C-reactive protein orchestrates acute allograft rejection in vascularized composite allotransplantation via subset-selective monocyte activation.

INTRODUCTION: Despite recent substantial progress in vascularized composite allotransplantation (VCA), such as face transplantations, short- and long-term allograft survival is severely limited by allograft rejection. The acute-phase response, directly after allogeneic transplantation, represents an immune-inflammatory reaction to ischemia/reperfusion and acts as an early initiator of graft rejection. Acute-phase reactants mediate this immune response via crosstalk with the mononuclear phagocyte system. OBJECTIVE: C-reactive protein (CRP), a well-known marker of inflammation, has pro-inflammatory properties and aggravates ischemia/reperfusion injury. Thus, we investigated how CRP impacts acute allograft rejection. METHODS: Based on clinical observations in facial VCAs, we applied a complex hindlimb transplantation model in rats to investigate whether CRP directly affects transplant rejection. We further analyzed subset-specific infiltration and tissue distribution of recipient-derived monocytes in the early phase of acute rejection and assessed their differential regulation by CRP using intravital imaging. RESULTS: We demonstrate that CRP accelerates allograft rejection and reduces allograft survival via selectively activating non-classical monocytes. The therapeutic stabilization of CRP abrogates this activating effect on monocytes, consequently attenuating acute allograft rejection. Intravital imaging of graft-infiltrating, recipient-derived monocytes during the early phase of acute rejection confirmed their differential regulation by CRP and their crucial role in driving the early stage of graft rejection. CONCLUSION: Differential activation of recipient-derived monocytes by CRP aggravates innate immune response and accelerates clinical allograft rejection Thus, therapeutic targeting of CRP represents a novel promising strategy for preventing acute allograft rejection and potentially reducing chronic allograft rejection.

Proximity labeling of host factor ANXA3 in HCV infection reveals a novel LARP1 function in viral entry.

Hepatitis C virus (HCV) infection is tightly connected to the lipid metabolism with lipid droplets (LDs) serving as assembly sites for progeny virions. A previous LD proteome analysis identified annexin A3 (ANXA3) as an important HCV host factor that is enriched at LDs in infected cells and required for HCV morphogenesis. To further characterize ANXA3 function in HCV, we performed proximity labeling using ANXA3-BioID2 as bait in HCV-infected cells. Two of the top proteins identified proximal to ANXA3 during HCV infection were the La-related protein 1 (LARP1) and the ADP ribosylation factor-like protein 8B (ARL8B), both of which have been previously described to act in HCV particle production. In follow-up experiments, ARL8B functioned as a pro-viral HCV host factor without localizing to LDs and thus likely independent of ANXA3. In contrast, LARP1 interacts with HCV core protein in an RNA-dependent manner and is translocated to LDs by core protein. Knockdown of LARP1 decreased HCV spreading without altering HCV RNA replication or viral titers. Unexpectedly, entry of HCV particles and E1/E2-pseudotyped lentiviral particles was reduced by LARP1 depletion, whereas particle production was not altered. Using a recombinant vesicular stomatitis virus (VSV)ΔG entry assay, we showed that LARP1 depletion also decreased entry of VSV with VSV, MERS, and CHIKV glycoproteins. Therefore, our data expand the role of LARP1 as an HCV host factor that is most prominently involved in the early steps of infection, likely contributing to endocytosis of viral particles through the pleiotropic effect LARP1 has on the cellular translatome.

Phosphatidylserine-exposing extracellular vesicles in body fluids are an innate defence against apoptotic mimicry viral pathogens.

Some viruses are rarely transmitted orally or sexually despite their presence in saliva, breast milk, or semen. We previously identified that extracellular vesicles (EVs) in semen and saliva inhibit Zika virus infection. However, the antiviral spectrum and underlying mechanism remained unclear. Here we applied lipidomics and flow cytometry to show that these EVs expose phosphatidylserine (PS). By blocking PS receptors, targeted by Zika virus in the process of apoptotic mimicry, they interfere with viral attachment and entry. Consequently, physiological concentrations of EVs applied in vitro efficiently inhibited infection by apoptotic mimicry dengue, West Nile, Chikungunya, Ebola and vesicular stomatitis viruses, but not severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus 1, hepatitis C virus and herpesviruses that use other entry receptors. Our results identify the role of PS-rich EVs in body fluids in innate defence against infection via viral apoptotic mimicries, explaining why these viruses are primarily transmitted via PS-EV-deficient blood or blood-ingesting arthropods rather than direct human-to-human contact.

[Robotic-Assisted DIEP Flap Harvest for Autologous Breast Reconstruction: Case Report, Technical Aspects and Identification of Suitable Patients]. / Die robotisch-assistierte Hebung der DIEP-Lappenplastik zur Brustrekonstruktion: Fallbericht, technische Aspekte und Identifikation geeigneter Patientinnen.

BACKGROUND: Robotic-assisted harvest of the deep inferior epigastric perforator (DIEP) flap is an innovative modification of the traditional open preparation for autologous breast reconstruction. It is assumed that donor-site morbidity (herniae, bulging) is reduced by minimising the fascial incision length in robotic-assisted DIEP flap harvest. MATERIAL & METHODS: This is the first report of a robotic-assisted DIEP harvest in Germany, which was performed in April 2023 at the University Hospital of Freiburg in an interdisciplinary approach of the Departments of Plastic Surgery, Urology and Gynaecology. To determine the value of this novel technique, we assessed the demand by retrospectively performing an analysis of potential patients and conducted a cost analysis based on the breast reconstructions with DIEP flap harvest performed between April 2021 and May 2023 at the Department of Plastic Surgery at Freiburg University Hospital. To this end, we carried out a retrospective analysis of preoperative CT angiographies to determine the proportion of patients suitable for a robotic-assisted procedure in a post-hoc analysis. Furthermore, we describe the basic robotic-assisted techniques and discuss the TEP and TAPP laparoscopic approaches. RESULTS: In line with the previously published literature, a short intramuscular course (≤25 mm) and a perforator diameter of≥1.5 mm and≥2.7 mm (subgroup) were defined as a crucial condition for the robotic-assisted procedure. We analysed 65 DIEP flaps harvested in 51 patients, of which 26 DIEP flaps in 22 patients met both criteria, i. e.≤25 mm intramuscular course and≥1.5 mm diameter of the perforator, while 10 DIEP flaps in 10 patients additionally met the criteria of the subgroup (≥2.7 mm diameter). Based on the intramuscular course of the perforators in the CT angiographies of those 26 DIEP flaps, a potential reduction of the fascial incision of 96.8±25.21 mm (mean±standard deviation) compared with the conventional surgical approach was calculated. The additional material costs in our case were EUR 986.01. However, ischaemia time was 33,5 minutes longer than the median of the comparative cohort. CONCLUSION: The robotic-assisted procedure has already proven to be a feasible alternative in a suitable patient population. However, further studies are needed to confirm that robotic-assisted DIEP flap harvest actually reduces harvest site morbidity and thereby justifies the additional costs and complexity.

Guest Encapsulation Alters the Thermodynamic Landscape of a Coordination Host.

The architecture of self-assembled host molecules can profoundly affect the properties of the encapsulated guests. For example, a rigid cage with small windows can efficiently protect its contents from the environment; in contrast, tube-shaped, flexible hosts with large openings and an easily accessible cavity are ideally suited for catalysis. Here, we report a "Janus" nature of a Pd6L4 coordination host previously reported to exist exclusively as a tube isomer (T). We show that upon encapsulating various tetrahedrally shaped guests, T can reconfigure into a cage-shaped host (C) in quantitative yield. Extracting the guest affords empty C, which is metastable and spontaneously relaxes to T, and the T⇄C interconversion can be repeated for multiple cycles. Reversible toggling between two vastly different isomers paves the way toward controlling functional properties of coordination hosts "on demand".

Specific Learning Disorders in Children and Adolescents with Obesity.

Specific learning disorders (SLDs) are the most frequently diagnosed developmental disorders in childhood. Different neurocognitive patterns have been found in patients with overweight and obesity, but no data on childhood obesity and SLDs have been reported. To increase our understanding of the relationship between neuropsychological developmental and obesity, we assessed the prevalence of SLD in a pediatric population with obesity. We retrospectively included 380 children and adolescents with obesity. For all participants, auxological, metabolic, demographic features, relationship and social skills, anamnestic data on pregnancy and the perinatal period, stages of development and family medical history were reviewed. SLD was defined according to the DSM-5 criteria. A group of 101 controls of normal weight was included. The overall prevalence of SLD was 10.8%, and SLD was more prevalent in patients with obesity (p < 0.001), with male predominance (p = 0.01). SGA was associated with SLD (p = 0.02). Speech retardation (p < 0.001), limited relationships with peers (p < 0.001) and didactic support (p < 0.001) were noted in the SLD group compared to the group without SLD. A higher prevalence of family history of neuropsychiatric disorders was observed in the SLD group (p = 0.04). A higher fasting glucose level was detected in patients with obesity and SLD compared to subjects without SLD (p = 0.01). An association between obesity and SLD could not be excluded, and an overlap of pathogenic factors for both conditions should be considered.

Post-prostatic-massage urine exosomes of men with chronic prostatitis/chronic pelvic pain syndrome carry prostate-cancer-typical microRNAs and activate proto-oncogenes.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) has a high prevalence of up to 15% and accounts for 90-95% of prostatitis diagnoses, and yet its etiopathogenesis and link to prostate cancer (PCa) are still unclear. Here, we investigated microRNAs in exosomes isolated from blood and post-prostatic-massage urine of CP/CPPS type IIIb patients and healthy men. THP-1 monocytes (human leukemia monocytic cell line) were treated with exosomes and subjected to mRNA arrays "Cancer Inflammation and Immunity Crosstalk" and "Transcription Factors." Using The Cancer Genome Atlas, the expression of CP/CPPS-associated microRNAs was analyzed in PCa and normal prostate tissue. In silico functional studies were carried out to explore the disease ontology of CP/CPPS. In CP/CPPS, urine exosomes exhibited significant upregulation of eight PCa-specific microRNAs (e.g., hsa-miR-501, hsa-miR-20a, and hsa-miR-106), whose target genes were significantly enriched for GO terms, hallmark gene sets, and pathways specific for carcinogenesis. In THP-1 monocytes, CP/CPPS-derived urine exosomes induced upregulation of PCa-associated proinflammatory genes (e.g., CCR2 and TLR2) and proto-oncogene transcription factors (e.g., MYB and JUNB). In contrast, CP/CPPS-derived blood exosomes exhibited molecular properties similar to those of healthy men. Thus, CP/CPPS exhibits molecular changes that constitute a risk for PCa and should be considered in the development of PCa biomarkers and cancer screening programs.

Development of Allogeneic Stem Cell-Based Platform for Delivery and Potentiation of Oncolytic Virotherapy.

We describe the repurposing and optimization of the TK-positive (thymidine kinase) vaccinia virus strain ACAM1000/ACAM2000™ as an oncolytic virus. This virus strain has been widely used as a smallpox vaccine and was also used safely in our recent clinical trial in patients with advanced solid tumors and Acute Myeloid Leukemia (AML). The vaccinia virus was amplified in CV1 cells and named CAL1. CAL1 induced remarkable oncolysis in various human and mouse cancer cells and preferentially amplified in cancer cells, supporting the use of this strain as an oncolytic virus. However, the therapeutic potential of CAL1, as demonstrated with other oncolytic viruses, is severely restricted by the patients' immune system. Thus, to develop a clinically relevant oncolytic virotherapy agent, we generated a new off-the-shelf therapeutic called Supernova1 (SNV1) by loading CAL1 virus into allogeneic adipose-derived mesenchymal stem cells (AD-MSC). Culturing the CAL1-infected stem cells allows the expression of virally encoded proteins and viral amplification prior to cryopreservation. We found that the CAL1 virus loaded into AD-MSC was resistant to humoral inactivation. Importantly, the virus-loaded stem cells (SNV1) released larger number of infectious viral particles and virally encoded proteins, leading to augmented therapeutic efficacy in vitro and in animal tumor models.

Can a mobile app technology reduce emergency department visits and readmissions after lung resection? A prospective cohort study.

BACKGROUND: Emergency department (ED) visits and readmissions after thoracic surgery are a major health care problem. We hypothesized that the addition of a novel post-discharge mobile app specific to thoracic surgery to an existing home care program would reduce ED visits and readmissions compared to a home care program alone. METHODS: We conducted a prospective cohort study of patients undergoing major lung resection for malignant disease between November 2016 and May 2018. Patients received either home care alone (control group) or home care plus a patient-input mobile app (intervention group). Primary outcomes were 30-day readmission and ED visit rates. Secondary outcomes included reasons for ED visits and readmissions, perioperative complications, 30-day mortality, anxiety (assessed with the Generalized Anxiety Disorder-7 Scale [GAD-7]) and app-related adverse events. We compared outcomes between the 2 groups, analyzing the data on an intention-to-treat basis. RESULTS: Despite the greater number of open surgery and anatomic resections in the intervention cohort, patients in that group were less likely than those in the control group to visit the ED within 30 days of discharge (24.0% v. 38.8%, p = 0.02). Thirty-day readmission rates were similar between the intervention and control groups (10.1% v. 12.2%, p = 0.6). In a subset of patients, there was no difference between the 2 groups in the proportion of patients with a GAD-7 score of 0 (control group 79.8%, intervention group 79.5%, p = NS), which indicated a similar absence of postdischarge anxiety and depression symptoms in the 2 cohorts. CONCLUSION: The addition of a mobile app to a home care program after thoracic surgery was associated with a reduced frequency of ED visits, in spite of the higher proportions of thoracotomies and anatomic resections in the app cohort. More studies are needed to evaluate the full effect of this new, emerging technology.

Screening Questionnaire for Vitamin D Insufficiency in Children with Obesity.

Non-invasive screening tools to identify children at high risk of vitamin D (VitD) deficiency are proactive measures in preventive care. Recently, a validated questionnaire (Evaluation dEficieNCy Questionnaire, EVIDENCe-Q) for identifying newly diagnosed VitD-insufficient adults has been developed. We tested the EVIDENCe-Q modified for children with obesity and evaluated the correlation between VitD and questionnaire scores to adapt this tool to the pediatric population. We enrolled 120 children with obesity (BMI ≥ 2). Clinical evaluation and VitD levels were considered. The modified EVIDENCe-Q included information regarding factors affecting control of VitD, with scores ranging between 0 (best) and 36 (worst). VitD and adiposity indices were inversely correlated. The threshold values for identifying severe deficiency (<10 mg/dL), deficiency (<20 mg/dL) and insufficiency (<30 mg/dL) were scores of 21, 19 and 23, respectively. According to those thresholds, the prevalence of severe deficiency, deficiency and insufficiency was 47.5%, 69.2% and 23.3%, respectively; the best accuracy was obtained with a questionnaire score cut-off of 19 for the VitD deficiency level. A novel simple screening tool such as the modified EVIDENCe-Q would be useful in clinical practice to identify potential cases of hypovitaminosis D and select at-risk patients. Considering the limited accuracy and specificity of our results, for the pediatric population a dedicated tool should be created. Phases of childhood and the role of adipose tissue could be considered in the definition of a questionnaire intended for pediatric patients with obesity.

Endohedrally Functionalized Heteroleptic Coordination Cages for Phosphate Ester Binding.

Metallosupramolecular hosts of nanoscopic dimensions, which are able to serve as selective receptors and catalysts, are usually composed of only one type of organic ligand, restricting diversity in terms of cavity shape and functional group decoration. We report a series of heteroleptic [Pd2 A2 B2 ] coordination cages that self-assemble from a library of shape complementary bis-monodentate ligands in a non-statistical fashion. Ligands A feature an inward pointing NH function, able to engage in hydrogen bonding and amenable to being functionalized with amide and alkyl substituents. Ligands B comprise tricyclic aromatic backbones of different shape and electronic situation. The obtained heteroleptic coordination cages were investigated for their ability to bind phosphate diesters as guests. All-atom molecular dynamics (MD) simulations in explicit solvent were conducted to understand the mechanistic relationships behind the experimentally determined guest affinities.

An Analysis of the Implantable Doppler Probe for Postoperative Free-Flap Monitoring and Risk Factor Analysis for Revision Surgery in Facial Reanimation Surgery.

Background: Postoperative monitoring after free functional gracilis transfer for smile reconstruction in long-standing facial paralysis is challenging as clinical assessments are limited. Objective: In patients receiving free gracilis transfer for smile reconstruction, we compared the implantable Doppler probe with a handheld Doppler/intraoperative blood flow regarding the reliability in detecting perfusion compromised free flaps. Methods: In a retrospective cohort study we analyzed facial paralysis patients who, after free functional smile reconstruction, were postoperatively monitored using the implantable Doppler probe. Furthermore, we conducted a multiple logistic regression analysis on risk factors for vascular complications. Results: We included 119 patients who received 125 free functional gracilis transfers. The sensitivity of the implanted Doppler probe was 1.0 and the specificity 0.88. There were no false-negative results (negative predictive value = 1.0). The calculated positive predictive value was 0.41. We used a handheld Doppler device to verify signal changes. The combined positive predictive value of both tests was 0.91. Previous surgery in the surgical field was a risk factor for impaired blood flow. Conclusions: The implantable Doppler probe proved to be a reliable tool for postoperative monitoring of free functional gracilis transfer in facial reanimation surgery. Special care should be taken in preoperated patients.

Increased acid sphingomyelinase levels in pediatric patients with obesity.

The level of secretory acid sphingomyelinase (S-ASM), a key enzyme in the sphingolipid metabolism, is elevated in a variety of human diseases, including in the serum of obese adults. Alterations in S-ASM were also found to induce morphological changes in erythrocytes. Consequently, the inhibition of S-ASM by functional Inhibitors of ASM (FIASMA) may have broad clinical implications. The purpose of this study was to assess S-ASM activity in pediatric patients with obesity and healthy matched controls, as well as to investigate the erythrocyte morphology using transmission electron microscopy. We recruited 46 obese patients (mean age 11 ± 2.9 years) and 44 controls (mean age 10.8 ± 2.9 years). S-ASM activity was significantly higher (Wilcoxon signed-rank test p-value: 0.004) in obese patients (mean 396.4 ± 49.7 pmol/ml/h) than in controls (mean 373.7 ± 23.1 pmol/ml/h). No evidence of morphological differences in erythrocytes was found between the two populations. We then carried out a case-control study based on the spontaneous reporting system database to compare FIASMAs with NON-FIASMAs in terms of weight gain risk. Children who received FIASMA had a significantly lower frequency of weight gain reports than patients who took NON-FIASMA agents (p < 0.001). Our findings suggest there is an intriguing possibility that S-ASM may play a role in pediatric obesity. This pilot study could serve as the basis for future studies in this interesting field of research.

Cooperativity of steric bulk and H-bonding in coordination sphere engineering: heteroleptic PdII cages and bowls by design.

Recently developed self-assembly strategies allow to rationally reduce the symmetry of metallosupramolecular architectures. In addition, the combination of multiple ligand types without creating compound mixtures has become possible. Among several approaches to realize non-statistical heteroleptic assembly, Coordination Sphere Engineering (CSE) makes use of secondary repulsive or attractive interactions in direct vicinity of the metal nodes. Previously, we used steric congestion to turn dinuclear [Pd2L4] cages with fourfold symmetry into [Pd2L3X2] (X = solvent, halide) bowl structures. Here, we introduce a new subtype of this strategy based on balancing hydrogen bonding and repulsive interactions between ligands carrying quinoline (LQu) and 1,8-naphthyridine (LNa) donors to generate trans-[Pd2L2] and [Pd2L3L'] cages, assisted by templation of encapsulated fullerenes. Combined with steric congestion caused by acridine (LAc) donors, we further report the first example of a heteroleptic [Pd2L2L'X2] bowl. Formation, structure and fullerene binding ability of these metallo-supramolecular hosts were studied by NMR, mass spectrometry and single crystal X-ray diffraction.

Outcomes of patients discharged home with a chest tube after lung resection: a multicentre cohort study.

BACKGROUND: Prolonged air leaks are increasingly treated in the outpatient setting, with patients discharged with chest tubes in place. We evaluated the incidence and risk factors associated with readmission, empyema development and further interventions in this patient population. METHODS: We undertook a retrospective cohort analysis of all patients from 4 tertiary academic centres (January 2014 to December 2017) who were discharged home with a chest tube after lung resection for a postoperative air leak lasting more than 5 days. We analyzed demographics, patient factors, surgical details, hospital readmission, reintervention, antibiotics at discharge, empyema and death. RESULTS: Overall, 253 of 2794 patients were analyzed (9.0% of all resections), including 30 of 759 from centre 1 (4.0%), 67 of 857 from centre 2 (7.8%), 9 of 247 from centre 3 (3.6%) and 147 of 931 from centre 4 (15.8%) (p < 0.001). Our cohort consisted of 56.5% men, and had a median age of 69 (range 19-88) years. Despite similar initial lengths of stay (p = 0.588), 49 patients (19.4%) were readmitted (21%, 0%, 23% and 11% from centres 1 to 4, respectively, p = 0.029), with 18 (36.7%) developing empyema, 11 (22.4%) requiring surgery and 3 (6.1%) dying. Only chest tube duration was a significant predictor of readmission (p < 0.001) and empyema development (p = 0.003), with a nearly threefold increased odds of developing empyema when the chest tube remained in situ for more than 20 days. CONCLUSION: Discharge with chest tube after lung resection is associated with serious adverse events. Given the high risk of empyema development, removal of chest tubes should be considered, when appropriate, within 20 days of surgery. Our data suggest a potential need for proactive postdischarge outpatient management programs to diminish risk of morbidity and death.

Artificial Intelligence-Driven Video Analysis for Novel Outcome Measures After Smile Reanimation Surgery.

Background: Since facial paralysis is a dynamic condition, the analysis of still photographs is not sufficient for measurement of facial reanimation outcomes. This study aimed at evaluating an artificial intelligence (AI)-driven software as a novel video assessment tool for smile reanimation surgery and at comparing it with the Terzis score. Methods: Patients with facial paralysis undergoing smile reanimation surgery between January 2008 and April 2020 were eligible for this retrospective study. Inclusion criteria were at least 6 months of follow-up and availability of both pre- and post-operative video documentation. The software output was given as intensity score (IS) values between 0 and 1, representing emotions/action units (AUs) that are absent or fully present, respectively. Results: During the study period, 240 patients underwent facial reanimation surgery, of whom 63 patients met the inclusion criteria. Postoperatively, the median IS of the happiness emotion and lip corner puller AU increased significantly (p < 0.001). There was a positive correlation of Terzis score with the IS of happiness emotion (r = 0.8) and lip corner puller AU (r = 0.74). Conclusions: The novel AI-driven video analysis is strongly correlated with the Terzis score and shows promise for objective functional outcome evaluation after smile reanimation surgery.

Predictive Ability of the Estimate of Fat Mass to Detect Early-Onset Metabolic Syndrome in Prepubertal Children with Obesity.

Body mass index (BMI), usually used as a body fatness marker, does not accurately discriminate between amounts of lean and fat mass, crucial factors in determining metabolic syndrome (MS) risk. We assessed the predictive ability of the estimate of FM (eFM) calculated using the following formula: FM = weight - exp(0.3073 × height2 - 10.0155 ×d-growth-standards/standards/body-mass-index-for-age-bmi-for-age weight- 1 + 0.004571 × weight - 0.9180 × ln(age) + 0.6488 × age0.5 + 0.04723×male + 2.8055) (exp = exponential function, score 1 if child was of black (BA), south Asian (SA), other Asian (AO), or other (other) ethnic origin and score 0 if not, ln = natural logarithmic transformation, male = 1, female = 0), to detect MS in 185 prepubertal obese children compared to other adiposity parameters. The eFM, BMI, waist circumference (WC), body shape index (ABSI), tri-ponderal mass index, and conicity index (C-Index) were calculated. Patients were classified as having MS if they met ≥ 3/5 of the following criteria: WC ≥ 95th percentile; triglycerides ≥ 95th percentile; HDL-cholesterol ≤ 5th percentile; blood pressure ≥ 95th percentile; fasting blood glucose ≥ 100 mg/dL; and/or HOMA-IR ≥ 97.5th percentile. MS occurred in 18.9% of obese subjects (p < 0.001), with a higher prevalence in females vs. males (p = 0.005). The eFM was correlated with BMI, WC, ABSI, and Con-I (p < 0.001). Higher eFM values were present in the MS vs. non-MS group (p < 0.001); the eFM was higher in patients with hypertension and insulin resistance (p < 0.01). The eFM shows a good predictive ability for MS. Additional to BMI, the identification of new parameters determinable with simple anthropometric measures and with a good ability for the early detection of MS, such as the eFM, may be useful in clinical practice, particularly when instrumentation to estimate the body composition is not available.

A hunt for OM45 synthetic petite interactions in Saccharomyces cerevisiae reveals a role for Miro GTPase Gem1p in cristae structure maintenance.

Om45 is a major protein of the yeast's outer mitochondrial membrane under respiratory conditions. However, the cellular role of the protein has remained obscure. Previously, deletion mutant phenotypes have not been found, and clear amino acid sequence similarities that would allow inferring its functional role are not available. In this work, we describe synthetic petite mutants of GEM1 and UGO1 that depend on the presence of OM45 for respiratory growth, as well as the identification of several multicopy suppressors of the synthetic petite phenotypes. In the analysis of our mutants, we demonstrate that Om45p and Gem1p have a collaborative role in the maintenance of mitochondrial morphology, cristae structure, and mitochondrial DNA maintenance. A group of multicopy suppressors rescuing the synthetic lethal phenotypes of the mutants on non-fermentable carbon sources additionally supports this result. Our results imply that the synthetic petite phenotypes we observed are due to the disturbance of the inner mitochondrial membrane and point to this mitochondrial sub-compartment as the main target of action of Om45p, Ugo1p, and the yeast Miro GTPase Gem1p.