92 research outputs found
Activity-dependent and -independent control of circadian rhythms in mammalian skeletal muscle
No full textAutonomous biological rhythms allow organisms to coordinate internal processes with environmental conditions. Mammals exhibit a diverse array of both behavioral and physiological rhythms that are generated by an endogenous molecular timing system composed of a central pacemaker within the suprachiasmatic nucleus (SCN) of the hypothalamus in addition to autonomous oscillators within the cells of peripheral tissues. Previous reports have shown that clock-controlled outputs are essential for the temporally coordinated execution of many tissue-specific functions, yet specific entrainment pathways for skeletal muscle, a peripheral tissue that accounts for the majority of daily energy consumption, remain largely speculative. Studies suggest that both neural and humoral factors contribute to phase-coordinate the expression of rhythmic genes in peripheral tissues, and locomotor activity, autonomic innervation and metabolic signals resulting from food availability are all probable mediators of rhythmic gene expression in skeletal muscle. Here we investigated entrainment of the skeletal muscle core oscillator by selectively manipulating each proposed pathway in vivo while monitoring expression profiles of the core clock genes Bmal1, Per1 and Per2. Monitoring circadian nucleocytoplasmic shuttling and transcriptional activity of the nerve activity-dependent sensor NFAT, we demonstrate that while some rhythmically expressed genes are strictly activity-dependent, motor innervation is not an important factor regulating phase entrainment of the core oscillator. Similarly, a chemical sympathectomy with 6-OHDA failed to significantly alter the phase of the core clock genes. However, two weeks of a restricted feeding schedule significantly shifted the phase of Bmal1 expression in skeletal muscle as in liver, while, surprisingly, both Per1 and Per2 expression lost rhythmicity. These results clearly show that the circadian transcriptome in skeletal muscle is composed of both activity-dependent and –independent genes, and furthermore, that entrainment of the skeletal muscle circadian oscillator depends on metabolic factors rather than on neural activity.I ritmi biologici autonomi permettono agli organismi di coordinare i processi interni con le condizioni ambientali. I mammiferi mostrano diversi tipi di ritmi comportamentali e fisiologici, che sono generati da un orologio molecolare endogeno composto da un “pacemaker” centrale presente all'interno del nucleo soprachiasmatico (SCN) dell'ipotalamo e degli oscillatori autonomi all'interno delle cellule dei tessuti periferici. Studi precedenti hanno indicato che i segnali generati da questo sono essenziali per la coordinazione temporale di molte funzioni tessuto-specifiche. Tuttavia, rimane in gran parte speculativo quale sia ruolo specifico di questo sistema nel muscolo scheletrico, un tessuto periferico in cui avviene la maggior parte del consumo di energia quotidiano. Alcuni studi suggeriscono che sia i fattori neuronali che quelli umorali contribuiscono all'espressione dei geni ritmici nei tessuti periferici e dall'attività locomotoria e che l’innervazione autonoma ed i segnali metabolici regolati dalla disponibilità di cibo sono i probabili mediatori dell'espressione di geni ritmici nel muscolo scheletrico. In questo lavoro di tesi abbiamo studiato il ruolo dell’orologio biologico nel muscolo scheletrico, analizzando selettivamente ogni via di segnale proposta “in vivo” e controllando i profili di espressione dei geni dell'orologio Bmal1, Per1 e Per2. L’osservazione della traslocazione circadiana nucleo-citoplasma e l’attività trascrizionale del fattore NFAT, un sensore dell’attività nervo-dipendente, ci ha permesso di dimostrare che l’espressione dei geni dell’orologio e’ direttamente correlato con l’attività e che l’innervazione non e’ essenziale nella regolazione dell’orologio biologico. Similmente, l’uso di un composto chimico (6-hydroxydopamine) non ci ha permesso di alterare significativamente la fase dei geni dell'orologio. Tuttavia, sottoponendo gli animali a due settimane di programma d'alimentazione limitato abbiamo osservato un significativo spostamento di fase dell’espressione Bmal1 nel muscolo scheletrico e nel fegato, mentre, l’espressione sia di Per1 che di Per2 ha perso la fase di ritmo. Questi risultati indicano chiaramente che la transcritoma circadiano nel muscolo scheletrico comprende sia geni attività-dipendente che indipendente e, che l’oscillazioni dell’orologio circadiano nel muscolo scheletrico dipendono dai fattori metabolici e non dall’attività neuronale
Skeletal muscle mass is controlled by the MRF4-MEF2 axis.
No full textPurpose of reviewThe review is focused on the unexpected role of myogenic regulatory factor 4 (MRF4) in controlling muscle mass by repressing myocyte enhancer binding factor 2 (MEF2) activity in adult skeletal muscle, and on the emerging role of MEF2 in skeletal muscle growth.Recent findingsThe MRF4s of the MyoD family (MyoD, MYF5, MRF4, myogenin) and the MEF2 factors are known to play a major role in embryonic myogenesis. However, their function in adult muscle tissue is not known. A recent study shows that MRF4 loss in adult skeletal muscle causes muscle hypertrophy and prevents denervation atrophy. This effect is mediated by MEF2 factors that promote muscle growth, with MRF4 acting as a repressor of MEF2 activity. The role of MEF2 in skeletal muscle growth is supported by the finding that muscle regeneration is impaired by muscle-specific triple knockout of Mef2a, c, and d genes.SummaryThe finding that the MRF4-MEF2 axis controls muscle growth opens a new perspective for preventing muscle wasting. A unique feature of this pathway is that MRF4 is exclusively expressed in skeletal muscle, thus reducing the risk that interventions aimed at down-regulating MRF4 or interfering with the interaction between MRF4 and MEF2 may have off-target effects in other tissues
The functional significance of the skeletal muscle clock: Lessons from Bmal1 knockout models
No full textThe circadian oscillations of muscle genes are controlled either directly by the intrinsic muscle clock or by extrinsic factors, such as feeding, hormonal signals, or neural influences, which are in turn regulated by the central pacemaker, the suprachiasmatic nucleus of the hypothalamus. A unique feature of circadian rhythms in skeletal muscle is motor neuron-dependent contractile activity, which can affect the oscillation of a number of muscle genes independently of the muscle clock. The role of the intrinsic muscle clock has been investigated using different Bmal1 knockout (KO) models. A comparative analysis of these models reveals that the dramatic muscle wasting and premature aging caused by global conventional KO are not present in muscle-specific Bmal1 KO or in global Bmal1 KO induced in the adult, therefore must reflect the loss of Bmal1 function during development in non-muscle tissues. On the other hand, muscle-specific Bmal1 knockout causes impaired muscle glucose uptake and metabolism, supporting a major role of the muscle clock in anticipating the sleep-to-wake transition, when glucose becomes the predominant fuel for the skeletal muscle
Raw "origscale" 24-h metabolomics intensity data from 8 different murine tissues under chow or high fat diet
No full textRaw 24-h metabolomic intensity data from 8 different murine tissues: suprachiasmatic nucleus (SCN), medial prefrontal cortex (mPFC), gastrocnemius skeletal muscle, interscapular brown adipose tissue (BAT), epididymal white adipose tissue (WAT), liver, serum, and cauda epididymal sperm. Six week old male C57BL6/J mice were purchased from JAX / Jackson Labs (Stock Number: 000664). Mice were were randomly assigned to experimental groups, maintained on a 12hr light/12hr dark cycle (ZT0 corresponds to lights on and ZT12 to lights off in the animal facility), and fed ad libitum for 10 weeks with either standard chow diet (Prolab RMH 2500) or high fat diet (HFD) composed of 60% Kcal from fat (Research Diets, D12492). Animals were separated into individual cages 1 week before tissue collection. Five male mice for each time point/diet were used. Tissues were immediately collected after cervical dislocation and stored at -80°C until further processing/analysis. Serum was prepared from an abdominal/thoracic blood sample and stored at -80°C. Sperm was collected after swimming out from the caudal portion of the epididymis in non-capacitating media (MEM without BSA) for 10min at 37°C.Non-targeted metabolite profiling, peak identification, and curation was performed by Metabolon (Durham, NC, USA) and by the Genome Analysis Center (GAC), Helmholtz Zentrum München (Neuherberg, Germany). Liver, serum, and sperm were processed and run by Metabolon on an HD3 system using described methods (Abbondante et al., 2016; Eckel-Mahan et al., 2012). Briefly, this analytical system combines a Linear Ion Trap MS/MS (LTQ XL, Thermo Scientific) coupled with UPLC (Acquity, Waters), and consists of 2 reverse phase (RP)/UPLC-MS/MS methods: 1) with positive ion mode electrospray ionization (ESI) optimized for acidic species, and 2) with negative ion mode ESI optimized for basic species. An additional GC/MS platform for volatile compounds was used in parallel. WAT and BAT samples were processed and run by the GAC on the same analytical system, with the exception of the GC/MS platform, and with curation again performed by Metabolon. Skeletal muscle and brain tissues (SCN & mPFC) were processed and run by Metabolon on their HD4 platform, which runs with High Resolution Accurate Mass (HRAM) MS/MS (QExactive, Thermo Scientific) also coupled with UPLC (Acquity, Waters). Overall, we processed and analyzed a total of 70 tissues each of liver, serum, BAT, and WAT (5 replicates x 2 groups x 7 time points, including additional time point ZT24), and 60 tissues each for SCN, mPFC, gastrocnemius skeletal muscle, and sperm (5 replicates x 2 groups x 6 time points). One biological replicate each from chow-fed SCN at ZT20 and from HFD-fed mPFC at ZT4 were lost during sample processing, leaving 4 remaining replicates each for these particular time points/diets. Two biological replicates from chow-fed mPFC at ZT4 were likewise lost, leaving 3 remaining replicates
NFAT isoforms control activity-dependent muscle fiber type specification
No full textThe intracellular signals that convert fast and slow motor neuron activity into muscle fiber type specific transcriptional programs have only been partially defined. The calcium/calmodulin-dependent phosphatase calcineurin (Cn) has been shown to mediate the transcriptional effects of motor neuron activity, but precisely how 4 distinct muscle fiber types are composed and maintained in response to activity is largely unknown. Here, we show that 4 nuclear factor of activated T cell (NFAT) family members act coordinately downstream of Cn in the specification of muscle fiber types. We analyzed the role of NFAT family members in vivo by transient transfection in skeletal muscle using a loss-of-function approach by RNAi. Our results show that, depending on the applied activity pattern, different combinations of NFAT family members translocate to the nucleus contributing to the transcription of fiber type specific genes. We provide evidence that the transcription of slow and fast myosin heavy chain (MyHC) genes uses different combinations of NFAT family members, ranging from MyHC-slow, which uses all 4 NFAT isoforms, to MyHC-2B, which only uses NFATc4. Our data contribute to the elucidation of the mechanisms whereby activity can modulate the phenotype and performance of skeletal muscle
Description of New Morphological Variation of Culex (Culex) coronator Dyar and Knab, 1906 and First Report of Culex (Carrollia) bonnei Dyar, 1921 Found in the Central Region of Peru
No full textPublisher Copyright: © The Author(s) 2024.Mosquitoes (Diptera: Culicidae) pose a significant threat to public health worldwide, especially in tropical and subtropical regions, where they act as primary vectors in transmission of infectious agents. In Peru, 182 culicid species have been identified and several species of the genus Culex are known to transmit arboviruses. However, knowledge of mosquito diversity and distribution remains limited, with many studies focusing on specific regions only. Here, we describe a new morphological variation of Cx. (Culex) coronator Dyar and Knab, 1906, and report the presence of Culex (Carrollia) bonnei Dyar, 1921 in the central region of Peru, Huanuco. Specimens were obtained through larvae collections and identified through morphologic characterization, including dissection of male genitalia, and molecular analyses. In total, 17 mosquitoes were analyzed, and the genitalia of the male specimens allowed the identification of Cx. coronator and Cx. bonnei. Partial sequences of the CoxI gene corresponding to these two species were obtained (N = 10). Phylogenetic analysis revealed that the sequences of Cx. coronator grouped in a monophyletic clade with sequences ascribed to other species corresponding to the subgenus Carrollia, while Cx. bonnei specimens formed a monophyletic clade with homologous sequences from GenBank. This study underscores the importance of continued efforts to study the diversity and distribution of mosquitoes in Peru, including their potential role as vectors of human pathogens, to underpin effective disease control and prevention strategies, highlighting the importance of a complemented morphological and molecular analysis.publishersversionpublishe
Wyeomyia (Dodecamyia) aphobema Dyar 1918
No full textWyeomyia (Dodecamyia) aphobema Dyar OUR SpEcImENS HaVE all THE cHaRacTERS dEScRIbEd IN LaNE (1953), aNd WERE IdENTIfIEd USINg THE KEY bY THaT aUTHOR. THE IdENTIfIcaTION WaS baSEd ON malE gENITalIa aNd fOURTH-INSTaR laRVaE (FIg. 2E,F,G,H). MalES Of Wy. (Dod.) aphobema aRE IdENTIfIablE bY HaVINg THE gONOcOXITE WITH a ROW Of 8 STRONg SETaE aNd lONg, cURVEd, SpaRSE ONES ON THE mIdlINE; gONOSTYlUS SImplE, ONE-fOURTH THE lENgTH Of THE gONOcOXITE, SlIgHTlY THIcKENEd apIcallY; gONOSTYlaR claW WITH 2 dIffERENTIaTEd TEETH; NINTH TERgUm WITH a VERY NaRROW cONcaVE INTERlObUlaR SpacE, EacH lObE WITH 4 OR 5 bROad cURVEd SETaE WITH pOINTEd apIcES, THE mESal ONES lOWER ON THE lObE THaN THE OUTER ONES. Bionomics and distribution. LaRVaE WERE cOllEcTEd fROm bROmElIad aXIlS. Wyeomyia aphobema IS alSO REcORdEd fROm BOlIVIa, BRazIl, COlOmbIa, EcUadOR, FRENcH GUIaNa, GUYaNa, PERU aNd SURINamE (WalTER REEd BIOSYSTEmaTIcS UNIT, 2013). Collection data. MISIONES PROVINcE: EldORadO, 10-V-2016, 2M, LE, PE, MG, 16-VII-2016, 1F, LE, PE. AlONSO cOll.; MOTTa aNd STEIN dET. SpEcImENS IMR.CUL 10-006 TO -009.Published as part of Stein, Marina, Alvarez, Carla N., Alonso, Ana C., Bangher, Débora N., Willener, Juana A. & Campos, Raúl E., 2018, New records of mosquitoes (Diptera: Culicidae) found in phytotelmata in Northern Argentina, pp. 87-100 in Zootaxa 4399 (1) on page 89, DOI: 10.11646/zootaxa.4399.1.5, http://zenodo.org/record/120647
Comparative analysis of muscle hypertrophy models reveals divergent gene transcription profiles and points to translational regulation of muscle growth through increased mTOR signaling
No full textSkeletal muscle mass is a result of the balance between protein breakdown and protein synthesis. It has been shown that multiple conditions of muscle atrophy are characterized by the common regulation of a specific set of genes, termed atrogenes. It is not known whether various models of muscle hypertrophy are similarly regulated by a common transcriptional program. Here, we characterized gene expression changes in three different conditions of muscle growth, examining each condition during acute and chronic phases. Specifically, we compared the transcriptome of Extensor Digitorum Longus (EDL) muscles collected (1) during the rapid phase of postnatal growth at 2 and 4 weeks of age, (2) 24 h or 3 weeks after constitutive activation of AKT, and (3) 24 h or 3 weeks after overload hypertrophy caused by tenotomy of the Tibialis Anterior muscle. We observed an important overlap between significantly regulated genes when comparing each single condition at the two different timepoints. Furthermore, examining the transcriptional changes occurring 24 h after a hypertrophic stimulus, we identify an important role for genes linked to a stress response, despite the absence of muscle damage in the AKT model. However, when we compared all different growth conditions, we did not find a common transcriptional fingerprint. On the other hand, all conditions showed a marked increase in mTORC1 signaling and increased ribosome biogenesis, suggesting that muscle growth is characterized more by translational, than transcriptional regulation
Toxorhynchites (Lynchiella) theobaldi Dyar & Knab
No full text<i>Toxorhynchites</i> (<i>Lynchiella</i>) <i>theobaldi</i> Dyar & Knab <p> OUR SpEcImENS HaVE all THE cHaRacTERS dEScRIbEd IN DaRSIE (1985), aNd THE SINglE fEmalE (FIg. 5B) aNd THE laRVal EXUVIaE WERE IdENTIfIEd USINg THE KEY bY THaT aUTHOR. THE fEmalE Of <i>Tx. theobaldi</i> maY bE dISTINgUISHEd fROm THE OTHER SpEcIES Of THE SUbgENUS <i>Lynchiella</i> bY HaVINg abdOmINal STERNa WITHOUT TUfTS Of REd ScalES, aNd mIdTaRSOmERE 3 aNd HINdTaRSOmERE 4 WITH WHITE ScalES.</p> <p> <b>Bionomics and distribution.</b> A SINglE laRVa WaS cOllEcTEd fROm aN INTERNOdE Of a <i>Guadua</i> SpEcIES Of bambOO. CURRENT dISTRIbUTION IN CENTRal aNd SOUTH AmERIca: ARgENTINa, BElIzE, BOlIVIa, BRazIl, COlOmbIa, COSTa RIca, EcUadOR, El SalVadOR, GUaTEmala, HONdURaS, MEXIcO, NIcaRagUa, PaNama, PaRagUaY, TRINIdad aNd TObagO, VENEzUEla (WalTER REEd BIOSYSTEmaTIcS UNIT, 2013; ROSSI, 2015). <i>Toxorhynchites theobaldi</i> WaS REcORdEd pREVIOUSlY fROm BUENOS AIRES, CHacO, FORmOSa, MISIONES aNd SalTa pROVINcES. IT IS REcORdEd HERE fROm CORRIENTES PROVINcE.</p> <p> <b>Collection data.</b> CORRIENTES PROVINcE: SaN CaYETaNO, RIacHUElO, 5-VI-2015, 1F, LE, PE. AlVaREz cOll. aNd dET. SpEcImENS IMR. CUL 22-004.</p>Published as part of <i>Stein, Marina, Alvarez, Carla N., Alonso, Ana C., Bangher, Débora N., Willener, Juana A. & Campos, Raúl E., 2018, New records of mosquitoes (Diptera: Culicidae) found in phytotelmata in Northern Argentina, pp. 87-100 in Zootaxa 4399 (1)</i> on page 96, DOI: 10.11646/zootaxa.4399.1.5, <a href="http://zenodo.org/record/1206470">http://zenodo.org/record/1206470</a>
Effect of timed dosing of usual antihypertensives according to patient chronotype on cardiovascular outcomes:the Chronotype sub-study cohort of the Treatment in Morning versus Evening (TIME) study
No full textBackground: Timing drug administration to endogenous circadian rhythms may enhance treatment efficacy. In the Chronotype sub-study of the Treatment in Morning versus Evening (TIME) clinical trial we examined whether timing of usual antihypertensive medications according to patient chronotype (a behavioural marker of personal circadian rhythm) may influence clinical cardiovascular outcomes.Methods: This was a cohort sub-study of TIME, a prospective, randomised, open-label, blinded-endpoint, UK clinical trial of morning versus evening dosing of usual antihypertensive medications and cardiovascular outcomes. On August 3rd, 2020, all active TIME participants were invited to complete a validated chronotype questionnaire. Chronotype was quantitatively assessed as the mid sleep time on free days corrected for sleep debt on workdays (MSFsc). We analysed associations between chronotype and antihypertensive dosing time and explored their combined effect on cardiovascular outcomes (a composite endpoint of hospitalisation for non-fatal myocardial infarction (MI) or non-fatal stroke, and single components) using proportional hazard time-to-event models adjusted for baseline covariates. These were used to specifically test for interactions between dosing time and chronotype.Findings: Between August 3, 2020, and March 31, 2021, 5358 TIME participants completed the online questionnaire. 2778 were previously randomised to morning dosing and 2580 to evening dosing of their usual antihypertensives. Chronotype was symmetrically distributed around a median MSFsc of 3:07 am. The composite endpoint increased for later MSFsc (later chronotype) dosed in the morning but not in those dosed in the evening (hazard ratios 1.46 [95% CI 1.14-1.86] and 0.96 [95% CI 0.70-1.30] per hour of MSFsc, respectively; interaction p = 0.036). Later chronotype was associated with increased risk of hospitalisation for non-fatal MI in the morning dosing group, and reduced risk in the evening dosing group (hazard ratios 1.62 [95% CI 1.18-2.22] and 0.66 [95% CI 0.44-1.00] per hour of MSFsc, respectively; interaction p < 0.001). No interaction between chronotype and antihypertensive dosing time was observed for stroke events.Interpretation: Alignment of dosing time of usual antihypertensives with personal chronotype could lower the incidence of non-fatal MI compared to a 'misaligned' dosing time regimen. Future studies are warranted to establish whether synchronizing administration time of antihypertensive therapy with individual chronotype reduces risk of MI.</p
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