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Exocytosis of Nonclassical Neurotransmitters
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
Xiao Su, Vincent R. Mirabella, Kenneth G. Paradiso, Zhiping P. Pang
Different from fast transmitters that form classical point-to-point transmission, dopamine was suggested to be released via a volume transmission mode, where neuromodulators diffuse to mediate effects in many cells over a large area or a longer distance (Agnati et al., 1995; Caille et al., 1996; Liu et al., 2018). Dopamine can also be released from soma and dendrites (Geffen et al., 1976). A large amount of morphological and functional evidence including immunohistochemistry, amperometry, and whole-cell voltage clamp support the belief that most of dopamine transmission is mediated by vesicular exocytosis (Caille et al., 1996; Kress et al., 2014; Staal et al., 2004; Uchigashima et al., 2016; Yung et al., 1995). The ablation of vesicular monoamine transporter type 2 (VMAT2) which is a major vesicular transporter for dopamine eliminates dopamine transmission (Fon et al., 1997). Here, we mainly focus on axonal dopamine release and related machinery involved in dopamine secretion.
Ayahuasca
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Wild Plants, 2020
Raquel Consul, Flávia Lucas, Maria Graça Campos
The aforementioned transport and storage mechanism can be summarized in three steps: first DMT is actively transported by the blood-brain barrier by an ATP-dependent Mg2+ uptake mechanism through the endothelial membrane. It is then internalized in neuronal cells by serotonin transporters (SERT) on the surface of neurons. Finally, DMT is sequestered in synaptic vesicles by the action of the monoamine vesicular transporter 2 (VMAT2). An inhibitory effect of serotonin uptake via SERT and VMAT2 by DMT was demonstrated (Carbonaro and Gatch 2016). Given these data, it appears unquestionable that this mechanism also reflects the influence of DMT in the CNS (Frecska et al. 2013).
Atherosclerosis
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
The vascular endothelium is permeable to a wide range of molecules. The permeability of the endothelium involves the presence of a pore system and the vesicular transport. Physiological studies on capillary transport revealed the existence of a two-pore system, one with small pores of approximately 9 μm in diameter and the other with large pores about 50 μm in diameter. Molecules up to 500,000 Da cross the endothelium by vesicular transport. The vesicular transport is bidirectional or emits invaginations on the luminal plasma membrane. LDL of about 22 μm in diameter can move across the normal endothelium in pinocytotic vesicles. This type of transport is unlikely for the larger chylomicrons and intact VLDL molecules.568 Albumin and fibrinogen cross the arterial endothelium, and there are focal and regional differences in the permeability to these macromolecules.
Human ovarian granulosa cells use clathrin-mediated endocytosis for LDL uptake: immunocytochemical and electron microscopic study
Published in Ultrastructural Pathology, 2023
Aynur Abdulova, Merjem Purelku, Hakan Sahin, Gamze Tanrıverdi
Regarding the clathrin-mediated endocytic pathway, an important component is the clathrin protein. Clathrin-coated vesicles have a three-layered structure consisting of an outer region formed by clathrin proteins in the form of a cage, an intermediate region consisting of a lipid membrane, as well as internal adaptor proteins (APs).8 Along with clathrin, more than 60 other cytosolic proteins are involved in the formation of clathrin-coated endocytic vesicles.9 All these proteins assemble from the cytosol to the endocytic region in a highly ordered manner. The collected vesicles are transported to the target site by SNARE (N-ethylmaleimide-sensitive factor binding protein receptor) proteins. SNAREs manage the transfer of material to be transported during vesicular transport. In an animal cell, there are at least 20 different organelle-associated SNARE proteins, each attached to a specific membrane involved in the biosynthetic-secretion or endocytic pathway. These proteins function as transmembrane proteins and are referred to as vesicular SNAREs (v-SNAREs) with characteristic spiral domains.10
A case report of infantile parkinsonism-dystonia-2 caused by homozygous mutation in the SLC18A2 gene
Published in International Journal of Neuroscience, 2023
Hongyin Zhai, Yaofeng Zheng, Yiduo He, Yong Zhang, Zhikuan Guo, Wenzhe Cui, Li Sun
The p.Pro237His mutation of VMAT2 was also detected in two New Zealand siblings of European descent and a 7-year-old female of Iraqi, and the affected ones were all inherited from their heterozygous consanguineous parents [6, 7]. Besides, the proline-to-leucine substitution (p.Pro387Leu) in VMAT2 was described in an original Saudi Arabian family [5]. Both the p.Pro237His and p.Pro387Leu mutations are located in the fifth VMAT2 transmembrane domain and close to the tenth VMAT2 transmembrane domain, which are highly conserved in vertebrate species. The above-mentioned patients presented with a series of clinical symptoms relating to abnormal monoaminergic neurotransmission, such as truncal hypotonia, a general paucity of movement, oculogyric crises, extrapyramidal signs and cognitive delay, and then were diagnosed as brain dopamine-serotonin vesicular transport disease. Treatment with direct dopamine agonists was followed by symptomatic improvement in affected individuals, whereas treatment with levodopa was associated with deterioration of the disease. As a result, the 6-month-old infant in this report was diagnosed as PKDYS2 according to a homozygous p.Pro237His mutations and clinical symptoms (parkinsonism, dystonia). Subsequent treatment with dopamine receptor agonist pramipexole was confirmed effective.
There and back again: a dendrimer’s tale
Published in Drug and Chemical Toxicology, 2022
Barbara Ziemba, Maciej Borowiec, Ida Franiak-Pietryga
Following endocytosis, the vacuoles with dendrimer cargo become accessible to early endosomes which then fuze with late endosomes and next with lysosomes to form phagolysosomes (Šamaj et al. 2004). Dendrimers may also get to transcytotic vesicles responsible for vesicular transport through the cell and exocytosis. In another scenario, a material taken up in the CvME process may be transported via caveolosomes to the endoplasmic reticulum (ER) or the Golgi apparatus (GA) (Pérez-Martínez et al. 2011, Fröhlich 2012) (Figure 2). Wu et al. tested PAMAM dendrimers with two different end-terminal functionalities (carboxylate or pyrrolidone) in two human endothelial cell lines, i.e., hCMEC/D3 (human brain capillary endothelial cells) and HUVEC (human umbilical vein endothelial cells). Both dendrimers mainly entered the cells via CME, and after the internalization, the majority of them were found in the endo-lysosomal compartments. Some fraction of nanoparticles, however, localized to the ER and the GA. The authors excluded CvME as a significant route of dendrimers uptake and suggested the involvement of recycling endosomes trafficking to the trans-Golgi network through specialized adaptors and retromer complex (Wu et al.2017).