Exocytosis and Endocytosis in Neuroendocrine Cells: Inseparable Membranes!

International audienceAlthough much has been learned concerning the mechanisms of secretory vesicle formation and fusion at donor and acceptor membrane compartments, relatively little attention has been paid toward understanding how cells maintain a homeostatic membrane balance through vesicular trafficking. In neurons and neuroendocrine cells, release of neurotrans-mitters, neuropeptides, and hormones occurs through calcium-regulated exocytosis at the plasma membrane. To allow recycling of secretory vesicle components and to preserve organelles integrity, cells must initiate and regulate compensatory membrane uptake. This review relates the fate of secretory granule membranes after full fusion exocytosis in neuroendocrine cells. In particular, we focus on the potential role of lipids in preserving and sorting secretory granule membranes after exocytosis and we discuss the potential mechanisms of membrane retrieval

Role of Intersectin-1 in membrane trafficking : identification of new molecular partners

L’homéostasie cellulaire est intimement liée au trafic membranaire, processus dynamique qui permet les échanges de lipides et de protéines entre les compartiments cellulaires mais aussi entre la cellule et le milieu extracellulaire. L’intersectin-1 (ITSN1) est une protéine d’échafaudage multifonctionnelle, impliquée dans les processus d’endocytose, d’exocytose, diverses voies de signalisation ainsi que dans la survie cellulaire. L’ensemble de mes travaux de doctorat a permis d’identifier deux nouveaux partenaires de l’ITSN1, RhoU et l’OPHN1, et de montrer leur implication dans le trafic membranaire. De plus je démontre que les variants d’épissage de l’ITSN1 pourraient avoir une spécificité d’interactiondifférente vis-à-vis de ses partenaires. Nous montrons aussi que l’ITSN1 est capable de former des complexes entre ses différentes isoformes. Ainsi, l'ensemble de ces données apportent de nouvelles connaissances sur l’interactôme d’ITSN1.The cellular homeostasis is tightly linked to the membrane trafficking, a dynamic process which allows lipid and protein exchange between the cellular compartments as well as the cell and the environment. Intersectin1 (ITSN1) is a multifunctional scaffold protein implicated in the processes of endocytosis and exocytosis, different signaling pathways and cell survival. In present study I have identified two new partners of ITSN1, RhoU and OPHN1, and demonstrated their implication in membrane trafficking. Surprisingly, I have also found that the alternative splicing of ITSN1-L can lead to the change of the specificity of its interaction with binding partners. In addition, I have shown that different ITSN1 isoforms are capable to form complexes with each other. All together these data add new knowledge to ITSN1 interactome

Role of Intersectin-1 in membrane trafficking : identification of new molecular partners

L’homéostasie cellulaire est intimement liée au trafic membranaire, processus dynamique qui permet les échanges de lipides et de protéines entre les compartiments cellulaires mais aussi entre la cellule et le milieu extracellulaire. L’intersectin-1 (ITSN1) est une protéine d’échafaudage multifonctionnelle, impliquée dans les processus d’endocytose, d’exocytose, diverses voies de signalisation ainsi que dans la survie cellulaire. L’ensemble de mes travaux de doctorat a permis d’identifier deux nouveaux partenaires de l’ITSN1, RhoU et l’OPHN1, et de montrer leur implication dans le trafic membranaire. De plus je démontre que les variants d’épissage de l’ITSN1 pourraient avoir une spécificité d’interactiondifférente vis-à-vis de ses partenaires. Nous montrons aussi que l’ITSN1 est capable de former des complexes entre ses différentes isoformes. Ainsi, l'ensemble de ces données apportent de nouvelles connaissances sur l’interactôme d’ITSN1.The cellular homeostasis is tightly linked to the membrane trafficking, a dynamic process which allows lipid and protein exchange between the cellular compartments as well as the cell and the environment. Intersectin1 (ITSN1) is a multifunctional scaffold protein implicated in the processes of endocytosis and exocytosis, different signaling pathways and cell survival. In present study I have identified two new partners of ITSN1, RhoU and OPHN1, and demonstrated their implication in membrane trafficking. Surprisingly, I have also found that the alternative splicing of ITSN1-L can lead to the change of the specificity of its interaction with binding partners. In addition, I have shown that different ITSN1 isoforms are capable to form complexes with each other. All together these data add new knowledge to ITSN1 interactome

Rôle de l'intersectin-1 au cours du trafic membranaire : identification de nouveaux partenaires moléculaires

The cellular homeostasis is tightly linked to the membrane trafficking, a dynamic process which allows lipid and protein exchange between the cellular compartments as well as the cell and the environment. Intersectin1 (ITSN1) is a multifunctional scaffold protein implicated in the processes of endocytosis and exocytosis, different signaling pathways and cell survival. In present study I have identified two new partners of ITSN1, RhoU and OPHN1, and demonstrated their implication in membrane trafficking. Surprisingly, I have also found that the alternative splicing of ITSN1-L can lead to the change of the specificity of its interaction with binding partners. In addition, I have shown that different ITSN1 isoforms are capable to form complexes with each other. All together these data add new knowledge to ITSN1 interactome.L’homéostasie cellulaire est intimement liée au trafic membranaire, processus dynamique qui permet les échanges de lipides et de protéines entre les compartiments cellulaires mais aussi entre la cellule et le milieu extracellulaire. L’intersectin-1 (ITSN1) est une protéine d’échafaudage multifonctionnelle, impliquée dans les processus d’endocytose, d’exocytose, diverses voies de signalisation ainsi que dans la survie cellulaire. L’ensemble de mes travaux de doctorat a permis d’identifier deux nouveaux partenaires de l’ITSN1, RhoU et l’OPHN1, et de montrer leur implication dans le trafic membranaire. De plus je démontre que les variants d’épissage de l’ITSN1 pourraient avoir une spécificité d’interactiondifférente vis-à-vis de ses partenaires. Nous montrons aussi que l’ITSN1 est capable de former des complexes entre ses différentes isoformes. Ainsi, l'ensemble de ces données apportent de nouvelles connaissances sur l’interactôme d’ITSN1

Role of Intersectin-1 in membrane trafficking (identification of new molecular partners)

L homéostasie cellulaire est intimement liée au trafic membranaire, processus dynamique qui permet les échanges de lipides et de protéines entre les compartiments cellulaires mais aussi entre la cellule et le milieu extracellulaire. L intersectin-1 (ITSN1) est une protéine d échafaudage multifonctionnelle, impliquée dans les processus d endocytose, d exocytose, diverses voies de signalisation ainsi que dans la survie cellulaire. L ensemble de mes travaux de doctorat a permis d identifier deux nouveaux partenaires de l ITSN1, RhoU et l OPHN1, et de montrer leur implication dans le trafic membranaire. De plus je démontre que les variants d épissage de l ITSN1 pourraient avoir une spécificité d interactiondifférente vis-à-vis de ses partenaires. Nous montrons aussi que l ITSN1 est capable de former des complexes entre ses différentes isoformes. Ainsi, l'ensemble de ces données apportent de nouvelles connaissances sur l interactôme d ITSN1.The cellular homeostasis is tightly linked to the membrane trafficking, a dynamic process which allows lipid and protein exchange between the cellular compartments as well as the cell and the environment. Intersectin1 (ITSN1) is a multifunctional scaffold protein implicated in the processes of endocytosis and exocytosis, different signaling pathways and cell survival. In present study I have identified two new partners of ITSN1, RhoU and OPHN1, and demonstrated their implication in membrane trafficking. Surprisingly, I have also found that the alternative splicing of ITSN1-L can lead to the change of the specificity of its interaction with binding partners. In addition, I have shown that different ITSN1 isoforms are capable to form complexes with each other. All together these data add new knowledge to ITSN1 interactome.STRASBOURG-Bib.electronique 063 (674829902) / SudocSudocFranceF

Intersectin: The Crossroad between Vesicle Exocytosis and Endocytosis

International audienceIntersectins (ITSNs) are a family of highly conserved proteins with orthologs from nematodes to mammals. In vertebrates, ITSNs are encoded by two genes (itsn1 and itsn2), which act as scaffolds that were initially discovered as proteins involved in endocytosis. Further investigation demonstrated that ITSN1 is also implicated in several other processes including regulated exocytosis, thereby suggesting a role for ITSN1 in the coupling between exocytosis and endocytosis in excitatory cells. Despite a high degree of conservation amongst orthologs, ITSN function is not so well preserved as they have acquired new properties during evolution. In this review, we will discuss the role of ITSN1 and its orthologs in exo-and endocytosis, in particular in neurons and neuroendocrine cells

GTPase-activating protein oligophrenin 1 is a new partner of multifunctional adapter protein intersectin 1

Intersectin 1 (ITSN1) is a multifunctional adaptor protein which is involved in endocytosis, exocytosis and cellular signaling and it is also associated with such pathologies as Down syndrome and Alzheimer’s disease. The aim of this study was to identify new ITSN1 protein partners which are implicated in membrane trafficking. Methods. In silico analysis by Scansite online resource had identified a GTPase activating protein oligophrenin 1 (OPHN1) as a potential partner of ITSN1 SH3A domain. GST pull-down and immunoprecipitation were used to prove complex formation between ITSN1 and OPHN1. Subcellular protein localization was determined by immunofluorescence and confocal microscopy. Results. We have shown that brain-specific and ubiquitously expressed SH3A domain isoforms of ITSN1 interact with OPHN1. ITSN1 and OPHN1 form complexes in both resting and stimulated to exocytosis PC12 cell line. Conclusions. GTPase activating protein OPHN1 and adaptor protein ITSN1 interact in PC12 cell line independently of exocytosis stimulation

In Vitro Study of Deuterium Effect on Biological Properties of Human Cultured Adipose-Derived Stem Cells

In current in vitro study we have shown the impact of deuterium content in growth medium on proliferation rate of human cultured adipose-derived stem cells (ADSC). ADSCs have also demonstrated morphological changes when cultured in deuterated growth medium: the cell cultures did not reach confluence but acquired polygonal morphology with pronounced stress fibers. At high deuterium concentrations the ADSCs population doubling time increased which indicated the cell cycle retardation and decrease of cell proliferation rate. The deuterated and deuterium-depleted growth media demonstrated acute and chronic cytotoxicity, respectively. The minimal migration ability was observed in deuterated medium whereas the highest migration activity was observed in the medium with the deuterium content close to natural. The cells in deuterated growth medium demonstrated decrease in metabolic activity after three days in culture. In contrast, in deuterium-depleted medium there was an increase in ADSC metabolic activity