype of unilateral PD models. All these are closely resembled the ones observed in PD monkeys. Meanwhile, this model was also sensitive to L-dopa treatment in a dose-dependent manner, which suggested that the motor deficits are dopamine dependent. Immunostaining showed a significant loss of dopaminergic neurons (∼95%) in the lesioned substantia nigra, which is a crucial PD pathological marker. Moreover, a control group of nigral saline injection did not show any motor deficits and pathological changes. Cytomorphologic analysis revealed that the size of nigral dopaminergic neurons in tree shrews is much bigger than that of rodents and is close to that of macaques. The morphologic similarity may be an important structural basis for the manifestation of the highly similar phenotypes between monkey and tree shrew PD models. Collectively, in this study, we have successfully developed a PD model in a small animal species that faithfully recapitulated the classic clinical symptoms and key pathological indicators of PD monkeys, providing a novel and low-cost avenue for evaluation of PD treatments and underlying mechanisms.

Validation of an acute respiratory infection phenotyping algorithm to support robust computerised medical record-based respiratory sentinel surveillance, England, 2023.

IntroductionRespiratory sentinel surveillance systems leveraging computerised medical records (CMR) use phenotyping algorithms to identify cases of interest, such as acute respiratory infection (ARI). The Oxford-Royal College of General Practitioners Research and Surveillance Centre (RSC) is the English primary care-based sentinel surveillance network.AimThis study describes and validates the RSC's new ARI phenotyping algorithm.MethodsWe developed the phenotyping algorithm using a framework aligned with international interoperability standards. We validated our algorithm by comparing ARI events identified during the 2022/23 influenza season in England through use of both old and new algorithms. We compared clinical codes commonly used for recording ARI.ResultsThe new algorithm identified an additional 860,039 cases and excluded 52,258, resulting in a net increase of 807,781 cases (33.84%) of ARI compared to the old algorithm, with totals of 3,194,224 cases versus 2,386,443 cases. Of the 860,039 newly identified cases, the majority (63.7%) were due to identification of symptom codes suggestive of an ARI diagnosis not detected by the old algorithm. The 52,258 cases incorrectly identified by the old algorithm were due to inadvertent identification of chronic, recurrent, non-infectious and other non-ARI disease.ConclusionWe developed a new ARI phenotyping algorithm that more accurately identifies cases of ARI from the CMR. This will benefit public health by providing more accurate surveillance reports to public health authorities. This new algorithm can serve as a blueprint for other CMR-based surveillance systems wishing to develop similar phenotyping algorithms.

Overlapping peri-implantation phenotypes of ZNHIT1 and ZNHIT2 despite distinct functions during early mouse development†.

Mammalian preimplantation development culminates in the formation of a blastocyst that undergoes extensive gene expression regulation to successfully implant into the maternal endometrium. Zinc-finger HIT domain-containing (ZNHIT) 1 and 2 are members of a highly conserved family, yet they have been identified as subunits of distinct complexes. Here, we report that knockout of either Znhit1 or Znhit2 results in embryonic lethality during peri-implantation stages. Znhit1 and Znhit2 mutant embryos have overlapping phenotypes, including reduced proportion of SOX2-positive inner cell mass cells, a lack of Fgf4 expression, and aberrant expression of NANOG and SOX17. Furthermore, we find that the similar phenotypes are caused by distinct mechanisms. Specifically, embryos lacking ZNHIT1 likely fail to incorporate sufficient H2A.Z at the promoter region of Fgf4 and other genes involved in cell projection organization resulting in impaired invasion of trophoblast cells during implantation. In contrast, Znhit2 mutant embryos display a complete lack of nuclear EFTUD2, a key component of U5 spliceosome, indicating a global splicing deficiency. Our findings unveil the indispensable yet distinct roles of ZNHIT1 and ZNHIT2 in early mammalian embryonic development.

Non-immune hydrops fetalis is associated with bi-allelic pathogenic variants in the MYB Binding Protein 1a (MYBBP1A) gene.

Non-immune hydrops fetalis (NIHF) is a rare entity characterized by excessive accumulation of fluid within the fetal extravascular compartments and body cavities. Here we present two intrauterine fetal demises with NIHF presenting with oligohydramnios, cystic hygroma, pleural effusion, and generalized hydrops with predominance of subcutaneous edema. The fetuses also presented with ascites, severe and precocious IUGR and skeletal anomalies. Whole exome sequencing was applied in order to screen for a possible genetic cause. The results identified biallelic variants in MYBBP1A in both fetuses. A previous report described another case with a similar phenotype having compound heterozygous variants in the same gene. The protein encoded by MYBBP1A is involved in several cellular processes including the synthesis of ribosomal DNA, the response to nucleolar stress, and tumor suppression. Our functional protein analysis through immunohistochemistry indicates that MYBBP1A is a gene expressed during fetal stages. Altogether, we concluded that MYBBP1A is associated with the development of hydrops fetalis. More cases and further studies are necessary to understand the role of this gene and the mechanism associated with NIHF.

Substantive Similarities Between Synovial Fluid and Synovial Tissue T cells in Inflammatory Arthritis Via Single-Cell RNA and T Cell Receptor Sequencing.

Synovial fluid (SF)-derived T cells are frequently studied as a proxy for investigating the synovial tissue (ST) T cell infiltrate in inflammatory arthritis. However, because ST is the primary site of inflammatory activity, there is debate as to whether SF provides a true reflection of the ST T cell population. In this study, we used single-cell RNA sequencing paired with single-cell T cell receptor (TCR) sequencing to directly compare memory T cells from paired samples of SF and ST from six patients with inflammatory arthritis to investigate their similarity in terms of TCR repertoire and T cell subset composition. The TCR repertoires of SF and ST T cells were strikingly similar, particularly for CD8+ T cells. A median of 49% of the total CD8+ TCR repertoire in SF was shared with ST, compared with 20% shared with blood. Similarly, 47% of the ST CD8+ TCR repertoire was shared with SF compared to 25% with blood. Furthermore, once the effect of collagenase digestion on gene expression by ST T cells had been accounted for, the frequencies of specific CD8+ and CD4+ T cell subsets were, in general, similar in SF and ST and were distinct from blood. Our results suggest that T cells migrate and equilibrate between the SF and ST and maintain similar phenotypes in both sites. We conclude that SF is an appropriate proxy for investigating the T cell infiltrate in inflamed synovium, particularly in terms of investigating the TCR repertoire.

Differential pathogenetic mechanisms of mutations in helix 2 and helix 6 of rhodopsin

Variants in rhodopsin (RHO) have been linked to autosomal dominant congenital stationary night blindness (adCSNB), which affects the ability to see in dim light, and the pathogenetic mechanism is still not well understood. In this study we report two novel RHO variants found in adCSNB families, p.W265R and p.A269V, that map in the sixth transmembrane domain of RHO protein. We applied in silico molecular simulation and in vitro biochemical and molecular studies to characterize the two new variants and compare the molecular determinants to two previously characterized adCSNB variants, p.G90D and p.T94I, that map in the second transmembrane domain of the RHO protein. We demonstrate that W265R and A269V cause constitutive activation of RHO with light-independent G protein coupling and impaired binding to arrestin. Differently, G90D and T94I are characterized by slow kinetics of RHO activation and deactivation. This study provides new evidence on the differential contribution of transmembrane α-helixes two and six to the interaction with intracellular transducers of RHO and mutations in these helixes result in a similar phenotype in patients but with distinct molecular effects.

QTL-Seq: Rapid, Cost-Effective, and Reliable Method for QTL Identification

QTL-seq is a powerful method that integrates whole-genome sequencing (WGS) with bulk-segregant analysis to rapidly and reliably identify quantitative trait loci (QTLs) associated with specific traits. This approach significantly advances traditional QTL mapping by eliminating the need for genome wide DNA markers such as SSR, RFLP, and INDELs, which are typically used in linkage-based QTL mapping. Instead, QTL-seq leverages WGS to detect all genetic variations such as SNPs, Indels, and Structural Variants across the entire genome, providing a comprehensive resource for marker development in marker-assisted selection. The QTL-seq process begins with the creation of genetically diverse mapping populations, such as F2 or RILs, followed by detailed phenotypic characterization. DNA from plants exhibiting similar phenotypes is pooled into bulk groups and sequenced, allowing for cost-effective and efficient QTL identification. Identified QTLs can be further validated through fine mapping using recombinant screenings and progeny testing, leading to the identification of candidate genes associated with traits of interest. In this study, we outline a user-friendly QTL-seq pipeline, from sequencing to data visualization, using the methodology and data provided by Takagi et al., 2013, to demonstrate its practical application. While the manuscript primarily focuses on describing the pipeline, we also conducted a case study analysis with real data to showcase its effectiveness. Our work contributes to the broader understanding of QTL-seq applications and offers practical recommendations for optimizing this method in future breeding programs.

Reliable delineation of Bacillus cytotoxicus from other members of the Bacillus cereus group by MALDI-TOF MS – An extensive validation study

Bacillus cytotoxicus is classified as a thermotolerant member of the Bacillus cereus group, producing the diarrhoea causing cytotoxin K1. This species came into the focus of food microbiologists when the type strain was isolated as the cause of a fatal food-borne outbreak. However, knowledge of the role of B. cytotoxicus as a food-borne microbe and data on its prevalence in food is still limited today. One reason for this is the lack of an easy to perform method of identification at the species level other than PCR, due to the highly similar phenotype of many B. cereus group representatives. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is widely used for the identification of microorganism species. This study describes the formal validation of a MALDI-TOF MS system for a reliable differentiation between B. cytotoxicus and other members of the B. cereus group. An extensive number of well-supported individual spectra from B. cytotoxicus, several other species of the B. cereus group, and 652 other microorganism species in a taxonomically wide range served as data sets. These were used to perform the validation for two database compilations: the commercial MALDI-Biotyper version K, and an extended compilation, including reference spectra from an open collection of spectra created by several users. Using both database combinations, the obtained values fulfil the formal criteria for the targeted identification of B. cytotoxicus in accordance with a national guideline for the validation of MALDI-TOF MS parameters in food analysis, with significant improvements due to the expanded database. By using 183 single spectra from 170 isolates, created in eleven different laboratories, the number of samples significantly exceeded the sample sizes for validation currently specified for ISO 16140–4:2020 for the validation of identification methods in food microbiology by single laboratories. Therefore, the method is suitable for routine application in an accredited laboratory context.

An integrative understanding of evolutionary convergence across organisms and biological scales.

The extent to which evolution is predictable is a long-standing question in biology, with implications for urgent biological issues such as viral evolution, the emergence of antibiotic resistance in bacteria, and organismal responses to climate change. Convergent evolution, the phylogenetically independent evolution of similar phenotypes, provides biological replicates useful for exploring patterns of predictability in evolution. Understanding evolutionary convergence requires synthesizing findings across biological scales and organisms. To this end, we organized a SICB-wide symposium entitled "Integrating research on convergent evolution across levels of biological organization, organisms, and time". Our symposium showcased interdisciplinary research on evolutionary convergence across diverse study systems and levels of biological organization, while highlighting new techniques and comparative methods for identifying patterns of predictability in convergently evolved traits. Here, we introduce findings from papers included in this symposium issue and identify common themes, highlight emerging questions, and discuss how we can integrate new techniques, tools, and systems to expand our understanding of evolutionary convergence.

Lysosomal membrane protein TMEM106B modulates hematopoietic stem and progenitor cell proliferation and differentiation by regulating LAMP2A stability.

Hematopoietic stem and progenitor cells (HSPCs) are successfully employed for hematological transplantations, and impaired HSPC function causes hematological diseases and aging. HSPCs maintain the lifelong homeostasis of blood and immune cells through continuous self-renewal and maintenance of the multilineage differentiation potential. TMEM106B is a transmembrane protein localized on lysosomal membranes and associated with neurodegenerative and cardiovascular diseases; however, its roles in HSPCs and hematopoiesis are unknown. Here, we established tmem106bb-/- knockout (KO) zebrafish and showed that tmem106bb KO reduced the proliferation of HSPCs during definitive hematopoiesis. The differentiation potential of HSPCs to lymphoid lineage was reduced, whereas the myeloid and erythroid differentiation potentials of HPSCs were increased in tmem106bb-/- zebrafish. Similar results were obtained with morpholino knockdown of tmem106bb. Mechanistically, TMEM106B interacted with LAMP2A, the lysosomal associated membrane protein 2A, impaired LAMP2A-Cathepsin A interaction, and enhanced LAMP2A stability; tmem106bb KO or TMEM106B knockdown caused LAMP2A degradation and impairment of chaperone-mediated autophagy (CMA). Knockdown of lamp2a caused similar phenotypes to that in tmem106bb-/- zebrafish, and overexpression of lamp2a rescued the impaired phenotypes of HSPCs in tmem106bb-/- embryos. These results uncover a novel molecular mechanism for the maintenance of HSPC proliferation and differentiation through stabilizing LAMP2A via TMEM106B-LAMP2A interaction.

Primary Cutaneous Spindle Cell B-Cell Follicle Center Lymphoma Presenting as Long-Standing Plaque of Cicatricial Alopecia: A Case Report With a Comprehensive Review of the Literature.

Primary cutaneous spindle B-cell lymphoma is an uncommon subtype of cutaneous lymphoma characterized by a distinct spindled cytology of neoplastic B cells. Despite sharing clinical, histopathological, and phenotypical similarities with primary cutaneous follicle center lymphoma, an indolent form of B-cell lymphoma, it also exhibits certain features akin to primary cutaneous diffuse large B-cell lymphoma. Notably, in rare instances, a more aggressive clinical course has been observed. This report details a rare case of primary cutaneous spindle cell B-cell follicle center lymphoma, manifested as a prolonged solitary plaque of cicatricial alopecia. In addition, we provide a comprehensive review of existing cases documented in the literature.

Experimental uncoupling of hosts and endosymbionts.

Many organisms harbor heritable bacterial symbionts that offer context-specific benefits to their hosts. In some of these symbioses, symbionts live inside host cells as endosymbionts. Studying the biology of endosymbiosis is challenging because it is hard to independently cultivate hosts and endosymbionts. A recent study, using a simple defined growth medium at ambient temperature, established an axenic culture of the pea aphid's heritable bacterial endosymbiont, Candidatus Fukatsuia symbiotica (G. P. Maeda, M. K. Kelly, A. Sundar, and N. A. Moran, mBio 15:e03253-23, 2024, https://doi.org/10.1128/mbio.03253-23). Notably, the monoculture was capable of host recolonization, was stably transmitted, and returned similar host phenotypes to those observed in native infections. This advance in uncoupling the cultivation of an endosymbiont and its host opens avenues for genetic manipulation of the endosymbiont that will facilitate hypothesis-driven work to explore the mechanisms of host-endosymbiont biology and potentially facilitate the development of symbiont-mediated practical-application biotechnologies.

Variable Craniofacial Shape and Development among Multiple Cave-Adapted Populations of Astyanax mexicanus.

Astyanax mexicanus is a freshwater fish species with blind cave morphs and sighted surface morphs. Like other troglodytic species, independently evolved cave-dwelling A. mexicanus populations share several stereotypic phenotypes, including the expansion of certain sensory systems, as well as the loss of eyes and pigmentation. Here, we assess the extent to which there is also parallelism in craniofacial development across cave populations. Since multiple forces may be acting upon variation in the A. mexicanus system, including phylogenetic history, selection, and developmental constraint, several outcomes are possible. For example, eye regression may have triggered a conserved series of compensatory developmental events, in which case we would expect to observe highly similar craniofacial phenotypes across cave populations. Selection for cave-specific foraging may also lead to the evolution of a conserved craniofacial phenotype, especially in regions of the head directly associated with feeding. Alternatively, in the absence of a common axis of selection or strong developmental constraints, craniofacial shape may evolve under neutral processes such as gene flow, drift, and bottlenecking, in which case patterns of variation should reflect the evolutionary history of A. mexicanus. Our results found that cave-adapted populations do share certain anatomical features; however, they generally did not support the hypothesis of a conserved craniofacial phenotype across caves, as nearly every pairwise comparison was statistically significant, with greater effect sizes noted between more distantly related cave populations with little gene flow. A similar pattern was observed for developmental trajectories. We also found that morphological disparity was lower among all three cave populations versus surface fish, suggesting eye loss is not associated with increased variation, which would be consistent with a release of developmental constraint. Instead, this pattern reflects the relatively low genetic diversity within cave populations. Finally, magnitudes of craniofacial integration were found to be similar among all groups, meaning that coordinated development among anatomical units is robust to eye loss in A. mexicanus. We conclude that, in contrast to many conserved phenotypes across cave populations, global craniofacial shape is more variable, and patterns of shape variation are more in line with population structure than developmental architecture or selection.

Phosphorous accumulation associated with mitochondrial PHT3-mediated enhanced arsenate tolerance in Chlamydomonas reinhardtii

Arsenate is a highly toxic element and excessive accumulation of arsenic in the aquatic environment easily triggers a problem threatening the ecological health. Phytoremediation has been widely explored as a method to alleviate As contamination. Here, the green algae, Chlamydomonas reinhardtii was investigated by profiling the accumulation of arsenate and phosphorus, which share the same uptake pathway, in response to arsenic stress. Both C. reinhardtii wild type C30 and the Crpht3 mutant were cultured under arsenic stress, and demonstrated a similar growth phenotype under limited phosphate supply. Sufficient phosphate obviously increased the uptake of polyphosphate and intercellular phosphate in the Crpht3 mutant, which increased the arsenic tolerance of the Crpht3 mutant under stress from 500 µmol L−1 As(V). Upregulation of the PHT3 gene in the Crpht3 mutant increased accumulation of phosphate in the cytoplasm under arsenate stress, which triggered a regulatory role for the differentially expressed genes that mediated improvement of the glutathione redox cycle, antioxidant activity and detoxification. While the wild type C30 showed weak arsenate tolerance because of little phosphate accumulation. These results suggest that the enhanced arsenic tolerance of the Crpht3 mutant is regulated by the PHT3 gene mediation. This study provides insight onto the responsive mechanisms of the PHT3 gene-mediated in alleviating arsenic toxicity in plants.

Coincidence of acral peeling skin syndrome and Nagashima-type palmoplantar keratosis in a Japanese pedigree with acral skin peeling.

Acral peeling skin syndrome (APSS; MIM 609796) is a rare genodermatosis characterized by painless focal cutaneous exfoliation of the dorsal hands and feet, typically displaying autosomal recessive inheritance. While cases associated with a founder mutation in TGM5 are relatively common in European Caucasian populations, no APSS cases have been reported from Japan or other East Asian countries. In contrast, Nagashima-type palmoplantar keratosis (NPPK; MIM 615598), caused by variants in SERPINB7, is relatively common in East Asia due to founder mutations. We describe a 27-year-old Japanese woman with spontaneous focal cutaneous exfoliation of the dorsal hand following prolonged glove use, indicative of APSS. Histopathological examination revealed a cleft between the stratum corneum and stratum granulosum and within the horny layer of the epidermis, supporting this diagnosis. However, her mother and maternal uncle exhibited similar symptoms, and there was no reported consanguinity in the patient's parents or grandparents, prompting suspicion of an autosomal dominant genodermatosis. Whole-genome sequencing (WGS) revealed compound heterozygous variants in TGM5 (c.1037G>A and c.684 + 1G>A) as suspected causative variants in the patient, leading to an APSS diagnosis, the first reported in East Asia. On the other hand, her mother and maternal uncle were diagnosed with NPPK due to compound heterozygous pathogenic variants in SERPINB7 (c.796C>T and c.455-1G>A). This case highlights the complexity of diagnosing skin disorders when multiple genodermatoses with similar phenotypes exist within a pedigree. Comprehensive genetic analyses, such as whole-exome sequencing and WGS, are invaluable for identifying causative variants in such complex cases.

Metabolic responses to albumin deficiency differ distinctly between partial and full ablation of albumin expression in mice

It had been observed that homozygous albumin knockout mice (Alb−/−) exhibit low plasma free fatty acid (FFA) concentration and improved blood glucose regulation. However, it was not yet known to what extent heterozygous albumin knockout (Alb+/−) mice would display a similar phenotype. Alb−/−, Alb+/−, and wild-type (WT) female mice were studied on a low-fat diet (LFD) or high-fat diet (HFD). On both diets, decreased plasma FFA concentration, and improved glucose tolerance test were observed in Alb−/−, but not in Alb+/−, compared to WT. Plasma adiponectin concentration showed greater elevation in Alb−/− than Alb+/−. Consistent with that, adiponectin gene expression was significantly higher in Alb−/− mice than in Alb+/− and WT mice. A dose-dependent response was observed for hepatic Acadl gene expression showing higher Acadl gene expression in Alb−/− mice than in Alb+/− and WT mice. In conclusion, although female Alb+/− mice exhibited some slight differences from WT mice (e.g., increased plasma adiponectin and hepatic Acadl gene expression), Alb+/− mice did not exhibit improved glucoregulation in comparison to WT mice, indicating that a minor suppression of albumin expression is not sufficient to improve glucoregulation. Furthermore, it is now clear that although the response of female mice to HFD might be unique from how males generally respond, still the complete albumin deficiency in Alb−/− mice and the associated FFA reduction is capable of improving glucoregulation in females on this diet. The present results have implications for the role of albumin and FFA in the regulation of metabolism.

Catalytic activity of Setd2 is essential for embryonic development in mice: establishment of a mouse model harboring patient-derived Setd2 mutation.

SETD2 is the only enzyme responsible for transcription-coupled histone H3 lysine 36 trimethylation (H3K36me3). Mutations in SETD2 cause human diseases including cancer and developmental defects. In mice, Setd2 is essential for embryonic vascular remodeling. Given that many epigenetic modifiers have recently been found to possess noncatalytic functions, it is unknown whether the major function(s) of Setd2 is dependent on its catalytic activity or not. Here, we established a site-specific knockin mouse model harboring a cancer patient-derived catalytically dead Setd2 (Setd2-CD). We found that the essentiality of Setd2 in mouse development is dependent on its methyltransferase activity, as the Setd2CD/CD and Setd2-/- mice showed similar embryonic lethal phenotypes and largely comparable gene expression patterns. However, compared with Setd2-/-, the Setd2CD/CD mice showed less severe defects in allantois development, and single-cell RNA-seq analysis revealed differentially regulated allantois-specific 5' Hoxa cluster genes in these two models. Collectively, this study clarifies the importance of Setd2 catalytic activity in mouse development and provides a new model for comparative study of previously unrecognized Setd2 functions.

Hepatocyte-specific loss of melanocortin 1 receptor disturbs fatty acid metabolism and promotes adipocyte hypertrophy.

Melanocortins mediate their biological functions via five different melanocortin receptors (MC1R - MC5R). MC1R is expressed in the skin and leukocytes, where it regulates skin pigmentation and inflammatory responses. MC1R is also present in the liver and white adipose tissue, but its functional role in these tissues is unclear. This study aimed at determining the regulatory role of MC1R in fatty acid metabolism. Male recessive yellow (Mc1re/e) mice, a model of global MC1R deficiency, and male hepatocyte-specific MC1R deficient mice (Mc1r LKO) were fed a chow or Western diet for 12 weeks. The mouse models were characterized for body weight and composition, liver adiposity, adipose tissue mass and morphology, glucose metabolism and lipid metabolism. Furthermore, qPCR and RNA sequencing analyses were used to investigate gene expression profiles in the liver and adipose tissue. HepG2 cells and primary mouse hepatocytes were used to study the effects of pharmacological MC1R activation. Chow- and Western diet-fed Mc1re/e showed increased liver weight, white adipose tissue mass and plasma triglyceride (TG) concentration compared to wild type mice. This phenotype occurred without significant changes in food intake, body weight, physical activity or glucose metabolism. Mc1r LKO mice displayed a similar phenotype characterized by larger fat depots, increased adipocyte hypertrophy and enhanced accumulation of TG in the liver and plasma. In terms of gene expression, markers of de novo lipogenesis, inflammation and apoptosis were upregulated in the liver of Mc1r LKO mice, while enzymes regulating lipolysis were downregulated in white adipose tissue of these mice. In cultured hepatocytes, selective activation of MC1R reduced ChREBP expression, which is a central transcription factor for lipogenesis. Hepatocyte-specific loss of MC1R disturbs fatty acid metabolism in the liver and leads to an obesity phenotype characterized by enhanced adipocyte hypertrophy and TG accumulation in the liver and circulation.

Unraveling the mechanism of thermotolerance by Set302 in Cryptococcus neoformans.

The underlying mechanism of thermotolerance, which is a key virulence factor essential for pathogenic fungi such as Cryptococcus neoformans, is largely unexplored. In this study, our findings suggest that Set302, a homolog of Set3 and a subunit of histone deacetylase complex Set3C, contributes to thermotolerance in C. neoformans. Specifically, the deletion of the predicted Set3C core subunit, Set302, resulted in further reduction in the growth of C. neoformans at 39°C, and survival of transient incubation at 50°C. Transcriptomics analysis revealed that the expression levels of numerous heat stress-responsive genes altered at both 30°C and 39°C due to the lack of Set302. Notably, at 39°C, the absence of Set302 led to the downregulation of gene expression related to the ubiquitin-proteasome system (UPS). Based on the GFP-α-synuclein overexpression model to characterize misfolded proteins, we observed a pronounced accumulation of misfolded GFP-α-synuclein at 39°C, consequently inhibiting C. neoformans thermotolerance. Furthermore, the loss of Set302 exacerbated the accumulation of misfolded GFP-α-synuclein during heat stress. Interestingly, the set302∆ strain exhibited a similar phenotype under proteasome stress as it did at 39°C. Moreover, the absence of Set302 led to reduced production of capsule and melanin. set302∆ strain also displayed significantly reduced pathogenicity and colonization ability compared to the wild-type strain in the murine infection model. Collectively, our findings suggest that Set302 modulates thermotolerance by affecting the degradation of misfolded proteins and multiple virulence factors to mediate the pathogenicity of C. neoformans.IMPORTANCECryptococcus neoformans is a pathogenic fungus that poses a potential and significant threat to public health. Thermotolerance plays a crucial role in the wide distribution in natural environments and host colonization of this fungus. Herein, Set302, a critical core subunit for the integrity of histone deacetylase complex Set3C and widely distributed in various fungi and mammals, governs thermotolerance and affects survival at extreme temperatures as well as the formation of capsule and melanin in C. neoformans. Additionally, Set302 participates in regulating the expression of multiple genes associated with the ubiquitin-proteasome system (UPS). By eliminating misfolded proteins under heat stress, Set302 significantly contributes to the thermotolerance of C. neoformans. Moreover, Set302 regulates the pathogenicity and colonization ability of C. neoformans in a murine model. Overall, this study provides new insight into the mechanism of thermotolerance in C. neoformans.