Prolactin and the Regulation if Secretion Including Membrane Flow: Potential Roles for Tubulin and Microtubules*
James A. Rillema in Actions of Prolactin on Molecular Processes, 1987
Secretion involves not only the exocytic transfer of condensed secretory product to the cell exterior, but usually there is an accompanying flow of water in which the secretory solids are suspended. Therefore, it is interesting to note that microtubules have also been implicated in the transport of water across vasopressin-sensitive cells, including toad urinary bladder7,160 and mammalian kidney collecting duct.161 Vasopressin or antidiuretic hormone (ADH) on the blood or basal side stimulates cyclic AMP production in these cells, leading to increased water permeability on the luminal or apical membrane, thus permitting a flow of water along the osmotic gradient from lumen to blood. Colchicine and other antimitotic drugs inhibit this action of vasopressin on transepithelial water transport. There is no evidence that a similar mechanism exists in secretory cells. However, postsecretory transport of secretory material through ducts requires a fluid medium, and alteration of the permeability of the membranes of the secretory cells to fluids and electrolytes might utilize tubulin within the membrane, if not microtubules. The variety of cells and tissues in which secretion is inhibited by microtubule-altering agents is compelling; however, each drug has its own set of side effects which should be thoroughly tested before assuming that the observed effect, such as inhibition of secretion, is due to a specific blockage of microtubule functioning.
Biology and Distribution of Spiders of Medical Importance
Jürg Meier, Julian White in Handbook of: Clinical Toxicology of Animal Venoms and Poisons, 2017
The two venom glands are situated partly in the cephalothorax and partly in the chelicerae, with the exception of the Mygalomorph spiders where they are contained wholly in the chelicerae. The glands consist of three principal parts: a muscular coat, a secreting layer and the duct of the gland. Suomalainen12 studied the structure of the venom gland in several species of 16 different spider families and concluded that the structure is fairly uniform in all species. The greatest differences are found in the secretory part of the gland: a syncytium consisting of star-shaped cells with very long branches. Secretion takes place from the branches into the spaces between the cells. Järlsfors et al.13 studied the innervation of the venom-secreting cells in the black-widow spider (L. mactans), and observed that the glandular epithelium is also innervated and probably this nervous supply stimulates or regulates the synthesis of the venom.
Neuroendocrine Factors
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan in Strength and Conditioning in Sports, 2023
Homeostasis is accomplished through the initiation of tissue responses and adaptations as a consequence of endocrine gland release of a hormone directly into the circulation, or by neural function and neurotransmitter release. A secretory cell is the functional unit of an endocrine gland. Endocrine glands are ductless and manufacture, store, and secrete hormones. Hormones are chemical messengers that are released in very small amounts and have specific effects on specific target tissues. Some hormone and hormone-like substances are produced and act within a cell (autocrine function), or a hormone can be released from one cell but act in another cell without entering the circulation (paracrine function). Neurons synthesize, store, and release neurotransmitters, which act to relay information (action potentials) from neuron to neuron or from a neuron to an effector tissue such as a muscle fiber. Some neurotransmitters act as hormones such as epinephrine. Therefore, hormones and neurotransmitters released by the endocrine and nervous systems have “neurohormonal” properties and integrative functions and effects.
Surface properties of Enterococcus faecalis cells isolated from chicken hearts determine their low ability to form biofilms
Published in Biofouling, 2018
Jolanta Cieśla, Dagmara Stępień-Pyśniak, Agnieszka Nawrocka, Małgorzata Łukowska, Tomasz Hauschild, Andrzej Wernicki, Andrzej Bieganowski
Among the strains that were analysed, only E. faecalis (ATCC 29212) showed negative results for the β-galactosidase and lactose tests and, additionally, completely destroyed the blood cells (β-haemolysis). This is linked to the production and extracellular secretion of certain substances. One such substances is cytolysin/haemolysin, which displays both haemolytic and bactericidal activities towards a number of eukaryotic cell types, including macrophages and polymorphonuclear neutrophils, as well as Gram-positive bacteria (Libertin et al. 1992). Another substance, gelatinase, is an extracellular zinc endopeptidase that hydrolyses collagen, gelatine, and small peptides and has been shown to exacerbate endocarditis in an animal model. The production of these substances may potentially contribute to virulence in enterococci (Toğay et al. 2010).
Strong stimulation triggers full fusion exocytosis and very slow endocytosis of the small dense core granules in carotid glomus cells
Published in Journal of Neurogenetics, 2018
Amy Tse, Andy K. Lee, Noriko Takahashi, Alex Gong, Haruo Kasai, Frederick W. Tse
Studies on exocytosis in a wide-range of neurosecretory systems have revealed full fusion, kiss-and-run and compound exocytosis as the three major modes of exocytosis (Wu, Hamid, Shin, & Chiang, 2014). In the full fusion mode, the fused granules merged with the plasma membrane, and the vesicular membrane was eventually retrieved via endocytosis. In the kiss-and-run mode, granules fuse transiently with the plasma membrane without complete loss of shape, protein or lipid (Harata, Aravanis, & Tsien, 2006). The compound mode involves the exocytosis of large granules formed via granule-granule fusion (Wu et al., 2014), or the fusion of a granule with another granule that has already fused with the plasma membrane (aka “sequential compound” exocytosis) (Kishimoto et al.,2006; Lam et al.,2013; Takahashi et al.,2004). The various forms of exocytosis may be utilized in the same cells for distinct modes of secretion (Kasai, Takahashi, & Tokumaru, 2012).
Growth rate alterations of human colorectal cancer cells by 157 gut bacteria
Published in Gut Microbes, 2020
Rahwa Taddese, Daniel R. Garza, Lilian N. Ruiter, Marien I. de Jonge, Clara Belzer, Steven Aalvink, Iris D. Nagtegaal, Bas E. Dutilh, Annemarie Boleij
Several functional categories were significantly associated with cell growth. Most of these functions were identified in specific bacterial families and consistently inhibited or enhanced cell growth in different cell lines. These functions may reflect novel pathways of bacterial interference with cell growth which, to our knowledge, have not been previously identified. Most functions are related to cell metabolism, secretion, and transport systems. For example, secretomes of Enterobacteriaceae that encode the “Vir-like type 4 secretion system” inhibited the growth of all cell lines. Similarly, the gene superclass “Membrane transport” was mostly associated with secretomes that inhibited cell growth (Supplementary Table S10). Molecules that are secreted by these bacterial transport systems may be responsible for the inhibiting effect. For example, the Vir-like type 4 secretion system allows bacteria to secrete proteinaceous effectors that kill competitors.90 Here, we report an important first step in understanding the cell growth enhancing or inhibiting effects of human gut bacteria by identifying putative transport systems for effector molecules.
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