Function (Oxford, England)最新文献

{"title":"Are Scientists Sufficiently Ambitious? Season 2.","authors":"Ole H Petersen","doi":"10.1093/function/zqad032","DOIUrl":"https://doi.org/10.1093/function/zqad032","url":null,"abstract":"S © t a he article “Are scientists sufficiently ambitious?” 1 is by far the ost downloaded editorial so far published in Function , and I av e had mor e personal r eactions to this piece than to any other tem presented in the journal. The reactions have overwhelmngl y been positi v e, since most collea gues a gr ee that the pr obems highlighted in the editorial are critically important. Howver, some correspondents have also made the point that it is ot sufficient to identify the pr ob lems. Solutions are needed. ence, I am now revisiting the theme, to pr opose w ays forw ard hat could rectify an increasingly difficult situation. One of the main pr ob lems identified in the original editoial was the current funding system that encourages generaion of more and more data, resulting in biologists “drowning n a sea of data and starving for knowledge.” 2 Because it is more xpensi v e to generate new data than to provide context, modls, and theories and because Uni v ersities incr easingl y ev alute staff on the basis of how much money they bring into the nstitution (overheads are essential for the sustainability of Uniersities), scientists ar e chasing r esear c h gr ants at the expense f most other acti vities. Unfortunatel y, this acti vity has become ncr easingl y time consuming, not least because the pr oba bilty of rejection is high. Many applications are written to ensure hat at least a few are successful. Even for those who mange to secur e funding, grant writing is taking up far too much ime, and for the many who fail, it is of course a waste of time. urthermore, it is not only the applicants who lose v alua b le ime. The elaborate evaluation system, which is deemed necesary to select the “best” proposals, takes a wa y time from many xperienced scientists, who serve as re vie wers and grant panel embers, time that could have been used for primary resear c h ctivities. One of the reasons for the declining success rates for grant pplications is the substantial rise in the number of applicants. his is ultimately due to increasing numbers of PhD students,","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10290528/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9799305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Site and Mechanism of ML252 Inhibition of Kv7 Voltage-Gated Potassium Channels.","authors":"Richard Kanyo,&nbsp;Shawn M Lamothe,&nbsp;Arturo Urrutia,&nbsp;Samuel J Goodchild,&nbsp;W Ted Allison,&nbsp;Richard Dean,&nbsp;Harley T Kurata","doi":"10.1093/function/zqad021","DOIUrl":"https://doi.org/10.1093/function/zqad021","url":null,"abstract":"<p><p>Kv7 (KCNQ) voltage-gated potassium channels are critical regulators of neuronal excitability and are candidate targets for development of antiseizure medications. Drug discovery efforts have identified small molecules that modulate channel function and reveal mechanistic insights into Kv7 channel physiological roles. While Kv7 channel activators have therapeutic benefits, inhibitors are useful for understanding channel function and mechanistic validation of candidate drugs. In this study, we reveal the mechanism of a Kv7.2/Kv7.3 inhibitor, ML252. We used docking and electrophysiology to identify critical residues involved in ML252 sensitivity. Most notably, Kv7.2[W236F] or Kv7.3[W265F] mutations strongly attenuate ML252 sensitivity. This tryptophan residue in the pore is also required for sensitivity to certain activators, including retigabine and ML213. We used automated planar patch clamp electrophysiology to assess competitive interactions between ML252 and different Kv7 activator subtypes. A pore-targeted activator (ML213) weakens the inhibitory effects of ML252, whereas a distinct activator subtype (ICA-069673) that targets the voltage sensor does not prevent ML252 inhibition. Using transgenic zebrafish larvae expressing an optical reporter (CaMPARI) to measure neural activity in-vivo, we demonstrate that Kv7 inhibition by ML252 increases neuronal excitability. Consistent with in-vitro data, ML213 suppresses ML252 induced neuronal activity, while the voltage-sensor targeted activator ICA-069673 does not prevent ML252 actions. In summary, this study establishes a binding site and mechanism of action of ML252, classifying this poorly understood drug as a pore-targeted Kv7 channel inhibitor that binds to the same tryptophan residue as commonly used pore-targeted Kv7 activators. ML213 and ML252 likely have overlapping sites of interaction in the pore Kv7.2 and Kv7.3 channels, resulting in competitive interactions. In contrast, the VSD-targeted activator ICA-069673 does not prevent channel inhibition by ML252.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10278987/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9713064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxidation Driven Reversal of PIP₂-dependent Gating in GIRK2 Channels.","authors":"Sun-Joo Lee,&nbsp;Shoji Maeda,&nbsp;Jian Gao,&nbsp;Colin G Nichols","doi":"10.1093/function/zqad016","DOIUrl":"https://doi.org/10.1093/function/zqad016","url":null,"abstract":"<p><p>Physiological activity of G protein gated inward rectifier K⁺ (GIRK, Kir3) channel, dynamically regulated by three key ligands, phosphoinositol-4,5-bisphosphate (PIP₂), Gβγ, and Na⁺, underlies cellular electrical response to multiple hormones and neurotransmitters in myocytes and neurons. In a reducing environment, matching that inside cells, purified GIRK2 (Kir3.2) channels demonstrate low basal activity, and expected sensitivity to the above ligands. However, under oxidizing conditions, anomalous behavior emerges, including rapid loss of PIP₂ and Na⁺-dependent activation and a high basal activity in the absence of any agonists, that is now paradoxically inhibited by PIP₂. Mutagenesis identifies two cysteine residues (C65 and C190) as being responsible for the loss of PIP₂ and Na⁺-dependent activity and the elevated basal activity, respectively. The results explain anomalous findings from earlier studies and illustrate the potential pathophysiologic consequences of oxidation on GIRK channel function, as well as providing insight to reversed ligand-dependence of Kir and KirBac channels.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/47/88/zqad016.PMC10165546.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9753469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Locomotion Induces Fundamentally Different Patterns of Ca²⁺ Signaling in Astrocytes and Neurons.","authors":"Hajime Hirase,&nbsp;Maiken Nedergaard","doi":"10.1093/function/zqad028","DOIUrl":"https://doi.org/10.1093/function/zqad028","url":null,"abstract":"A modest literature links the onset of locomotion with increased intracellular calcium (Ca 2 + ) in neurons and astrocytes of the sensory and motor cortex, but a formal comparison of Ca 2 + responses in the two cell types has been lacking. The new study by Fedotova et al. 1 systematically compared Ca 2 + activity induced by locomotion in neurons and astrocytes of awake, behaving mice. A main strength of this study lies in the detailed analysis of Ca 2 + dynamics for the two cell types, in consideration of the coupled activity of neurons and astrocytes during spontaneous locomotion. The authors used recombinant adeno-associated viral (AAV) vectors to express the genetically encoded Ca 2 + sensor GCaMP6f selecti v el y in either astrocytes or excitator y neur ons (AA V5-gfaABC1D-cyto-GCaMP6f or AA V2/9-CamKII-GCaMP6f, r especti v el y) in the somatosensor y cortex. The mice were first trained to accommodate head-fixation to a mobile home cage device mounted on a microscope stage, with detection of locomotion onset by tr ac king softw","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10290529/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10109638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Capsaicin-Induced Endocytosis of Endogenous Presynaptic Ca_V2.2 in DRG-Spinal Cord Co-Cultures Inhibits Presynaptic Function.","authors":"Krishma H Ramgoolam, Annette C Dolphin","doi":"10.1093/function/zqac058","DOIUrl":"10.1093/function/zqac058","url":null,"abstract":"<p><p>The N-type calcium channel, Ca_V2.2 is key to neurotransmission from the primary afferent terminals of dorsal root ganglion (DRG) neurons to their postsynaptic targets in the spinal cord. In this study, we have utilized Ca_V2.2_HA knock-in mice, because the exofacial epitope tag in Ca_V2.2_HA enables accurate detection and localization of endogenous Ca_V2.2. Ca_V2.2_HA knock-in mice were used as a source of DRGs to exclusively study the presynaptic expression of N-type calcium channels in co-cultures between DRG neurons and wild-type spinal cord neurons. Ca_V2.2_HA is strongly expressed on the cell surface, particularly in TRPV1-positive small and medium DRG neurons. Super-resolution images of the presynaptic terminals revealed an increase in Ca_V2.2_HA expression and increased association with the postsynaptic marker Homer over time in vitro. Brief application of the TRPV1 agonist, capsaicin, resulted in a significant down-regulation of cell surface Ca_V2.2_HA expression in DRG neuron somata. At their presynaptic terminals, capsaicin caused a reduction in Ca_V2.2_HA proximity to and co-localization with the active zone marker RIM 1/2, as well as a lower contribution of N-type channels to single action potential-mediated Ca²⁺ influx. The mechanism of this down-regulation of Ca_V2.2_HA involves a Rab11a-dependent trafficking process, since dominant-negative Rab11a (S25N) occludes the effect of capsaicin on presynaptic Ca_V2.2_HA expression, and also prevents the effect of capsaicin on action potential-induced Ca²⁺ influx. Taken together, these data suggest that capsaicin causes a decrease in cell surface Ca_V2.2_HA expression in DRG terminals via a Rab11a-dependent endosomal trafficking pathway.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9761886/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9899621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Skeletal Muscle Nuclei in Mice are not Post-mitotic.","authors":"Agnieszka K Borowik, Arik Davidyan, Frederick F Peelor, Evelina Voloviceva, Stephen M Doidge, Matthew P Bubak, Christopher B Mobley, John J McCarthy, Esther E Dupont-Versteegden, Benjamin F Miller","doi":"10.1093/function/zqac059","DOIUrl":"10.1093/function/zqac059","url":null,"abstract":"<p><p>The skeletal muscle research field generally accepts that nuclei in skeletal muscle fibers (ie, myonuclei) are post-mitotic and unable to proliferate. Because our deuterium oxide (D₂O) labeling studies showed DNA synthesis in skeletal muscle tissue, we hypothesized that resident myonuclei can replicate <i>in vivo</i>. To test this hypothesis, we used a mouse model that temporally labeled myonuclei with GFP followed by D₂O labeling during normal cage activity, functional overload, and with satellite cell ablation. During normal cage activity, we observed deuterium enrichment into myonuclear DNA in 7 out of 7 plantaris (PLA), 6 out of 6 tibialis anterior (TA), 5 out of 7 gastrocnemius (GAST), and 7 out of 7 quadriceps (QUAD). The average fractional synthesis rates (FSR) of DNA in myonuclei were: 0.0202 ± 0.0093 in PLA, 0.0239 ± 0.0040 in TA, 0.0076 ± 0. 0058 in GAST, and 0.0138 ± 0.0039 in QUAD, while there was no replication in myonuclei from EDL. These FSR values were largely reproduced in the overload and satellite cell ablation conditions, although there were higher synthesis rates in the overloaded PLA muscle. We further provided evidence that myonuclear replication is through endoreplication, which results in polyploidy. These novel findings contradict the dogma that skeletal muscle nuclei are post-mitotic and open potential avenues to harness the intrinsic replicative ability of myonuclei for muscle maintenance and growth.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9772608/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9939565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring Integrins in Smooth Muscle Function: Addressing Challenging Levels of Complexity and Deciphering Organ-specific Codes of Contraction?","authors":"Martin Hennenberg","doi":"10.1093/function/zqac053","DOIUrl":"10.1093/function/zqac053","url":null,"abstract":"","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2022-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/38/7e/zqac053.PMC9646521.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10487220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ER Redox Homeostasis Regulates Proinsulin Trafficking and Insulin Granule Formation in the Pancreatic Islet β-Cell.","authors":"Kristen E Rohli,&nbsp;Cierra K Boyer,&nbsp;Shelby C Bearrows,&nbsp;Marshall R Moyer,&nbsp;Weston S Elison,&nbsp;Casey J Bauchle,&nbsp;Sandra E Blom,&nbsp;Jianchao Zhang,&nbsp;Yanzhuang Wang,&nbsp;Samuel B Stephens","doi":"10.1093/function/zqac051","DOIUrl":"10.1093/function/zqac051","url":null,"abstract":"<p><p>Defects in the pancreatic β-cell's secretion system are well-described in type 2 diabetes (T2D) and include impaired proinsulin processing and a deficit in mature insulin-containing secretory granules; however, the cellular mechanisms underlying these defects remain poorly understood. To address this, we used an in situ fluorescent pulse-chase strategy to study proinsulin trafficking. We show that insulin granule formation and the appearance of nascent granules at the plasma membrane are decreased in rodent and cell culture models of prediabetes and hyperglycemia. Moreover, we link the defect in insulin granule formation to an early trafficking delay in endoplasmic reticulum (ER) export of proinsulin, which is independent of overt ER stress. Using a ratiometric redox sensor, we show that the ER becomes hyperoxidized in β-cells from a dietary model of rodent prediabetes and that addition of reducing equivalents restores ER export of proinsulin and insulin granule formation and partially restores β-cell function. Together, these data identify a critical role for the regulation of ER redox homeostasis in proinsulin trafficking and suggest that alterations in ER redox poise directly contribute to the decline in insulin granule production in T2D. This model highlights a critical link between alterations in ER redox and ER function with defects in proinsulin trafficking in T2D. Hyperoxidation of the ER lumen, shown as hydrogen peroxide, impairs proinsulin folding and disulfide bond formation that prevents efficient exit of proinsulin from the ER to the Golgi. This trafficking defect limits available proinsulin for the formation of insulin secretory granules during the development of T2D.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/e4/0d/zqac051.PMC9614934.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10491242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondrial Telomerase Reverse Transcriptase, a Target for Cardiovascular Disease?","authors":"Keiichi Torimoto, Satoru Eguchi","doi":"10.1093/function/zqac047","DOIUrl":"10.1093/function/zqac047","url":null,"abstract":"","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/23/39/zqac047.PMC9508814.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10486962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Adaptable Physiological Model of Endocytic Megalin Trafficking in Opossum Kidney Cells and Mouse Kidney Proximal Tubule.","authors":"Katherine E Shipman, Kimberly R Long, Isabella A Cowan, Youssef Rbaibi, Catherine J Baty, Ora A Weisz","doi":"10.1093/function/zqac046","DOIUrl":"10.1093/function/zqac046","url":null,"abstract":"<p><p>The cells that comprise the proximal tubule (PT) are specialized for high-capacity apical endocytosis necessary to maintain a protein-free urine. Filtered proteins are reclaimed via receptor-mediated endocytosis facilitated by the multiligand receptors megalin and cubilin. Despite the importance of this pathway, we lack a detailed understanding of megalin trafficking kinetics and how they are regulated. Here, we utilized biochemical and quantitative imaging methods in a highly differentiated model of opossum kidney (OK) cells and in mouse kidney in vivo to develop mathematical models of megalin traffic. A preliminary model based on biochemically quantified kinetic parameters was refined by colocalization of megalin with individual apical endocytic compartment markers. Our model predicts that megalin is rapidly internalized, resulting in primarily intracellular distribution of the receptor at steady state. Moreover, our data show that early endosomes mature rapidly in PT cells and suggest that Rab11 is the primary mediator of apical recycling of megalin from maturing endocytic compartments. Apical recycling represents the rate-limiting component of endocytic traffic, suggesting that this step has the largest impact in determining the endocytic capacity of PT cells. Adaptation of our model to the S1 segment of mouse PT using colocalization data obtained in kidney sections confirms basic aspects of our model and suggests that our OK cell model largely recapitulates in vivo membrane trafficking kinetics. We provide a downloadable application that can be used to adapt our working parameters to further study how endocytic capacity of PT cells may be altered under normal and disease conditions.</p>","PeriodicalId":73119,"journal":{"name":"Function (Oxford, England)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/ac/52/zqac046.PMC9614980.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10500127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}