Biology subjects

Lopez, L. R.

Publications and source records attributed to Lopez, L. R..

4 recordsLinked to original sources

bioRxiv2025

Cyclin Y Overexpression Drives a Fatal Metabolic Syndrome via Defective Glucose Homeostasis

Cyclin Y (CCNY) is a membrane-associated, non-canonical cyclin best known for regulating WNT/beta-catenin signaling via the recruitment of CDK14/16 protein kinases. Whereas its role in the activation of members of the atypical CDK14-18 subfamily is established, its function in systemic metabolism remains poorly defined. Here, we report that CCNY overexpression drives a fatal metabolic syndrome. Using a novel inducible knock-in mouse model, we demonstrate that CCNY overexpression causes severe cachexia and profound hypoglycemia, resulting in death of adult mice independent of tumor burden. While these mutant mice maintain normal food intake and hepatic synthetic function, they succumb to metabolic starving state. Proteomics reveals that CCNY interacts with and stabilizes Pyruvate Dehydrogenase Kinase 4 (PDK4), in agreement with defective pyruvate use at mitochondria and enforcing a Warburg-like shift to aerobic glycolysis. Phosphoproteomic analysis indicates activation of apoptotic pathways and defective phosphorylation of several enzymes critical for glycolysis and gluconeogenesis as well as amino acid metabolism in addition to other metabolic routes. Altogether, these data suggest that CCNY overexpression uncouples nutrient sensing from utilization, a finding with possible therapeutic implications in CCNY-high cancers with similar changes in metabolic pathways.

cell biology↗

bioRxiv2021

A nadA mutation confers nicotinic acid auxotrophy in pro-carcinogenic intestinal Escherichia coli NC101

Inflammatory bowel diseases and inflammation-associated colorectal cancer are linked to blooms of adherent-invasive Escherichia coli (AIEC) in the intestinal microbiota. AIEC are functionally defined by their ability to adhere/invade epithelial cells and survive/replicate within macrophages. Changes in micronutrient availability can alter AIEC physiology and interactions with host cells. Thus, culturing AIEC for mechanistic investigations often involves precise nutrient formulation. We observed that the pro-inflammatory and pro-carcinogenic AIEC strain NC101 failed to grow in minimal media (MM). We hypothesized that NC101 was unable to synthesize a vital micronutrient normally found in the host gut. Through nutrient supplementation studies, we identified that NC101 is a nicotinic acid (NA) auxotroph. NA auxotrophy was not observed in the other non-toxigenic E. coli or AIEC strains we tested. Sequencing revealed NC101 has a missense mutation in nadA, a gene encoding quinolinate synthase A that is important for de novo NAD biosynthesis. Correcting the identified nadA point mutation restored NC101 prototrophy without impacting AIEC function, including motility and AIEC-defining survival in macrophages. Our findings, along with the generation of a prototrophic NC101 strain, will greatly enhance the ability to perform in vitro functional studies that are needed for mechanistic investigations on the role of intestinal E. coli in digestive disease. ImportanceInflammatory bowel diseases (IBD) and colorectal cancer (CRC) are significant global health concerns that are influenced by gut resident microbes, like adherent-invasive Escherichia coli (AIEC). Nutrient availability influences specialized metabolite production, AIEC-defining functional attributes, and AIEC:host interactions. NC101 is a pro-inflammatory and pro-carcinogenic AIEC strain commonly used for studies on IBD and CRC. We identified that NC101 growth in vitro requires a micronutrient found in the host gut. By correcting an identified mutation, we generated an NC101 strain that no longer has micronutrient restrictions. Our findings will facilitate future research that necessitates precise nutrient manipulation, enhancing AIEC functional studies and investigations on other auxotrophic intestinal microbiota members. Broadly, this will improve the study of bacterial:host interactions impacting health and disease.

microbiology↗

bioRxiv2020

Lack of adaptation to centriolar defects leads to p53-independent microcephaly in the absence of Cep135

Autosomal Recessive Primary Microcephaly (MCPH) is a rare disease associated to proteins involved in centrosomal and spindle dynamics including Cep135 (MCPH8). Although Cep135 has been associated to centriolar assembly, the mechanisms associated to the pathogenesis underlying MCPH8 mutations are unclear. By using a series of CRISPR/Cas9-edited murine Cep135 alleles, we report here that lack of Cep135 results in perinatal lethality accompanied by significant microcephaly in a dosis-dependent manner. Cep135 deficiency, but not that of other centrosomal microcephaly proteins such as Aspm or Cdk5rap2, induces centrosome duplication defects, and perturbed centriole structure and dynamics. Whereas other cell types are able to quickly adapt to these defects, neural progenitors display a prolonged response leading to chromosomal instability and cell death in later developmental stages. Genetic ablation of Trp53 in these mutant embryos prevents apoptotic cell death but does not rescue the microcephaly induced by Cep135 loss. These results suggest that microcephaly can arise from the lack of adaptation to centriole defects in neural progenitors of the developing neocortex in a p53-independent manner.

cell biology↗

bioRxiv2019

Yersiniabactin producing AIEC promote inflammation-associated fibrosis in gnotobiotic Il10-/- mice

Fibrosis is a significant complication of intestinal disorders associated with microbial dysbiosis and pathobiont expansion, notably Crohns disease (CD). Mechanisms that favor fibrosis are not well understood and therapeutic strategies are limited. Here we demonstrate that colitis susceptible Il10-deficient mice develop inflammation-associated fibrosis when mono-associated with adherent/invasive Escherichia coli (AIEC) that harbor the yersiniabactin (Ybt) pathogenicity island. Inactivation of Ybt siderophore production in AIEC nearly abrogated fibrosis development in inflamed mice. In contrast, inactivation of Ybt import through its cognate receptor FyuA enhanced fibrosis severity. This corresponded with increased colonic expression of profibrogenic genes prior to the development of histological disease, therefore suggesting causality. FyuA-deficient AIEC also exhibited greater localization within sub-epithelial tissues and fibrotic lesions that was dependent on Ybt biosynthesis and corresponded with increased fibroblast activation in vitro. Together, these findings suggest that Ybt establishes a pro-fibrotic environment in the host in the absence of binding to its cognate receptor and indicates a direct link between intestinal AIEC and the induction of inflammation-associated fibrosis.

microbiology↗