Biology subjects

Ostinelli, G.

Publications and source records attributed to Ostinelli, G..

3 recordsLinked to original sources

bioRxiv2026

MTFP1 preserves β-cell cristae structure and bioenergetics to ensure insulin release and glucose homeostasis

Pancreatic {beta}-cells are uniquely dependent on mitochondrial metabolism to couple glucose sensing to insulin secretion, a process impaired in diabetes. Mitochondrial fission process 1 (MTFP1) is an inner mitochondrial membrane protein that plays pleiotropic, tissue-specific roles in mitochondrial function and dynamics. Our previous work has identified Mtfp1 mRNA as a target for miR-125b, a microRNA that negatively regulates insulin secretion from {beta}-cells. Nevertheless, the function of MTFP1 in these cells remained unexplored. Here, we show that MTFP1 is essential for normal glucose-stimulated insulin secretion (GSIS) in mouse and human cell lines and islets, and that mice with {beta}-cell-specific elimination of MTFP1 develop glucose intolerance. Whereas {beta}-cell survival and mitochondrial content were unaffected, oxidative phosphorylation and ATP production were sharply lowered. These changes were accompanied by disruption of mitochondrial cristae structure and a reduced contact surface with the endoplasmic reticulum, providing a mechanistic basis for defective stimulus-secretion coupling. Conversely, MTFP1 overexpression in mouse and human islets sufficed to improve mitochondrial respiration and GSIS. Finally, MTFP1 downregulation blocked the positive effects of miR-125b elimination in GSIS and mitochondrial respiration, unveiling MTFP1 as a downstream effector of miR-125b. Together, our findings identify MTFP1 as a critical regulator of {beta}-cell mitochondrial architecture and function, necessary for efficient insulin secretion and glucose homeostasis, and a potential therapeutic target to enhance {beta}-cell bioenergetic resilience in diabetes.

cell biology↗

bioRxiv2024

High-throughput measurement of adipocyte size with open-source software using whole-slide adipose tissue images

The aim of this study was to create and validate a high-throughput method based on open-source software for the measurement of adipocyte diameters in white adipose tissue histological sections. Human omental and subcutaneous adipose tissue samples collected during bariatric surgery were used to prepare hematoxylin and eosin-stained histological slides. Digital images were acquired. Adipocyte diameters were measured both manually and with an automated procedure created using ImageJ. Comparative analysis of our automated method with the manual measurement and associations of the mean adipocyte diameters with cardiometabolic markers were used to validate our method. A total of 377 adipose samples (190 participants) were included in the analysis. Pearson correlation of mean adipocyte diameters shows a strong linear relationship between methods (r=0.88, p<0.0001). The average diameter measured with the automated method was significantly smaller (8.1{+/-}5.3{micro}m difference, p<0.0001) compared to the manual method, likely reflecting bias in selecting the cells measured with the manual approach. Pearson correlation analyses between mean omental adipocyte diameters and markers of cardiometabolic risk show that the diameters of both methods are significantly associated with the same parameters (fasting concentrations of TG, HDL-Chol, homeostasis model assessment insulin resistance, and visceral adiposity index values) with no significant differences between methods. There were also no significant differences between the manual and automated method regarding the correlations between mean subcutaneous adipocyte diameters and anthropometric or metabolic markers. In conclusion, we have created and validated a rapid automated method based on open-source software to measure adipocyte diameters from whole-slide adipose tissue images.

cell biology↗

bioRxiv2022

Increased adipose tissue indices of androgen catabolism and aromatization in women with metabolic dysfunction

BackgroundBody fat distribution is a risk factor for obesity-associated comorbidities, and adipose tissue dysfunction plays a role in this association. In humans, there is a sex difference in body fat distribution, and steroid hormones are known to regulate several cellular processes within adipose tissue. Our aim was to investigate if intra-adipose steroid concentration and expression or activity of steroidogenic enzymes were associated with features of adipose tissue dysfunction in individuals with severe obesity. MethodsSamples from 40 bariatric candidates (31 women, 9 men) were included in the study. Visceral (VAT) and subcutaneous adipose tissue (SAT) were collected during surgery. Adipose tissue morphology was measured by a combination of histological staining and semi-automated quantification. Following extraction, intra-adipose and plasma steroid concentrations were determined by liquid chromatography, electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Aromatase activity was estimated using product-over-substrate ratio, while AKR1C2 activity was measured directly by fluorogenic probe. Gene expression was measured by quantitative PCR. ResultsVAT aromatase activity was positively associated with VAT adipocyte hypertrophy (p-valueadj < 0.01) and negatively with plasma HDL-cholesterol (p-valueadj < 0.01), while SAT aromatase activity predicted dyslipidemia in women even after adjustment for waist circumference, age and hormonal contraceptive use. We additionally compared women with high and low visceral adiposity index (VAI) and found that VAT excess is characterized by adipose tissue dysfunction, increased androgen catabolism mirrored by increased AKR1C2 activity and higher aromatase expression and activity indices. ConclusionIn women, increased androgen catabolism or aromatization is associated with visceral adiposity and adipose tissue dysfunction. DISCLOSURE SUMMARYAT obtained consulting fees form Bausch Health, Novo Nordisk and research funding from Johnson & Johnson Medical Companies as well as Medtronic and GI Windows for studies unrelated to this manuscript. The other authors have nothing to disclose.

physiology↗