Biology subjects

Rizzo, A.

Publications and source records attributed to Rizzo, A..

4 recordsLinked to original sources

bioRxiv2024

A Dual Role for the PP2A Phosphatase in Hippo Signalling Regulation

Hippo signalling is an evolutionarily conserved pathway that regulates tissue growth. The FERM domain protein Expanded plays a crucial role in integrating polarity cues to activate the Hippo pathway. Previous work has shown that the apicobasal polarity protein Crumbs can limit Hippo activity by promoting the phosphorylation and degradation of Expanded. Here, we provide evidence that PP2AWrd can counteract the effects of Crumbs, by dephosphorylating and stabilising Expanded. Indeed, we demonstrate that the PP2AWrd holoenzyme can increase Hippo signalling activity, in contrast to the previously established Hippo pathway inhibitory role of the PP2ACka-containing STRIPAK complex. We also uncover a role for PP2AWrd and PP2ATws in the regulation of Expanded proteostasis. Remarkably, the upstream Hippo regulator, Kibra interacts with PP2AWrd and prevents Expanded degradation. However, Kibra is unable to antagonise Crumbs-mediated Expanded regulation, in agreement with the previously established role of Crumbs in inhibiting Kibra function. Overall, our work characterises a novel Hippo-activating role for PP2A in the stabilisation of Expanded and provides new insights into how PP2A tightly controls Hippo activity in response to polarity stimuli.

developmental biology↗

bioRxiv2024

Genomic sequencing to detect cross-breeding quality in dogs: an example studying disorders in sexual development

BackgroundDisorders of Sexual Development (DSD) in dogs, similar to humans, arise from irregularities in genetic determinants, gonadal differentiation, or phenotypic sex development. The French Bulldog, a breed that has seen a surge in popularity and demand, has also shown a marked increase in DSD incidence. This study aims to characterize the genetic underpinnings of DSD in a French Bulldog named Brutus, exhibiting ambiguous genitalia and internal sexual anatomy, and to explore the impact of breeding practices on genetic diversity within the breed. MethodsWe utilized a comprehensive approach combining conventional cytogenetics, molecular techniques, and deep sequencing to investigate the genetic profile of Brutus. The sequence data were compared to three other male French Bulldogs genome sequences with typical reproductive anatomy, including Brutuss father, and the canine reference genome (CanFam6). FindingsOur findings revealed a 22% mosaicism (78, XX/77, XX), the absence of the SRY gene, and the presence of 43 unique Single Nucleotide Variants (SNVs) not inherited from the father. Notably, the Run of Homozygosity (ROH) analysis showed Brutus has a significantly higher number of homozygous segments compared to other Bulldogs, with a total length of these fragments 50% greater than the average, strongly suggesting this dog is the product of the mating between siblings. While no direct causative genes for the DSD phenotype were identified four candidate loci warranting further investigation were highlighted. ConclusionsOur study highlighted the need for a better annotated and curated reference dog genome to define genes causative of any specific phenotype, suggests a potential genetic basis for the DSD phenotype in dogs, and underscores the consequences of uncontrolled breeding practices in French Bulldogs. These findings highlight the importance of implementing strategic genetic management to preserve genetic health and diversity in canine populations.

genomics↗

bioRxiv2024

Functional exploration of in vivo and in vitro lignocellulose-fed rumen bacterial microbiomes reveals novel enzymes involved in polysaccharide breakdown

BackgroundPlant cell walls are the main carbon sources for ruminal bacteria, which have evolved to produce sophisticated multi-functional enzyme cocktails in response to the structural diversity of lignocelulloses. Since a large proportion of ruminal bacteria are not yet cultured, we developed a high-throughput activity-based metagenomic approach to gain insight into this enzymatic diversity. ResultsA multi-step screening methodology was implemented to identify metagenomic clones acting on polysaccharides and polyaromatic compounds. This approach was used to explore the functional potential of two different microbial consortia derived from in vivo and in vitro enrichments of the bovine rumen microbiome on wheat straw. One hundred and sixty-eight fosmid clones were isolated from libraries. Five to seven times more {beta}-mannanase and {beta}-glucanase clones, and seven times less xylanase clones were obtained from the in vitro enrichment compared to the in vivo one. The sequencing of 51 fosmids, covering in total 1.4 Gb of metagenomic DNA, enabled the identification of various novel glycoside-hydrolases, esterases and oxidoreductases mostly encoded by unknown bacterial genera. Functional analysis showed that most of the identified xylanases belonged to Firmicutes members that were not enriched in the fermenter, while most cellulases and mannanases originate from Bacteroidetes. ConclusionThese enzymes, that, for most of them, had not been previously identified by in depth-metagenome sequencing, present a high potential for biotechnological applications, as they could be used alone or in cocktails to break down plant cell walls. The relationships established between enzyme function and taxonomy highlight the complementary roles played by ruminal Firmicutes and Bacteroidetes in plant cell wall degradation.

biochemistry↗

bioRxiv2023

In vivo photopharmacology with light-activated opioid drugs

Traditional methods for site-specific drug delivery in the brain are slow, invasive, and difficult to interface with recordings of neural activity. Here, we demonstrate the feasibility and experimental advantages of in vivo photopharmacology using "caged" opioid drugs that are activated in the brain with light after systemic administration in an inactive form. To enable bidirectional manipulations of endogenous opioid receptors in vivo, we developed PhOX and PhNX, photoactivatable variants of the mu opioid receptor agonist oxymorphone and the antagonist naloxone. Photoactivation of PhOX in multiple brain areas produced local changes in receptor occupancy, brain metabolic activity, neuronal calcium activity, neurochemical signaling, and multiple pain- and reward-related behaviors. Combining PhOX photoactivation with optical recording of extracellular dopamine revealed adaptations in the opioid sensitivity of mesolimbic dopamine circuitry during chronic morphine administration. This work establishes a general experimental framework for using in vivo photopharmacology to study the neural basis of drug action. HighlightsA photoactivatable opioid agonist (PhOX) and antagonist (PhNX) for in vivo photopharmacology. Systemic pro-drug delivery followed by local photoactivation in the brain. In vivo photopharmacology produces behavioral changes within seconds of photostimulation. In vivo photopharmacology enables all-optical pharmacology and physiology.

neuroscience↗