C. Dogra - Academia.edu (original) (raw)

Papers by C. Dogra

The FASEB Journal, 2005

Mechanosensitive cation channels (MSC) are ubiquitous in eukaryotic cell types. However, the phys... more Mechanosensitive cation channels (MSC) are ubiquitous in eukaryotic cell types. However, the physiological functions of MSC in several tissues remain in question. In this study we have investigated the role of MSC in skeletal myogenesis. Treatment of C2C12 myoblasts with gadolinium ions (MSC blocker) inhibited myotube formation and the myogenic index in differentiation medium (DM). The enzymatic activity of creatine kinase (CK) and the expression of myosin heavy chain-fast twitch (MyHCf) in C2C12 cultures were also blocked in response to gadolinium. Treatment of C2C12 myoblasts with gadolinium ions did not affect the expression of either cyclin A or cyclin D1 in DM. Other inhibitors of MSC such as streptomycin and GsTMx-4 also suppressed the expression of CK and MyHCf in C2C12 cultures. The inhibitory effect of gadolinium ions on myogenic differentiation was reversible and independent of myogenic cell type. Realtime-polymerase chain reaction analysis revealed that inhibition of MSC decreases the expression of myogenic transcription factors MyoD, myogenin, and Myf-5. Furthermore, the activity of skeletal ␣-actin promoter was suppressed on MSC blockade. Treatment of C2C12 myoblasts with gadolinium ions prevented differentiation-associated cell death and inhibited the cleavage of poly (ADP-ribose) polymerase and activation of caspase-3. On the other hand, delivery of active caspase-3 protein to C2C12 myoblasts reversed the inhibitory effect of gadolinium ions on myogenesis. Our data suggest that inhibition of MSC suppresses myogenic differentiation by inhibiting the caspase-3 activity and the expression of myogenic regulatory factors.-Wedhas, N., Klamut, H. J., Dogra, C., Srivastava, A. K., Mohan, S., Kumar, A. Inhibition of mechanosensitive cation channels inhibits myogenic differentiation by suppressing the expression of myogenic regulatory factors and caspase-3 activity.

Molecular and Cellular Biochemistry, 2008

Inactivation of dystrophin gene is the primary cause of Duchenne muscular dystrophy (DMD) in huma... more Inactivation of dystrophin gene is the primary cause of Duchenne muscular dystrophy (DMD) in humans and mdx mice. However, the underpinning mechanisms, which govern the pathogenesis of dystrophin-deficient skeletal muscle, remain poorly understood. We have previously reported activation of mitogen-activated protein kinases (MAPK), nuclear factor-kappa B (NF-κB), and phosphatidyl-inositol 3-kinase/Akt (PI3K/Akt) signaling pathways in diaphragm muscle of mdx mice. In

Phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-kappa B (NF-kappaB) signaling pathway... more Phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-kappa B (NF-kappaB) signaling pathways play a critical role in mediating survival signals. In this study we have investigated how loss of dystrophin (the primary cause of Duchenne muscular dystrophy) modulates the activation of PI3K/Akt and NF-kappaB signaling pathways in skeletal muscle in response to mechanical stimulation. Activation of Akt was significantly higher in diaphragm muscle from dystrophin-deficient mdx mice compared to normal mice at both prenecrotic and necrotic states. Higher activation of Akt was also observed in cultured dystrophin-deficient primary myotubes differentiated in vitro. Application of passive mechanical stretch ex vivo synergistically increased the activation of Akt in diaphragm of mdx mice. Stretch-induced activation of PDK-1 and PI3K were also higher in diaphragm of mdx mice compared to normal mice. Pretreatment of diaphragm with PI3K inhibitor LY294002 blocked the activation of Akt in normal and mdx mice. Higher activation of Akt was associated with increased phosphorylation of its downstream targets glycogen synthase kinase 3beta (GSK3beta), FKHR, and mammalian target of rapamycin (mTOR). Treatment of diaphragm muscle with LY294002 inhibited the stretch-induced activation of IkappaB (IkappaB) kinase (IKK) and NF-kappaB transcription factor in normal and mdx mice. Mechanical stretch also reduced the interaction of HDAC1 with RelA subunit of NF-kappaB in diaphragm muscle. Finally, cellular levels of Bcl-2, cIAP1, and integrin beta1 and activation of integrin linked kinase were higher in diaphragm muscle of mdx mice compared to normal mice. Taken together, our data suggest that loss of dystrophin and/or mechanical stretch results in the up-regulation of P13K/Akt and NF-kappaB signaling pathways in skeletal muscle.

DIVERSITY AND EVOLUTION OF I&amp;amp;amp;amp;amp;amp;#x27;m GENES IN HEXACHLOROCYCLOHEXAN... more DIVERSITY AND EVOLUTION OF I&amp;amp;amp;amp;amp;amp;#x27;m GENES IN HEXACHLOROCYCLOHEXANE DEGRADING SPHINGOMONAS PAUCIMOBILIS STRAINS AND THEIR USE IN BIOREMEDIATION RUP LAL, CHARU DOGRA, RINKU PAL, SHWETA MAHLOTRA, POONAM SHARMA, OM ...

Applied and environmental microbiology, 2005

Trends in Biotechnology, 2006

The FASEB Journal, 2007

TWEAK cytokine has been implicated in several biological responses including inflammation, angiog... more TWEAK cytokine has been implicated in several biological responses including inflammation, angiogenesis, and osteoclastogenesis. We have investigated the role of TWEAK in regulating skeletal muscle mass. Addition of soluble TWEAK protein to cultured myotubes reduced the mean myotube diameter and enhanced the degradation of specific muscle proteins such as CK and MyHCf. The effect of TWEAK on degradation of MyHCf was stronger than its structural homologue, TNF-␣. TWEAK increased the ubiquitination of MyHCf and the transcript levels of atrogin-1 and MuRF1 ubiquitin ligases. TWEAK inhibited phosphorylation of Akt kinase and its downstream targets GSK-3␤, FOXO1, mTOR, and p70S6K. Furthermore,

Journal of Biological Chemistry, 2007

Fibroblast growth factor-inducible 14 (Fn14), distantly related to tumor necrosis factor receptor... more Fibroblast growth factor-inducible 14 (Fn14), distantly related to tumor necrosis factor receptor superfamily and a receptor for TWEAK cytokine, has been implicated in several biological responses. In this study, we have investigated the role of Fn14 in skeletal muscle formation in vitro. Flow cytometric and Western blot analysis revealed that Fn14 is highly expressed on myoblastic cell line C2C12 and mouse primary myoblasts. The expression of Fn14 was decreased upon differentiation of myoblasts into myotubes. Suppression of Fn14 expression using RNA interference inhibited the myotube formation in both C2C12 and primary myoblast cultures. Fn14 was required for the transactivation of skeletal alpha-actin promoter and the expression of specific muscle proteins such as myosin heavy chain fast type and creatine kinase. RNA interference-mediated knockdown of Fn14 receptor in C2C12 myoblasts decreased the levels of myogenic regulatory factors MyoD and myogenin upon induction of differentiation. Conversely, overexpression of MyoD increased differentiation in Fn14-knockdown C2C12 cultures. Suppression of Fn14 expression in C2C12 myoblasts also inhibited the differentiation-associated increase in the activity of serum response factor and RhoA GTPase. In addition, our data suggest that the role of Fn14 during myogenic differentiation could be independent of TWEAK cytokine. Collectively, our study suggests that the Fn14 receptor is required for the expression of myogenic regulatory factors and differentiation of myoblasts into myotubes.

Journal of Biological Chemistry, 2006

In this study we have investigated the effect and the mechanisms by which tumor necrosis factor-l... more In this study we have investigated the effect and the mechanisms by which tumor necrosis factor-like weak inducer of apoptosis (TWEAK) modulates myogenic differentiation. Treatment of C2C12 myoblasts with TWEAK inhibited their differentiation evident by a decrease in ...

Biodegradation, 2008

Anaerobic dechlorination of technical grade hexachlorocyclohexane (THCH) was studied in a continu... more Anaerobic dechlorination of technical grade hexachlorocyclohexane (THCH) was studied in a continuous upflow anaerobic sludge blanket (UASB) reactor with methanol as a supplementary substrate and electron donor. A reactor without methanol served as the experimental control. The inlet feed concentration of THCH in both the experimental and the control UASB reactor was 100 mg l À1 . After 60 days of continuous operation, the removal of THCH was >99% in the methanol-supplemented reactor as compared to 20-35% in the control reactor. THCH was completely dechlorinated in the methanol fed reactor at 48 h HRT after 2 months of continuous operation. This period was also accompanied by increase in biomass in the reactor, which was not observed in the experimental control. Batch studies using other supplementary substrates as well as electron donors namely acetate, butyrate, formate and ethanol showed lower % dechlorination (<85%) and dechlorination rates (<3 mg g À1 d À1 ) as compared to methanol (98%, 5 mg g À1 d À1 ). The optimum concentration of methanol required, for stable dechlorination of THCH (100 mg l À1 ) in the UASB reactor, was found to be 500 mg l À1 . Results indicate that addition of methanol as electron donor enhances dechlorination of THCH at high inlet concentration, and is also required for stable UASB reactor performance.

Applied and Environmental Microbiology, 2002

programs for the control of mosquitoes. Commercial formulations of HCH consist of a mixture of fo... more programs for the control of mosquitoes. Commercial formulations of HCH consist of a mixture of four isomers, ␣, ␤, ␥, and ␦. While all these isomers pose serious environmental problems, ␤-HCH is more problematic due to its longer persistence in the environment. We have studied the degradation of HCH isomers by Sphingomonas paucimobilis strain B90 and characterized the lin genes encoding enzymes from strain B90 responsible for the degradation of HCH isomers. Two nonidentical copies of the linA gene encoding HCH dehydrochlorinase, which were designated linA1 and linA2, were found in S. paucimobilis B90. The linA1 and linA2 genes could be expressed in Escherichia coli, leading to dehydrochlorination of ␣-, ␥-, and ␦-HCH but not of ␤-HCH, suggesting that S. paucimobilis B90 contains another pathway for the initial steps of ␤-HCH degradation. The cloning and characterization of the halidohydrolase (linB), dehydrogenase (linC and linX), and reductive dechlorinase (linD) genes from S. paucimobilis B90 revealed that they share ϳ96 to 99% identical nucleotides with the corresponding genes of S. paucimobilis UT26. No evidence was found for the presence of a linE-like gene, coding for a ring cleavage dioxygenase, in strain B90. The gene structures around the linA1 and linA2 genes of strain B90, compared to those in strain UT26, are suggestive of a recombination between linA1 and linA2, which formed linA of strain UT26.

Applied and Environmental Microbiology, 2006

Incubation of resting cells of Sphingobium indicum B90A, Sphingobium japonicum UT26, and Sphingob... more Incubation of resting cells of Sphingobium indicum B90A, Sphingobium japonicum UT26, and Sphingobium francense Sp؉ showed that they were able to transform ␤and ␦-hexachlorocyclohexane (␤-and ␦-HCH, respectively), the most recalcitrant hexachlorocyclohexane isomers, to pentachlorocyclohexanols, but only resting cells of strain B90A could further transform the pentachlorocyclohexanol intermediates to the corresponding tetrachlorocyclohexanediols. Moreover, experiments with resting cells of Escherichia coli expressing the LinB proteins of strains B90A, UT26, and Sp؉ indicated that LinB was responsible for these transformations. Purified LinB proteins from all three strains also effected the formation of the respective pentachlorocyclohexanols. Although the three LinB enzymes differ only marginally with respect to amino acid sequence, they showed interesting differences with respect to substrate specificity. When LinB from strain B90A was incubated with ␤and ␦-HCH, the pentachlorocyclohexanol products were further transformed and eventually disappeared from the incubation mixtures. In contrast, the LinB proteins from strains UT26 and Sp؉ could not catalyze transformation of the pentachlorocyclohexanols, and these products accumulated in the incubation mixture. A mutant of strain Sp؉ lacking linA and linB did not degrade any of the HCH isomers, including ␤-HCH, and complementation of this mutant by linB from strain B90A restored the ability to degrade ␤and ␦-HCH.

Applied and Environmental Microbiology, 2005

Sphingomonas paucimobilis B90A contains two variants, LinA1 and LinA2, of a dehydrochlorinase tha... more Sphingomonas paucimobilis B90A contains two variants, LinA1 and LinA2, of a dehydrochlorinase that catalyzes the first and second steps in the metabolism of hexachlorocyclohexanes (R. Kumari, S. Subudhi, M. Suar, G. Dhingra, V. Raina, C. Dogra, S. Lal, J. R. van der Meer, C. Holliger, and R. Lal, Appl. Environ. Microbiol. 68:6021-6028, 2002). On the amino acid level, LinA1 and LinA2 were 88% identical to each other, and LinA2 was 100% identical to LinA of S. paucimobilis UT26. Incubation of chiral ␣-hexachlorocyclohexane (␣-HCH) with Escherichia coli BL21 expressing functional LinA1 and LinA2 S-glutathione transferase fusion proteins showed that LinA1 preferentially converted the (؉) enantiomer, whereas LinA2 preferred the (؊) enantiomer. Concurrent formation and subsequent dissipation of ␤-pentachlorocyclohexene enantiomers was also observed in these experiments, indicating that there was enantioselective formation and/or dissipation of these enantiomers. LinA1 preferentially formed (3S,4S,5R,6R)-1,3,4,5,6-pentachlorocyclohexene, and LinA2 preferentially formed (3R,4R,5S,6S)-1,3,4,5,6-pentachlorocyclohexene. Because enantioselectivity was not observed in incubations with whole cells of S. paucimobilis B90A, we concluded that LinA1 and LinA2 are equally active in this organism. The enantioselective transformation of chiral ␣-HCH by LinA1 and LinA2 provides the first evidence of the molecular basis for the changed enantiomer composition of ␣-HCH in many natural environments. Enantioselective degradation may be one of the key processes determining enantiomer composition, especially when strains that contain only one of the linA genes, such as S. paucimobilis UT26, prevail.

Current Science, 2004

Forty-five soil samples of surface (015 cm) and sub-surface (1530 cm) soils from agricultural s... more Forty-five soil samples of surface (015 cm) and sub-surface (1530 cm) soils from agricultural sites of Delhi, Haryana, Haridwar, Uttar Pradesh (UP) and around the hexachlorocyclohexane (HCH) manufacturing plant of IPL (Indian Pesticide Limited) and nine samples of different ...

Journal of Bacteriology, 2004

The organization of lin genes and IS6100 was studied in three strains of Sphingomonas paucimobili... more The organization of lin genes and IS6100 was studied in three strains of Sphingomonas paucimobilis (B90A, Sp, and UT26) which degraded hexachlorocyclohexane (HCH) isomers but which had been isolated at different geographical locations. DNA-DNA hybridization data revealed that most of the lin genes in these strains were associated with IS6100, an insertion sequence classified in the IS6 family and initially