Biology subjects

Lu, C.

Publications and source records attributed to Lu, C..

At least 163 records · Page 9Linked to original sources

bioRxiv2020

Optimization of Spectral Library Size Improves DIA-MS Proteome Coverage

Efficient peptide and protein identification from data-independent acquisition mass spectrometric (DIA-MS) data typically rely on an experiment-specific spectral library with a suitable size. Here, we report a computational strategy for optimizing the spectral library for a specific DIA dataset based on a comprehensive spectral library, which is accomplished by a priori analysis of the DIA dataset. This strategy achieved up to 44.7% increase in peptide identification and 38.1% increase in protein identification in the test dataset of six colorectal tumor samples compared with the comprehensive pan-human library strategy. We further applied this strategy to 389 carcinoma samples from 15 tumor datasets and observed up to 39.2% increase in peptide identification and 19.0% increase in protein identification. In summary, we present a computational strategy for spectral library size optimization to achieve deeper proteome coverage of DIA-MS data.

bioinformatics↗

bioRxiv2020

The BTB transcription factors ZBTB11 and ZFP131 maintain pluripotency by pausing POL II atpro-differentiation genes

In pluripotent cells, a delicate activation-repression balance maintains pro-differentiation genes ready for rapid activation. The identity of transcription factors (TFs) that specifically repress pro-differentiation genes remains obscure. By targeting ~1,700 TFs with CRISPR loss-of-function screen, we found that ZBTB11 and ZFP131 are required for embryonic stem cell (ESC) pluripotency. ZBTB11 and ZFP131 maintain promoter-proximally paused Polymerase II at pro-differentiation genes in ESCs. ZBTB11 or ZFP131 loss leads to NELF pausing factor release, an increase in H3K4me3, and transcriptional upregulation of genes associated with all three germ layers. Together, our results suggest that ZBTB11 and ZFP131 maintain pluripotency by preventing premature expression of pro-differentiation genes and present a generalizable framework to maintain cellular potency. One-sentence summaryA Transcription Factor-wide CRISPR screen identifies ZBTB11 and ZFP131 maintaining pluripotency by pausing POL II at pro-differentiation genes

developmental biology↗

bioRxiv2020

Circular RNA as a potential biomarker for forensic age prediction using multiple machine learning models: A preliminary study

In forensic science, accurate estimation of the age of a victim or suspect can facilitate the investigators to narrow a search and aid in solving a crime. Aging is a complex process associated with various molecular regulation on DNA or RNA levels. Recent studies have shown that circular RNAs (circRNAs) upregulate globally during aging in multiple organisms such as mice and elegans because of their ability to resist degradation by exoribonucleases. In the current study, we attempted to investigate circRNAs potential capability of age prediction. Here, we identified more than 40,000 circRNAs in the blood of thirteen Chinese unrelated healthy individuals with ages of 20-62 years according to their circRNA-seq profiles. Three methods were applied to select age-related circRNAs candidates including false discovery rate, lasso regression, and support vector machine. The analysis uncovered a strong bias for circRNA upregulation during aging in human blood. A total of 28 circRNAs were chosen for further validation in 50 healthy unrelated subjects aged between 19 and 72 years by RT-qPCR and finally, 7 age-related circRNAs were chosen for final age prediction models. Several different algorithms including multivariate linear regression (MLR), regression tree, bagging regression, random forest regression (RFR), and support vector regression (SVR) were compared based on root mean square error (RMSE) and mean average error (MAE) values. Among five modeling methods, random forest regression (RFR) performed better than the others with an RMSE value of 5.072 years and an MAE value of 4.065 years (R2 = 0.902). In this preliminary study, we firstly used circRNAs as additional novel age-related biomarkers for developing forensic age estimation models. We propose that the use of circRNAs to obtain additional clues for forensic investigations and serve as aging indicators for age prediction would become a promising field of interest. Author summaryIn forensic investigations, estimation of the age of biological evidence recovered from crime scenes can provide additional information such as chronological age or the appearance of a culprit, which could give valuable investigative leads especially when there is no eyewitness available. Hence, generating an accurate model for age prediction using body fluids such as blood commonly seen at a crime scene can be of vital importance. Various molecular changes on DNA or RNA levels were discovered that they upregulated or downregulated during a persons lifetime. Although some biomarkers have been proved to be associated with aging and used to predict age, several disadvantages such as low sensitivity, prediction accuracy, instability and susceptibility of diseases or immune states, thus limiting their applicability in the field of age estimation. Here, we utilized a novel biomarker namely circular RNA (circRNA) to generate highly accurate age prediction models. We propose that circRNA is more suitable for forensic degradation samples because of its unique molecular structure. This preliminary research offers a new thought for exploring potential biomarker for age prediction.

genetics↗

bioRxiv2020

Target lipidomics reveals associations between serum sphingolipids and insulin sensitivity by the glucose clamp

BackgroundThis study aimed to systematically investigate the associations between serum sphingolipids and insulin sensitivity as well as insulin secretion. This study also aimed to reveal potential predictors for insulin sensitivity or give perceptive insight into disease processes. MethodsWe conducted a lipidomics evaluation of molecularly distinct SPs in the serum of 86 consecutive Chinese adults with or without obesity and diabetes using electrospray ionization mass spectrometry coupled with liquid chromatography. The GIR30 was measured under steady conditions to assess insulin sensitivity by the gold standard hyperinsulinemic-euglycemic clamp. We created the ROC curves to detect the serum SMs diagnostic value and establish the diagnosis of insulin sensitivity. ResultsDifferential correlation network analysis illustrated correlations amongst lipids, insulin sensitivity, insulin secretion and other clinical indexes. Total and subspecies of serum SMs and globotriaosylceramides (Gb3s) were positively related to GIR30, free FAs (FFA 16:1, FFA20:4), some long chain GM3 and complex ceramide GluCers showed strong negative correlations with GIR30. Notably, ROC curves showed that SM/Cer and SM d18:0/26:0 may be good serum lipid predictors of diagnostic indicators of insulin sensitivity close to conventional clinical indexes such as 1/HOMA-IR (all areas under the curve >0.80) based on GIR30 as standard diagnostic criteria. ConclusionsThese results provide novel associations between serum sphingolipid between insulin sensitivity measured by the hyperinsulinemic-euglycemic clamp. We further identify two specific SPs that may represent prognostic biomarkers for insulin sensitivity.

physiology↗

bioRxiv2020

Did the Himalayan Uplift Drive Evolution of Aquatic Biodiversity Across Asia? Snowtrout (Cyprinidae: Schizothorax) as a Test Case

The Himalayan uplift, a tectonic event of global importance, seemingly disseminated aquatic biodiversity broadly across Asia. But surprisingly, this hypothesis has yet to be tested. We do so herein by sequencing 1,140 base-pair of mtDNA cytochrome-b for 72 tetraploid Nepalese/Bhutanese Snowtrout (Schizothorax spp.), combining those data with 67 GENBANK(R) sequences (59 ingroup/8 outgroup), then reconstructing phylogenetic relationships using maximum likelihood/ Bayesian analyses. Results indicate Snowtrout originated in Central Asia, dispersed across the Qinghai-Tibetan Plateau (QTP), then into Bhutan via south-flowing tributaries of the east-flowing Yarlung-Tsangpo River (YLTR). The headwaters of five large Asian rivers provided dispersal corridors into southeast Asia. South of the Himalaya, the YLTR transitions into a westward-flowing Brahmaputra River that facilitated successive colonization of Himalayan drainages: First Bhutan, then Nepal, followed by far-western drainages subsequently captured by the Indus River. We found greater species-divergences across rather than within-basins, implicating vicariant evolution as a driver. The Himalaya is a component of the "third-pole" [Earths largest (but rapidly shrinking) glacial reservoir outside the Arctic/Antarctic]. Its unique aquatic biodiversity must not only be recognized (as herein) but also conserved through broad, trans-national collaborations. Our results effectively contrast phylogeography with taxonomy as a necessary first step in this process. The Himalaya is the most extensive and recently evolved mountain system on Earth (length=2400km; width=240km; elevation=75-8800m), with a global significance underscored by its large-scale lithospheric, cryospheric, and atmospheric interactions [1]. These have not only driven global climate, but also defined the cultural and biological endemism of the region [2]. Massive, tectonically derived mountain chains such as the Alps and the Himalaya are hypothesized as being fundamental to the formation of global biodiversity gradients via vicariance and local adaptation, with a significantly stronger signal in terrestrial rather than aquatic systems [3]. Here we test how orogeny (the deformation and folding of Earths crust by lateral compression) has contributed to the diversification of freshwater fishes broadly across Asia. We do so by evaluating the phylogeography of an endemic high-elevation fish, the Snowtrout (Schizothorax: Cyprinidae).

evolutionary biology↗

bioRxiv2020

Cell-type-specific epigenomic variations associated with BRCA1 mutation in pre-cancer human breast tissues

BRCA1 germline mutation carriers are predisposed to breast cancers. Epigenomic regulations have been known to strongly interact with genetic variations and potentially mediate biochemical cascades involved in tumorigenesis. Due to the cell-type specificity of epigenomic features, profiling of individual cell types is critical for understanding the molecular events in various cellular compartments within complex breast tissue. Here we report cell-type-specific profiling of genome-wide histone modifications including H3K27ac and H3K4me3 in basal, luminal progenitor, mature luminal, and stromal cells extracted from pre-cancer BRCA1 mutation carriers and non-carriers, conducted using a low-input technology that we developed. We discover that basal and stromal cells present the most extensive epigenomic differences between mutation carriers (BRCA1mut/+) and non-carriers (BRCA1+/+) while luminal progenitor and mature luminal cells are relatively unchanged with the mutation. Furthermore, the epigenomic changes in basal cells due to BRCA1 mutation appear to facilitate their transformation into luminal progenitor cells. Our findings shed light on the pre-cancer epigenomic dynamics due to BRCA1 mutation and how they may contribute to eventual development of predominantly basal-like breast cancer.

genomics↗

bioRxiv2020

A structural model of a Ras-Raf signalosome

The protein K-Ras functions as a molecular switch in signaling pathways regulating cell growth. In the MAPK pathway, which is implicated in many cancers, multiple K-Ras proteins are thought to assemble at the cell membrane with Ras-effector proteins from the Raf family. Here we propose an atomistic structural model for such an assembly. Our starting point was an asymmetric, GTP-mediated K-Ras dimer model, which we generated using unbiased molecular dynamics simulations and verified with mutagenesis experiments. Adding further K-Ras monomers in a head-to-tail fashion led to a compact helical assembly, a model we validated using electron microscopy and cell-based experiments. This assembly stabilizes K-Ras in its active state and presents composite interfaces to facilitate Raf binding. Guided by existing experimental data, we then positioned C-Raf, the downstream kinase MEK1, and accessory proteins (Galectin-3 and 14-3-3{sigma}) on the helical assembly. The resulting Ras-Raf signalosome model offers an explanation for a large body of data on MAPK signaling.

molecular biology↗

bioRxiv2020

Epigenome dysregulation resulting from NSD1 mutation in head and neck squamous cell carcinoma

Epigenetic dysregulation has emerged as an important mechanism of oncogenesis. To develop targeted treatments, it is important to understand the epigenetic and transcriptomic consequences of mutations in epigenetic modifier genes. Recently, mutations in the histone methyltransferase gene NSD1 have been identified in a subset of head and neck squamous cell carcinomas (HNSCCs) - one of the most common and deadly cancers. Here, we use whole (epi)genome approaches and genome editing to dissect the downstream effects of loss of NSD1 in HNSCC. We demonstrate that NSD1 mutations are directly responsible for loss of intergenic H3K36me2 domains, followed by loss of DNA methylation, and gain of H3K27me3 in the affected genomic regions. We further show that those regions are enriched in cis-regulatory elements and that subsequent loss of H3K27ac correlates with reduced expression of their target genes. Our analysis identifies genes and pathways affected by the loss of NSD1 and paves the way to further understanding the interplay among chromatin modifications in cancer.

genomics↗

bioRxiv2020

bHLH11 negatively regulates Fe homeostasis by its EAR motifs recruiting corepressors in Arabidopsis

Iron (Fe) homeostasis is essential for plant growth and development. Many transcription factors play pivotal roles in the maintenance of Fe homeostasis. bHLH11 was identified as a negative transcription factor regulating Fe homeostasis, however, the underlying molecular mechanism remains elusive. We generated two loss-of-function bhlh11 mutants which display the enhanced sensitivity to Fe excess, the increased Fe accumulation and the elevated expression of Fe deficiency responsive genes. bHLH11 protein, localized in both the cytoplasm and nucleus, decreases in response to Fe deficiency. Coexpression assays indicate that bHLH IVc transcription factors (TFs) (bHLH34, bHLH104, bHLH105, and bHLH115) facilitate the nuclear accumulation of bHLH11 protein. Further analysis indicates that bHLH11 represses the transactivity of bHLH IVc TFs towards bHLH Ib genes (bHLH38, bHLH39, bHLH100, and bHLH101). bHLH11 contains two EAR motifs which are responsible for the repression function by recruiting the TOPLESS/TOPLESS-RELATED (TPL/TPRs) corepressors. Correspondingly, the expression of Fe uptake genes increases in the tpr1 tpr4 tpl mutant. Moreover, genetic analysis reveals that bHLH11 has functions independent of FIT. This study provides insights into the complicate Fe homeostasis signaling network. One-sentence summarybHLH IVc proteins promote the bHLH11 protein accumulation in the nucleus where bHLH11 inhibits the transcriptional activation ability of bHLH IVc via its EAR motifs recruiting the TOPLESS/TOPLESS-RELATED corepressors.

plant biology↗

bioRxiv2020

CRISPR/Cpf1 mediated genome editing enhances Bombyx mori resistance to BmNPV

CRISPR/Cas12a (Cpf1) is a single RNA-guided endonuclease that provides new opportunities for targeted genome engineering through the CRISPR/Cas9 system. Only AsCpf1 have been developed for insect genome editing, and the novel Cas12a orthologs nucleases and editing efficiency require more study in insect. We compared three Cas12a orthologs nucleases, AsCpf1, FnCpf1, and LbCpf1, for their editing efficiencies and antiviral abilities in vitro. The three Cpf1 efficiently edited the BmNPV genome and inhibited BmNPV replication in BmN-SWU1 cells. The antiviral ability of the FnCpf1 system was more efficient than the SpCas9 system after infection by BmNPV. We created FnCpf1xgIE1 and SpCas9xsgIE1 transgenic hybrid lines and evaluated the gene editing efficiency of different systems at the same target site. We improved the antiviral ability using the FnCpf1 system in transgenic silkworm. This study demonstrated use of the CRISPR/Cpf1 system to achieve high editing efficiencies in the silkworm, and illustrates the use of this technology for increasing disease resistance. Author SummaryGenome editing is a powerful tool that has been widely used in gene function, gene therapy, pest control, and disease-resistant engineering in most parts of pathogens research. Since the establishment of CRISPR/Cas9, powerful strategies for antiviral therapy of transgenic silkworm have emerged. Nevertheless, there is still room to expand the scope of genome editing tool for further application to improve antiviral research. Here, we demonstrate that three Cpf1 endonuclease can be used efficiency editing BmNPV genome in vitro and in vivo for the first time. More importantly, this Cpf1 system could improve the resistance of transgenic silkworms to BmNPV compare with Cas9 system, and no significant cocoons difference was observed between transgenic lines infected with BmNPV and control. These broaden the range of application of CRISPR for novel genome editing methods in silkworm and also enable sheds light on antiviral therapy.

microbiology↗

bioRxiv2020

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

There are two Fe-uptake strategies for maintaining Fe homeostasis in plants. As a special graminaceous plant, rice applies both strategies. However, it remains unclear how these two strategies are regulated in rice. IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2) is critical for regulating Fe uptake in rice. In this study, we identified an interacting partner of OsIRO2, Oryza sativa FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT), which encodes a bHLH transcription factor. The OsIRO2 protein is localized in the cytoplasm and nucleus, but OsFIT facilitates the accumulation of OsIRO2 in the nucleus. Loss-of-function mutations to OsFIT result in decreased Fe accumulation, severe Fe-deficiency symptoms, and disrupted expression of Fe-uptake genes. In contrast, OsFIT overexpression promotes Fe accumulation and the expression of Fe-uptake genes. Genetic analyses indicated that OsFIT and OsIRO2 function in the same genetic node. Further analysis suggested that OsFIT and OsIRO2 form a functional transcription activation complex to initiate the expression of Fe-uptake genes. Our findings provide a mechanism understanding of how rice maintains Fe homeostasis. One-sentence summaryOsFIT interacts with and facilitates the accumulation of OsIRO2 in the nucleus where the OsFIT-OsIRO2 transcription complex initiates the transcription of Fe deficiency responsive genes.

plant biology↗

bioRxiv2020

Phenotype Prediction using a Tensor Representation and Deep Learning from Data Independent Acquisition Mass Spectrometry

A novel approach for phenotype prediction is developed for mass spectrometric data. First, the data-independent acquisition (DIA) mass spectrometric data is converted into a novel file format called "DIA tensor" (DIAT) which contains all the peptide precursors and fragments information and can be used for convenient DIA visualization. The DIAT format is fed directly into a deep neural network to predict phenotypes without the need to identify peptides or proteins. We applied this strategy to a collection of 102 hepatocellular carcinoma samples and achieved an accuracy of 96.8% in classifying malignant from benign samples. We further applied refined model to 492 samples of thyroid nodules to predict thyroid cancer; and achieved a predictive accuracy of 91.7% in an independent cohort of 216 test samples. In conclusion, DIA tensor enables facile 2D visualization of DIA proteomics data as well as being a new approach for phenotype prediction directly from DIA-MS data.

bioinformatics↗

bioRxiv2020

A single-cell RNAseq atlas of the pathogenic stage of Schistosoma mansoni identifies a key regulator of blood feeding

Schistosomiasis is an ancient and chronic neglected tropical disease that infects over 240 million people and kills over 200,000 of the worlds poorest people every year1, 2. There are no vaccines and because there is only one drug available, the need for new therapeutics is great. The causative agents of this disease are flatworm parasites that dwell inside the hosts circulation, often for decades, where they feed on blood and lay eggs which are primarily responsible for disease pathology. As metazoans comprised of multiple tissue types, understanding the schistosomes tissues on a molecular level and their functions during what can be decades of successful parasitism could suggest novel therapeutic strategies. Here, we employ single-cell RNAseq to characterize 43,642 cells from the pathogenic (adult) stage of the schistosome lifecycle. From these data, we characterize 68 molecularly distinct cell populations that comprise nearly all tissues described morphologically, including the nervous and reproductive systems. We further uncover a lineage of somatic stem cells responsible for producing and maintaining the parasites gut - the primary tissue responsible for digestion of host blood. Finally, we show that a homologue of hepatocyte nuclear factor 4 (hnf4) is expressed in this gut lineage and required for gut maintenance, blood feeding and inducing egg-associated pathology in vivo. Together, the data highlight the utility of this single-cell RNAseq atlas to understand schistosome biology and identify potential therapeutic interventions.

microbiology↗

bioRxiv2020

SMRT sequencing yields the chromosome-scale reference genome of tea tree, Camellia sinensis var. sinensis

Tea is the oldest and most popular nonalcoholic beverage consumed in the world. It provides abundant secondary metabolites that account for its diverse flavors and health benefits. Here we present the first high-quality chromosome-length reference genome of C. sinensis var. sinensis using long read single-molecule real time (SMRT) sequencing and Hi-C technologies to anchor the [~]2.85-Gb genome assembly into 15 pseudo-chromosomes with a scaffold N50 length of [~]195.68 Mb. We annotated at least 2.17 Gb ([~]74.13%) of repetitive sequences and high-confidence prediction of 40,812 protein-coding genes in the [~]2.92-Gb genome assembly. This accurately assembled genome allows us to comprehensively annotate functionally important gene families such as those involved in the biosynthesis of catechins, theanine and caffeine. The contiguous genome assembly provides the first view of the repetitive landscape allowing us to accurately characterize retrotransposon diversity. The large tea tree genome is dominated by a handful of Ty3-gypsy long terminal repeat (LTR) retrotransposon families that recently expanded to high copy numbers. We uncover the latest bursts of numerous non-autonomous LTR retrotransposons that may interfere with the propagation of autonomous retroelements. This reference genome sequence will largely facilitate the improvement of agronomically important traits relevant to the tea quality and production.

genomics↗

bioRxiv2019

Osmotic stress-induced, rapid clustering of IGF2BP proteins nucleates stress granule assembly

Stress granules (SGs) are formed in the cytoplasm by liquid-liquid phase separation (LLPS) of translationally-stalled mRNA and RNA-binding proteins during stress response. Understanding the mechanisms governing SG assembly requires imaging SG formation in real time. Here we used live cell imaging and super-resolution imaging to visualize SG assembly in human cells. We found that IGF2BP proteins formed microscopically visible clusters almost instantaneously upon osmotic stress, prior to the recruitment of G3BP1 and TIA1. The rapid clustering of IGF2BP1 was ATP-independent and was mediated by its KH3/4 di-domains and an intrinsically disordered region (IDR), whereas ATP depletion inhibited the recruitment of G3BP1 and TIA1. Moreover, we detected cytoplasmic clusters of IGF2BP1 below the optical resolution in normal cells and found IGF2BP1 forming a dense granule associated with multiple clusters of poly(A) mRNA in mature SGs. Thus, ATP-independent, rapid clustering of IGF2BP nucleates SG assembly during osmotic stress.

cell biology↗

bioRxiv2019

PulseDIA: in-depth data independent acquisition mass spectrometry using enhanced gas phase fractionation

An inherent bottleneck of data independent acquisition (DIA) analysis by Orbitrap-based mass spectrometers is the relatively large window width due to the relatively slow scanning rate compared to TOF. Here we present a novel gas phase separation and MS acquisition method called PulseDIA-MS, which improves the specificity and sensitivity of Orbitrap-based DIA analysis. This is achieved by dividing the ordinary DIA-MS analysis covering the entire mass range into multiple injections for DIA-MS analyses with complementary windows. Using standard HeLa digests, the PulseDIA method identified 69,530 peptide precursors from 9,337 protein groups with ten MS injections of 30 min LC gradient. The PulseDIA scheme containing two complementary windows led to the highest gain of peptide and protein identifications per time unit compared to the conventional 30 min DIA method. We further applied the method to profile the proteome of 18 cholangiocarcinoma (CCA) tissue samples (benign and malignant) from nine patients. PulseDIA identified 7,796 protein groups in these CCA samples, with 14% increase of protein identifications, compared to the conventional DIA method. The missing value for protein matrix dropped by 7% with PulseDIA acquisition. 681 proteins were significantly dysregulated in tumorous CCA samples. Together, we presented and benchmarked an alternative DIA method with higher sensitivity and lower missing rate.

cancer biology↗

bioRxiv2019

Design and assessment of TRAP-CSP fusion antigens as effective malaria vaccines

The circumsporozoite protein (CSP) and thrombospondin-related adhesion protein (TRAP) are major targets for pre-erythrocytic malaria vaccine development. However, the most advanced CSP-based vaccine RTS,S provides only partial protection, highlighting the need for innovative approaches for vaccine design and development. Here we design and characterize TRAP-CSP fusion antigens, and evaluate their immunogenicity and protection against malaria infection. TRAP N-terminal folded domains were fused to CSP C-terminal fragments consisting of the C-terminal TSR domain with or without the intervening repeat region. Homogenous, monomeric and properly folded fusion proteins were purified from mammalian transfectants. Notably, fusion improved expression of chimeras relative to the TRAP or CSP components alone. Immunization of BALB/c mice with the P. berghei TRAP-CSP fusion antigens formulated in AddaVax adjuvant elicited antigen-specific antibody responses. Remarkably, fusion antigens containing the CSP repeat region conferred complete sterile protection against P. berghei sporozoite challenge, and furthermore, mice that survived the challenge were completely protected from re-challenge 16 weeks after the first challenge. In contrast, fusion antigens lacking the CSP repeat region were less effective, indicating that the CSP repeat region provided enhanced protection, which correlated with higher antibody titers elicited by fusion antigens containing the CSP repeat region. In addition, we demonstrated that N-linked glycans had no significant effect on antibody elicitation or protection. Our results show that TRAP-CSP fusion antigens could be highly effective vaccine candidates. Our approach provides a platform for designing multi-antigen/multi-stage fusion antigens as next generation more effective malaria vaccines.

microbiology↗

bioRxiv2019

Membrane-type 1 matrix metalloproteinase (MMP-14) modulates tissue homeostasis by a non-proteolytic mechanism

Membrane-type 1 matrix metalloproteinase (MT1-MMP, MMP-14), a transmembrane proteinase with a short cytoplasmic tail, is a major effector of extracellular matrix (ECM) remodeling. Genetic silencing of MT1-MMP in mouse (Mmp14-/-) and man causes dwarfism, osteopenia, arthritis and lipodystrophy, abnormalities ascribed to defective collagen turnover. We have previously shown non-proteolytic functions of MT1-MMP mediated by its cytoplasmic tail, where the unique tyrosine (Y573) controls intracellular signaling. The Y573D mutation blocks TIMP2/MT1-MMP-induced Erk1/2 and Akt signaling without affecting proteolytic activity. Here we report that a mouse with the MT1-MMP Y573D mutation (Mmp14Y573D/Y573D) shows abnormalities similar to, but also different from those of Mmp14-/- mice. Skeletal stem cells (SSC) of Mmp14Y573D/Y573D mice show defective differentiation consistent with the mouse phenotype, which is rescued by wild-type SSC transplant. These results provide the first in vivo demonstration that MT1-MMP modulates bone, cartilage and fat homeostasis by controlling SSC differentiation through a mechanism independent of proteolysis.

cell biology↗