bluuebunny/crossref_metadata_2025_split huggingface dataset:
LKB1/AMPK Signaling in the Diaphragm
Authors: Brown Jacob Daniel , Mongillo Anthony D. , DiGiovanni Ryan A. , Lane Matt D. , Winder William W. , Thomson David M. 
Published: June 2021

The LKB1/AMP‐Activated Protein Kinase (AMPK) signaling pathway is a major regulator of skeletal muscle metabolic processes. During exercise, LKB1‐mediated phosphorylation of AMPK leads to its activation, promoting mitochondrial biogenesis and glucose transport, among other effects. The roles of LKB1 and AMPK have not been characterized in the diaphragm. Two methods of AMPK activation were used to characterize LKB1/AMPK signaling in diaphragms from muscle‐specific LKB1 knockout (KO) and littermate control (C) mice: (1) acute injection of 5‐aminoimidazole‐4‐carboxamide ribonucleoside (AICAR) and (2) 5‐min direct electrical stimulation (ES) of the diaphragm. Diaphragms were excised 60 minutes post‐AICAR injection and immediately after ES. AMPK phosphorylation increased with AICAR and ES in C but not KO mice. Acetyl CoA Carboxylase (ACC) phosphorylation increased with AICAR in C but not KO mice, but increased in both genotypes with ES. No differences in Hexokinase 2 (HK2) levels were evident. CREB phosphorylation was lower in KO diaphragms. While Cytochrome C (Cyto C) levels were lower in KO diaphragms, Uncoupling Protein 3 (UCP‐3) levels were not different between genotypes. In conclusion, AMPK is activated in an LKB1‐dependent manner in the diaphragm by AICAR injection and direct ES.This study was supported by National Institute of Arthritis and Musculoskeletal and Skin Diseases Grant AR‐051928.
Interaction between Nicotine and Estradiol in Regulation of Gene Expression in Substantia Nigra (SN) in Animal Model of Parkinson's Disease (PD)
Authors: Serova Lidia I , Nostramo Regina , Maharjan Shreekrishna , Sabban Esther L 
Published: June 2021

The incidence of PD is two fold higher in men than in women. Nicotine (N), which reduces the risk of PD, exhibits sex specific effects. We found that injections of estradiol benzoate (EB) to ovariectomized (OVX) rats change the sensitivity of GTP cyclohydrolase I (GTPCH), the rate‐limiting enzyme for biosynthesis of essential co‐factor for tyrosine hydroxylase (TH), to N. We hypothesize that N and EB have interactive effects on physiology of SN in rats with PD at the level of regulation of GTPCH gene.PD rats were generated by infusion of 6‐OHDA in striatum of OVX rats. The control group received ascorbic acid. 6‐OHDA rats were injected with EB or vehicle (V) once daily for 13 days. EB or V treated rats were divided into two subgroups and from 14th day, in addition to EB or V, were administered saline or N every 12 hrs. Rats with 6‐OHDA lesions developed forelimb and sensory‐motor deficits while those with EB itself, and in combination with N, improved apomorphine induced rotation behavior. TH and GTPCH mRNA levels were lower in the SN of 6‐OHDA rats compared to controls. N restored both mRNAs in SN only in EB treated rats, with significant interactive effects for GTPCH mRNA. The improvement might be mediated by regulation of nAChR subtype expression. Significant interactive effects of N and EB were found on mRNA levels of α3, α6, α7 subunits of nAChR in SN of the PD rats.Supported by American Parkinson Disease Association.
N‐acetyl Glucosamine probe upon binding to endothelial lectins selectively modulate flow‐induced; cardiac contractility, A‐V delay and vascular smooth muscle tone
Authors: Ramiro‐Diaz Juan M , Barajas‐Espinosa Alma , Castillo‐Hernandez Jesus R , Torres‐Tirado David , Rubio Rafael 
Published: June 2021

Coronary flow modifies cardiac and vascular functions. Stress exerted by flow on the luminal capillary wall may be transduced by glycosidic and lectinic structures in the endothelial glycocalyx. To test this, we synthesized a monosaccharide polymer formed by N‐acetyl Glucosamine (Pol‐GlcNac) covalently linked to a 70 KDa dextran. This polymer was intracoronarily administered in perfused guinea pig hearts at increasing concentrations. Left intraventricular pressure (CC), and the Auricular‐Ventricular delay was (A‐VD) measured. Pol‐GlcNac increases the A‐VD and decreases the CC. The effect of this polymer was not easily washed. To visualize polymer binding sites, PolNGlc covalently linked to a dextran‐FITC was synthesized. Histological slices were made on polymer‐FITC perfused and subsequently washed hearts. Confocal microscopy revealed the polymer retained on vascular endothelium and coincided with factor VIII: an endothelial marker. These results demonstrate the presence of lectinic receptors with affinity to GlcNac.To establish that Pol‐GlcNac binding to endothelium can regulate flow‐induced release of paracrine agonists, we used isolated guinea pigs aortas perfused at different flows. Flow induced relaxation was measured and blocked by a combination of L‐NAME and indometacin, indicating the mediation of paracrine effectors. Pol‐GlcNac also blocked flow induced relaxations. This suggests thatPol‐GlcNac binding to the endothelial lumen blocks the flow‐induced paracrine mediators release.Funded by CONACyT SEP‐42567, CONACyT‐SALUD 2004‐C01‐156
Nociceptin/Orphanin FQ (N/OFQ) stimulated diuresis is mediated via inhibition of vasopressin secretion: a role for the hypothalamic paraventricular nucleus (PVN)
Authors: Wainford Richard David , Glatzer Nicholas R , Tasker Jeffrey G , Kapusta Daniel R 
Published: June 2021

The role(s) of vasopressin (AVP) and the hypothalamic PVN in mediating the diuretic response to intracerebroventricular (i.c.v.) and PVN microinjection of N/OFQ was examined in rats.MethodsN/OFQ was injected i.c.v. (5.5 nmol) in conscious instrumented Sprague‐Dawley rats (n=6/group) infused i.v. with isotonic saline (50 μl/min), AVP (170 pg/kg/min) or a V2‐ AVP receptor antagonist (10 nmol/kg/hr) and urine was collected for 80‐min (10‐min periods). In other studies, blood was collected 10‐min post‐i.c.v. or PVN (100 pmol) N/OFQ injection and assayed for AVP. N/OFQ peptide (NOP) receptor immunohistochemistry (IHC) was performed in rat brains expressing GFP in AVP neurons.ResultsI.c.v. and PVN injection of N/OFQ produced a profound diuresis (PVN N/OFQ peak diuresis; 40‐min, Δ164±22 μl/min, P<0.05) in rats. I.v. infusion of a V2‐receptor antagonist increased basal urine output and prevented a further i.c.v. N/OFQ‐induced diuresis. I.v. infusion of AVP reduced basal urine output and prevented the diuretic response to i.c.v. N/OFQ. In naïve rats, 10‐min post‐i.c.v. or PVN N/OFQ, plasma AVP levels were significantly reduced (i.c.v. vehicle, 2.2±0.2 pg/ml; i.c.v. N/OFQ, 1.4±0.1; PVN N/OFQ, 1.3±0.1 P<0.05). IHC studies demonstrated the presence of NOP receptors on AVP expressing PVN magnocellular neurons.ConclusionIn conscious rats, N/OFQ acts within the PVN, likely at the level of magnocellular neurons, to suppress AVP secretion and thereby produce diuresis. Supported by DK43337, HL 071212, AHA 0855293E, P20 RR018766 to DRK and NS042081 (JGT).
Renal NOS isoforms and splicing in 13 week obese female Zucker rats on antioxidant vs regular diet
Authors: Inman Sharon R , Slyvka Yuriy , Feldman Yelena , Nowak Felicia V 
Published: June 2021

NO and NOS activity are important for development of diabetic nephropathy and an antioxidant fortified (AO) diet may protect the kidney in the case of diabetes. Female obese Zucker rats (fa/fa) were studied at 13 weeks of age on regular (REG) and AO diets. AO diet was started at 4 weeks. NOS isoforms (n‐neuronal, e‐endothelial and i‐inducible) and their splice forms were tested with Western blot. The AO diet resulted in lower levels of all NOS isoforms both in kidney cortex and medulla compared to the REG diet. There was no significant difference in NOS expression between cortex and medulla in either group. The following splice forms were present in rat kidneys on AO diet: iNOS (122‐124, 77‐83, 72‐75 kDa), nNOS (110‐113, 76‐77, 68‐70 kDa), eNOS (110‐116, 73‐77, 66‐68 kDa). Animals on the REG diet had the following splice forms: iNOS (114‐118, 76‐79, 70‐72 kDa), nNOS (110‐114, 74‐79, 68‐72 kDa), eNOS (102‐103, 70‐72, 64‐66, 38 kDa). The difference between content of NOS isoforms is the result of an increase in the largest and smallest splice forms of eNOS and iNOS in kidney cortex. In medulla the difference is the result of increase of all splice forms for iNOS and nNOS, but for eNOS only the largest and smallest splice form increased and a new smaller additional 38 kDa form was seen in rats on the REG diet.ConclusionAO diet decreased the expression of NOS isoforms in kidneys in obese Zucker rats. Supported by NIH R15 DK073066 to SRI and FVN.
Increased intestinal secretory cell differentiation in mice administered total parenteral nutrition
Authors: Kechele Daniel O. , VanDussen Kelli L. , Feng Yongjia , Teitelbaum Daniel H. , Samuelson Linda C. 
Published: June 2021

Intestinal atrophy occurs when total parenteral nutrition (TPN) is used to supply nutrients directly into the blood instead of normal ingestion. The cellular basis for the intestinal remodeling has not been fully described. In this study we analyzed the jejunum of mice that received TPN for 7 days compared to freely‐fed sham‐operated and normal C57BL/6 controls. Intestine was characterized by histological staining to assess the four major epithelial cell types: goblet cells, endocrine cells, Paneth cells and enterocytes. PAS/alcian blue staining revealed a 1.5‐fold increase in the number of goblet cells. Moreover the staining characteristics showed a shift from acidic to neutral mucin production in the TPN goblet cells. Increased numbers of endocrine and Paneth cells were also suggested by immunohistochemical staining against the pan‐endocrine cell marker chromogranin A and the Paneth cell marker cryptdin. Thus, TPN administration induced an expansion of all three intestinal secretory cell types. Our findings suggest that TPN disturbed the normal differentiation of multipotential progenitors into secretory vs. absorptive cells, a process known to be regulated by Notch signaling. Future studies will analyze the expression of transcription factors known to be critical effectors of Notch‐mediated lineage determination to understand the mechanism of cellular remodeling in the TPN intestine.Funded by NIH.
ENaC trafficking via Rab‐dependent pathways
Authors: Karpushev Alexey , Levchenko Vladislav , Pavlov Tengis S , Lam Vy , Vinnakota Kalyan C , Wakatsuki Tetsuro , Staruschenko Alexander 
Published: June 2021

The epithelial Na+ channel (ENaC) is an essential channel responsible for Na+ reabsorption, and it is regulated by different signaling pathways, including small G proteins. Rab proteins are well‐established as a participant in the regulation of trafficking. Co‐expression of Rab11a and Rab3a with ENaC results in a significant increase in channel activity. Biochemical and imaging methods demonstrate that Rab11a colocalized with ENaC and increased ENaC activity by affecting the plasma membrane levels of this channel. Rab11a increases ENaC activity in an additive manner with dominant‐negative dynamin, which is a GTPase responsible for endocytosis. Brefeldin A, an inhibitor of intracellular protein translocation, blocked the stimulatory action of Rab11a on ENaC activity. This is consistent with a mechanism of increased trafficking toward the plasma membrane. We further demonstrate that coexpression of ENaC with Rab11a and SGK1 together had no effect on Rab11a dependent increase of ENaC activity suggesting that SGK1 might be involved into Rab11a dependent vesicle exocytosis. These results demonstrate a novel role for Rab small GTPases in the control of epithelial ion transport. We conclude that ENaC channels, present on the apical plasma membrane, are being exchanged with channels from the intracellular (recycling) endosomes in a Rab11‐dependent manner.Supported by AHA and ASN.
Mice presenting skeletal muscle hypertrophic phenotype driven by mIGF‐1 over‐expression have improved carbohydrate metabolism and insulin sensitivity.
Authors: Christoffolete Marcelo Augusto , de Oliveira‐Costa Monique , Okamoto Maristela M. , Turri Antonio , Lohmann Tania Ochi , Ribeiro Miriam Oliveira , Machado Ubiratan Fabres , Musarò Antonio , Moriscot Anselmo Sigari 
Published: June 2021

ObjectiveIn this study, we aim to characterize the metabolic profile of mice presenting higher muscle mass driven by mIGF‐1, a muscle specific trophic factor.MethodsWT and mIGF‐1 TG mice were obtained from our inbreed colony. O2 consumption and CO2 generation was determined in an open circuit respirometer. kITT (%/min) was determined by calculating the slope of the linear regression of neperian logarithm of glycemia values over time in a standard 15 min ivITT test using 0.125U/Kg of insulin. The results were expressed as mean±SEM.ResultsAs expected, 3 months old TG mice were heavier than age matched WT mice (33.3 + 0.3 vs 29.7 + 0.4 g, p<0.0001, n=9‐15, respectively). TG mice have a higher non‐protein respiratory quotient then WT (0.9 + 0.03 vs 0.74 + 0.02, p<0.001, n=7, respectively). This data suggested a preference for carbohydrate as major fuel source in TG mice. TG mice have a higher rate of glucose disposal when compared to WT (3.25 + 0.14 vs 2.39 + 0.03 %/min, p<0.01, n=3‐5, respectively). These data altogether reveals a shift in metabolism towards higher carbohydrate utilization and improved insulin sensitivity in mIGF‐1 TG mice.
Triolein‐induced renal arterial vasoconstriction and its reversal in a rat model
Authors: Patel Sapna , Adler F. , McIff T. , Poisner A. , Herndon B. , Quinn T. , Molteni A. 
Published: June 2021

Fat embolism syndrome (FES) is a respiratory process that may occur after bone fractures and is manifested by severe pulmonary vasoconstriction. It can be modeled in the rat by intravenous (iv) triolein. Our past work has shown the benefits of an ACE‐ inhibitor (captopril) or A2‐type 1 receptor blocker (losartan) on triolein treated pulmonary vessels. To investigate renal vascular effects of FES, we studied the histopathological changes in small arteries with and without treatment by these drugs (n=5/group). Rats received 0.2 ml triolein with necropsy at 24, 48, 96, or 264 hrs. Others received triolein and 50 mg/kg captopril or 10 mg/kg losartan with necropsy at 48 hrs (n=5/group). Saline controls were necropsied at 24 and 264 hrs (4‐5/group). At 400x, 3 vessels per high power field were digitally captured. The diameters of the lumen and medial wall were measured and statistically analyzed. Triolein vs control produced renal vasoconstriction up to 96 hr, p=0.03. Luminal dilation occurred at 48 hr in rats that received treatment with captopril or losartan. Lipid droplets were seen in the glomeruli at all times with the largest at 24 hr, progressively diminishing in size with time. Adventitial edema was evident in triolein‐dosed rats compared to controls (trend, p=0.09). This FES model produces renal vessel constriction that clears independently by 264 hrs. Treatment with captopril or losartan preserves vessel patency. This suggests the reversibility of FES‐related renal vascular changes, and, that the renin‐angiotensin system plays a role in its pathogenesis.Funding: MA & EJ Asher Orthopedic Research Endowment.
2‐APB mediated effects on hypoxic calcium influx in rat carotid body glomus cells
Authors: Lahiri Sukhamay , Patel Gopal , Baby Santhosh , Roy Arijit 
Published: June 2021

Hypoxia depolarizes the glomus cells of the carotid body and induces calcium rise which was reversed by 2‐APB, an inhibitor of store‐operated calcium channels situated in the endoplasmic reticulum (ER), whereas those by hypercapnia and high extracellular [K+] were not, although both hypoxia and hypercapnia depolarize the glomus cells. Hypoxia‐dependent calcium rise was triggered by a reduction of IP3‐receptors and 2‐APB significantly reversed this response. Further, mitochondrial inhibitions completely overlapped the 2‐APB inhibition, suggesting same mechanism of effects. Also, ATP elevated the [Ca2+]i in normoxia due to calcium influx and the release from the [Ca2+]i stores, both of which were inhibited by 2‐APB. This reaction, as revealed by 2‐APB, is unique and is due to possible involvement of phosphorylation mechanisms in hypoxia, and not operated in hypercapnia. Therefore we hypothesize that store‐operated calcium channels in the ER, where IP3 receptors reside, is reacted with 2‐APB and is critical for the inhibitory response. However, 2‐APB did not block hypercapnic‐ and high extracellular [K+]‐dependent calcium increase.Hypercapnia and high extracellular K+ have no access to this [Ca2+]i stores of ER, and hence have no effects.Supported by NIH grant 43413.
Effect of impact exercise on skeletal muscle and bone in OI model mice
Authors: Weber Bettina Anne , Ferreira J. Andries , Carleton Stephanie , McCambridge Amanda , Phillips Charlotte , Brown Marybeth 
Published: June 2021

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder in which mutations in type I procollagen genes result in bone deformity and fragility. The OI model mice (oim/+) are heterozygous for a null mutation in the COL1A2 gene of type I collagen and have reduced bone biomechanical integrity compared to wild type (WT) mice. Bone is inherently mechanosensitive, responding and adapting to its mechanical environment. Bone formation occurs in response to high mechanical loads; often changing its geometry to strengthen the skeleton. The largest physiological loads bones typically experience are from muscles. We postulate that even though the OI bone material is biomechanically weaker, the bone will respond to muscle loading, especially during pubertal growth to generate an inherently stronger bone. In a small pilot study, we characterized the muscle mass and contractile generating capacity of non‐exercised and exercised oim/+ mice. We found that therapeutic inclusion of impact exercise can lead to an increase in the contractile generating capacity of the gastrocnemius and soleus muscles as well as bone biomechanical integrity.This knowledge is important in our ultimate understanding of muscle and bone function in OI model mice and ultimately, humans with this disease.
Human Nat5/San, a novel protein expressing both N‐alpha and N‐epsilon acetyltransferase activity
Authors: Evjenth Rune Henrik , Hole Kristine , Karlsen Odd Andre , Ziegler Mathias , Arnesen Thomas , Lillehaug Johan R 
Published: June 2021

Protein acetylation is among the most common protein modifications in eukaryotic cells. There are two types of acetylation; N‐epsilon and N‐alpha which are performed by distinct types of enzymes. N‐epsilon acetylation is performed by histone acetyltransferases (HAT) targeting epsilon‐amino group of lysines within histone proteins, a central modification in regulating gene transcription.Protein N‐terminal acetylation is performed by different N‐terminal acetyltransferase complexes (NAT). In yeast, three different NAT complexes are identified. One of them; NatA, is composed of two main subunits; Ard1p (catalytic subunit) and Nat1p (auxiliary subunit). Nat5p is a third subunit physically associated with NatA, but with unknown functions.We wanted to investigate the substrates of hNat5. Purified recombinant hNat5 and oligopeptide substrates were mixed and separated with reverse phase HPLC to study hNat5 acetylation activity. We found that hNat5 prefers substrates with N‐termini Met‐Leu‐Xxx‐Pro. In addition, mass spectrometry analysis of hNat5 incubated with acetyl CoA, demonstrated that hNat5 has autoacetylation activity. Autoacetylation and acetylation of other subset of substrates indicate activity similar to HAT.In conclusion, we here present a novel human acetyltransferase, hNat5 with a dual activity targeting both N‐terminal (NAT activity) and lysine ‐ amino groups (HAT activity).
Adenovirus type 36 reduces fatty acid oxidation by increasing Cidec/FSP27
Authors: Wang Zhong Q , Zhang Xian H , Yu Yongmei , Cefalu william T 
Published: June 2021

It is well documented that adenovirus type 36 infection (Ad‐36) results in obesity. However, the molecular mechanism of Ad‐36 cause obesity remains unknown. Recent studies suggest that Cell death‐inducing DNA fragmentation factor‐alpha‐like effectors (CIDE) family proteins play important roles in modulating energy homeostasis, aging and the development of metabolic diseases such as obesity and diabetes. Cidec/FSP27 is one of Cide family identified as a novel lipid droplet‐associated protein in adipocytes.We sought to investigate the effect of Ad‐36 infection on fatty acid oxidation, Cidec/FSP27, PGC 1a, LPL, UCP3 and ACC protein abundance in primary cultured human skeletal muscle cells. Muscle cells were infected with various doses (1.9 ‐ 7.6 PFU/cells) of Ad‐36 and adenovirus type 2 (Ad‐2) with non‐lipogenesis as negative control as well as uninfected control.Our data show that Ad‐36 significantly reduces fatty acid oxidation with does dependant manner (100±7%, 62±9%, 56±11%, and 43±5% in control, 1.9, 3.8, 7.6 doses of Ad‐36, P<0.01 and P<0.001 respectively), but Ad‐2 had little effect on fatty acid oxidation (P>0.05). Ad‐36 at dose of 3.8 PFU/cell substantially increased Cidec/FSP27, ACC abundance, slightly decreased LPL and increased PCG 1a proteins comparison with control (3.37±0.4, 2.02±0.21, 0.74±0.04 and 1.82 ±0.47 fold respectively). Ad‐2 only slightly increased these proteins (1.27±0.13, 1.28 ±0.24, 1.07±0.07 and 1.26±0.14 fold of control, p>0.05 respectively).This study suggests that Ad‐36 promotes Cidec/FSP27 and ACC protein expression, and decreases LPL abundance. Ad‐36 reduces fatty acid oxidation and increases lipid accumulation in the muscle cells may be mediated by elevated Cidec/FSP27 protein.
Design and signaling mechanism of light‐regulated histidine kinases
Authors: Möglich Andreas , Ayers Rebecca A , Moffat Keith 
Published: June 2021

Signal transduction proteins are organized into sensor (input) domains that perceive a signal and, in response, regulate the biological activity of effector (output) domains. We reprogrammed the input signal specificity of a normally oxygen‐sensitive, light‐inert histidine kinase by replacing its chemosensor domain by a light‐oxygen‐voltage (LOV) photosensor domain. Illumination of the resultant fusion kinase YF1 reduced net kinase activity by ~1000‐fold in vitro. YF1 also controls gene expression in a light‐dependent manner in vivo. Signals are transmitted from the LOV sensor domain to the histidine kinase domain via a 40‐60º rotational movement within an α‐helical coiled coil linker; light is acting as a rotary switch. These signaling principles are broadly applicable to domains linked by α‐helices, and to both chemo‐ and photosensors. Conserved sequence motifs guide the rational design of light‐regulated variants of histidine kinases and other proteins.Funded by NIH grant GM036452 to K.M.