Clinically Applicable AI System for Accurate Diagnosis, Quantitative Measurements, and Prognosis of COVID-19 Pneumonia Using Computed Tomography.

Many COVID-19 patients infected by SARS-CoV-2 virus develop pneumonia (called novel coronavirus pneumonia, NCP) and rapidly progress to respiratory failure. However, rapid diagnosis and identification of high-risk patients for early intervention are challenging. Using a large computed tomography (CT) database from 3,777 patients, we developed an AI system that can diagnose NCP and differentiate it from other common pneumonia and normal controls. The AI system can assist radiologists and physicians in performing a quick diagnosis especially when the health system is overloaded. Significantly, our AI system identified important clinical markers that correlated with the NCP lesion properties. Together with the clinical data, our AI system was able to provide accurate clinical prognosis that can aid clinicians to consider appropriate early clinical management and allocate resources appropriately. We have made this AI system available globally to assist the clinicians to combat COVID-19.

Systemic inflammatory markers in ageing, Alzheimer's disease and other dementias.

Systemic inflammation with alterations in inflammatory markers is involved in aging and Alzheimer's disease. However, few studies have investigated the longitudinal trajectories of systemic inflammatory markers during aging and Alzheimer's disease, and specific markers contributing to Alzheimer's disease remain undetermined. In this study, a longitudinal cohort (cohort 1: n = 290; controls, 136; preclinical Alzheimer's disease, 154) and a cross-sectional cohort (cohort 2: n = 351; controls, 62; Alzheimer's disease, 63; vascular dementia, 58; Parkinson's disease dementia, 56; behavioural variant frontotemporal dementia, 57; dementia with Lewy bodies, 55) were included. Plasma levels of inflammatory markers were measured every 2 years during a 10-year follow-up in the longitudinal cohort and once in the cross-sectional cohort. The study demonstrated that the inflammatory markers significantly altered during both aging and the development of Alzheimer's disease. However, only complement C3, interleukin-1ß, and interleukin-6 exhibited significant changes in participants with preclinical Alzheimer's disease, and their longitudinal changes were significantly associated with the development of Alzheimer's disease compared to controls over the 10-year follow-up. In the cross-sectional cohort, complement C3 demonstrates specificity to Alzheimer's disease, while interleukin-1ß and interleukin-6 were also altered in other dementias. The study provides a new perspective on the involvement of inflammatory markers in the aging process and the development of Alzheimer's disease, implying that regulating inflammation may have a pivotal role in promoting successful aging and in the prevention and treatment of Alzheimer's disease.

The Hyperproliferation Mechanism of Cholesteatoma Based on Proteomics: SNCA Promotes Autophagy-Mediated Cell Proliferation Through the PI3K/AKT/CyclinD1 Signaling Pathway.

Cholesteatoma is a chronic inflammatory ear disease with abnormal keratinized epithelium proliferation and tissue damage. However, the mechanism of keratinized epithelium hyperproliferation in cholesteatoma remains unknown. Hence, our study sought to shed light on mechanisms affecting the pathology and development of cholesteatoma, which could help develop adjunctive treatments. To investigate molecular changes in cholesteatoma pathogenesis, we analyzed clinical cholesteatoma specimens and paired ear canal skin with mass spectrometry-based proteomics and bioinformatics. From our screen, alpha-synuclein (SNCA) was overexpressed in middle ear cholesteatoma and might be a key hub protein associated with inflammation, proliferation, and autophagy in cholesteatoma. SNCA was more sensitive to lipopolysaccharide-induced inflammation, and autophagy marker increase was accompanied by autophagy activation in middle ear cholesteatoma tissues. Overexpression of SNCA activated autophagy and promoted cell proliferation and migration, especially under lipopolysaccharide inflammatory stimulation. Moreover, inhibiting autophagy impaired SNCA-mediated keratinocyte proliferation and corresponded with inhibition of the PI3K/AKT/CyclinD1 pathways. Also, 740Y-P, a PI3K activator reversed the suppression of autophagy and PI3K signaling by siATG5 in SNCA-overexpressing cells, which restored proliferative activity. Besides, knockdown of SNCA in RHEK-1 and HaCaT cells or knockdown of PI3K in RHEK-1 and HaCaT cells overexpressing SNCA both resulted in attenuated cell proliferation. Our studies indicated that SNCA overexpression in cholesteatoma might maintain the proliferative ability of cholesteatoma keratinocytes by promoting autophagy under inflammatory conditions. This suggests that dual inhibition of SNCA and autophagy may be a promising new target for treating cholesteatoma.

Delivering synaptic protein mRNAs via extracellular vesicles ameliorates cognitive impairment in a mouse model of Alzheimer's disease.

BACKGROUND: Synaptic dysfunction with reduced synaptic protein levels is a core feature of Alzheimer's disease (AD). Synaptic proteins play a central role in memory processing, learning, and AD pathogenesis. Evidence suggests that synaptic proteins in plasma neuronal-derived extracellular vesicles (EVs) are reduced in patients with AD. However, it remains unclear whether levels of synaptic proteins in EVs are associated with hippocampal atrophy of AD and whether upregulating the expression of these synaptic proteins has a beneficial effect on AD. METHODS: In this study, we included 57 patients with AD and 56 healthy controls. We evaluated their brain atrophy through magnetic resonance imaging using the medial temporal lobe atrophy score. We measured the levels of four synaptic proteins, including synaptosome-associated protein 25 (SNAP25), growth-associated protein 43 (GAP43), neurogranin, and synaptotagmin 1 in both plasma neuronal-derived EVs and cerebrospinal fluid (CSF). We further examined the association of synaptic protein levels with brain atrophy. We also evaluated the levels of these synaptic proteins in the brains of 5×FAD mice. Then, we loaded rabies virus glycoprotein-engineered EVs with messenger RNAs (mRNAs) encoding GAP43 and SNAP25 and administered these EVs to 5×FAD mice. After treatment, synaptic proteins, dendritic density, and cognitive function were evaluated. RESULTS: The results showed that GAP43, SNAP25, neurogranin, and synaptotagmin 1 were decreased in neuronal-derived EVs but increased in CSF in patients with AD, and the changes corresponded to the severity of brain atrophy. GAP43 and SNAP25 were decreased in the brains of 5×FAD mice. The engineered EVs efficiently and stably delivered these synaptic proteins to the brain, where synaptic protein levels were markedly upregulated. Upregulation of synaptic protein expression could ameliorate cognitive impairment in AD by promoting dendritic density. This marks the first successful delivery of synaptic protein mRNAs via EVs in AD mice, yielding remarkable therapeutic effects. CONCLUSIONS: Synaptic proteins are closely related to AD processes. Delivery of synaptic protein mRNAs via EVs stands as a promising effective precision treatment strategy for AD, which significantly advances the current understanding of therapeutic approaches for the disease.

The value of gadolinium-enhanced MRI in predicting the development of sudden hearing loss into Ménière's disease.

OBJECTIVE: To compare the clinical features of sudden hearing loss (SHL) in patients with and without endolymphatic hydrops (EH), and to investigate the association between SHL with EH and Ménière's disease (MD). METHODS: The clinical data of 63 SHL patients with first symptoms were evaluated retrospectively. Patients were separated into two groups based on the results of gadolinium-enhanced magnetic resonance imaging: EH and non-EH groups. Independent sample t-test and U-test were used to compare groups for continuous variables, and the chi-squared test, corrected chi-squared test and Bonferroni correction test were used to compare groups for binary and ordinal variables. The binary logistic regression model was utilised for univariate and multivariate analysis of follow-up patient prognosis. RESULTS: The EH and non-EH groups contained 32 and 31 patients, respectively. The EH group had a higher prevalence of low-tone descending hearing loss. Fifty-one patients were followed for more than 2 years. In the EH group, 11 and 15 patients were diagnosed with sudden sensorineural hearing loss (SSNHL) and MD, respectively, while in the non-EH group, 24 patients were diagnosed with SSNHL and only one with MD. EH, low-tone descending hearing loss and vertigo were risk factors for the diagnosis of MD in a subgroup univariate regression analysis of patients experiencing SHL. EH was found to be a risk factor for the progression of SHL into MD in a multifactor regression analysis. CONCLUSIONS: Patients with SHL who have EH are more likely to present with low-tone descending hearing loss. EH is a risk factor for the subsequent development of MD.

Tubule-derived INHBB promotes interstitial fibroblast activation and renal fibrosis.

Upstream stimuli for myofibroblast activation are of considerable interest for understanding the mechanisms underlying renal fibrosis. Activin B, a member of the TGF-ß family, exists as a homodimer of inhibin subunit beta B (INHBB), but its role in renal fibrosis remains unknown. We found that INHBB expression was significantly increased in various renal fibrosis models and human chronic kidney disease specimens with renal fibrosis. Notably, the increase of INHBB occurred mainly in the tubular epithelial cells (TECs). In vivo, inhibiting INHBB blocked the activation of interstitial fibroblasts and ameliorated the renal fibrosis induced by unilateral ureteral obstruction or ischemia-reperfusion injury, while ectopic expression of INHBB in the TECs was able to activate interstitial fibroblasts and initiate interstitial fibrosis. In vitro, overexpression of INHBB in TECs led to the secretion of activin B, thereby promoting the proliferation and activation of interstitial fibroblasts through activin B/Smad signaling. Furthermore, inhibition of activin B/Smad signaling attenuated the fibrotic response caused by tubular INHBB. Mechanistically, the upregulation of INHBB depended on the transcription factor Sox9 in the injured TECs. Clinical analyses also identified a positive correlation between Sox9 and INHBB expression in human specimens, suggesting the Sox9/INHBB axis as a positive regulator of renal fibrosis. In conclusion, tubule-derived INHBB is implicated in the pathogenesis of renal fibrosis by activating the surrounding fibroblasts in a paracrine manner, thereby exhibiting as a potential therapeutic target. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Lens regeneration using endogenous stem cells with gain of visual function.

The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure poses notable risks of complications. Here we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method of cataract removal that preserves endogenous LECs and achieves functional lens regeneration in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from current practice, as it preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.

A case of vertebral artery compression syndrome mimicking primary lateral sclerosis.

PURPOSE: Vertebral artery compression syndrome (VACS) is an under-recognised condition that may be misdiagnosed as motor neuron disease. We report a case presenting features initially suggestive of primary lateral sclerosis (PLS) but later found to be VACS. CASE PRESENTATION: A 65-year-old man with hypertension was referred to our neurology department in the suspect of PLS. He presented with a 10-year history of involuntary jerk of the left lower limb, which ascended to the left upper limb 9 years later. He also developed intermittent painful spasms with a tendency to drag his left leg. His symptoms fluctuated with blood pressure. Neurological examination revealed upper motor neuron signs without lower motor neuron or sensory involvement. Electrophysiology studies were unremarkable. Brain MRI disclosed the left side of medulla oblongata was compressed by the tortuous left vertebral artery. Diffusion tensor tractography confirmed the corresponding corticospinal tract disruption. He was diagnosed with VACS and treated with antispasmodic medications and antihypertensive drugs. CONCLUSIONS: VACS should be considered into the differential diagnoses of PLS. A thorough clinical assessment and careful interpretation of brain MRI with advanced diffusion neuroimages can help confirm the diagnosis.

Characterizing dynamic changes of plasma cell-free Echinococcus granulosus DNA before and after cystic echinococcosis treatment initiation.

Over one million people are living with cystic echinococcosis (CE) and alveolar echinococcosis (AE). For CE, long-term albendazole treatment is often needed, which requires regular follow-up. Follow-up is mainly through imaging which is insensitive to subtle changes and subjective to experience. We investigated the changes of Echinococcus granulosus (Eg) cell-free DNA (cfDNA) in plasma of CE patients before and after albendazole treatment to evaluate its potential as an objective marker for treatment follow-up. Plasma samples of nine CE patients were collected before and after treatment. We identified Eg cfDNA from every sample through high-throughput sequencing. Eg cfDNA concentration and fragment length increased significantly after the treatment period. Ultrasound examination before and after the treatment initiation reflected the drug effects to a certain extent, as the cyst size of four patients reduced. Our findings indicated that Eg cfDNA from plasma could be a potential marker in the monitoring of CE treatment.

Lanosterol reverses protein aggregation in cataracts.

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Integrated Analysis of Angiogenesis-Mediated Tumor Immune Microenvironment Pattern in Hepatocellular Carcinoma (HCC) and a Novel Prognostic Model Construction to Predict Patient Outcome.

BACKGROUND Hepatocellular carcinoma (HCC) is a malignant tumor which is famous for its high heterogeneity and complex pathogenesis. Angiogenesis is an important driver of tumor progression and immune-suppressive microenvironment formation. MATERIAL AND METHODS A training set was acquired from the TCGA-LIHC cohort. An angiogenesis-active subtype was identified by consensus clustering analysis. The tumor subtype's immune microenvironment pattern was analyzed using quanTIseq. DEGs-mediated biology function was analyzed by enrichment analysis based on GO and KEGG. A prognostic model was constructed using LASSO Cox regression analysis and validated by 2 external datasets derived from GEO and ICGC. Quantitative real-time PCR assay was conducted to analyze CDCA8's expression status in the HCC line and normal liver cell line. RESULTS In HCC, patients with the angiogenesis-active subtype had a poor prognosis. Angiogenesis can shape the tumor microenvironment into high-M2 microphage infiltration and activity pattern. Here, we identified an angiogenesis-active HCC subtype and constructed an angiogenesis feature-based prognostic model to predict patient outcome. The external validation sets were enrolled to verify the accuracy of this model. CONCLUSIONS Our research demonstrated angiogenesis can confer the tumor immune-suppressive characteristic. We provide a robust method to evaluate the HCC's angiogenesis potential and help identify the angiogenesis-active subtype. Validation in the external validation cohort further confirmed the accuracy of our prognostic model.

WNT7A and PAX6 define corneal epithelium homeostasis and pathogenesis.

The surface of the cornea consists of a unique type of non-keratinized epithelial cells arranged in an orderly fashion, and this is essential for vision by maintaining transparency for light transmission. Cornea epithelial cells (CECs) undergo continuous renewal from limbal stem or progenitor cells (LSCs), and deficiency in LSCs or corneal epithelium--which turns cornea into a non-transparent, keratinized skin-like epithelium--causes corneal surface disease that leads to blindness in millions of people worldwide. How LSCs are maintained and differentiated into corneal epithelium in healthy individuals and which key molecular events are defective in patients have been largely unknown. Here we report establishment of an in vitro feeder-cell-free LSC expansion and three-dimensional corneal differentiation protocol in which we found that the transcription factors p63 (tumour protein 63) and PAX6 (paired box protein PAX6) act together to specify LSCs, and WNT7A controls corneal epithelium differentiation through PAX6. Loss of WNT7A or PAX6 induces LSCs into skin-like epithelium, a critical defect tightly linked to common human corneal diseases. Notably, transduction of PAX6 in skin epithelial stem cells is sufficient to convert them to LSC-like cells, and upon transplantation onto eyes in a rabbit corneal injury model, these reprogrammed cells are able to replenish CECs and repair damaged corneal surface. These findings suggest a central role of the WNT7A-PAX6 axis in corneal epithelial cell fate determination, and point to a new strategy for treating corneal surface diseases.

TGF-ß-mediated upregulation of Sox9 in fibroblast promotes renal fibrosis.

TGF-ß signaling plays a principal role in renal fibrosis, but the precise mechanisms and the downstream factors are still largely unknown. Sox9 exhibits diverse roles in regulating the production of extracellular matrix proteins. Here we found that Sox9 was induced by TGF-ß in the kidney fibroblast and acted as an important downstream mediator of TGF-ß signaling in promoting renal fibrosis. TGF-ß/Smad signaling mediated the upregulation of Sox9 in kidney fibroblast by binding to a conserved enhancer. In different mouse models of renal fibrosis, as well as in the kidney biopsy tissue from patients with renal fibrosis, Sox9 expression significantly increased. Immunostaining confirmed the upregulation of Sox9 in the kidney fibroblast during renal fibrosis. Delivery of Sox9 knockdown plasmid to the kidney by ultrasound microbubble-mediated gene transfer suppressed the unilateral ureteral obstruction (UUO) or folic acid-induced mouse renal fibrosis, whereas ectopic expression of Sox9 aggravated renal fibrosis. In addition, we identified Sox9 as a direct target of miR-30. Notably, miR-30 expression was significantly inhibited by TGF-ß1 in the kidney fibroblast and the downregulation of miR-30 was observed in renal fibrosis. Mechanistically, inhibition of miR-30 independently strengthened the effect of TGF-ß/Smad signaling on Sox9 upregulation. Adenovirus-mediated ectopic expression of miR-30 in kidney fibroblast greatly reduced UUO-induced renal fibrosis by targeting Sox9. These findings link Sox9 to intrinsic mechanisms of TGF-ß signaling in renal fibrosis and may have therapeutic potential for tissue fibrosis.

Circulating tumour DNA methylation markers for diagnosis and prognosis of hepatocellular carcinoma.

An effective blood-based method for the diagnosis and prognosis of hepatocellular carcinoma (HCC) has not yet been developed. Circulating tumour DNA (ctDNA) carrying cancer-specific genetic and epigenetic aberrations may enable a noninvasive 'liquid biopsy' for diagnosis and monitoring of cancer. Here, we identified an HCC-specific methylation marker panel by comparing HCC tissue and normal blood leukocytes and showed that methylation profiles of HCC tumour DNA and matched plasma ctDNA are highly correlated. Using cfDNA samples from a large cohort of 1,098 HCC patients and 835 normal controls, we constructed a diagnostic prediction model that showed high diagnostic specificity and sensitivity (P < 0.001) and was highly correlated with tumour burden, treatment response, and stage. Additionally, we constructed a prognostic prediction model that effectively predicted prognosis and survival (P < 0.001). Together, these findings demonstrate in a large clinical cohort the utility of ctDNA methylation markers in the diagnosis, surveillance, and prognosis of HCC.

Deciphering the origin of mito-nuclear discordance in two sibling caddisfly species.

An increasing number of phylogenetic studies have reported discordances among nuclear and mitochondrial markers. These discrepancies are highly relevant to widely used biodiversity assessment approaches, such as DNA barcoding, that rely almost exclusively on mitochondrial markers. Although the theoretical causes of mito-nuclear discordances are well understood, it is often extremely challenging to determine the principal underlying factor in a given study system. In this study, we uncovered significant mito-nuclear discordances in a pair of sibling caddisfly species. Application of genome sequencing, ddRAD and DNA barcoding revealed ongoing hybridization, as well as historical hybridization in Pleistocene refugia, leading us to identify introgression as the ultimate cause of the observed discordance pattern. Our novel genomic data, the discovery of a European-wide hybrid zone and the availability of established techniques for laboratory breeding make this species pair an ideal model system for studying species boundaries with ongoing gene flow.

High RNA-Binding Motif Protein 3 (RBM3) Expression is Independently Associated with Prolonged Overall Survival in Intestinal-Type Gastric Cancer.

BACKGROUND High expression of the RNA-binding motif protein 3 (RBM3) has previously been described as a favorable clinicopathological factor in several cancers, including ovarian cancer, colorectal cancer, prostate cancer, and breast cancer. The aim of this study was to examine the prognostic implications of RBM3 expression in gastric cancer. MATERIAL AND METHODS Immunohistochemical analysis of RBM3 expression from 123 patients showed that upregulated RBM3 was mainly found in intestinal-type (n=78, case=59) cancer compared to diffuse-type (n=15, case=8) and mixed-type (n=30, case=17). There were no significant differences in RBM3 expression in subgroups of clinicopathological parameters. RBM3 expression was strongly associated with p53 but not with Ki-67. Cox univariate analysis revealed that high RBM3 expression was closely associated with prolonged overall survival time (HR 0.504, 95% CI: 0.300-0.845, P=0.009). Multivariate analysis remained supporting these associations when adjusted for age, sex, tumor size, differentiation grade, TNM stage, lymphatic invasion, and Ki-67 and p53 expression (HR 0.541, 95% CI: 0.308-0.952, P=0.033), where Lauren grade was not included. Lauren grade was the only factor with independent prognostic significance in a model adjusted for all factors. These results were confirmed by Kaplan-Meier analysis. RESULTS Therefore, together with the upregulated RBM3 expression observed in intestinal-type of Lauren grade, we suggest that upregulation of RBM3 is partially responsible for the favorable overall survival in cases with intestinal Lauren grade, which is demonstrated by the box diagram and Kaplan-Meier analysis. Our results showed that high RBM3 expression in gastric cancer is mainly found in intestinal-type of Lauren grade and is associated with longer overall survival time. CONCLUSIONS We found that RBM3 is a potential biomarker of good prognosis and deserves further validation.

Whole-genome sequencing of cultivated and wild peppers provides insights into Capsicum domestication and specialization.

As an economic crop, pepper satisfies people's spicy taste and has medicinal uses worldwide. To gain a better understanding of Capsicum evolution, domestication, and specialization, we present here the genome sequence of the cultivated pepper Zunla-1 (C. annuum L.) and its wild progenitor Chiltepin (C. annuum var. glabriusculum). We estimate that the pepper genome expanded ∼0.3 Mya (with respect to the genome of other Solanaceae) by a rapid amplification of retrotransposons elements, resulting in a genome comprised of ∼81% repetitive sequences. Approximately 79% of 3.48-Gb scaffolds containing 34,476 protein-coding genes were anchored to chromosomes by a high-density genetic map. Comparison of cultivated and wild pepper genomes with 20 resequencing accessions revealed molecular footprints of artificial selection, providing us with a list of candidate domestication genes. We also found that dosage compensation effect of tandem duplication genes probably contributed to the pungent diversification in pepper. The Capsicum reference genome provides crucial information for the study of not only the evolution of the pepper genome but also, the Solanaceae family, and it will facilitate the establishment of more effective pepper breeding programs.

Transcription Factor PAX6 (Paired Box 6) Controls Limbal Stem Cell Lineage in Development and Disease.

PAX6 is a master regulatory gene involved in neuronal cell fate specification. It also plays a critical role in early eye field and subsequent limbal stem cell (LSC) determination during eye development. Defects in Pax6 cause aniridia and LSC deficiency in humans and the Sey (Small eye) phenotype in mice (Massé, K., Bhamra, S., Eason, R., Dale, N., and Jones, E. A. (2007) Nature 449, 1058-1062). However, how PAX6 specifies LSC and corneal fates during eye development is not well understood. Here, we show that PAX6 is expressed in the primitive eye cup and later in corneal tissue progenitors in early embryonic development. In contrast, p63 expression commences after that of PAX6 in ocular adnexal and skin tissue progenitors and later in LSCs. Using an in vitro feeder-free culture system, we show that PAX6 knockdown in LSCs led to up-regulation of skin epidermis-specific keratins concomitant with differentiation to a skin fate. Using gene expression analysis, we identified the involvement of Notch, Wnt, and TGF-ß signaling pathways in LSC fate determination. Thus, loss of PAX6 converts LSCs to epidermal stem cells, as demonstrated by a switch in the keratin gene expression profile and by the appearance of congenital dermoid tissue.