Biology subjects

Cornell, R.

Publications and source records attributed to Cornell, R..

9 recordsLinked to original sources

bioRxiv2025

Gas-sensing neurons prime mitochondrial fitness to offset metabolic stress

Animals integrate environmental and internal cues to maintain homeostasis and health. The mitochondrial stress response is an essential cytoprotective mechanism, and priming its activation provides a survival advantage. Here, we show that the Caenorhabditis elegans receptor guanylyl cyclase GCY-9 regulates neuropeptide signalling from carbon dioxide sensing neurons to govern a non-canonical mitochondrial stress response in the intestine. This stress response induces atypical mitochondrial chaperone transcription, confers mitochondrial stress resistance, and increases mitochondrial membrane potential and respiration. GCY-9 loss disrupts pathogen avoidance, leading to indiscriminate feeding. We show that starvation decreases GCY-9 expression and propose that the resultant cytoprotective program is launched to offset risks associated with this behaviour. Thus, environmental sensing by peripheral neurons can pre-emptively enhance systemic mitochondrial function in response to metabolic uncertainty. One-Sentence SummaryProtecting mitochondria by integrating environmental signals

neuroscience↗

bioRxiv2024

An MITF- and mTOR-dependent FLCN pathway suppresses TFE3-driven metastasis in melanoma

Melanoma cells have the ability to switch from a melanocytic and proliferative state to a mesenchymal and invasive state and back again. This plasticity drives intra-tumoral heterogeneity, progression, and therapeutic resistance. Microphthalmia-associated Transcription Factor (MITF) promotes the melanocytic/proliferative phenotype, but factors that drive the mesenchymal/invasive phenotype and the mechanisms that effect the switch between cell states are unclear. Here, we identify the MITF paralog TFE3 and the non-canonical mTORC1 pathway as regulators of the mesenchymal state. We show that TFE3 expression drives the metastatic phenotype in melanoma cell lines and tumors. Deletion of TFE3 in MITF-low melanoma cell lines suppresses their ability to migrate and metastasize. Further, MITF suppresses the mesenchymal phenotype by directly or indirectly activating expression of FNIP1, FNIP2, and FLCN, which encode components of the non-canonical mTORC1 pathway, thereby promoting cytoplasmic retention and lysosome-mediated degradation of TFE3. These findings highlight a molecular pathway controlling melanoma plasticity and invasiveness.

cancer biology↗

bioRxiv2023

A neuro-intestinal circuit controls mitochondrial dynamics and stress resistance

Neurons coordinate inter-tissue protein homeostasis to systemically manage cytotoxic stress. Specific neuropeptidergic signals coordinate the systemic mitochondrial stress response (UPRmt), but whether chemical neurotransmitters also influence this process is unclear. Here, we show that gamma-aminobutyric acid (GABA) inhibits, and acetylcholine (ACh) promotes the UPRmt in the Caenorhabditis elegans intestine. GABA controls the UPRmt by regulating extra-synaptic ACh release through metabotropic GABAB receptors GBB-1/2. We find that elevated ACh levels in animals that are GABA-deficient or lack ACh-degradative enzymes induce the UPRmt through ACR-11, an intestinal nicotinic 7 receptor. This neuro-intestinal circuit is critical for nonautonomously regulating mitochondrial dynamics and organismal survival of oxidative stress. These findings establish chemical neurotransmission as a crucial regulatory layer for nervous system control of systemic protein homeostasis and stress responses. One-Sentence SummaryRegulation of mitochondrial health with neurotransmission.

neuroscience↗

bioRxiv2022

An intestinal sphingolipid promotes neuronal health across generations

Maternal diet and environment can influence the neuronal health of offspring. Here, we report that diet-induced intestinal sphingolipid biosynthesis reduces adult-onset neurodegeneration intergenerationally in Caenorhabditis elegans. Feeding C. elegans with ursolic acid (UA), a natural plant product, provides neuroprotection by enhancing maternal provisioning of sphingosine-1-phosphate (S1P) - a bioactive sphingolipid. S1P promotes neuronal health across generations by upregulating transcription of the acid ceramidase-1 (asah-1) gene in the intestine. Intergenerational intestine-to-oocyte S1P transfer is essential for promoting neuronal health and is dependent on the lipoprotein yolk receptor RME-2 (Receptor-Mediated Endocytosis-2). Spatially regulating sphingolipid biosynthesis is critical, as inappropriate asah-1 neuronal expression causes developmental axon outgrowth defects. Our results reveal that sphingolipid homeostasis impacts the development and intergenerational health of the nervous system. One-Sentence SummaryAn intestinal lipid prevents neurodegeneration across generations.

neuroscience↗

bioRxiv2022

Conditional degradation of UNC-31/CAPS enables spatiotemporal analysis of neuropeptide function

Neuropeptide release from dense-core vesicles in Caenorhabditis elegans is promoted by UNC-31, ortholog of the calcium-dependent activator protein for secretion (CAPS). Loss of UNC-31 causes multiple phenotypes in C. elegans including reduced motility, retention of late-stage eggs and reduction in evoked synaptic release. However, the ability to analyze UNC-31 function over discrete timescales and in specific neurons is lacking. Here, we generated and validated a tool to enable UNC-31 expression and spatiotemporal functional analysis. We show that endogenously tagged UNC-31 is expressed in major ganglia and nerve cords from late-embryonic stages through to adult. Using the auxin-inducible degradation system, we depleted UNC-31 post-embryonically from the nervous system and revealed defects in egg-laying, locomotion and vesicle release that were comparable to unc-31 null mutant animals. In addition, we found that depleting UNC-31 specifically from the BAG sensory neurons causes increased intestinal fat storage, highlighting the spatial sensitivity of this system. Together, this protein degradation tool may be used to facilitate studies of neuropeptide function at precise cellular and temporal scales. Significance statementAnimal behavior and physiology is controlled by neuropeptides that are released from specific neuronal sources. The ability to dissect discrete neuropeptide functions requires precise manipulation of neuropeptide release. We have developed and validated a tool that enables precise spatiotemporal regulation of neuropeptide release that will enable researchers to examine neuropeptide function at exceptional resolution.

neuroscience↗

bioRxiv2021

BRN2 is a non-canonical melanoma tumor-suppressor

While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, we show that BRN2 haplo-insufficiency is sufficient to promote melanoma initiation and metastasis, acting as a non-canonical tumor suppressor. Mechanistically, BRN2 directly modulates PTEN expression, and PI3K signaling, to drive tumor initiation and progression. Collectively our results reveal that somatic deletion of one BRN2 allele elicits melanoma initiation and progression. SIGNIFICANCEHere, we report frequent mono-allelic loss of the transcription factor BRN2 in human cutaneous melanoma metastases. We developed a mouse model for Brn2-deficient melanoma based on the most common alterations (BrafV600E and Pten loss) in human melanoma and established the role of Brn2 as a functional regulator of tumor initiation, tumor growth, and the formation of metastases in vivo. Mechanistically, BRN2 loss increases PI3K-signaling through PTEN repression, either via MITF induction or not. Overall, we describe a novel tumor suppressor of high prevalence in human melanoma that regulates several steps of in vivo melanomagenesis through two previously unknown molecular mechanisms.

cancer biology↗

bioRxiv2020

Cell state diversity promotes metastasis through heterotypic cluster formation in melanoma

In melanoma, transcriptional profiling has revealed multiple co-existing cell states, including proliferative versus invasive sub-populations that have been posited to represent a "go or grow" tradeoff. Both of these populations are maintained in tumors, but how they physically interact to promote metastasis is unknown. We demonstrate that these subpopulations form spatially structured heterotypic clusters that cooperate in the seeding of metastasis. We unexpectedly found that INV cells were tightly adherent to each other, and formed clusters with a rim of PRO cells. Intravital imaging demonstrated cooperation between these populations, in which the INV cells facilitated the spread of less metastatic PRO cells. We identified the TFAP2 neural crest transcription factor as a master regulator of both clustering and the PRO/INV states. Our data suggest a framework for the co-existence of these two divergent cell populations, in which differing cell states form heterotypic clusters that promote metastasis via cell-cell cooperation.

cancer biology↗

bioRxiv2020

MITF reprograms the extracellular matrix and focal adhesion in melanoma

The microphthalmia associated transcription factor (MITF) is a critical regulator of melanocyte development and differentiation. It also plays an important role in melanoma where it has been described as a molecular rheostat that, depending on activity levels, allows reversible switching between different cellular states. Here we show that MITF directly represses the expression of genes associated with the extracellular matrix (ECM) and focal adhesion pathways in human melanoma cells as well as of regulators of epithelial to mesenchymal transition (EMT) such as CDH2, thus affecting cell morphology and cell-matrix interactions. Importantly, we show that these effects of MITF are reversible, as expected from the rheostat model. The number of focal adhesion points increased upon MITF knockdown, a feature observed in drug resistant melanomas. Cells lacking MITF are similar to the cells of minimal residual disease observed in both human and zebrafish melanomas. Our results suggest that MITF plays a critical role as a repressor of gene expression and is actively involved in shaping the microenvironment of melanoma cells in a cell-autonomous manner.

cancer biology↗

bioRxiv2020

Analysis of zebrafish periderm enhancers facilitates identification of a regulatory variant near human KRT8/18

Genome wide association studies for non-syndromic orofacial cleft (OFC) have identified single nucleotide polymorphisms (SNPs) at loci where the presumed risk-relevant gene is expressed in oral periderm. The functional subsets of such SNPs are difficult to predict because the sequence underpinnings of periderm enhancers are unknown. We applied ATAC-seq to models of human palate periderm, including zebrafish periderm, mouse embryonic palate epithelia, and a human oral epithelium cell line, and to complementary mesenchymal cell types. We identified sets of enhancers specific to the epithelial cells and trained gapped-kmer support-vector-machine classifiers on these sets. We used the classifiers to predict the effect of 14 OFC-associated SNPs at 12q13 near KRT18. All the classifiers picked the same SNP as having the strongest effect, but the significance was highest with the classifier trained on zebrafish periderm. Reporter and deletion analyses support this SNP as lying within a periderm enhancer regulating KRT18/KRT8 expression.

developmental biology↗