Arrestiny jsou významné intracelulární proteiny regulující G-protein-spřaženou receptorovou (GPCR) signalizaci. Tvoří komplexy s většinou GPCRs (po jejich aktivaci navázáním agonisty a fosforylaci) a hrají klíčovou roli v procesech receptorové homologní desenzitizace, sekvestrace a downregulace, které vedou k terminaci aktivace G-proteinů. V lidském organismu je zastoupeno deset typů arrestinů náležících do dvou skupin: mezi zrakové/beta arrestiny a alfa arrestiny. Nedávno bylo zjištěno, že skupina zrakových/beta arrestinů (která je tvořena čtyřmi členy: rod arrestinem, ß-arrestinem 1, ß-arrestinem 2 a cone arrestinem) je odvozena od nově objevených alfa arrestinů. Označení „alfa“ je velmi výstižné, tato skupina arrestinů je fylogeneticky starší a název je komplementární k názvu skupiny beta. Rod a cone arrestiny se nacházejí v buňkách sítnice, kde regulují funkci fotoreceptorů. ß-arrestiny jsou ubikvitně vyjádřeny, jejich nejvyšší koncentrace byly zjištěny v mozku a ve slezině. Kromě tradiční role v desenzitizaci (a následujících procesech) podporují ß-arrestiny též tvorbu signalizačních komplexů s tyrozinkinázou Src a s mitogenem-aktivovanými proteinkinázami, které umožňují G-protein-spřaženým receptorům signalizovat nezávisle na G-proteinech. V těchto kaskádách slouží jako „scaffolding“ a adaptorové proteiny a regulují buněčné procesy jako např. chemotaxi, apoptózu a metastázování. ß-arrestiny se tak stávají lákavým terapeutickým cílem pro léčbu některých nádorových onemocnění (např. karcinomu prsu, plic, kolorekta), alergického astmatu, hypertenze a dalších nemocí., Arrestins are important intracellular proteins, multifunctional regulators of G-protein-coupled receptor (GPCR) signaling. They form complexes with most GPCRs (following agonist binding and phosphorylation of receptors) and play a central role in the processes of homologous desensitization, sequestration and downregulation of receptors, which lead to termination of G-protein activation. Humans have ten arrestin subtypes pertaining to two subfamilies, visual/beta arrestins and alpha arrestins. Visual/beta subfamily (which contains four members: rod arrestin, ß-arrestin 1, ß-arrestin 2 and cone arrestin) was branched from new fi nding alpha arrestins relatively recently. “Alpha“ fi ts because this subfamily is ancient/ancestral, and it complements the name of the beta class. The rod and the cone arrestins are expressed in the retina, where they regulate photoreceptor function. The ß-arrestins are ubiquitously expressed proteins whose highest levels of expression are in the brain and spleen. Besides their role in desensitization (and following processes), ß-arrestins promote the formation of signaling complexes with tyrosine kinase Src and mitogen-activated protein kinase cascades allowing G-protein-coupled receptors to signal independently from G-protein. They serve as scaffold and adaptor proteins in these cascades and regulate cellular processes such as chemotaxis, apoptosis, and metastasis. Thus, novel therapies focused on these proteins may prove useful in the treatment of some cancer disorders (for example breast, lung, and colorectal carcinomas), allergic asthma, hypertension, etc., Fořtová M., Průša R., Zima T., and Lit.: 35
In many insect species with a pupa covered by various "shells" (puparium, host remains, etc.) pupal-adult ecdysis and emergence to the open air represent two discrete steps. However, in Trichogramma, as well as in other insect parasitoids, these two processes have never been studied separately. We investigated the temporal pattern of pupal-adult ecdysis and of adult emergence from the host chorion in Trichogramma embryophagum Hartig (Hymenoptera: Trichogrammatidae) in laboratory conditions (12L : 12D, 20°C). Adult ecdysis was arrhythmic, while adult emergence showed a strong rhythmicity. The time lag between ecdysis and emergence varied from one to almost two days, depending on the circadian time of the ecdysis. The proportion of ecdysed adults that stayed in the host chorion ranged up to 60% (just before the highest peak of emergence). The cumulative percentage of ecdysed adults gradually increased with time, independently of whether the light was turned on in accordance with the entrained circadian rhythm or 4 h earlier. This arrhythmic ecdysis could be explained by the fact that the ecdysed adults get into a well protected space inside the host chorion and the timing of this event is adaptively neutral.
Impaired cerebrovascular reactivity (CVR), an important risk factor for future stroke, is affected by a presence carotid stenosis. However, in some cases CVR can be impaired in the absence of carotid stenosis due to several poorly characterized mechanisms. We hypothesized that arterial stiffening as observed in coronary heart disease (CHD) could be associated with alteration in CVR in CHD patients without carotid stenosis. The study population consisted of patients referred for coronary angiography without significant carotid stenosis (<50 %). CVR was evaluated by breath holding index (BHI) measured with transcranial color code duplex ultrasound. Arterial stiffness was assessed by pulse wave velocity (PWV) measured by the oscillometric method. The extent of coronary atherosclerosis was quantified by Gensini score (GS). Out of 186 subjects, sixty-two patients fulfilled the inclusion and exclusion criteria. BHI decreased with increasing PWV (r = -0.47, p<0.001). Decrease in BHI was significantly inversely associated with GS (r = -0.61, p<0.001). GS was associated with PWV (p<0.001). In conclusion, impaired CVR was associated with increased arterial stiffening in CHD patients in the absence of significant carotid stenosis. Thus, we speculate that increased arterial stiffness may at least partially contribute to the pathophysiology of CVR alteration in coronary artery disease., D. Rucka, J. Marek, Z. Rucklova, J.-C. Lubanda, S. Havranek, J. Skvaril, P. Varejka, M. Chochola, D. Karetova, J. Korinek, A. Linhart., and Obsahuje bibliografii