Biology subjects

Capellini, T. D.

Publications and source records attributed to Capellini, T. D..

17 recordsLinked to original sources

bioRxiv2026

Evolutionary trade-offs between growth and reproduction under obesogenic conditions: sex-biased skeletal and gonadal maturation in mice

Adolescence is a brief period during which finite energy resources are reallocated from linear growth toward reproductive maturation. Rising childhood obesity and earlier onset of puberty suggest that modern, energy rich diets may distort these evolved energy allocation rules, but causal mechanisms remain unclear. Here, we expose male and female wild-type and leptin receptor deficient (Db/Db) to either high fat or normal chow diets. We longitudinally analyze metabolic, skeletal, gonadal, endocrine and insulin-receptor phenotypes from 4-10 weeks of age (sexual maturation window in mice). In WT males, HFDs increased adiposity and impaired glucose tolerance, and selectively remodeled joint morphology, advanced gonadal maturation, and shifted insulin receptor expression from growth plates to testes. Together, these changes indicate a rebalancing of energy use toward reproduction at the expense of skeletal and metabolic health. WT females showed subtler systemic metabolic disruption but clear diet-responsive changes in growth plate and ovarian maturation. Our findings indicate that energy-rich diets during adolescence shift evolved allocation rules to prioritize reproductive readiness over skeletal robustness in a sex-dependent manner, with potential consequences for precocious puberty and bone health in humans.

evolutionary biology↗

bioRxiv2025

Massively parallel functional screen identifies thousands of regulatory differences in human versus chimpanzee postcranial skeletal development

Every element of the human skeleton exhibits some differences in comparison to our closest living relatives, chimpanzees. Many of these skeletal modifications underpin key events in human evolution, enabling our species to walk upright, manipulate tools with precision, and support enlarged brains. Identifying the genomic changes that underlie these features remains an outstanding challenge due to the substantial number of differences between the human and chimpanzee genomes. To identify human-chimp sequence differences that modulate gene expression in the developing postcranial skeleton, we used a massively parallel reporter assay (MPRA) to screen the human and chimp versions of 70,000 regulatory elements present in the prenatal skeletal template for differential activity. After testing our library in two cartilage and one bone marrow-derived lymphoblast line, we identify 30,736 regions (45.2%) with activity in our assay. Of the active regions, we find that 11,542 (37.6%; or 17% of the entire pool) regions exhibited differential activity between the human and chimpanzee. We find that human ancestor quickly evolved regions (HAQERs) were predictive of differential activity while Human Accelerated Regions were not and both sets failed to predict the magnitude of effect, unlike the total number of base pair differences between species, which was weakly correlated with effect size. These findings reveal that human skeletal evolution involves widespread regulatory changes distributed across thousands of elements rather than concentrated effects at a few key loci, supporting a polygenic model for the evolution of complex morphological traits.

evolutionary biology↗

bioRxiv2025

Combined ADAMTS10 and ADAMTS17 inactivation exacerbates bone shortening and skin phenotypes

Weill-Marchesani syndrome (WMS) is characterized by severe short stature, short hands and feet (brachydactyly), joint contractures, tight skin, and heart valve, eye, and skin anomalies. Whereas recessive WMS is caused by mutations in ADAMTS10, ADAMTS17, or LTBP2, dominant WMS is caused by mutations in FBN1 (encoding fibrillin-1). Since bone growth is driven by chondrocyte proliferation and hypertrophy in the growth plates, the genetics of WMS suggests that the affected ECM proteins act within the same pathway to regulate chondrocyte and growth plate function. Here, we investigated the role of the secreted ADAMTS proteases ADAMTS10 and ADAMTS17 in growth plate function and ECM formation. We generated Adamts10;Adamts17 double knockout (DKO) mice, which showed significant postnatal lethality compared to single Adamts10 or Adamts17 KO mice. Importantly, we observed severe bone shortening DKO mice, which correlated with a narrower hypertrophic zone in their growth plates. ADAMTS17 substrates identified by N-terminomics and yeast two-hybrid screening identified the ECM proteins fibronectin and collagen VI (COL6). However, validation experiments did not reveal direct proteolysis of either fibronectin or COL6 by ADAMTS17. We then investigated ECM formation in primary ADAMTS10- and ADAMTS17-deficient skin fibroblasts and observed compromised fibronectin deposition concomitant with aberrant intracellular accumulation of fibrillin-1. These findings support a role for ADAMTS17 in ECM protein secretion and assembly. Collectively, our data suggest that ADAMTS10 and ADAMTS17 regulate bone growth by regulating chondrocyte hypertrophy or hypertrophic chondrocyte turnover. Mechanistically, ADAMTS17 appears to be a critical regulator of ECM protein secretion or pericellular matrix assembly, whereas ADAMTS10 likely modulates ECM formation at later stages, possibly regulating the spatio-temporal deposition of fibrillin isoforms.

cell biology↗

bioRxiv2024

Complex regulatory interactions at GDF5 shape joint morphology and osteoarthritis disease risk

Our ability to pinpoint causal variants using GWAS is dependent on understanding the dynamic epigenomic and epistatic context of each associated locus. Being the best studied skeletal locus, GDF5 associates with many diseases and has a complex cis-regulatory architecture. We interrogate GDF5 regulatory interactions and model disease variants in vitro and in vivo. For all regulatory regions we see that local epigenetic activation/repression impacts patterns of joint-specific expression and disease risk. By modeling the most cited risk variant in mice we found that it had no impact on expression, joint morphology, or disease. Yet, we identified significant epistatic expression interactions between this risk variant and others lying within regulatory regions subject to repression or activation. These findings are important lessons on how regulatory interactions and local epistasis work in the etiology of disease risk, and that assessment of individual variants of high GWAS significance need not alone be considered causal. TeaserGenetic interactions at the most studied skeletal disease locus reveal hidden complexities in pinpointing causal mutations.

genetics↗

bioRxiv2024

Dynamic transcriptional and epigenetic changes define postnatal tendon growth

Tendons are dynamic structures that efficiently transmit forces and enable movement. From birth, tendons undergo dramatic changes from a principally cellular tissue to a hypocellular one characterized by a dense and highly ordered extracellular matrix. During this time, tendon cells change morphology from rounded to stellate in appearance and their proliferative rates decline. There is also significant expansion and maturation of the extracellular matrix (ECM) as tendons grow in length and diameter and alter their biomechanical properties to sustain increased physical activities. Surprisingly, for such an important stage of tendon maturation, we understand very little about the transcriptional and epigenetic regulators that direct these processes. Here, we present a roadmap of genes that are differentially regulated during the early neonatal and postnatal time period. We find differentially expressed genes fall into specific transcriptional modules, representing expression increases, decreases, or gene sets undergoing dynamic changes over postnatal time. By pairing our transcriptomic data with epigenetic data, we were able to perform an integrative analysis of the datasets and further define modules with highly correlated changes in gene expression and chromatin accessibility. From this analysis, several new pathways emerge. Among them, we focus on Yap1, a transcriptional co-activator of the Hippo signaling pathway. We observe accessible regions near to differentially expressed genes, containing motifs for TEAD, the transcription factor that binds Yap to regulate transcription. Conditional loss of Yap1 at postnatal stages results in altered expression of Col1a1 and disrupted matrix organization and density, suggesting that Yap is important for refining tendon ECM maturation. Together, our analyses identify a regulator of matrix maturation and provides a rich dataset with which to interrogate transcriptional networks and pathways during this poorly understood time in tendon growth.

developmental biology↗

bioRxiv2024

Leveraging single cell multiomic analyses to identify factors that drive human chondrocyte cell fate

Cartilage plays a crucial role in skeletal development and function, and abnormal development contributes to genetic and age-related skeletal disease. To better understand how human cartilage develops in vivo, we jointly profiled the transcriptome and open chromatin regions in individual nuclei recovered from distal femurs at 2 fetal timepoints. We used these multiomic data to identify transcription factors expressed in distinct chondrocyte subtypes, link accessible regulatory elements with gene expression, and predict transcription factor-based regulatory networks that are important for growth plate or epiphyseal chondrocyte differentiation. We developed a human pluripotent stem cell platform for interrogating the function of predicted transcription factors during chondrocyte differentiation and used it to test NFATC2. We expect new regulatory networks we uncovered using multiomic data to be important for promoting cartilage health and treating disease, and our platform to be a useful tool for studying cartilage development in vitro. Statement of SignificanceThe identity and integrity of the articular cartilage lining our joints are crucial to pain-free activities of daily living. Here we identified a gene regulatory landscape of human chondrogenesis at single cell resolution, which is expected to open new avenues of research aimed at mitigating cartilage diseases that affect hundreds of millions of individuals world-wide.

developmental biology↗

bioRxiv2024

Parallel evolution at the regulatory base-pair level contributes to mammalian inter-specific differences in polygenic traits.

Parallel evolution occurs when distinct lineages with similar ancestral states converge on a new phenotype. Parallel evolution has been well documented at the organ, gene pathway, and amino-acid sequence level but in theory it can also occur at individual nucleotides within non-coding regions. To examine the role of parallel evolution in shaping the biology of mammalian complex traits, we used data on single nucleotide polymorphisms (SNPs) influencing human intraspecific variation to predict trait values in other species for eleven complex traits. We found that the alleles at SNP positions associated with human intraspecific height and red blood cell count variation are associated with interspecific variation in the corresponding traits across mammals. These associations hold for deeper branches of mammalian evolution as well as between strains of collaborative cross mice. While variation in red blood cell count between primates uses both ancient and more recently evolved genomic regions, we found that only primate-specific elements were correlated with primate body size. We show that the SNP positions driving these signals are flanked by conserved sequences, maintain synteny with target genes, and overlap transcription factor binding sites. This work highlights the potential of conserved but tunable regulatory elements to be reused in parallel to facilitate evolutionary adaptation in mammals.

evolutionary biology↗

bioRxiv2022

Lineage-Specific Differences and Regulatory Networks Governing Human Chondrocyte Development

To address large gaps in our understanding of the molecular regulation of articular and growth plate cartilage development in humans, we used our directed differentiation approach to generate these distinct cartilage tissues from human embryonic stem cells. The resulting transcriptomic profiles of hESC-derived articular and growth plate chondrocytes were similar to fetal epiphyseal and growth plate chondrocytes, with respect to genes both known and previously unknown to cartilage biology. With the goal to characterize the regulatory landscapes accompanying these respective transcriptomes, we mapped chromatin accessibility in hESC-derived chondrocyte lineages, and mouse embryonic chondrocytes, using ATAC-sequencing. Integration of the expression dataset with the differentially accessible genomic regions revealed lineage-specific gene regulatory networks. We validated functional interactions of two transcription factors (RUNX2 in growth plate chondrocytes and RELA in articular chondrocytes) with their predicted genomic targets. The maps we provide thus represent a framework for probing regulatory interactions governing chondrocyte differentiation. This work constitutes a substantial step towards comprehensive and comparative molecular characterizations of distinct chondrogenic lineages, and sheds new light on human cartilage development and biology.

developmental biology↗

bioRxiv2022

A spatio-temporally constrained gene regulatory network directed by PBX1/2 acquires limb patterning specificity via HAND2

During development cell fates are specified by tightly controlled gene expression programs. PBX TALE transcription factors control gene regulatory networks (GRN) that direct vertebrate tissue patterning and organ morphogenesis. How PBX1/2 proteins acquire context-specific functions, despite widespread embryonic expression of Pbx1/2, remains elusive. In mouse limb buds, mesenchymal-specific loss of PBX1/2 or of the transcriptional regulator HAND2 results in similar phenotypes, suggesting that PBX1/2- and HAND2-dependent programs converge to control limb development. To investigate this scenario, we combined tissue-specific and temporally-controlled mutagenesis with multi-omics approaches using the murine hindlimb bud as a model. We reconstructed a GRN collaboratively directed by PBX1/2 and HAND2, demonstrating that Pbx1-Hand2 genetically interact in vivo during hindlimb patterning, with PBX1 concomitantly acting as an upstream regulator of Hand2. At organismal-level resolution the GRN is active within restricted subsets of posterior-proximal hindlimb mesenchymal cells, wherein Pbx1/2 and Hand2 are co-expressed with their target genes. Genome-wide profiling of PBX1 binding across multiple tissues further revealed that HAND2 selects a subset of PBX-bound regions to impart limb patterning functionality. This research elucidates mechanisms underlying limb bud-specific functions by PBX1/2, while informing general principles by which promiscuous transcription factors cooperate with select cofactors to instruct distinct developmental programs.

developmental biology↗

bioRxiv2022

A quiescent resident progenitor pool is the central organizer of tendon healing

A tendons ordered extracellular matrix (ECM) is integral for transmitting force and highly prone to injury. How tendon cells, or tenocytes, embedded within this dense ECM mobilize and contribute to healing is unknown. Here, we identify a specialized Axin2+ population in mouse and human tendons that remains latent in homeostasis yet initiates the healing response and serves as a major source of tendon progenitors. Axin2+ tenocytes readily expand in vitro and express stem cell markers. In vivo, Axin2+-descendants are major functional contributors to repair: Axin2+ tenocytes proliferate, acquire injury responsive states, and re-adopt a tenocyte fate post-injury. Specific loss of Wnt secretion in Axin2+ cells alters their progenitor identity, disrupts their activation upon injury, and severely compromises any healing response. Our work highlights an unusual paradigm, wherein quiescent Axin2+ tenocytes self-regulate their identity and mobilization upon injury and provide the key initiating signal to organize a tendon-wide healing response.

cell biology↗

bioRxiv2021

Regulatory dissection of the severe COVID-19 risk locus introgressed by Neanderthals

Individuals infected with the SARS-CoV-2 virus present with a wide variety of phenotypes ranging from asymptomatic to severe and even lethal outcomes. Past research has revealed a genetic haplotype on chromosome 3 that entered the human population via introgression from Neanderthals as the strongest genetic risk factor for the severe COVID-19 phenotype. However, the specific variants along this introgressed haplotype that contribute to this risk and the biological mechanisms that are involved remain unclear. Here, we assess the variants present on the risk haplotype for their likelihood of driving the severe COVID-19 phenotype. We do this by first exploring their impact on the regulation of genes involved in COVID-19 infection using a variety of population genetics and functional genomics tools. We then perform an locus-specific massively parallel reporter assay to individually assess the regulatory potential of each allele on the haplotype in a multipotent immune-related cell line. We ultimately reduce the set of over 600 linked genetic variants to identify 4 introgressed alleles that are strong functional candidates for driving the association between this locus and severe COVID-19. These variants likely drive the locus impact on severity by putatively modulating the regulation of two critical chemokine receptor genes: CCR1 and CCR5. These alleles are ideal targets for future functional investigations into the interaction between host genomics and COVID-19 outcomes.

genetics↗

bioRxiv2021

Intronic regulation of SARS-CoV-2 receptor (ACE2) expression mediated by immune signaling and oxidative stress pathways

The angiotensin-converting enzyme 2 (ACE2) protein has been highly studied as a key catalytic regulator of the renin-angiotensin system (RAS), involved in fluid homeostasis and blood pressure modulation. In addition to its important physiological role as a broadly-expressed membrane-bound protein, ACE2 serves as a cell-surface receptor for some viruses - most notably, coronaviruses such as SARS-CoV and SARS-CoV-2. Differing levels of ACE2 expression may impact viral susceptibility and subsequent changes to expression may be a pathogenic mechanism of disease risk and manifestation. Therefore, an improved understanding of how ACE2 expression is regulated at the genomic and transcriptional level may help us understand not only how the effects of pre-existing conditions (e.g., chronic obstructive pulmonary disease) may manifest with increased COVID-19 incidence, but also the mechanisms that regulate ACE2 levels following viral infection. Here, we initially perform bioinformatic analyses of several datasets to generate hypotheses about ACE2 gene-regulatory mechanisms in the context of immune signaling and chronic oxidative stress. We then identify putative non-coding regulatory elements within ACE2 intronic regions as potential determinants of ACE2 expression activity. We perform functional validation of our computational predictions in vitro via targeted CRISPR-Cas9 deletions of the identified ACE2 cis-regulatory elements in the context of both immunological stimulation and oxidative stress conditions. We demonstrate that intronic ACE2 regulatory elements are responsive to both immune signaling and oxidative-stress pathways, and this contributes to our understanding of how expression of this gene may be modulated at both baseline and during immune challenge. Our work supports the further pursuit of these putative mechanisms in our understanding, prevention, and treatment of infection and disease caused by ACE2-utilizing viruses such as SARS-CoV, SARS-CoV-2, and future emerging SARS-related viruses. Author SummaryThe recent emergence of the virus SARS-CoV-2 which has caused the COVID-19 pandemic has prompted scientists to intensively study how the virus enters human host cells. This work has revealed a key protein, ACE2, that acts as a receptor permitting the virus to infect cells. Much research has focused on how the virus physically interacts with ACE2, yet little is known on how ACE2 is turned on or off in human cells at the level of the DNA molecule. Understanding this level of regulation may offer additional ways to prevent or lower viral entry into human hosts. Here, we have examined the control of the ACE2 gene, the DNA sequence that instructs ACE2 protein receptor formation, and we have done so in the context of immune stimulation. We have indeed identified a number of DNA on/off switches for ACE2 that appear responsive to immuno-logical and oxidative stress. These switches may fine-tune how ACE2 is turned on or off before, during, and/or after infection by SARS-CoV-2 or other related coronaviruses. Our studies help pave the way for additional functional studies on these switches, and their potential therapeutic targeting in the future.

genetics↗

bioRxiv2020

Early temporal dynamics of cellular responses to SARS-CoV-2

Type I interferons (IFNs) are our first line of defence against a virus. Protein over-expression studies have suggested the ability of SARS-CoV-2 proteins to block IFN responses. Emerging data also suggest that timing and extent of IFN production is associated with manifestation of COVID-19 severity. In spite of progress in understanding how SARS-CoV-2 activates antiviral responses, mechanistic studies into wildtype SARS-CoV-2-mediated induction and inhibition of human type I IFN responses are lacking. Here we demonstrate that SARS-CoV-2 infection induces a mild type I IFN response in vitro and in moderate cases of COVID-19. In vitro stimulation of type I IFN expression and signaling in human airway epithelial cells is associated with activation of canonical transcriptions factors, and SARS-CoV-2 is unable to inhibit exogenous induction of these responses. Our data demonstrate that SARS-CoV-2 is not adept in blocking type I IFN responses and provide support for ongoing IFN clinical trials. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/158154v2_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@193c540org.highwire.dtl.DTLVardef@7b106forg.highwire.dtl.DTLVardef@1741cfforg.highwire.dtl.DTLVardef@1bde68_HPS_FORMAT_FIGEXP M_FIG GRAPHICAL SUMMARY C_FIG

immunology↗

bioRxiv2020

Bi-fated tendon-to-bone attachment cells are regulated by shared enhancers and KLF transcription factors

The connection between different tissues is vital for the development and function of any organs and systems. In the musculoskeletal system, the attachment of elastic tendons to stiff bones poses a mechanical challenge that is solved by the formation of a transitional tissue, which allows the transfer of muscle forces to the skeleton without tearing. Here, we show that tendon-to-bone attachment cells are bi-fated, activating a mixture of chondrocyte and tenocyte transcriptomes, which is regulated by sharing regulatory elements with these cells and by Kruppel-like factors transcription factors (KLF). To uncover the molecular identity of attachment cells, we first applied high-throughput RNA sequencing to murine humeral attachment cells. The results, which were validated by in situ hybridization and single-molecule in situ hybridization, reveal that attachment cells express hundreds of chondrogenic and tenogenic genes. In search for the underlying mechanism allowing these cells to express these genes, we performed ATAC sequencing and found that attachment cells share a significant fraction of accessible intergenic chromatin areas with either tenocytes or chondrocytes. Epigenomic analysis further revealed transcriptional enhancer signatures for the majority of these regions. We then examined a subset of these regions using transgenic mouse enhancer reporter. Results verified the shared activity of some of these enhancers, supporting the possibility that the transcriptome of attachment cells is regulated by enhancers with shared activities in tenocytes or chondrocytes. Finally, integrative chromatin and motif analyses, as well as the transcriptome data, indicated that KLFs are regulators of attachment cells. Indeed, blocking the expression of Klf2 and Klf4 in the developing limb mesenchyme led to abnormal differentiation of attachment cells, establishing these factors as key regulators of the fate of these cells. In summary, our findings show how the molecular identity of bi-fated attachment cells enables the formation of the unique transitional tissue that connect tendon to bone. More broadly, we show how mixing the transcriptomes of two cell types through shared enhancers and a dedicated set of transcription factors can lead to the formation of a new cell fate that connects them.

developmental biology↗

bioRxiv2018

Predicting bilateral knee pain from MR imaging using deep neural networks

Background and objectiveIt remains difficult to characterize pain in knee joints with osteoarthritis solely by radiographic findings. We sought to understand how advanced machine learning methods such as deep neural networks can be used to analyze raw MRI scans and predict bilateral knee pain, independent of other risk factors. MethodsWe developed a deep learning framework to associate information from MRI slices taken from the left and right knees of subjects from the Osteoarthritis Initiative with bilateral knee pain. Model training was performed by first extracting features from two-dimensional (2D) sagittal intermediate-weighted turbo spin echo slices. The extracted features from all the 2D slices were subsequently combined to directly associate using a fused deep neural network with the output of interest as a binary classification problem. ResultsThe deep learning model resulted in predicting bilateral knee pain on test data with 70.1% mean accuracy, 51.3% mean sensitivity, and 81.6% mean specificity. Systematic analysis of the predictions on the test data revealed that the model performance was consistent across subjects of different Kellgren-Lawrence grades. ConclusionThe study demonstrates a proof of principle that a machine learning approach can be applied to associate MR images with bilateral knee pain. SIGNIFICANCE AND INNOVATIONKnee pain is typically considered as an early indicator of osteoarthritis (OA) risk. Emerging evidence suggests that MRI changes are linked to pre-clinical OA, thus underscoring the need for building image-based models to predict knee pain. We leveraged a state-of-the-art machine learning approach to associate raw MR images with bilateral knee pain, independent of other risk factors.

bioengineering↗

bioRxiv2018

The Role of Gdf5 Regulatory Regions on Development of Hip Morphology and Susceptibility to Osteoarthritis and Dislocation

Given GDF5 involvement in hip development, and osteoarthritis (OA) and developmental hip dysplasia (DDH) risk, here we sought to assess the role(s) of GDF5 and its regulatory sequence on the development of hip morphology linked to injury risk. The brachypodism (bp) mouse, which harbors a Gdf5 inactivating mutation, was used to survey how Gdf5 loss of function impacts the development of hip morphology. Two transgenic Gdf5 reporter BAC lines were used to assess the spatiotemporal expression of Gdf5 regulatory sequences. Each BAC line was also used to assess the functional roles of upstream and downstream sequence on hip morphology. bp/bp mice had shorter femora with smaller femoral heads and necks as well as larger alpha angles, smaller anterior offsets, and smaller acetabula, compared to bp/+ mice (p<0.04). Regulatory sequences downstream of Gdf5 drove strong prenatal (E17) expression and low postnatal (6 months) expression across regions of femoral head and acetabulum. Conversely, upstream regulatory sequences drove very low expression at E17 and no detectable expression at 6 months. Importantly, downstream, but not upstream Gdf5 regulatory sequences fully restored all the key morphologic features disrupted in bp/bp mice. Hip morphology is profoundly affected by Gdf5 absence, and downstream regulatory sequences mediate its effects by controlling Gdf5 expression during development. This downstream region contains numerous enhancers harboring risk variants related to hip OA, DDH, and dislocation. We posit that subtle alterations to morphology driven by changes in downstream regulatory sequence underlie this locus role in hip injury risk.

genetics↗

bioRxiv2018

A robust method for RNA extraction and purification from a single adult mouse tendon

BackgroundMechanistic understanding of tendon molecular and cellular biology is crucial towards furthering our abilities to design new therapies for tendon and ligament injuries and disease. Recent transcriptomic and epigenomic studies in the field have harnessed the power of mouse genetics to reveal new insights into tendon biology. However, many mouse studies pool tendon tissues or use amplification methods to perform RNA analysis, which can significantly increase the experimental costs and limit the ability to detect changes in expression of low copy transcripts.\n\nMethodsSingle Achilles tendons were harvested from uninjured, contralateral injured, and wild type mice between 3-5 months of age, and RNA was extracted. RNA Integrity Number (RIN) and concentration were determined, and RT-qPCR gene expression analysis was performed.\n\nResultsAfter testing several RNA extraction approaches on single adult mouse Achilles tendons, we developed a protocol that was successful at obtaining high RIN and sufficient concentrations suitable for RNA analysis. We found that the RNA quality was sensitive to the time between tendon harvest and homogenization, and the RNA quality and concentration was dependent on the duration of homogenization. Using this method, we demonstrate that analysis of Scx gene expression in single mouse tendons reduces the biological variation caused by pooling tendons from multiple mice. We also show successful use of this approach to analyze Sox9 and Col1a2 gene expression changes in injured compared with uninjured control tendons.\n\nDiscussionOur work presents a robust, cost-effective, and straightforward method to extract high quality RNA from a single adult mouse Achilles tendon at sufficient amounts for RNA-seq and RT-qPCR. We show this can reduce biological variation and decrease the overall costs associated with experiments. This approach can also be applied to other skeletal tissues as well as precious human samples.

molecular biology↗