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No description available.

Cancer cachexia is a debilitating, paraneoplastic syndrome commonly associated with late stage malignancy. It is estimated that ~25% of cancer-related deaths are due directly to complications arising from cachexia (Barton, 2001). Cachexia manifests as severe body wasting, primarily due to the loss of skeletal muscle mass. This study tested the hypothesis that muscle atrophy associated with cancer cachexia could be attenuated by using a unilateral, functional overload (FO) model applied concurrently with tumor development. To accomplish this, Morris hepatoma MH-7777 cells were implanted in adult female, Buffalo rats (n = 12) and allowed to incubate for 6 weeks. FO surgeries (n = 12) were performed five days prior to MH-7777 cell implantation. Over the course of six weeks, healthy, age, sex and strain-matched, vehicle-injected rats (n = 12) gained ~5% of body weight compared to tumor-bearing rats that lost ~6% of body weight when adjusted for tumor mass. Tumor-bearing animals experienced significant atrophy to gastrocnemius, tibialis anterior, extensor digitorum longus, plantaris and diaphragm muscles. FO successfully reversed plantaris muscle atrophy in cachectic, tumor-bearing rats (n=5). FO plantaris masses were ~24% larger than contralateral controls. However, this hypertrophic response was not as great as FO plantaris muscles from healthy, sham-operated controls (~44% larger than contralateral controls, n=5). FO plantaris muscles from tumor-bearing rats had ~1.5 fold increase in myonuclei/fiber ratios compared those of sham-operated, tumor-bearing controls (n = 6). Therefore, cancer cachexia did not prevent myonuclear accretion necessary for skeletal muscle hypertrophy. Little data exists on adaptations to myosin heavy chain (MHC) isoforms in cachectic skeletal muscle. Plantaris muscles from tumor-bearing rats displayed decreased percentages of MHC type I compared to plantaris muscles from vehicle-injected controls (7% vs. 3%, respectively). However, FO plantaris muscles from tumor-bearing rats had an increased percentage of MHC type I and decreased percentage of MHC type IIb compared to sham-operated tumor-bearing rats, adaptations commonly seen in trained muscles. Therefore, cancer cachexia did not prevent the capability of skeletal muscle to respond normally to hypertrophic stimuli. This study also attempted to characterize a mechanism responsible for the hypertrophic response, increased myonuclei/fiber ratio and transition toward a slower MHC profile in FO plantaris muscles from tumor-bearing rats. Recently, the Ca2+/calmodulin-dependent protein phosphatase, calcineurin, has been suggested as a critical factor regulating skeletal muscle growth and fiber-type dependent gene expression (Chin, 1998; Wu, 2000; Olson, 2000; Otis, 2001). The protein content of the catalytic subunit (CaNa) and the regulatory subunit (CaNb) of calcineurin were unchanged in plantaris muscles from tumor-bearing animals compared to healthy controls. Furthermore, total and specific (normalized to CaNa protein content) calcineurin phosphatase activity were not altered in any group. Therefore, calcineurin activity did not appear to be associated with the regulation of the morphological and physiological response of hypertrophying plantaris muscles in cachectic, tumor-bearing rats. Overall, this study indicated that atrophied plantaris muscles from tumor-bearing animals have a reduced capacity to hypertrophy potentially due to a decreased myonuclei/fiber ratio. Furthermore, it is unlikely that changes to mass and MHC isoform expression are associated with calcineurin phosphatase activity. / Ph. D.

Force regulation at the level of the actin-myosin cross-bridge (XB) can be described by a 2 state model in which the XB's cycle between a strongly bound (SB), force generating state and a weakly bound (WB), non-force generating state. This cycle can be characterized by the apparent rate constants for transition into the SB state (fapp) and returning to the WB state (gapp), Increases in XB force can be accounted for by an increase in fapp a decrease in gapp., or both. While effort towards understanding XB force regulation has focused on the notion that force production is primarily regulated by fapp the purpose of this investigation was to determine if gapp continues to force regulation at the XB and to determine whether gapp differs in,muscles with differing contractile characteristics. / Ph. D.

The anti-S2 peptides, the stabilizer and destabilizer, were designed to target myosin sub-fragment 2 (S2) in muscle. When the peptides are coupled to a heart-targeting molecule, they can reach the cardiomyocytes and interfere with cardiac muscle contraction. Monoclonal antibodies, MF20 and MF30, are also known to interact with light meromyosin and S2 respectively. The MF30 antibody compared to anti-S2 peptides and the MF20 antibody is used as a control to test the central hypothesis that: Both the anti-S2 peptides and antibodies bind to myosin S2 with high affinity, compete with MyBPC, and possibly interact with titin, in which case the anti-S2 peptides have further impact on myosin helicity and reach the heart with the aid of tannic acid to modulate cardiomyocytes' contraction in live mice. In this research, the effects of anti-S2 peptides and antibodies on myosin S2 were studied at the molecular and tissue levels. The anti-myosin binding mechanism to whole myosin was determined based on total internal reflectance fluorescence spectroscopy (TIRFS), and a modified cuvette was utilized to accommodate this experiment. The binding graphs indicated the cooperative binding of the peptides and antibodies with high affinity to myosin. Anti-myosin peptides and antibodies competition with Myosin Binding Protein C (MyBPC) was revealed through the super-resolution expansion microscopy using wildtype skeletal and cardiac myofibrils, and MyBPC knock-out cardiac myofibril. This new emerging technique depends on using the regular confocal microscope in imaging expanded myofibril after embedding in a swellable hydrogel polymer and digestion. A decrease in the fluorescent intensity at the C-zone was observed in myofibrils labeled with fluorescently labeled anti-S2 peptides or antibodies supporting the competition with MyBPC, which further was confirmed by the absence of this reduction at the C-zone in the knockout MyBPC cardiac tissue. The anti-S2 peptide's ability to reach inside the cardiomyocytes was tested by injecting fluorescently labeled anti-S2 peptides bound to tannic acid in live mice, the destabilizer peptide reached the heart 6X more than the stabilizer peptide. Some of the peptides labeled cardiac arterioles and T-tubules as detected by super-resolution microscopic images, meanwhile some peptides reached inside the cardiomyocytes and labeled some sarcomeres. This dissertation demonstrates the ability of anti-S2 peptides and antibodies in modifying myosin as they bind cooperatively with high affinity to myosin and compete with the regulatory protein MyBPC, in addition to the possible interaction between the stabilizer peptide and titin. Lastly, the peptides succeeded in labeling some cardiac sarcomeres in live mice.

No / L-type voltage gated calcium channels play essential role in contraction of various skeletal and vascular smooth muscles, thereby plays important role in regulating blood pressure. Dihydropyridine receptors have been targeted for development of newer antihypertensive agents, one of the structurally analogs nucleus dihydropyrimidines have been reported earlier by us as a potential agent toward development of calcium channel modulator. A pre-synthetic QSAR was run and on the basis of structure activity relationship a series of twenty three molecules was synthesized and studied by myosin light chain kinase assay (MLCK), Angiotensin Converting Enzyme (ACE) colorimetric assay, non-invasive blood pressure (NIBP) and invasive blood pressure (IBP) methods. Molecules with significant efficacy were studied for their single crystal X-ray diffraction, molecular docking, molecular dynamics and post-synthetic QSAR. The NIBP and IBP methods screened molecules with better percentage inhibition versus time compared to standard drug Nifedipine. The lead compound ethyl 2-methyl-4-(3-nitrophenyl)-4H-pyrimido [2,1-b] [1,3] benzothiazole-3-carboxylate (26) presented a triclinic structure with polymeric chain packing in lattice. 26 exhibited IC50 on MLCK assay of 2.1+/-1.7 muM with selectivity of L-type calcium channels and comparative to Nifedipine. It offered satisfactory physicochemical properties with partition coefficient of (ClogP) 4.64. Its pharmacokinetic profile is also good with Cmax at 0.40 mug/ml by oral route with Tmax reaching in 0.5 h which means in 30 min. 26 also exhibits superior t1/2 of 5.4 h and oral bioavailability of (F) 56.75% with an AUC0-infinity of 0.84 mug h/ml. Molecular docking studies indicates toward the interaction of lead compound via hydrogen bonds with Lys144, Glu181 and Asp183, it forms the Van der Walls interactions with Ser18, Asp20, Asn187, Pro185, Glu180, Glu181 and Arg10 with Glide score and Glide energy to be -3.602 and -47.098, respectively. Post-synthetic QSAR of newly synthesized molecules indicates toward improvement with respect to steric descriptor which contributed negatively in former series.

Fully differentiated muscle fibers can undergo considerable phenotypic changes in order to adjust to changing conditions of the physiological environment. It is generally accepted that the electrical impulses a muscle receives play a role in modulating the quantities of metabolic proteins (glycolytic and oxidative enzymes) and types of contractile proteins (myosin heavy chain, MHC) that are expressed. Research has shown that decreased neuromuscular activation following spinal cord transection (ST) results in adaptations in the physiological characteristics of paralyzed muscles, including atrophy and an accompanying loss of force production, and transformations of contractile and metabolic proteins toward a more fatigable state. However, it remains unclear whether or not a strong interdependence of energy metabolism and MHC isoform composition persists. Therefore, the goal of this study was to identify and quantify relative myosin heavy chain (MHC) isoform expression and metabolic enzyme profile adaptations at multiple time points (1, 3 and 6 months) in soleus fibers of rats following spinal cord transection (ST). To accomplish this, female Sprague-Dawley rats (~150 g, n = 15) were subjected to complete transection of the spinal cord at a mid-thoracic level. Age and weight-matched, non-operated rats served as controls (n = 15). The soleus was processed for quantitative single fiber histochemical analyses for succinate dehydrogenase (SDH, oxidative marker) and a-glycerophosphate dehydrogenase (GPD, glycolytic marker) activities (~30 fibers/muscle) and immunohistochemical analysis for MHC isoform composition. The total number of soleus fibers analyzed was ~900. Oxidative capacity was increased in muscle fibers at all time points after ST. Specifically, SDH activity was significantly higher than controls by 142, 127 and 206% at 1, 3 and 6 months post-ST, respectively. ISDH, a measure of total oxidative power, also increased in muscle fibers at all time points after ST. For example, 6 months after ST ISDH activity was 93% higher than controls (91.8-3.8 vs. 47.6-0.9 OD x 10-3, respectively). Glycolytic capacity peaked one month after ST. Thereafter, glycolytic capacity of all fibers steadily declined. For example, by 6 months, GPD activity had declined by 76% compared to 1 month GPD activities (3.3-0.2 vs. 13.7-1.4 OD x 10-3, respectively). These data suggest that the increases in glycolytic capacity are transient as fibers transition toward a faster MHC phenotype and then return towards control levels as fibers of a given type become phenotypically stable. The GPD/SDH ratio, an index of metabolic substrate utilization, peaked at one month after ST (394-41) and significantly decreased at 3 months (224-10) and at 6 months (95-7) after ST. Therefore, a shift occurred such that a greater dependence on oxidative metabolism was apparent. These data suggest that the oxidative capacities of soleus muscle fibers are not compromised after ST. In fact, as the fibers transitioned toward faster MHC isoforms, the GPD/SDH ratio was maintained or decreased, suggesting a reliance on oxidative metabolism regardless of MHC isoform composition. This might imply a dissociation between the contractile and metabolic characteristics of paralyzed soleus muscle fibers. However, these data are consistent with previous data and suggest that the increased fatigability observed after chronic reductions in neuromuscular activity are not due to compromised capacities for ATP synthesis. / Master of Science

Das Ziel dieser Studie war es, die Beteiligung der nichtmuskulären schweren Myosinketten an der Kontraktion der glatten Muskeln unter physiologischen Bedingungen zu untersuchen. Als Versuchsmodell wurde die Harnblase von neugeborenen Wildtyp und transgenen Mäusen verwendet, bei denen das Gen für die glattmuskelspezifischen schweren Myosinketten durch "Gene Targeting" funktionell eliminiert wurde (Knock-Out). Das Fehlen der Expression der glattmuskelspezifischen schweren Myosinketten wurde durch Elektrophorese und Immunfärbung bestätigt. Im Gegensatz dazu blieb die Expression der nichtmuskulären schweren Myosinketten unverändert. Die mechanische Analyse des glatten Muskels wurde mit intakten Muskelpräparaten aus der Harnblase durchgeführt. Das Muskelpräparat wurde in KCl-Lösung oder mit Phorbolester stimuliert. Die Aktivierung mittels depolarisierender KCl-Lösung führte bei neugeborenen Wildtyp Mäusen zuerst zu einer transienten Kontraktion (Phase 1) mit hoher Kraftentwicklung und maximaler Verkürzungsgeschwindigkeit, und danach zu einer tonischen Kontraktion (Phase 2) mit niedrigerer Kraftentwicklung und maximaler Verkürzungsgeschwindigkeit. Blasenpräparate neugeborener Knock-Out Mäuse dagegen zeigten keine Phase 1, sondern nur eine tonische Kontraktion, die mit Wildtyp Mäusen vergleichbar war. Daher scheint nichtmuskuläres Myosin an der tonischen Kontraktion des glatten Muskels beteiligt zu sein. Durch Stimulierung mit Phorbolester waren ähnliche tonische Muskelkontraktionen der Blasenpräparate sowohl bei Wildtyp als auch bei Knock-Out Mäusen zu beobachten. Vermutlich wird also das nichtmuskuläre Myosin durch Stimulierung mit Phorbolester aktiviert. Intrazelluläre Filamente wurden durch Immunfluoreszenz mit einem spezifischen Antikörper gegen nichtmuskuläre schwere Myosinketten in kultivierten primären glatten Muskelzellen untersucht. Dabei zeigten die Muskelzellen sowohl von Wildtyp als auch von Knock-Out Mäusen intrazelluläre dicke Myosinfilamente, was für die Beteiligung des nichtmuskulären Myosins an der glatten Muskelkontraktion spricht. Entsprechend wurden intrazelluläre Filamente mit einem Antikörper gegen glattmuskelspezifische schwere Myosinketten in kultivierten primären glatten Muskelzellen untersucht. Wie erwartet, konnten nur in glatten Muskelzellen von Wildtyp Mäusen intrazelluläre Filamente nachgewiesen werden, nicht aber in denen von Knock-Out Mäusen. In dieser Arbeit konnte zum ersten Mal gezeigt werden, dass nichtmuskuläres Myosin zumindest an der tonischen Kontraktion glatter Muskelzellen beteiligt sein kann. / The aim of the present study was to investigate the involvement of non-muscle myosin heavy chain in smooth muscle contraction under physiological conditions. As an experimental model urinary bladder from neonatal wild-type mice as well as from neonatal mice with disrupted smooth muscle myosin heavy chain expression was used. This animal model was established through gene targeting technology, resulting in complete elimination of the expression of smooth muscle myosin heavy chains. The lack of expression of smooth muscle myosin heavy chains was confirmed by electrophoresis and immunoblotting. On the other hand, non-muscle myosin heavy chain expression remained normal, as verified by Western blot analysis. The mechanical analysis of smooth muscle was performed with intact urinary bladder preparations, stimulated using prolonged KCl depolarization or with phorbol ester. Prolonged activation by KCl depolarization of intact bladder preparations from wild-type neonatal mice produced an initial transient state (phase 1) of high force generation and maximal shortening velocity, followed by a sustained state (phase 2) with lower force generation and maximal shortening velocity. In contrast, bladder preparations from homozygous knockout neonatal mice did not exhibit phase 1, but phase 2 could be observed, i.e. a similar isometric force and maximal shortening velocity, compared to wild-type phase 2. Thus, non-muscle myosin appears to be recruited in the sustained phase of smooth muscle contraction during prolonged KCl depolarization in the animal model used. Upon stimulation with phorbol ester a similar sustained contraction was observed in both wild-type and knockout smooth muscle preparations. Therefore, non-muscle myosin may also be recruited during phorbol ester stimulation in both wild-type and knockout muscle preparations. The participation of non-muscle myosin in smooth muscle contraction was further supported by the finding of longitudinally arranged intracellular filaments in cultivated smooth muscle cells from both wild-type and knockout mice by immunofluorescence microscopy, using a specific antibody raised against non-muscle myosin heavy chain. In a similar way, smooth muscle myosin heavy chain structures were investigated in cultivated smooth muscle cells. As expected, longitudinally arranged intracellular filamentous structures of smooth muscle myosin were observed in wild-type smooth muscle cells, but not in smooth muscle cells from knockout mice. In conclusion, in neonatal smooth muscle the initial phase of contraction elicited by KCl depolarization is generated by smooth muscle myosin heavy chain recruitment. Upon prolonged KCl depolarization non-muscle myosin is recruited in the sustained phase of contraction, as well as upon stimulation with phorbol ester. Thus, it was possible, for the first time, to verify the involvement of the non-muscle myosin in smooth muscle contraction in vivo. The results of the present study contribute to the understanding of the regulatory mechanisms of smooth muscle contraction.

Myosin subfragment-2 (S2) is an intrinsically unstable coiled coil. This dissertation tests if the mechanical stability of myosin S2 would influence the availability of myosin S1 heads to actin thin filaments. The elevated instability in myosin S2 coiled coil could be one of the causes for hypercontractility in Familial Hypertrophic Cardiomyopathy (FHC). As hypothesized FHC mutations, namely E924K and E930del, in myosin S2 displayed an unstable myosin S2 coiled coil compared to wild type as measured by Fluorescence Resonant Energy Transfer (FRET) and gravitational force spectroscopy (GFS). To remedy this, anti-S2 peptides; the stabilizer and the destabilizer peptides by namesake were designed in our lab to increase and decrease the stability of myosin S2 coiled coil to influence the actomyosin interaction. Firstly, the effectiveness of anti-S2 peptides were tested on muscle myosin S2 peptides across MYH11 (smooth), MYH7 (cardiac), and MYH2 (skeletal) with GFS and FRET. The results demonstrated that the mechanical stability was increased by the stabilizer and decreased by the destabilizer across the cardiac and skeletal myosin S2 isoform but not for the smooth muscle isoform. The destabilizer peptide had dissociation binding constants of 9.97 × 10-1 μM to MYH7 isoform, 1.00 μM to MYH2 isoform, and no impact on MYH11, and the stabilizer peptide had dissociation binding constants of 2.12 × 10-2 μM to MYH7 isoform, 3.41 × 10-1 μM to MYH2 isoform, and no impact on MYH11 revealed by FRET. In presence of the stabilizer, FRET assay, affinity of the E930del and E924K increased by 10.23 and 0.60 fold respectively. The force required to uncoil muscle myosin S2 peptides in the presence of the stabilizer peptide was more than in its absence in muscle myosin S2 isoforms of MYH7 (1.80 fold higher), MYH2 (1.40 fold higher), and E930del (2.60 fold higher) and no change for MYH11 compared to control. The force required to uncoil muscle myosin S2 in presence of the destabilizer was less than in its absence in both MYH7 (2.00 fold lower) and MYH2 (2.5 fold lower) but the same for MYH11 compared to their controls. Both FRET and GFS assays demonstrated that both anti-S2 peptides do not have any impact on smooth muscle myosin S2 isoform. In FRET assay, there was no significant difference in the lifetime value in the presence or absence of anti-S2 peptides in smooth muscle myosin S2. In GFS assay, there was no significant difference in the force required to uncoil the dimer in presence or absence of the anti-S2 peptides smooth muscle myosin S2. Effectively, the stabilizer peptide improved the stability of FHC mutant (E924K and E930del) myosin S2 peptide. FHC mutations showed high lifetime value in FRET assay and low force to uncoil coiled coil myosin S2 in GFS assay. In the presence of the stabilizer, lifetime value decreased in FRET assay and more force was required to uncoil myosin S2 coiled coil in GFS assay. This study demonstrated that structure of muscle myosin S2 can be altered by small peptides. The stabilizer peptide enhanced dimer formation in wild type and mutant cardiac, and skeletal myosin S2 peptides, and destabilizer increased flexibility of cardiac and skeletal myosin S2 wild type peptide. Neither anti-S2 peptides had impacts on smooth muscle myosin S2 isoform. The study thus effectively demonstrates the mechanical stability of myosin S2 coiled coil in striated muscle system could be modified using the specific anti-S2 peptides. Stabilizer of the anti-S2 peptide was effective to remedy the dampened stability of FHC myosin S2 coiled coil thus providing a new dimension of treating cardiovascular and skeletal muscle disorders by targeting the structural property of muscle proteins.