Caldesmon Inhibits Active Crossbridges in Unstimulated Vascular Smooth Muscle

Earley, James J.; Su, Xiaoling; Moreland, Robert S.

doi:10.1161/01.res.83.6.661

Cited by 78 publications

(82 citation statements)

References 32 publications

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“…It has been reported that extraction of caldesmon from a permeabilized smooth muscle preparation increased the Ca 2ϩ sensitivity of force development (20) and, conversely, that addition of caldesmon or a C-terminal fragment to permeabilized chicken gizzard fibers inhibited contraction (21)(22). It has also been reported recently that, in arterial strips made caldesmon-deficient by the use of antisense oligodeoxynucleotides, increased basal crossbridge cycling rates are inhibited by the addition of caldesmon (23).…”

Section: Phosphorylation Of Sermentioning

confidence: 81%

Regulation of Vascular Smooth Muscle Tone by N-terminal Region of Caldesmon

Lee¹,

Gallant²,

Guo³

et al. 2000

Journal of Biological Chemistry

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To assess the functional significance of tethering actin to myosin by caldesmon in the regulation of smooth muscle contraction, we investigated the effects of synthetic peptides, containing the myosin-binding sequences in the N-terminal region of caldesmon, on force directly recorded from single permeabilized smooth muscle cells of ferret portal vein. Two peptides were used, IK29C and MY27C, containing residues from Ile 25 to Lys 53 and from Met 1 to Tyr 27 of the human and chicken caldesmon sequence, respectively, plus an added cysteine at the C terminus. In cells clamped at pCa 6.7, both peptides increased basal tone. Pretreatment of cells at pCa 6.7 with IK29C or MY27C decreased the amplitude of subsequent phenylephrine-induced contractions but not microcystin-racemic mixture-induced contractions. In all cases the effects of the peptides were concentration-dependent, and IK29C was more potent than MY27C, in agreement with their relative affinity toward myosin. The peptides were ineffective after the phenylephrine contraction was established. MY27C did not further increase the magnitude of contraction caused by a maximally effective concentration of IK29C, consistent with the two peptides having the same mechanism of action. Neither polylysine nor two control peptides containing scrambled sequences of IK29C, which do not bind myosin, had any effect on basal or phenylephrine-induced force. Our results suggest that IK29C and MY27C induce contraction by competing with the myosin-binding domain of endogenous caldesmon. Digital imaging of fluoroisothiocyanatetagged IK29C confirmed the association of the peptide with intracellular filamentous structures. The results are consistent with a model whereby tethering of actin to myosin by caldesmon may play a role in regulating vascular tone by positioning the C-terminal domain of caldesmon so that it is capable of blocking the actomyosin interaction.

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Section: Phosphorylation Of Sermentioning

confidence: 81%

Regulation of Vascular Smooth Muscle Tone by N-terminal Region of Caldesmon

Lee¹,

Gallant²,

Guo³

et al. 2000

Journal of Biological Chemistry

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“…Bladder strips were also processed for the determination of myosin-to-actin ratios with minor modifications of techniques previously reported (5). Briefly, aliquots of the homogenized tissues were subjected to SDS-PAGE.…”

Section: Methodsmentioning

confidence: 99%

Effect of partial outlet obstruction on rabbit urinary bladder smooth muscle function

Stein

Stanton

et al. 2003

American Journal of Physiology-Renal Physiology

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Bladder outlet obstruction secondary to benign prostate hyperplasia is associated with many cellular changes. This study was designed to determine whether these changes involve the contractile apparatus. Bladder smooth muscles from rabbits subjected to partial outlet obstruction for 2 wk were mounted for isometric force, isotonic shortening velocity, and myosin light chain (MLC) phosphorylation levels. Muscle strips from obstructed bladders exhibited spontaneous phasic activity; muscle strips from control bladders did not. Muscle strips from obstructed bladders exhibited increased sensitivity and higher levels of stress in response to the cumulative addition of KCl or carbachol compared with control. During noncumulative addition of KCl or carbachol, no differences in sensitivity were noted. Muscle strips from obstructed bladders had elevated basal MLC phosphorylation levels and stimulation produced small increases in MLC phosphorylation compared with control. V max during KCl stimulation of muscle strips from obstructed bladders was 10-fold lower than control. Our results suggest that bladder outlet obstruction produces a muscle cell that develops higher levels of force but with greatly reduced cross bridge cycling rates.

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“…In an in vitro reconstituted system, caldesmon inhibits actomyosin ATPase activity. In vivo studies using smooth muscle cells have supported the inhibitory function of caldesmon in smooth muscle contraction (Katsuyama et al, 1992;Pfitzer et al, 1993;Huber, 1997;Earley et al, 1998;Burton and Marston, 1999). A recent report has implied a similar function for caldesmon in nonmuscle cells (Helfman et al, 1999).…”

Section: Introductionmentioning

confidence: 96%

Mutant Caldesmon Lacking cdc2 Phosphorylation Sites Delays M-Phase Entry and Inhibits Cytokinesis

Yamashiro

Chern

Yamakita

et al. 2001

MBoC

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Caldesmon is phosphorylated by cdc2 kinase during mitosis, resulting in the dissociation of caldesmon from microfilaments. To understand the physiological significance of phosphorylation, we generated a caldesmon mutant replacing all seven cdc2 phosphorylation sites with Ala, and examined effects of expression of the caldesmon mutant on M-phase progression. We found that microinjection of mutant caldesmon effectively blocked early cell division of Xenopus embryos. Similar, though less effective, inhibition of cytokinesis was observed with Chinese hamster ovary (CHO) cells microinjected with 7th mutant. When mutant caldesmon was introduced into CHO cells either by protein microinjection or by inducible expression, delay of M-phase entry was observed. Finally, we found that 7th mutant inhibited the disassembly of microfilaments during mitosis. Wild-type caldesmon, on the other hand, was much less potent in producing these three effects. Because mutant caldesmon did not inhibit cyclin B/cdc2 kinase activity, our results suggest that alterations in microfilament assembly caused by caldesmon phosphorylation are important for M-phase progression.

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Caldesmon Inhibits Active Crossbridges in Unstimulated Vascular Smooth Muscle

Cited by 78 publications

References 32 publications

Regulation of Vascular Smooth Muscle Tone by N-terminal Region of Caldesmon

Regulation of Vascular Smooth Muscle Tone by N-terminal Region of Caldesmon

Effect of partial outlet obstruction on rabbit urinary bladder smooth muscle function

Mutant Caldesmon Lacking cdc2 Phosphorylation Sites Delays M-Phase Entry and Inhibits Cytokinesis

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