physiological function
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Author(s):  
Renu Minda

I wish to suggest a physiological function for alpha-synuclein (a-syn) that has the potential to explain its role in pathology. Intraneuronal proteinaceous Lewy Bodies (LBs), the pathological hallmark of Parkinson’s disease and other synucleinopathies, consist majorly of a-syn. Ample evidence suggests that LBs are not the result of simple amyloidosis of cytosolic a-syn. Benign soluble unstructured a-syn gets converted into toxic species which preferentially accumulates in LBs. But how these aberrant a-syn molecules are produced in the cytosol, is still not clear. The present hypothesis is an effort to relate a metabolic reaction specific to neuronal function, that is, phase transition, with the pathobiology of a-syn. During high frequency stimulation, which entails rapid phase transition reactions at the presynaptic compartment, aberrant interaction of a-syn with the membrane occasionally generates toxic a-syn molecules. My conjecture is that the physiological function of a-syn is to modulate membrane fluidity by a process wherein it goes through a conformation cycle driven by a flux of energy from mitochondria. It is the range of toxic a-syn produced during aberrant phase transition reaction that is responsible for pathology, not the normal a-syn that reenters the conformation cycle, thereby, resolving the paradox of the Janus-face of a-syn.


2022 ◽  
Vol 13 (1) ◽  
pp. 1-2
Author(s):  
Karthikeyan Pethusamy ◽  
Ruby Dhar ◽  
Arun Kumar ◽  
Subhradip Karmakar

Cell to Cell communications is the pivot for life processes. Any event that disrupts this leads to the loss of physiological function, eventually leading to cell death. Evolutionarily, cells developed an elaborate mechanism to undertake this paramount responsibility through cell surface glycocalyx, receptors, integrins, and other recognition molecules. Cells also exchange through local acting soluble mediators as well as through vesicles and exosomes. Recent development in this field led to the identification of a spectacular network of membrane process that seems to be the supremo of all that was known about cellular communications. These are called membrane nanotubes or tunneling nanotubes (TNT). Cellular communication can be subdivided into contact and contactless. The former provides more rapid and molecule transfer as compared to the latter. Tunneling nanotubes (TNTs) are a novel type of contact-based communication. TNTs are straight, thin membrane extensions connecting cells over long distances first reported in PC12 cells in 2004. TNT is believed to form from actin-based membrane protrusion. There are three different models of TNT formation. a>Protrusions from one cell grow and extend until it reaches the other cell, followed by a membrane fusion. b> Membrane protrusions grow from both cells until they meet and establish a connection c> TNT formation by cell dislodgement when cells migrate further apart from each other, and during this movement, TNT is formed. It is possible that all these three models may be operational depending on cell types and context. Tunneling nanotubes (TNT) are dynamic connections between cells, representing a novel route for cell-to-cell communication. TNT was reported in various cell types, like epithelial cells, neuronal cells, mesenchyma cells, and immune cells engaged in intercellular exchanges of molecules, subcellular organelles, and pathogen and viruses transport routes. TNT can extend up to 200 µm in length and about 50 nm to 1500 nm in diameter in macrophages. TNT can be established between similar cell types (homo-TNT) or between one cell type and another ( hetro TNT) and thus may be involved in the initiation and growth of cancer as well as dissemination of cancer cells. TNTs are also assumed to play a role in treatment resistance, e.g., in chemotherapy treatment of cancer. Recently, TNT has been used to hijack mitochondria from healthy cells by the cancer cells as a source of energy. TNT was also reported to transport miRNA and other RNA to the surrounding stroma creating an environment suitable for cancer growth. More research in this discipline is needed to understand the full function of these wonderful nanostructures.


2021 ◽  
Vol 50 (2) ◽  
pp. 55-57
Author(s):  
V. V. Abramchenko

The author introduces the conception o f potentially reversible myometrial dysfunction with unaffected main physiological function o f myometrium (viability o f myometrium). This dysfunction is connected with the disturbances o f uterine haemodynamics. The phenomenon o f reversible myometrial dysfunction reflects the process o f prolonged decreased contractile ability o f the uterus.The therapy o f reversible myometrial dysfunction phenomenon should be directed to blood flow restoration under the conditions o f uterine hypoperfusion.The special treatment is not required fo r myometrium with reserved main physiological functions (tonus, excitability) because restoration o f myometrial contractile ability improves spontaneously in case o f blood flow restoration.With the aim o f prophylaxis o f myometrial dysfunction and delayed rehabilitation o f the uterine contractile function administration o f Ca antagonists, beta-adrenomymetics, antioxidants and preparations, which improve myometrial metabolic processes, is recommended before the expected delivery.


Author(s):  
Emma Ong-Pålsson ◽  
Jasenka Rudan Njavro ◽  
Yvette Wilson ◽  
Martina Pigoni ◽  
Andree Schmidt ◽  
...  

AbstractThe membrane protein seizure 6–like (SEZ6L) is a neuronal substrate of the Alzheimer’s disease protease BACE1, and little is known about its physiological function in the nervous system. Here, we show that SEZ6L constitutive knockout mice display motor phenotypes in adulthood, including changes in gait and decreased motor coordination. Additionally, SEZ6L knockout mice displayed increased anxiety-like behaviour, although spatial learning and memory in the Morris water maze were normal. Analysis of the gross anatomy and proteome of the adult SEZ6L knockout cerebellum did not reveal any major differences compared to wild type, indicating that lack of SEZ6L in other regions of the nervous system may contribute to the phenotypes observed. In summary, our study establishes physiological functions for SEZ6L in regulating motor coordination and curbing anxiety-related behaviour, indicating that aberrant SEZ6L function in the human nervous system may contribute to movement disorders and neuropsychiatric diseases.


Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 15
Author(s):  
Eduardo Fuentes-Lemus ◽  
Per Hägglund ◽  
Camilo López-Alarcón ◽  
Michael J. Davies

Covalent crosslinks within or between proteins play a key role in determining the structure and function of proteins. Some of these are formed intentionally by either enzymatic or molecular reactions and are critical to normal physiological function. Others are generated as a consequence of exposure to oxidants (radicals, excited states or two-electron species) and other endogenous or external stimuli, or as a result of the actions of a number of enzymes (e.g., oxidases and peroxidases). Increasing evidence indicates that the accumulation of unwanted crosslinks, as is seen in ageing and multiple pathologies, has adverse effects on biological function. In this article, we review the spectrum of crosslinks, both reducible and non-reducible, currently known to be formed on proteins; the mechanisms of their formation; and experimental approaches to the detection, identification and characterization of these species.


2021 ◽  
Vol 14 ◽  
Author(s):  
Ying Gao ◽  
Lingxin Kong ◽  
Shan Liu ◽  
Kangding Liu ◽  
Jie Zhu

The effective conduction of action potential in the peripheral nervous system depends on the structural and functional integrity of the node of Ranvier and paranode. Neurofascin (NF) plays an important role in the conduction of action potential in a saltatory manner. Two subtypes of NF, NF186, and NF155, are involved in the structure of the node of Ranvier. In patients with chronic inflammatory demyelinating polyneuropathy (CIDP), anti-NF antibodies are produced when immunomodulatory dysfunction occurs, which interferes with the conduction of action potential and is considered the main pathogenic factor of CIDP. In this study, we describe the assembling mechanism and anatomical structure of the node of Ranvier and the necessary cell adhesion molecules for its physiological function. The main points of this study are that we summarized the recent studies on the role of anti-NF antibodies in the changes in the node of Ranvier function and its impact on clinical manifestations and analyzed the possible mechanisms underlying the pathogenesis of CIDP.


2021 ◽  
Vol 10 (24) ◽  
pp. 5852
Author(s):  
Jeremy D. Henson ◽  
Luis Vitetta ◽  
Michelle Quezada ◽  
Sean Hall

The stress response is a well-defined physiological function activated frequently by life events. However, sometimes the stress response can be inappropriate, excessive, or prolonged; in which case, it can hinder rather than help in coping with the stressor, impair normal functioning, and increase the risk of somatic and mental health disorders. There is a need for a more effective and safe pharmacological treatment that can dampen maladaptive stress responses. The endocannabinoid system is one of the main regulators of the stress response. A basal endocannabinoid tone inhibits the stress response, modulation of this tone permits/curtails an active stress response, and chronic deficiency in the endocannabinoid tone is associated with the pathological complications of chronic stress. Cannabidiol is a safe exogenous cannabinoid enhancer of the endocannabinoid system that could be a useful treatment for stress. There have been seven double-blind placebo controlled clinical trials of CBD for stress on a combined total of 232 participants and one partially controlled study on 120 participants. All showed that CBD was effective in significantly reducing the stress response and was non-inferior to pharmaceutical comparators, when included. The clinical trial results are supported by the established mechanisms of action of CBD (including increased N-arachidonylethanolamine levels) and extensive real-world and preclinical evidence of the effectiveness of CBD for treating stress.


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