Biology subjects

Weng, X.

Publications and source records attributed to Weng, X..

At least 19 recordsLinked to original sources

bioRxiv2026

HDA6-mediated histone deacetylation restricts premature tapetal PCD to maintain male fertility during early flowering in Arabidopsis

Histone deacetylation regulates plant development, yet its role in male gametophyte development and fertility remains unclear. Here, we show that histone deacetylase 6 (HDA6), an RPD3-like histone deacetylase, epigenetically regulates timely tapetal programmed cell death (PCD) and male fertility, predominantly during early flowering in Arabidopsis. Loss of HDA6 in axe1-4 causes early-stage male sterility followed by fertility recovery, accompanied by premature tapetal PCD, impaired pollen development and defective pollen wall formation. HDA6 interacts with squamosa promoter binding protein-like 8 (SPL8) to repress Arabidopsis NAC domain containing protein 087 (ANAC087) through H3K9/K14 deacetylation. In axe1-4, ANAC087 derepression activates cysteine endopeptidase 1 (CEP1), triggering precocious tapetal PCD. Genetic suppression of ANAC087 or CEP1 restores male fertility. Thus, HDA6-SPL8 establishes a stage-dependent epigenetic checkpoint that restrains the ANAC087-CEP1 cell death pathway and ensures timely tapetal PCD. Our study reveals how chromatin regulation integrates with developmental timing to safeguard plant male fertility.

plant biology↗

bioRxiv2026

Compressed representations underpin knowledge awareness in sequence learning

Humans can acquire sequence structure before its presence enters awareness, and in some learners this implicit knowledge later becomes accessible and reportable. Yet the neural reformatting that enables this transition remains unclear. Here we used electro/magnetoencephalography (EEG/MEG) to resolve how category-based triplet rules were organized before and after awareness emerged. We found that implicit sequence knowledge was already represented in an abstract, compressed format. Within this format, rule information generalized across triplet elements, and regular-sequence elements became more similar while perceptual-category structure remained separable. Compression rate quantified how efficiently local rule information entered this shared format, and its pre-awareness level predicted later awareness specifically in the event-related potential P3 window. MEG source imaging localised pre-transition compression to left middle temporal cortex and showed post-awareness expansion into prefrontal cortex. Pre-awareness directional connectivity further showed that temporal-to-prefrontal theta-band transfer was rule-specific and predicted later awareness. Overall, these findings identify a mechanism supporting conscious access to abstract sequence-rule knowledge, involving cross-element representational compression and theta-band routing from the compression source to prefrontal cortex.

neuroscience↗

bioRxiv2026

High prevalence of KPC-3 in carbapenem-resistant Pseudomonas aeruginosa across multiple clonal lineages in China

Background The epidemiology of Klebsiella pneumoniae carbapenemase (KPC)-producing Pseudomonas aeruginosa is rapidly evolving in China. While blaKPC-2 remains the predominant KPC variant in P. aeruginosa, blaKPC-3 has rarely been documented in this pathogen. This study investigated the molecular epidemiology, resistance and virulence characteristics, and plasmid features of blaKPC-3-producing CRPA isolates collected from a tertiary hospital in eastern China. Methods A total of 65 non-duplicate CRPA isolates collected in 2023 were subjected to whole-genome sequencing. Antimicrobial susceptibility testing, phylogenetic analysis, plasmid characterization, conjugation experiments, and virulence assays were performed. Results Among the 65 CRPA isolates, 37 (56.9%) carried blaKPC-3. These blaKPC-3-positive isolates belonged to four sequence types (STs), including ST1076 (62.2%), ST463 (21.6%), ST646 (10.8%), and ST3393 (5.4%). To our knowledge, this is the first report of blaKPC-3 in P. aeruginosa ST463, ST646 and ST3393. All isolates exhibited extensive drug resistance, and 51.8% were resistant to ceftazidime-avibactam. Phylogenetic analysis indicated that blaKPC-3 dissemination was driven by both clonal expansion and horizontal transmission. Comparative genomic analysis identified three kinds of blaKPC-3 -carrying plasmid. A transferable IncP-2 megaplasmid was widely distributed among ST1076, ST646, and ST3393 isolates, whereas non-transferable IncP-10 plasmids were primarily restricted to ST463. The genetic environments and plasmid backbones of blaKPC-3 were highly conserved and closely related to those of blaKPC-2 and its variants, suggesting evolution from pre-existing blaKPC-2-associated plasmids. Virulence analysis demonstrated marked heterogeneity across lineages. ST463 isolates co-harbored exoU and exoS, exhibited enhanced biofilm formation and pyocyanin production, and caused significantly higher mortality in the G. mellonella infection model, indicating a hypervirulent phenotype. Conclusions The blaKPC-3 is becoming an increasingly important determinant of carbapenem resistance in P. aeruginosa in China. The IncP-2 megaplasmid and IncP-10 plasmid derived blaKPC-3 spread across multiple lineages. Continuous genomic surveillance and enhanced infection control measures are urgently needed to prevent its further prevalence in clinical settings.

microbiology↗

bioRxiv2026

Barcode-integrated reverse transcription for accurate, complete, and low-input RNA sequencing

In conventional total-RNA sequencing, unwanted RNA is removed by ribosomal-RNA depletion or messenger-RNA enrichment, and contaminating genomic DNA is cleared by DNase, both before reverse transcription. A sample index is added only later, during amplification, so each sample is carried through reverse transcription and cleanup on its own. These steps lose material that low-input samples cannot spare, and the per-sample handling limits throughput. Here we describe BIRT (Barcode-Integrated Reverse Transcription), a hairpin primer that carries a sample barcode and begins reverse transcription preferentially at RNA 3' ends, folding both barcoding and 3'-end capture into first-strand synthesis. Barcoding at reverse transcription enables early pooling, so samples are combined before any cleanup. It also authenticates RNA against DNA contamination: the primer barcodes RNA 909-fold more often than genomic DNA, and non-barcoded reads, which report DNA, are discarded. The 3'-end preference recovers terminal sequence that random priming loses: for a typical small nucleolar RNA, 66% of reads begin within two nucleotides of the mature 3' end, against a few percent for random hexamers. We pair BIRT with PERD (Probes for Excess RNA Depletion), a modular set of blocking probes that removes unwanted RNA within the same reaction without distorting expression (Pearson r = 0.98). We have applied BIRT to 8,079 samples across seven species, from cultured cells and primary tissue to FFPE and extracellular-vesicle RNA.

molecular biology↗

bioRxiv2026

Uncovering genetic mechanisms underlying trait variation in switchgrass using explainable artificial intelligence

Uncovering the genetic architecture of quantitative traits is challenging because polygenic control yields small individual gene effects and because gene-gene and genotype-by-environment interactions add further complexity. To understand the genetic basis of polygenic traits and their plasticity across environments, we integrated genome-wide SNPs and RNA-seq transcript data with interpretable statistical and machine learning models in a switchgrass (Panicum virgatum) diversity panel grown at contrasting field sites in Michigan and Texas. Notably, in addition to single environments, our trait prediction models were able to predict phenotypic differences, across environments i.e., plasticity. By interpreting trait prediction models with explainable machine learning methods, we identified genes that are the most predictive of flowering time and annual biomass production across environments, based on their associated gene expression levels and nearby SNPs. This approach recovered canonical flowering regulators and revealed novel, environment-specific candidate flowering genes. Further, transcriptome models consistently recovered more switchgrass genes homologous to experimentally validated genes in Arabidopsis and rice than SNP-based models. Feature interaction scores from the models also allow the identification of trait and environment-dependent gene-gene interactions, where flowering time showed stronger and more abundant interactions than biomass. While some of the interactions identified are consistent with the link between flowering time and yield, most are novel predictors that need to be further evaluated. These findings provide insight into the genetic basis of trait variation and plasticity across environments and help prioritize candidate genes for functional validation and cultivar improvement.

genetics↗

bioRxiv2026

Ultrashort optical-pin excitation for scattering brain imaging

Imaging neural structures deep in brain tissue is central to understanding brain function, yet remains fundamentally limited by strong optical scattering and the requirement for accurate three-dimensional (3D) optical sectioning. Laser-scanning microscopy is a promising technique for brain imaging; however, maintaining excitation focus integrity in scattering media while preserving axial confinement poses a persistent photonic challenge. Here we introduce the optical pin, an ultrashort excitation regime engineered at the angular-spectrum level to address this limitation. By broadening the transverse angular bandwidth of a Bessel-type field while preserving its conical momentum-space architecture, the optical pin introduces a controlled longitudinal wave-vector spread that compresses the axial interference length to the micrometer scale, restoring Gaussian-like sectioning without sacrificing multi-angle interference. This excitation design yields substantially enhanced imaging performance, including [~]1.5-fold contrast improvement and [~]2.6-fold increased robustness to scattering. We validate the approach across transparent, scattering, and biological specimens, including bead phantoms, C. elegans, and mouse brain tissue. As a system-level excitation strategy, the optical pin is readily compatible with existing laser-scanning microscopy platforms and is particularly suited for scattering-limited brain imaging.

neuroscience↗

bioRxiv2025

Adiponectin plays a key role in macrophage-driven inflammation of adipose tissue caused by Chronic Intermittent Hypoxia

BackgroundThe inflammatory response driven by macrophages in adipose tissue is a key contributor to CIH-induced metabolic disorders. The precise mechanism underlying CIH-induced inflammation in adipose tissue macrophages remains elusive. Adiponectin (Ad) is a highly abundant adipokine secreted by adipocytes that plays a crucial role in insulin sensitivity. MethodsThis study aims to elucidate the pivotal roles of adipocytes and Ad in CIH-induced macrophage inflammation using a co-culture cell approach. The direct co-culture method involved the physical interaction between iBMDM cells and 3T3-L1 adipocytes, while the indirect co-culture method utilized adipocyte-conditioned media as the culture medium for macrophages. Following CIH treatment and Ad intervention, the expression levels of inflammatory factors in the conditioned media of each cell group were quantified. Statistical significance was defined as P < .05. ResultsResults showed CIH did not directly cause the release of inflammatory factors in individually cultured iBMDM cells and 3T3-L1 adipocytes; however, it significantly increased the release of inflammatory factors in co-cultured cells. Ad alleviates the pro-inflammatory effect of adipocytes on macrophages under CIH conditions. ConclusionCIH could disrupt adipocyte function and promote macrophage inflammation through paracrine mechanisms.

cell biology↗

bioRxiv2025

Dynamic mechanisms of time-of-day-dependent adaptive immunity and vaccination responses

The timing of vaccine administration during the day significantly affects immunogenicity and efficacy, yet the mechanism governing the time-of-day dependent adaptive immunity and vaccine response remains elusive. Using mathematical modeling, we elucidate that the bistability arising from the self-enhancing homing process of antigen-presenting dendritic cells plays a key role in the time-of-day-dependent adaptive immune response. Modeling analyses of circadian-controlled immune responses to three vaccine types demonstrate that vaccine-specific differences in time-of-day-dependent immunity originate from distinctions in the circadian-regulated activation of antigen-presenting dendritic cells. This divergence is amplified by bistability in the dendritic cell homing process, resulting in long-term distinctions in adaptive immunity across vaccine types. The model results reveal a dynamic mechanism by which adaptive immune responses maintain circadian variations over extended time periods, suggesting that the timing of vaccine administration within the day is a promising strategy for effective disease prevention. Author SummaryInfection with the same pathogen in the morning or afternoon, or receiving the same vaccine at different times of the day, often leads to significantly different consequences in terms of infection severity or vaccine efficacy. This phenomenon is known as the time-of-day-dependent immune response. Although it is relatively common, the underlying dynamic mechanisms remain mostly unclear. In this paper, we employ mathematical modeling to investigate in detail the dynamics of adaptive immune responses following vaccination. We reveal that the kinetic origin of the time-of-day-dependent immune response lies in the positive feedback process during the homing of antigen-presenting cells, particularly dendritic cells. The bistability induced by self-activation, under the regulation of the circadian clock, plays a decisive role in generating this diurnal time dependency. The discovery of this mechanism suggests that time-of-day-specific vaccination is an effective strategy to optimize vaccine efficacy.

systems biology↗

bioRxiv2025

Mapping the functional differentiation and interactions among the inferior, medial frontal and posterior temporal cortex in semantic control

Semantic control refers to the ability to flexibly retrieve and manipulate stored knowledge to support context-appropriate behavior. A left-lateralized network comprising the left inferior frontal gyrus (IFG), posterior middle temporal gyrus (pMTG), and dorsal medial prefrontal cortex (dmPFC) has been consistently implicated in this process. While previous studies have established the necessity of the IFG and pMTG in semantic control, the causal role of the left dmPFC remains unclear. Additionally, it is unknown whether each of these three regions exhibits internal functional differentiation and how they interact to support semantic control. To address these questions, we combined task-based functional magnetic resonance imaging (fMRI) with fMRI-guided transcranial magnetic stimulation (TMS). We found that dmPFC, like IFG and pMTG, is causally involved in semantic control. All three regions exhibited a consistent anterior-posterior functional gradient: anterior subregions were selectively engaged during high-demand semantic processing, whereas posterior subregions responded to both easy and hard tasks. Furthermore, combined activation patterns of these regions better predicted the behavioral differences between hard and easy semantic tasks compared to the activation patterns of any single region. Semantic control modulated both the autoinhibition within individual regions and the functional connectivity among them, suggesting these regions operate in a coordinated network rather than in isolation. These findings advance our understanding of the neural architecture supporting flexible semantic behavior. Significance StatementUnderstanding how the brain supports flexible semantic behavior is critical for both cognitive neuroscience and clinical neuropsychology. While prior studies have consistently implicated the left IFG, pMTG, and dmPFC in semantic control, the causal contribution of the dmPFC and the functional dynamics among these regions have remained unclear. This study provides the first causal evidence for the dmPFCs role in semantic control, reveals functional differentiation within the IFG and pMTG, and shows that these regions interact as an integrated network. These findings challenge the notion of functionally homogeneous control nodes and highlight a topographically organized, interactive system underlying controlled semantic retrieval. This work refines our mechanistic understanding of semantic control and may inform clinical models of language and conceptual deficits.

neuroscience↗

bioRxiv2025

A synthetic chlorophagy receptor promotes plant fitness by mediating chloroplast microautophagy

Chloroplasts are major photosynthetic and protein-containing organelles in green plants and algae. Unwanted chloroplast proteins and entire chloroplasts are cleared through various degradation pathways including autophagy. Nevertheless, canonical chlorophagy receptors remain unidentified, and whether and to what extent chlorophagy can be enhanced to benefect the plants remain unknown. Here we designed and validated a synthetic chloroplast autophagy receptor using biochemical, genetical, and imaging approaches. This synthetic receptor, LIR-SNT-BFP, was constructed by fusing a fragment containing the LC3-interacting region (LIR) of the selective autophagy receptor NBR1 and the N-terminal amphipathic -helix of the chloroplast outer envelope protein SFR2. The fusion protein LIR-SNT-BFP coated the chloroplast and attracted ATG8a in planta. Upon induction, the synthetic receptor elicited vacuole-mediated microautophagy of entire chloroplasts independent of the ATG8 conjugation machinery proteins ATG5 or ATG7. Meanwhile, it induced chloroplast division; however the induced chlorophagy was independent of PDV2. Notably, moderate chlorophagy improves rosette growth, but excessive levels are detrimental. Furthermore, induced chlorophagy partially protects against herbicide-induced leaf chlorosis. This study demonstrates controlled chloroplast degradation using a synthetic chlorophagy receptor.

plant biology↗

bioRxiv2025

NtLLG4-mediated unconventional polar exocytosis of NtPPME1 coordinates cell wall rigidity and membrane dynamics to control pollen tube integrity

Plant fertilization relies on controlled pollen tube growth that integrates membrane dynamics and cell wall expansion. We previously identified an unconventional exocytic pathway wherein Golgi-derived secretory vesicles (GDSVs) bypass the trans-Golgi network to deliver Nicotiana tabacum pectin methylesterase 1 (NtPPME1), thereby modulating cell wall rigidity. However, the mechanisms linking this patwhay with membrane dynamics and signaling remain elusive. Here, we used cryo-FIB-SEM and 3D tomography to identified GDSVs as a distinct vesicle population at the pollen tube tip. We further demonstrated that tobacco LORELEI-like-GPI-anchored protein 4 (NtLLG4), a key signaling molecule controlling membrane dynamics and integrity, functions as a receptor for NtPPME1, regulating its polar exocytosis via GDSVs to control cell wall stiffness. Furthermore, we identified trafficking signals which direct the unconventional exocytosis of NtPPME1 across intracellular organelles. Our findings reveal a crucial mechanism coupling cell wall rigidity with membrane signaling to control pollen tube growth and integrity during fertilization. TeaserWe reveal a mechanism coupling cell wall rigidity with member signaling to control pollen tube growth and integrity during plant fertilization.

plant biology↗

bioRxiv2025

Evaluation of Candidate ''Kill or Cure'' Strategies to Treat MFN2-related Lipodystrophy

The R707W mutation in mitofusin 2, encoded by MFN2, causes a form of Multiple Symmetrical Lipomatosis (MFN2-MSL). This resembles sporadic, alcohol-associated MSL, combining loss of lower body adipose tissue with upper body adipose hyperplasia. Morbidity and sometimes mortality arise both from mechanical complications of head and neck adipose overgrowth, and metabolic complications. We reasoned that interventions that either mitigate the underlying cellular pathology, or that exacerbate it to induce selective death of hyperplastic adipose tissue may be beneficial. We thus assessed the effect of a metabolic or pharmacologic stressors or rapamycin in Mfn2R707W/R707W mice and or derived preadipocytes. 50mmol ethanol had little effect on WT or Mfn2R707W/R707W white preadipocytes, but increased mitochondrial content and blunted mitolysosome formation in Mfn2R707W/R707Wbrown preadipocytes. Daily consumption of 20% EtOH increased brown adipose tissue mass in female Mfn2R707W/R707W mice, and serum lactate in males. 200nM rapamycin - a candidate treatment - increased size and mitolysosome content of WT and Mfn2R707W/R707W white and brown preadipocytes, but these effects were blunted in Mfn2R707W/R707W cells. In male but not female Mfn2R707W/R707W mice, rapamycin reduced or reversed weight gain, reduced brown adipose mass, and increased serum Fgf21. Finally, a panel of other metabolic and pharmacological mitochondrial stressors solicited no selective death or ISR in Mfn2R707W/R707W preadipocytes. We conclude that ethanol mildly exacerbates MFN-MSL in mice, while rapamycin is tolerated. Lack of sensitisation to mitochondrial stressors implies that the MSL-inducing effect of MFN2 R707W may not be exerted through compromised oxidative phosphorylation.

physiology↗

bioRxiv2024

Irx3/5 define the cochlear sensory domain and regulate vestibular and cochlear sensory patterning in the mammalian inner ear

The mammalian inner ear houses the vestibular and cochlear sensory organs dedicated to sensing balance and sound, respectively. These distinct sensory organs arise from a common prosensory region, but the mechanisms underlying their divergence remain elusive. Here, we showed that two evolutionarily conserved homeobox genes, Irx3 and Irx5, are required for the patterning and segregation of the saccular and cochlear sensory domains, as well as for the formation of auditory sensory cells. Irx3/5 were highly expressed in the cochlea, their deletion resulted in a significantly shortened cochlea with a loss of the ductus reuniens that bridged the vestibule and cochlea. Remarkably, ectopic vestibular hair cells replaced the cochlear non-sensory structure, the Greater Epithelial Ridge. Moreover, most auditory sensory cells in the cochlea were transformed into hair cells of vestibular identity, with only a residual organ of Corti remaining in the mid-apical region of Irx3/5 double knockout mice. Conditional temporal knockouts further revealed that Irx3/5 are essential for controlling cochlear sensory domain formation before embryonic day 14. Our findings demonstrate that Irx3/5 regulate the patterning of vestibular and cochlear sensory cells, providing insights into the separation of vestibular and cochlear sensory organs during mammalian inner ear development.

developmental biology↗

bioRxiv2024

BCL2L13 Influences Autophagy and Ceramide Metabolism without Affecting Temozolomide Resistance in Glioblastoma

Temozolomide (TMZ) resistance in glioblastoma (GBM) arises through metabolic rewiring that links mitochondrial function, autophagy balance, and sphingolipid metabolism. TMZ resistant (R) U251 cells exhibited suppressed apoptosis and complete blockade of autophagy flux, evidenced by LC3II and p62 accumulation and insensitivity to Bafilomycin A1. BCL2L13, strongly upregulated in R cells, emerged as a dual regulator of mitophagy and ceramide metabolism. BCL2L13 knockdown (KD) produced opposite effects in TMZ sensitive (NR) and resistant cells: in NR cells, KD elevated LC3II, reduced respiratory reserve, and triggered compensatory lipid synthesis; in R cells, KD decreased LC3II without restoring flux or TMZ sensitivity. Lipidomic profiling revealed that BCL2L13 loss reactivated CerS6 in NR cells, increasing C16:0 and mid-chain ceramides, while relieving CerS2 inhibition in R cells, elevating very long chain (C22 to C24) and glycosylated ceramides. These distinct sphingolipid signatures were confirmed by PLS-DA and KEGG enrichment, which highlighted steroid hormone, arachidonic, and linoleic acid metabolism in NR KD cells versus neuroactive ligand-receptor and signaling pathways in R KD cells. Together, these findings position BCL2L13 as a molecular integrator of mitochondrial respiration, autophagy flux, and CerS-dependent lipid remodeling, unveiling a context-specific metabolic mechanism that supports GBM cell survival under chemotherapeutic stress.

cancer biology↗

bioRxiv2024

A Novel Role of Hyaluronan and its Membrane Receptors, CD44 and RHAMM in Obesity-Related Glomerulopathy

Obesity-related glomerulopathy (ORG) contributes to diabetic nephropathy and kidney cancer, leading to chronic/end-stage kidney disease. To date, treatments for ORG are limited because of incomplete understanding of the disease pathogenesis. Here, we identified a novel role for hyaluronan (HA) and its membrane receptors, CD44 and RHAMM in obesity-associated renal inflammation, fibrosis, tubular injury, and kidney dysfunction. Pharmacological and genetic ablation of HA, CD44 or RHAMM reversed these renal disorders induced by high fat diet feeding in mice in vivo. Increased HA content, and CD44 and RHAMM expression damaged the kidney via activation of TGF-{beta}1/Smad2/3, P38/JNK MAPK and ROCK/ERK pathways. We further established a link between renal insulin resistance and ECM remodelling using human kidney cells in vitro, shedding mechanistic insight into the role of HA, CD44 and RHAMM in the pathogenesis of ORG. Furthermore, in human kidney biopsies gene expression of CD44 and RHAMM was increased in chronic kidney disease and diabetic nephropathy, and their levels were correlated with markers of kidney (dys)function (GFR, serum creatinine, proteinuria). Our findings provide evidence for HA-CD44/RHAMM as a potential therapeutic target in ORG and consequent prevention of chronic kidney disease.

physiology↗

bioRxiv2024

Single-cell multiomics reveals a gene regulatory circuit promoting leukemia cell differentiation

Cancer differentiation therapy aims to induce maturation of neoplastic cells, yet how cell fate is determined in oncogenic cellular contexts is poorly understood. Here we integrate chromatin accessibility and transcriptome analysis at single-cell levels to investigate the mechanism driving the differentiation trajectory of the PML/RAR+ acute promyeloid leukemia (APL) cell line model, NB4, under the induction of all-trans-retinoid acid (ATRA). We show that differentiating NB4 cells navigate through an intermediate cell fate decision point that leads to either terminal granulopoiesis or a transient immature-lymphocyte-like state. Functional perturbation studies indicate that ATRA signaling activates discrete PML/RAR-target enhancers to induce a positive feedforward gene regulatory circuit involving two myeloid-lineage transcription factors, SPI1 and CEBPE, which is both necessary and sufficient to activate a myelocytic gene expression program in NB4. Further, ectopic expression of SPI1 and CEBPE also promotes myelocytic differentiation in non-APL leukemia cell lines HL60 and K562. Together, these results shed light on the differentiation trajectory of therapy-induced cell decisions of APL and suggest a gene regulatory circuit that may be broadly exploited to promote terminal differentiation of leukemia.

cancer biology↗

bioRxiv2023

Female Alms1-deficient mice develop echocardiographic features of adult but not infantile Alström Syndrome cardiomyopathy

BackgroundAlstrom Syndrome (AS), a multisystem disorder caused by biallelic ALMS1 mutations, features major cardiac complications often causing early mortality. These are biphasic, including infantile dilated cardiomyopathy, and distinct adult-onset cardiomyopathy. Cardiomyocyte maturation defects, cardiac fibrosis and early atherosclerosis have all been invoked as contributors to heart failure in AS, but their relative importance and inter-relationships are unknown. MethodsCardiac function of global Alms1 knockout mice was assessed by echocardiography at postnatal day 15 (P15) and at 8 and 23 weeks of age. Echocardiography was also undertaken in female mice with Pdgfr-Cre-driven Alms1 deletion in cardiac fibroblasts and a small proportion of cardiomyocytes. Histological and transcriptional analysis of myocardium at P15 and 24 weeks of age was also performed. ResultsCardiac function was unaltered in knockout mice of both sexes at P15 and 8 weeks of age. At 23 weeks of age female but not male knockout mice showed increased left atrial area, decreased isovolumic relaxation time, and reduced ejection fraction, consistent with early restrictive cardiomyopathy. No histological or transcriptional changes could be identified in myocardium of 23-week old female Alms1 KO mice, however. Pdgfr-Cre-driven Alms1 KO in females did not recapitulate the phenotype of global KO at 23 weeks. ConclusionsAdult female, but not male, Alms1-deficient mice show echocardiographic evidence of cardiac dysfunction, consistent with the restrictive cardiomyopathy of AS. The explanation for sexual dimorphism remains unclear, but may involve metabolic or endocrine differences between sexes. No infantile cardiomyopathy was found in this study.

physiology↗

bioRxiv2023

Mesenchymal-specific Alms1 knockout in mice recapitulates key metabolic features of Alström Syndrome

BackgroundAlstrom Syndrome (AS), a multi-system disease caused by mutations in the ALMS1 gene, includes obesity with disproportionately severe insulin resistant diabetes, dyslipidemia, and hepatosteatosis. How loss of ALMS1 causes this phenotype is poorly understood, but prior studies have circumstancially implicated impaired adipose tissue expandability. We set out to test this by comparing the metabolic effects of selective Alms1 knockout in mesenchymal cells including preadipocytes to those of global Alms1 knockout. MethodsGlobal Alms1 knockout (KO) mice were generated by crossing floxed Alms1 and CAG-Cre mice. A Pdgfr-Cre driver was used to abrogate Alms1 function selectively in mesenchymal stem cells (MSCs) and their descendants, including preadipocytes. We combined metabolic phenotyping of global and Pdgfr+ Alms1-KO mice on a 45% fat diet with measurements of body composition and food intake, and histological analysis of metabolic tissues. ResultsGlobal Alms1 KO caused hyperphagia, obesity, insulin resistance, dyslipidaemia, and fatty liver. Pdgfr-cre driven KO of Alms1 (MSC KO) recapitulated insulin resistance, fatty liver, and dyslipidaemia in both sexes. Other phenotypes were sexually dimorphic: increased fat mass was only present in female Alms1 MSC KO mice. Hyperphagia was not evident in male Alms1 MSC KO mice, but was found in MSC KO females, despite no neuronal Pdgfr expression. ConclusionsMesenchymal deletion of Alms1 recapitulates the metabolic features of AS, including severe fatty liver. This confirms a key role for Alms1 in the adipose lineage, where its loss is sufficient to cause systemic metabolic effects and damage to remote organs. AS should be regarded as a forme fruste of lipodystrophy. Therapies should prioritise targeting positive energy balance.

physiology↗