Circadian organization of lipid landscape is perturbed in type 2 diabetic patients

Lipid homeostasis in humans follows a diurnal pattern in muscle and pancreatic islets, altered upon metabolic dysregulation. We employ tandem and liquid-chromatography mass spectrometry to investigate daily regulation of lipid metabolism in subcutaneous white adipose tissue (SAT) and serum of type 2 diabetic (T2D) and non-diabetic (ND) human volunteers (n = 12). Around 8% of ≈440 lipid metabolites exhibit diurnal rhythmicity in serum and SAT from ND and T2D subjects. The spectrum of rhythmic lipids differs between ND and T2D individuals, with the most substantial changes observed early morning, as confirmed by lipidomics in an independent cohort of ND and T2D subjects (n = 32) conducted at a single morning time point. Strikingly, metabolites identified as daily rhythmic in both serum and SAT from T2D subjects exhibit phase differences. Our study reveals massive temporal and tissue-specific alterations of human lipid homeostasis in T2D, providing essential clues for the development of lipid biomarkers in a temporal manner.

Reversal of MYB-dependent suppression of MAFB expression overrides leukaemia phenotype in MLL-rearranged AML

The transcription factor MYB plays a pivotal role in haematopoietic homoeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). We have previously demonstrated that not all AML subtypes display the same dependency on MYB expression and that such variability is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML remains to be further elucidated. Here, we investigate the role of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-rearranged and t(8;21) leukaemias upon MYB suppression is not seen in AML cells with a complex karyotype. Transcriptome analyses revealed that MYB ablation produces consensual increase of MAFB expression in MYB-dependent cells and, interestingly, the ectopic expression of MAFB could phenocopy the effect of MYB suppression. Accordingly, in silico stratification analyses of molecular data from AML patients revealed a reciprocal relationship between MYB and MAFB expression, highlighting a novel biological interconnection between these two factors in AML and supporting new rationales of MAFB targeting in MLL-rearranged leukaemias.

COVID-19 lockdown negatively impacted on adherence to denosumab therapy: incidence of non-traumatic fractures and role of telemedicine

PURPOSE

Coronavirus disease (COVID-19) lockdowns have impacted on management of osteoporosis and the use of telemedicine is increasingly widespread albeit supported by little evidence so far. The aim of the study is to assess adherence to denosumab and incidence of non-traumatic fractures during the lockdown compared to the pre-COVID-19 year and to explore the effectiveness of telemedicine in the management of osteoporotic patients.

METHODS

Retrospective, longitudinal, single-center study on patients receiving subcutaneous denosumab therapy every 6 months. Each patient was scheduled to undergo 2 visits: one during the pre-COVID-19 period (March 2019-March 2020) and another visit during the lockdown period (March 2020-March 2021). Data on new fractures, adherence, risk factors for osteoporosis and the modality of visit (telemedicine or face-to-face) were collected.

RESULTS

The prevalence of non-adherent patients was higher during the lockdown (35 of 269 patients, 13.0%) than the pre-COVID-19 period (9 of 276 patients, 3.3%) (p < 0.0001). During the lockdown, the number of new non-traumatic fractures was higher than the pre-COVID-19 year (p < 0.0001): 10 patients out of 269 (3.7%) experienced a fragility fracture and 2 patients (0.7%) a probable rebound fracture during the lockdown period, whereas no patient had fragility/rebound fractures during the pre-COVID-19 period. No difference was found in the prevalence of non-adherence and new non-traumatic fractures comparing patients evaluated with tele-medicine to those evaluated with face-to-face visit.

CONCLUSION

Non-adherent patients and new non-traumatic fractures (including rebound fractures) were more prevalent during the lockdown in comparison to the pre-COVID-19 period, regardless of the modality of medical evaluation.

ER-Golgi-localized proteins TMED2 and TMED10 control the formation of plasma membrane lipid nanodomains

To promote infections, pathogens exploit host cell machineries such as structural elements of the plasma membrane. Studying these interactions and identifying molecular players are ideal for gaining insights into the fundamental biology of the host cell. Here, we used the anthrax toxin to screen a library of 1,500 regulatory, cell-surface, and membrane trafficking genes for their involvement in the intoxication process. We found that endoplasmic reticulum (ER)-Golgi-localized proteins TMED2 and TMED10 are required for toxin oligomerization at the plasma membrane of human cells, an essential step dependent on localization to cholesterol-rich lipid nanodomains. Biochemical, morphological, and mechanistic analyses showed that TMED2 and TMED10 are essential components of a supercomplex that operates the exchange of both cholesterol and ceramides at ER-Golgi membrane contact sites. Overall, this study of anthrax intoxication led to the discovery that lipid compositional remodeling at ER-Golgi interfaces fully controls the formation of functional membrane nanodomains at the cell surface.

Sphingolipids control dermal fibroblast heterogeneity

Human cells produce thousands of lipids that change during cell differentiation and can vary across individual cells of the same type. However, we are only starting to characterize the function of these cell-to-cell differences in lipid composition. Here, we measured the lipidomes and transcriptomes of individual human dermal fibroblasts by coupling high-resolution mass spectrometry imaging with single-cell transcriptomics. We found that the cell-to-cell variations of specific lipid metabolic pathways contribute to the establishment of cell states involved in the organization of skin architecture. Sphingolipid composition is shown to define fibroblast subpopulations, with sphingolipid metabolic rewiring driving cell-state transitions. Therefore, cell-to-cell lipid heterogeneity affects the determination of cell states, adding a new regulatory component to the self-organization of multicellular systems.

S-acylation controls SARS-CoV-2 membrane lipid organization and enhances infectivity

SARS-CoV-2 virions are surrounded by a lipid bilayer that contains membrane proteins such as spike, responsible for target-cell binding and virus fusion. We found that during SARS-CoV-2 infection, spike becomes lipid modified, through the sequential action of the S-acyltransferases ZDHHC20 and 9. Particularly striking is the rapid acylation of spike on 10 cytosolic cysteines within the ER and Golgi. Using a combination of computational, lipidomics, and biochemical approaches, we show that this massive lipidation controls spike biogenesis and degradation, and drives the formation of localized ordered cholesterol and sphingolipid-rich lipid nanodomains in the early Golgi, where viral budding occurs. Finally, S-acylation of spike allows the formation of viruses with enhanced fusion capacity. Our study points toward S-acylating enzymes and lipid biosynthesis enzymes as novel therapeutic anti-viral targets.

GRASP55 regulates intra-Golgi localization of glycosylation enzymes to control glycosphingolipid biosynthesis

The Golgi apparatus, the main glycosylation station of the cell, consists of a stack of discontinuous cisternae. Glycosylation enzymes are usually concentrated in one or two specific cisternae along the cis‐trans axis of the organelle. How such compartmentalized localization of enzymes is achieved and how it contributes to glycosylation are not clear. Here, we show that the Golgi matrix protein GRASP55 directs the compartmentalized localization of key enzymes involved in glycosphingolipid (GSL) biosynthesis. GRASP55 binds to these enzymes and prevents their entry into COPI‐based retrograde transport vesicles, thus concentrating them in the trans‐Golgi. In genome‐edited cells lacking GRASP55, or in cells expressing mutant enzymes without GRASP55 binding sites, these enzymes relocate to the cis‐Golgi, which affects glycosphingolipid biosynthesis by changing flux across metabolic branch points. These findings reveal a mechanism by which a matrix protein regulates polarized localization of glycosylation enzymes in the Golgi and controls competition in glycan biosynthesis.

New-Onset Cancer in the HF Population: Epidemiology, Pathophysiology, and Clinical Management

PURPOSE OF REVIEW

Oncological treatments are known to induce cardiac toxicity, but the impact of new-onset cancer in patients with pre-existing HF remains unknown. This review focuses on the epidemiology, pathophysiological mechanisms, and clinical implications of HF patients who develop malignancies.

RECENT FINDINGS

Novel findings suggest that HF and cancer, beside common risk factors, are deeply linked by shared pathophysiological mechanisms. In particular, HF itself may enhance carcinogenesis by producing pro-inflammatory cytokines, and it has been suggested that neurohormonal activation, commonly associated with the failing heart, might play a pivotal role in promoting neoplastic transformation. The risk of malignancies seems to be higher in HF patients compared to the general population, probably due to shared risk factors and common pathophysiological pathways. Additionally, management of these patients represents a challenge for clinicians, considering that the co-existence of these diseases significantly worsens patients' prognosis and negatively affects therapeutic options for both diseases.

Golgi maturation-dependent glycoenzyme recycling controls glycosphingolipid biosynthesis and cell growth via GOLPH3

Glycosphingolipids are important components of the plasma membrane where they modulate the activities of membrane proteins including signalling receptors. Glycosphingolipid synthesis relies on competing reactions catalysed by Golgi-resident enzymes during the passage of substrates through the Golgi cisternae. The glycosphingolipid metabolic output is determined by the position and levels of the enzymes within the Golgi stack, but the mechanisms that coordinate the intra-Golgi localisation of the enzymes are poorly understood. Here, we show that a group of sequentially-acting enzymes operating at the branchpoint among glycosphingolipid synthetic pathways binds the Golgi-localised oncoprotein GOLPH3. GOLPH3 sorts these enzymes into vesicles for intra-Golgi retro-transport, acting as a component of the cisternal maturation mechanism. Through these effects, GOLPH3 controls the sub-Golgi localisation and the lysosomal degradation rate of specific enzymes. Increased GOLPH3 levels, as those observed in tumours, alter glycosphingolipid synthesis and plasma membrane composition thereby promoting mitogenic signalling and cell proliferation. These data have medical implications as they outline a novel oncogenic mechanism of action for GOLPH3 based on glycosphingolipid metabolism.

Monosymptomatic enuresis: the therapeutic weapons

Nocturnal enuresis (NE) was defined by the World Health Organization (ICD-10) and the American Psychiatric Association (DSM-5) as bed-wetting in children aged >5 years. In cases of mental retardation, the developmental age may be equivalent to 5 years. In this review, we focus on the current knowledge about the etiology of enuresis and the most recent therapeutical options. Both non-pharmacological and pharmacological therapies are included, although the relative effectiveness of each remains uncertain. To date, motivational, alarm and drug therapies are the mainstay of treatment. Alarm therapy remains the first-line treatment modality for NE, while desmopressin is the most commonly used medical treatment.

Renal involvement in paediatric Fabry disease

Anderson-Fabry Disease (AFD) is a rare, X-linked inborn error of glycosphingolipid catabolism caused by a deficient or absent activity of the lysosomal enzyme, α-galactosidase A, resulting in the progressive multisystem lysosomal accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3). Among the wide spectrum of clinical signs and symptoms and the life-threatening complications of Fabry disease, renal failure causes significant morbidity and mortality. Various evidence shows that the accumulation of Gb3 in different renal cells is present since the first years of life, many years and usually decades before manifest symptoms and signs of renal involvement. Early renal damage can be demonstrated by clinical signs as microalbuminuria and proteinuria, developing as early as in the second decade of life. A decline in GFR is uncommon at paediatric ages but may be seen as early as adolescence. Renal biopsy is rarely used in paediatric patients with Fabry disease although evidence shows that it may be considered a valid tool for the diagnosis of early and potentially reversible nephropathy, as well as for the evaluation of the effectiveness of enzyme replacement therapy (ERT). Although there is consensus in considering the early initiation of ERT as the only tool able to prevent the progression of nephropathy, the issue on the correct timing for the onset of ERT in pediatric age remains open in the management of this chronic and progressive disease.

Renal anomalies in newborns with vacterel association: case series and literature review

Nocturnal enuresis (NE) was defined by the World Health Organization (ICD-10) and the American Psychiatric Association (DSM-5) as bed-wetting in children aged >5 years. In cases of mental retardation, the developmental age may be equivalent to 5 years. In this review, we focus on the current knowledge about the etiology of enuresis and the most recent therapeutical options. Both non-pharmacological and pharmacological therapies are included, although the relative effectiveness of each remains uncertain. To date, motivational, alarm and drug therapies are the mainstay of treatment. Alarm therapy remains the first-line treatment modality for NE, while desmopressin is the most commonly used medical treatment.

Pediatric urolithiasis

Urolithiasis is a well-known condition that can affect any part of the urinary tract. With a rate of 3-5% the incidence of upper urinary tract for long has been higher in adults (1-3), but recently it has increased among children reaching 3,3% . Indeed, more than 1% of all urinary stones are seen in patients aged less than 18 years (4). Pediatric urolithiasis is endemic in Turkey and Far East and it is probably due to malnutrition and racial factors (5). The spontaneous stone passage is more likely in children than in adults, indeed ureteral calculi spontaneously pass into 41-63% of children (1). Rate of stone passage depends on size and stone location in the urinary system. Stones sized less than 5 mm have a passage rate ranging from 40% to 98%, whilst stones > 5 mm have between 55% and 50% (6). In the last decade, the use of alpha blockers has proven well efficacious in helping spontaneous passage of distal ureteric stones in adults (7-9). The latest EAU guidelines support their use in adults while remain vague about their use in children because of unclear safety and efficacy (4). In search of evidence supporting or not the use of medical expulsive therapy in children we reviewed the literature dealing with the management of urolithiasis in pediatric patients. The primary aim of the present study was to evaluate the efficacy of medical expulsive therapy (MET), defined as stone expulsion rate, with a-blockers compared to a control group. The secondary aim was to assess the safety, defined as side effects rate, of MET compared to a control group.

Nephrotic syndrome: immunological mechanisms

Nephrotic Syndrome (NS) is a rare diseases (around 2-7 cases per 100.000 children per year) characterized by proteinuria ≥50 mg/kg/day (or ≥40 mg/m2/h) or a proteinuria/creatininuria ratio >2 (mg/mg); hypoalbuminaemia less than 25 g/l and edema. The protein leakage, with the consequent hypoalbunaemia and edema, due to podocyte alterations may be caused by genetic diseases, immunological mechanisms, infections, toxins or malignancy. However, most commonly the exact etiology is unknow. The idiopathic NS may be classified based on response to corticosteroid therapy or the hytological appearance. The first classification identifies steroid-resistant NS (no response after 4 weeks of steroid therapy); frequently relapsing NS (≥ 2 relapses in first 6 months or ≥4 relapses in 1-year); steroid dependent NS (relapses during steroid decalage or within 2 weeks from steroid therapy interruption). The hystological classification is based on light and electron microscopy after renal biopsy, which is indicated in case of onset disease before 1 year or after 12 years of age. Macroscopic hematuria: persistent hypertension and/or microscopic hematuria and/or low plasma C3 renal failure not related to hypovolemia; steroid resistence: secondary or relatedsyndromes NS. Minimal change disease (MCD) is the most common form of idiopahtic NS in children, with good response to steroid treatment, and it is characterized by normal glomerular appearance on light microscopy and evidence of podocyte foot alterations on electron microscopy, due to immunological related damage. Focal segmental glomerulosclerosis (FSGS) is described inidiopahtic NS, particularly in steroiddependent or steroid-resistant forms, and is characterized by evidence of focal glomerular damage with secondary sclerosis and adhesion with Bowman's capsule; the electron appearance is the same of MCD one. Recent authors hypotizethat the FSGS is an evolution of MCD. These 2 idiopathic NS forms may be expression of the same immunological disease, with 2 different severity grades; so they may be considered different moments of the same disease spectrum. Less common idiopathic NS forms are membrano proliferative glomerulonephritis; membranous nephropathy; IgM-nephropathy; C1q nephropathy and thin basement membrane disease (1, 2, 3).

Meeting Report - The 2019 FEBS special meeting on sphingolipid biology: sphingolipids in physiology and pathology

Sphingolipids are a fundamental class of molecules that are involved in structural, organizational and signaling properties of eukaryotic membranes. Defects in their production or disposal lead to acquired and inherited human diseases. A growing community of scientists has embraced the challenge to dissect different aspects of sphingolipid biology using a variety of approaches, and a substantial part of this community met last May in the beautiful town of Cascais in Portugal. Over 200 scientists from 26 countries animated the conference, held in a 15th century citadel, sharing their data and opinions on the current understanding and future challenges in sphingolipid research. Here, we report some of their contributions to provide the readers with a bird's-eye view of the themes discussed at the meeting.

Microplastics occurrence in the Tyrrhenian waters and in the gastrointestinal tract of two congener species of seabreams

In this work it is reported for the first time the characterization of microplastics from sea water samples and in two congener species of seabreams: Pagellus erythrinus and P. bogaraveo, Mediterranean fish species of great commercial importance. An experimental survey was conducted on May-June 2017 in the southernmost part of the Tyrrhenian Sea. Microplastics found in the sea water and in the grastrointestinal tract of two teleosts were characterized by Raman and IR spectroscopies. Microplastics found in sea water samples appeared in the form of fragments made of plastics of low and high density (PVC and LPDE). All the microplastics found in fish belonged to Nylon 66, typical fibers used in industry and in fisheries. Our findings highlighted the importance of further studies along the food web chain for a better understanding of the diffusion and possible consequences of this terrible threat.

Glycosphingolipid metabolism in cell fate specification

Glycosphingolipids (GSLs) are ubiquitous components of eukaryotic plasma membranes that consist of a ceramide backbone linked to a glycan moiety. Both the ceramide and the glycan parts of GSLs display structural variations that result in a remarkable repertoire of diverse compounds. This diversity of GSLs is exploited during embryogenesis, when different GSLs are produced at specific developmental stages and along several differentiation trajectories. Importantly, plasma membrane receptors interact with GSLs to modify their activities. Consequently, two otherwise identical cells can respond differently to the same stimulus owing to their different GSL composition. The metabolic reprograming of GSLs is in fact a necessary part of developmental programs, as its impairment results in developmental failure or tissue-specific defects. Moreover, single-cell variability is emerging as a fundamental player in development: GSL composition displays cell-to-cell variability in syngeneic cell populations owing to the regulatory gene expression circuits involved in microenvironment adaptation and in differentiation. Here, we discuss how GSLs are synthesized and classified and review the role of GSLs in the establishment and maintenance of cell identity. We further highlight the existence of the regulatory circuits that modify GSL pathways and speculate how GSL heterogeneity might contribute to developmental patterning.

Role and Function of Sphingomyelin Biosynthesis in the Development of Cancer

Sphingomyelin (SM) biosynthesis represents a complex, finely regulated process, mostly occurring in vertebrates. It is intimately linked to lipid transport and it is ultimately carried out by two enzymes, SM synthase 1 and 2, selectively localized in the Golgi and plasma membrane. In the course of the SM biosynthetic reaction, various lipids are metabolized. Because these lipids have both structural and signaling functions, the SM biosynthetic process has the potential to affect diverse important cellular processes (such as cell proliferation, cell survival, and migration). Thus defects in SM biosynthesis might directly or indirectly impact the normal physiology of the cell and eventually of the organism. In this chapter, we will focus on evidence supporting a role for SM biosynthesis in specific cellular functions and how its dysregulation can affect neoplastic transformation.

Glycosphingolipid metabolic reprogramming drives neural differentiation

Neural development is accomplished by differentiation events leading to metabolic reprogramming. Glycosphingolipid metabolism is reprogrammed during neural development with a switch from globo- to ganglio-series glycosphingolipid production. Failure to execute this glycosphingolipid switch leads to neurodevelopmental disorders in humans, indicating that glycosphingolipids are key players in this process. Nevertheless, both the molecular mechanisms that control the glycosphingolipid switch and its function in neurodevelopment are poorly understood. Here, we describe a self-contained circuit that controls glycosphingolipid reprogramming and neural differentiation. We find that globo-series glycosphingolipids repress the epigenetic regulator of neuronal gene expression AUTS2. AUTS2 in turn binds and activates the promoter of the first and rate-limiting ganglioside-producing enzyme GM3 synthase, thus fostering the synthesis of gangliosides. By this mechanism, the globo-AUTS2 axis controls glycosphingolipid reprogramming and neural gene expression during neural differentiation, which involves this circuit in neurodevelopment and its defects in neuropathology.