Biology subjects

Graciotti, L.

Publications and source records attributed to Graciotti, L..

3 recordsLinked to original sources

bioRxiv2026

Integrated metabolic and proteostatic profiling reveals remodeling of proteolytic pathways associated with redox-bioenergetic dysfunction in a PAHenu2 mouse model of phenylketonuria

Phenylketonuria (PKU) is a genetic metabolic disorder caused by the lack of functional phenylalanine hydroxylase (PAH). Elevated levels of phenylalanine (Phe) are known to be neurotoxic; however, the molecular mechanisms underlying Phes effects remain elusive. This study investigates the impact of PKU on proteostasis, redox balance, and metabolism in BTBR PAHenu2 mice, a severe disease animal model. Combined proteomics and metabolomics revealed impaired redox homeostasis in the brain and disrupted mitochondrial energy metabolism (ATP and TCA intermediates). The dysregulation was further supported by decreased levels of ATP, reduced glutathione (GSH), cysteine, and reduced catalase activity. Western blot analyses revealed substantial remodeling of protein degradation systems: the 19S regulatory (Rpt1) subunit and 26S proteasome content and activity were significantly increased, and ubiquitinated protein levels were elevated, indicating protein turnover and activation of the ubiquitin-proteasome system. Autophagy was also activated, as evidenced by a reduced LC3-II/LC3-I ratio, decreased p62 levels, unchanged ATG5 levels, and increased HSPA8 protein expression. By contrast, UPR markers remained stable despite an increase in the oxidized-to-reduced PDI ratio, suggesting a localized shift without activation of a full ER stress response. In parallel, systemic alterations were assessed in whole blood. Indeed, GSH, cysteine, ATP and ADP were decreased in PKU, whereas NADPH increased. These changes were accompanied by reduced activities of GSH reductase and GSH peroxidase, thereby confirming metabolic and redox disruption. Collectively, these findings indicate that PKU is associated with activation of protein degradation pathways as an adaptive response to cellular stress combined with redox imbalance and energy dysregulation. Highlights- Proteasome complex levels and activity were upregulated in PAHenu2 mouse brains - Autophagy was also enhanced in PAHenu2 mouse brains - Despite increased PDI oxidation, the Unfolded Protein Response was not activated - Redox and energy metabolism were disrupted in both brain and blood

molecular biology↗

bioRxiv2025

Role of Hypertrophic Adipocytes, Collagen VI and CD38 in Fat Fibrosis of Patients with Obesity

Fat fibrosis correlates to metabolic consequences in patients with obesity, and is due to three types of collagen: I and III (fibrillar) and VI (non-fibrillar). In this sudy the extent of fibrosis in obese patients (n 50) was significant only in visceral parenchymal fat (4.7% vs 2.5% in controls (n 15) P<0.0001) and not in subcutaneous fat. Electron microscopy, in vivo and in vitro data, suggested that obese adipocytes are responsible for fibrillar collagen (I and III) production. COL6 (gene producing the non fibrillar form) resulted less expressed. In line, patients with COL6 mutations, showed increased fibrotic tissue even in subcutaneous fat: about 6.5 times vs controls in the patient with the severe form (Ullrich) and 2.8 times in two patients with the milder form (Bethlem). Approximately 15% of obese adipocytes were dead (perilipin1 negative), and consequent infiltrating macrophages showed hyperexpression of CD38, an ectoenzyme implicated in systemic fibrosis. Correlations with gene expression confirmed the importance also of myofibroblasts and the extracellular matrix peptidase D. All together our data support a role for obese adipocytes in the fibrillar collagen production and evidentiate collagen VI and CD38 as new molecular determinants, reinforcing the idea of a multi-factorial origin of fat fibrosis.

cell biology↗

bioRxiv2021

Visceral Fat Inflammation and Fat Embolism are associated with Lung's Lipidic Hyaline Membranes in COVID-19 patients

BackgroundVisceral obesity is a critical determinant of severe coronavirus disease-2019 (COVID-19). Methods: In this study, we performed a comprehensive histomorphologic analysis of autoptic visceral adipose tissues (VAT), lungs and livers of 19 COVID-19 and 23 non-COVID-19 subjects. ResultsAlthough there were no between-groups differences in body-mass-index and adipocytes size, higher prevalence of CD68+ macrophages in COVID-19 subjects VAT was detected (p=0.005) and accompanied by crown-like structures presence, signs of adipocytes stress and death. Consistently, human adipocytes were successfully infected by SARS-CoV2 in vitro and displayed lower cell viability. Being VAT inflammation associated with lipids spill-over from dead adipocytes, we studied lipids distribution employing Oil-Red-O staining (ORO). Lipids were observed within lungs and livers interstitial spaces, macrophages, endothelial cells, and vessels lumen, features suggestive of fat embolism syndrome, more prevalent among COVID-19 individuals (p<0.001). Notably, signs of fat embolism were more prevalent among obese (p=0.03) independently of COVID-19 diagnosis, suggesting that such condition may be an obesity complication, exacerbated by SARS-CoV2 infection. Importantly, all infected subjects lungs presented lipids-rich (ORO+) hyaline membranes, formations associated with COVID-19-related pneumonia, present only in one control with non-COVID-19 pneumonia. ConclusionsThis study describes for the first time novel COVID-19-related features possibly underlying the unfavorable prognosis in obese SARS-CoV2-infected-subjects.

pathology↗