Biology subjects

Levy, T.

Publications and source records attributed to Levy, T..

25 records · Page 2Linked to original sources

bioRxiv2022

MMP2 loss leads to defective parturition and severe dystocia in mice

Parturition is the final step of mammalian reproduction and an essential process for the species survival. During pregnancy, the uterus is maintained quiescence which is important for fetal growth and development. However, at term, fundamental changes in myometrial contractility are initiated for efficient expulsion of the fetus. These changes involve tissue remodeling that requires changes in the extracellular matrix (ECM). The gelatinases subgroup of matrix metalloproteinases (MMPs), has only two members: MMP2 and MMP9, which are both known to participate in uterine ECM remodeling throughout the estrus cycle as well as during pregnancy, parturition and postpartum involution. Yet, no knowledge exists regarding their loss-of-function impact on the uterus. Here we investigated the effect of MMP2 and/or MMP9 genetic loss on parturition process. Single and double knockout (dKO) mice for MMP2 and/or MMP9 were used. We found high percentages of dystocia in mmp2-/-, mmp2-/-mmp9+/- and dKO females, but not in mmp9-/- females. Histological analysis of nulliparous uterine tissue of WT, mmp2-/-, mmp9-/- and dKO, at 8 weeks, 4 months and 8-9.5 months, revealed that the uterine tissue of mmp2-/- presents alterations in tissue size and structure, mainly when reaching to 8-9.5 months of age, including enlarged total tissue, myometrium, endometrium and luminal cavity. Additionally, Massons Trichrome staining suggested a mechanism of extensive fibrosis in mmp2-/- myometrium, which may lead to dystocia. Altogether, our research highlights a novel cause for dystocia pathology mediated by loss of MMP2 activity in uterine tissue during mammalian parturition.

physiology↗

bioRxiv2022

4EBP1/2 support tumorigenicity and cell survival during energetic stress by translationally regulating fatty acid synthesis

Energetic stress compels cells to evolve adaptive mechanisms to maintain homeostasis. Here, we report that the negative regulators of mRNA translation initiation eukaryotic initiation factor 4E binding proteins 1/2 (4EBP1/2) are essential to promote the survival of mammalian cells and budding yeast under glucose starvation. Functionally, 4EBP1/2 inhibit fatty acid synthesis upon energetic stress via repression of Acetyl-CoA Carboxylase Alpha (ACACA) mRNA translation, sparing NADPH, to maintain intracellular redox balance. This has important relevance in cancers, as we uncovered that oncogene-transformed cells and glioma cells exploit the 4EBP1/2 regulation of ACACA expression and redox balance to combat energetic stress, thereby supporting transformation and tumorigenicity in vitro and in vivo. Clinically, high EIF4EBP1 (encoding 4EBP1) expression is associated with poor outcomes in several cancer types, including glioma. Our data reveal that 4EBP1/2 are conserved mediators of the survival response to energetic stress which are exploited by cancer cells for metabolic adaptation.

cell biology↗

bioRxiv2022

Organ- and function-specific organization and bioelectronic modulation of vagus fascicles and fibers

Vagal fibers travel inside fascicles and form branches to innervate organs and regulate organ functions. Vagus nerve stimulation (VNS) therapies activate fibers non-selectively, often resulting in reduced efficacy and side effects from non-targeted organs. Transverse and longitudinal arrangement of fibers according to functions they mediate and organs they innervate is unknown, however it is crucial for selective VNS. Using microcomputed tomography, we found that, in swine, fascicles are arranged in 2 overlapping axes, with sensory and motor fascicles separated cephalad and merging caudad, and larynx-, heart- and lung-specific fascicles separated caudad and progressively merging cephalad. Using immunohistochemistry, we found that the distribution of single fibers is highly nonuniform: myelinated afferents and efferents occupy separate fascicles, unmyelinated efferents co-localize with myelinated afferents, and small unmyelinated afferents are widely distributed. Using a multi-contact cuff electrode, we delivered fascicular cervical VNS in anesthetized and awake swine. Compound action potentials, from distinct fiber types, and organ responses, including laryngeal muscle, cough, breathing, heart rate and blood pressure responses are elicited in a radially asymmetric manner, with consistent angular separations. These results indicate that vagal fibers are anatomically organized according to functions they mediate and organs they innervate and can be asymmetrically activated by fascicular cervical VNS.

neuroscience↗

bioRxiv2022

Sex-specific regulation of metabolic health and vertebrate lifespan by AMP biosynthesis

Energy homeostasis is disrupted with age, which then fuels multiple age-related pathologies. The AMP-activated protein kinase (AMPK) is the primary sensor of cellular energy in eukaryotes. However, the genetic regulation of vertebrate aging by AMPK remains poorly understood. Here, we manipulate energy levels in the turquoise killifish by mutating APRT, a key enzyme in AMP biosynthesis. These manipulations produced a male-specific lifespan extension and restored metabolic plasticity. Exploring the observed sex differences using an integrated omics approach implicated the mitochondria as an important player. Mechanistically, APRT regulated mitochondrial functions and AMPK activity, mimicking energy starvation in heterozygous cells. A fasting-like state was also detected, particularly in heterozygous males, which leads to resistance to high-fat diet. Finally, life-long intermittent fasting eliminated the male-specific longevity benefits mediated by the APRT mutation. These observations identify the AMP/AMPK axis as a sex-specific regulator of vertebrate longevity and metabolic health.

genetics↗

bioRxiv2021

Craniofacial cartilage organoids from human embryonic stem cells via a neural crest cell intermediate

Severe birth defects or major injuries to the face require surgical reconstruction and rehabilitation. The ability to make bona fide craniofacial cartilage - cartilage of the head and face - from patient-derived induced pluripotent stem cells (iPSCs) to repair these birth defects and injuries has tremendous translational applications, but is not yet possible. The neural crest is the normal developmental pathway for craniofacial cartilage, however, the knowledge of cell signaling pathways that drive neural crest differentiation into craniofacial chondrocytes is limited. Here we describe a differentiation protocol that generated self-organizing craniofacial cartilage organoids from human embryonic stem cells (hESCs) and IPSCs through a neural crest stem cell (NCSC) intermediate. Histological staining of cartilage organoids revealed tissue architecture typical of hyaline cartilage. Organoids were composed of rounded aggregates of glassy, gray matrix that contained scattered small nuclei in lacunae. Mass spectrometry shows that the organoids express robust levels of cartilage markers including aggrecan, perlecan, proteoglycans, and many collagens. Organoids expressed markers indicative of neural crest lineage, as well as growth factors that are candidates for chondrocyte differentiation factors. The data suggest that chondrocyte differentiation is initiated by autocrine loops driven by a combination of secreted growth factors that bind to chondrocyte receptors. Craniofacial cartilage organoids were continuously cultured for one year, reaching up to one centimeter in diameter. The ability to grow craniofacial cartilage from NCSCs provides insights into the cell signaling mechanisms of differentiation into craniofacial cartilage, which lays the groundwork for understanding mechanistic origins of congenital craniofacial anomalies and repairing cartilaginous structures of the head and face.

developmental biology↗

bioRxiv2020

Episignatures stratifying ADNP syndrome show modest correlation with phenotype

ADNP syndrome, also known as Helsmoortel-van Der Aa syndrome, is a neurodevelopmental condition associated with intellectual disability/developmental delay, autism spectrum disorder, and multiple medical comorbidities. ADNP syndrome is caused by mutations in the activity-dependent neuroprotective protein (ADNP). A recent study identified genome-wide DNA methylation changes in 22 individuals with ADNP syndrome, adding to the group of neurodevelopmental disorders with an epigenetic signature. This methylation signature segregated those with ADNP syndrome into two groups, based on the location of the mutations. Here, we conducted an independent study on 24 individuals with ADNP syndrome and replicated the existence of the two, mutation-dependent ADNP episignatures. To probe whether the two distinct episignatures correlate with clinical outcomes, we used deep behavioral and neurobiological data from two prospective cohorts of individuals with a genetic diagnosis of ADNP syndrome. We found limited phenotypic differences between the two ADNP groups, and no evidence that individuals with more widespread methylation changes are more severely affected. Also, in spite of the methylation changes, we observed no profound alterations in the blood transcriptome of individuals with ADNP syndrome. Our data warrant caution in harnessing methylation signatures in ADNP syndrome as a tool for clinical stratification, at least with regards to behavioral phenotypes.

developmental biology↗

bioRxiv2020

PAG1 directs SRC-family kinase intracellular localization to mediate receptor tyrosine kinase-induced differentiation

All receptor tyrosine kinases (RTKs) activate similar downstream signaling pathways through a common set of effectors, yet it is not fully understood how different receptors elicit distinct cellular responses to cause cell proliferation, differentiation, or other cell fates. We tested the hypothesis that regulation of SRC Family Kinase (SFK) signaling by the scaffold protein, PAG1, influences cell fate decisions following RTK activation. We generated a neuroblastoma cell line expressing a PAG1 fragment that lacks the membrane spanning domain (PAG1-) and localized to the cytoplasm. PAG1- cells exhibited higher amounts of active SFKs and increased growth rate. PAG1- cells were unresponsive to TRKA and RET signaling, two RTKs that induce neuronal differentiation, but retained responses to EGFR and KIT. Under differentiation conditions, PAG1- cells continued to proliferate and did not extend neurites or increase {beta}-III tubulin expression. FYN and LYN were sequestered in multivesicular bodies (MVBs), and dramatically more FYN and LYN were in the lumen of MVBs in PAG1- cells. In particular, activated FYN was sequestered in PAG1- cells, suggesting that disruption of FYN localization led to the observed defects in differentiation. The results demonstrate that PAG1 directs SFK intracellular localization to control activity and to mediate signaling by RTKs that induce neuronal differentiation.

cell biology↗