23 research outputs found
Microphthalmia with linear skin lesions (MLS) syndrome, an unconventional mitochondrial disorder
No full textSynthetic long non-coding RNAs [SINEUPs] rescue defective gene expression in vivo
No full textNon-coding RNAs provide additional regulatory layers to gene expression as well as the potential to being exploited as therapeutic tools. Non-coding RNA-based therapeutic approaches have been attempted in dominant diseases, however their use for treatment of genetic diseases caused by insufficient gene dosage is currently more challenging. SINEUPs are long antisense non-coding RNAs that up-regulate translation in mammalian cells in a gene-specific manner, although, so far evidence of SINEUP efficacy has only been demonstrated in in vitro systems. We now show that synthetic SINEUPs effectively and specifically increase protein levels of a gene of interest in vivo. We demonstrated that SINEUPs rescue haploinsufficient gene dosage in a medakafish model of a human disorder leading to amelioration of the disease phenotype. Our results demonstrate that SINEUPs act through mechanisms conserved among vertebrates and that SINEUP technology can be successfully applied in vivo as a new research and therapeutic tool for gene-specific up-regulation of endogenous functional proteins
The HOPS Complex Subunit VPS39 controls ciliogenesis through autophagy
No full textPrimary cilia are microtubule-based organelles that assemble and protrude from the surface of most mammalian cells during quiescence. The biomedical relevance of cilia is indicated by disorders ascribed to cilia dysfunction, known as ciliopathies, that display distinctive features including renal cystic disease. In this report, we demonstrate that VPS39, a component of the homotypic fusion and vacuole protein sorting (HOPS) complex, acts as a negative regulator of ciliogenesis in human renal cells, by controlling the localization of the intraflagellar transport 20 (IFT20) protein at the base of cilia through autophagy. Moreover, we show that VPS39 controls ciliogenesis through autophagy also in vivo in renal tubules of Medaka fish. These observations suggest a direct involvement of the HOPS complex in the regulation of autophagy-mediated ciliogenesis and eventually in target selection. Interestingly, we show that the impact of autophagy modulation on ciliogenesis is cell-type dependent and strictly related to environmental stimuli. This report adds a further tile to the cilia-autophagy connection and suggests that VPS39 could represent a new biological target for the recovery of the cilia-related phenotypes observed in the kidneys of patients affected by ciliopathies
A medaka model to study the the molecular basis of Microphthalmia with Linear Skin defects (MLS) syndrome
No full textThe Microphthalmia with linear skin defects (MLS) syndrome is an X- linked dominant male-lethal neuro-developmental disorder associated to mutations in the holocytochrome c-type synthetase (HCCS) transcript. Female patients display unilateral or bilateral microphthalmia and linear skin defects, additional features include central nervous system (CNS) malformation and mental retardation. HCCS codifies a mitochondrial protein that catalyzes the attachment of heme to both apocytochrome c and c1, necessary for proper functioning of the mitochondrial respiratory chain. Although mutation analysis clearly indicates a role for HCCS in the pathogenesis of this genetic condition, the molecular mechanisms underlying the developmental anomalies in the presence of HCCS dysfunction are still unknown. Previous studies demonstrated the early lethality of mouse embryonic Hccs knock-out stem cells. To overcome the problem of the possible embryonic lethality, we decided to generate an animal model for MLS syndrome in the medaka fish (Oryzia latipes) using a morpholino-based technology. Fish models (zebrafish and medaka) are considered good models to study developmental biology processes and in particular eye developmental defects.
Three specific morpholinos directed against different portions of the olhccs transcript have been designed and injected and our data indicated that all morpholinos effectively downregulate the expression of the olhccs gene. The injection of the three different morpholinos resulted in a pathological phenotype, which resembles the human condition. Morphants displayed microphthalmia, coloboma, and microcephaly associated to a severe cardiac pathology. To date, this is the only animal model that recapitulates the phenotype observed in MLS syndrome. Analysis with markers for specific retinal cell types showed defects in differentiation of the ventral neural retina. Characterization of morphants revealed that hccs down-regulation results in impairment of mitochondrial functions, overproduction of reactive oxygen species (ROS) and a strong increase of apoptosis mediated by activation of the mitochondrial-dependent cell death pathway in the CNS and in the eyes. Our results clearly indicate that HCCS plays a critical role in mitochondria and imply that MLS should be considered a mitochondrial disease.
It is well established that the intrinsic mitochondrial dependent apoptotic pathway rely on the formation of apoptosomes, which require the presence and/or the activity of cytochrome c, Apaf1, and caspase 9. Detailed studies of the mechanisms that underlie intrinsic apoptosis have shown that the heme group of cytochrome c is necessary for Apaf1 activation, apoptosome formation and activation of caspase 9. Interestingly, our data indicate that, in our model, the mitochondrial dependent apoptosis is triggered by caspase 9 activation and occur in a Bcl-dependent but apoptosome-independent manner suggesting that at least in some tissues the apoptosis can occur in a non-canonical way. Our data support the evidence of an apoptosome-indipendent activation of caspase 9 and suggest the possibility that this event might be tissue specific. Our study shed new light into the functional role of HCCS in the mitochondria. In addition, we provide strong evidences that mitochondrial mediated apoptotic events underlie microphtalmia providing new insights into the mechanisms of this developmental defect
A medaka model to study the molecular basis of Microphhalmia with linear skin defects (MLS) syndrome.
No full textPh.D in Molecular Medicine ciclo IV/XXI.
Anno academico 2009-2010
Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA): An Unconventional Mitochondrial Disorder
No full textMitochondrial disorders, although heterogeneous, are traditionally described as conditions characterized by encephalomyopathy, hypotonia, and progressive postnatal organ failure. Here, we provide a systematic review of Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA), a rare, unconventional mitochondrial disorder which presents as a developmental disease; its main clinical features include microphthalmia with different degrees of severity, linear skin lesions, and central nervous system malformations. The molecular basis of this disorder has been elusive for several years. Mutations were eventually identified in three X-linked genes, i.e., HCCS, COX7B, and NDUFB11, which are all endowed with defined roles in the mitochondrial respiratory chain. A peculiar feature of this condition is its inheritance pattern: X-linked dominant male-lethal. Only female or XX male individuals can be observed, implying that nullisomy for these genes is incompatible with normal embryonic development in mammals. All three genes undergo X-inactivation that, according to our hypothesis, may contribute to the extreme variable expressivity observed in this condition. We propose that mitochondrial dysfunction should be considered as an underlying cause in developmental disorders. Moreover, LSDMCA should be taken into consideration by clinicians when dealing with patients with microphthalmia with or without associated skin phenotypes
The impairment of HCCS leads to MLS syndrome by activating a non-canonical cell death pathway in the brain and eyes.
No full textMitochondrial-dependent (intrinsic) programmed cell death (PCD) is an essential homoeostatic mechanism that selects bioenergetically proficient cells suitable for tissue/organ development. However, the link between mitochondrial dysfunction, intrinsic apoptosis and developmental anomalies has not been demonstrated to date. Now we provide the evidence that non-canonical mitochondrial-dependent apoptosis explains the phenotype of microphthalmia with linear skin lesions (MLS), an X-linked developmental disorder caused by mutations in the holo-cytochrome c-type synthase (HCCS) gene. By taking advantage of a medaka model that recapitulates the MLS phenotype we demonstrate that downregulation of hccs, an essential player of the mitochondrial respiratory chain (MRC), causes increased cell death via an apoptosome-independent caspase-9 activation in brain and eyes. We also show that the unconventional activation of caspase-9 occurs in the mitochondria and is triggered by MRC impairment and overproduction of reactive oxygen species (ROS). We thus propose that HCCS plays a key role in central nervous system (CNS) development by modulating a novel non-canonical start-up of cell death and provide the first experimental evidence for a mechanistic link between mitochondrial dysfunction, intrinsic apoptosis and developmental disorders
The Role of MicroRNAs in Mitochondria-Mediated Eye Diseases
No full textThe retina is among the most metabolically active tissues with high-energy demands. The peculiar distribution of mitochondria in cells of retinal layers is necessary to assure the appropriate energy supply for the transmission of the light signal. Photoreceptor cells (PRs), retinal pigment epithelium (RPE), and retinal ganglion cells (RGCs) present a great concentration of mitochondria, which makes them particularly sensitive to mitochondrial dysfunction. To date, visual loss has been extensively correlated to defective mitochondrial functions. Many mitochondrial diseases (MDs) show indeed neuro-ophthalmic manifestations, including retinal and optic nerve phenotypes. Moreover, abnormal mitochondrial functions are frequently found in the most common retinal pathologies, i.e., glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR), that share clinical similarities with the hereditary primary MDs. MicroRNAs (miRNAs) are established as key regulators of several developmental, physiological, and pathological processes. Dysregulated miRNA expression profiles in retinal degeneration models and in patients underline the potentiality of miRNA modulation as a possible gene/mutation-independent strategy in retinal diseases and highlight their promising role as disease predictive or prognostic biomarkers. In this review, we will summarize the current knowledge about the participation of miRNAs in both rare and common mitochondria-mediated eye diseases. Definitely, given the involvement of miRNAs in retina pathologies and therapy as well as their use as molecular biomarkers, they represent a determining target for clinical applications
Realtà e Prospettive nel management sanitario: uno studio all’ombra dei leader
No full text2016 - 2017The appropriate and sustainable management of health care organizations is a timely and relevant topic. It achieves a growing popularity in light of the deep processes of institutional and structural changes which are affecting the health care context in the last few years. Therefore, it is crucial to push forward our knowledge about the management tools and approaches which allow to enhance the effectiveness of health care organizations, whose dimension – as required by recent legislative reforms – is continuously growing.
Clinical leadership – that is to say the leadership which is enacted within health care organizations by providers of health services – is a momentous topic in the field of health care management and organization. This thesis aims at illuminating a “dark side” of clinical leadership: the role of gender differences in triggering diverging approaches to clinical leadership. For this purpose, a qualitative analysis was performed, which involved a medium-sized health care organization operating in Italy. A mixed approach was used, which joined a high level, “managerial” interpretation with a more depth, psychological interpretation of clinical leaders’ behaviors and approaches.
Attention has been paid to the organizational implications of the specific leadership styles implemented by two key informants, who were identified as the primary sources of information for the purpose of this study. In line with the main aim of this study, a man and a woman were involved in this research. The psychological determinants of leaders’ approaches and behaviors were carefully investigated, in an attempt to point out gender-based differences. The two leaders belonged to the same health care organizations and had the same organizational role; they supervised two organizational units which were comparable in terms of health competencies and clinical practices.
This thesis is organized as follows. Firstly, the “leadership” concept is presented, sticking to the prevailing theoretical frameworks which assist in underpinning this construct. Gender-based theories were elicited, in order to pave the way for the study development. Then, the strategic leadership mind-set is presented, focusing on the psychological and cognitive dimensions inspiring leaders’ practices.
The second chapter proposes a literature review of the “clinical leadership” concept, identifying the management implications that it is able to generate on the proper functioning of health care organizations; once again, a particular emphasis is put on gender differences in the exercise of clinical leadership.
The third chapter shows the research strategy and design. A single case study approach was taken. It was implemented through the “shadowing” method. The two leaders who were engaged in this analysis were carefully observed by the author during their every-day working activity; moreover, multiple semi-structured interviews were administered, in order to deepen the research findings.
The result of this study point out that the styles of clinical leadership may be either transformational or transactional. Even though the approach taken does not allow generalization, the exercise of leadership is deeply affected by gender-based biases. On the one hand, female leaders are more inclined to embrace a transformational clinical leadership style; on the other hand, male leaders are more likely to use a transactional style. It is worth noting that differences in clinical leadership have relevant implications on the
management of individual units within health care organizations; also, they affect the relationship between leaders, followers and supervisors. Lastly, yet importantly, such differences influence the patient-provider relationship, with drawbacks on the providers’ ability to fully detect and meet the needs of their patients. [edited by Author]XVI n.s. (XXX ciclo
The impairment of HCCS leads to MLS syndrome by activating a non-canonical cell death pathway in the brain and eyes
No full textMitochondrial-dependent (intrinsic) programmed cell death (PCD) is an essential homoeostatic mechanism that selects bioenergetically proficient cells suitable for tissue/organ development. However, the link between mitochondrial dysfunction, intrinsic apoptosis and developmental anomalies has not been demonstrated to date. Now we provide the evidence that non-canonical mitochondrial-dependent apoptosis explains the phenotype of microphthalmia with linear skin lesions (MLS), an X-linked developmental disorder caused by mutations in the holo-cytochrome c-type synthase (HCCS) gene. By taking advantage of a medaka model that recapitulates the MLS phenotype we demonstrate that downregulation of hccs, an essential player of the mitochondrial respiratory chain (MRC), causes increased cell death via an apoptosome-independent caspase-9 activation in brain and eyes. We also show that the unconventional activation of caspase-9 occurs in the mitochondria and is triggered by MRC impairment and overproduction of reactive oxygen species (ROS). We thus propose that HCCS plays a key role in central nervous system (CNS) development by modulating a novel non-canonical start-up of cell death and provide the first experimental evidence for a mechanistic link between mitochondrial dysfunction, intrinsic apoptosis and developmental disorders. The X-linked disorder microphtalmia with skin lesions (MLS) is caused by HCCS gene mutations. The disease phenotype is now be explained by the increased non-conventional caspase-9 -mediated cell death in the brain and eyes due to HCCS impairment. © 2013 The Authors. Published by John Wiley and Sons, Ltd on behalf of EMBO.Italian Telethon Foundation (BF, grant TGM11CB3); the Spanish MICINN (BFU2010-16031); CIBERER (PB); EMBO short-term fellowship; Company of Biologists LtdPeer Reviewe
