Phosphorylation of Nonmuscle Myosin Heavy Chain IIA on Ser1917Is Mediated by Protein Kinase CβII and Coincides with the Onset of Stimulated Degranulation of RBL-2H3 Mast Cells

Contractile activity of the cardiac myocyte is required for maintaining cell mass and phenotype, including expression of the cardiac-specific α-myosin heavy chain (α-MHC) gene. An E-box hemodynamic response element (HME) located at position −47 within the α-MHC promoter is both necessary and sufficient to confer contractile responsiveness to the gene and has been shown to bind upstream stimulatory factor-1 (USF1). When studied in spontaneously contracting cardiac myocytes, there is enhanced binding of USF1 to the HME compared with quiescent cells, which correlates with a threefold increase in α-MHC promoter activity. A molecular mechanism by which contractile function modulates α-MHC transcriptional activity may involve signaling via phosphorylation of USF1. The present studies showed that purified rat USF1 was phosphorylated in vitro by protein kinase C (PKC) and cAMP-dependent protein kinase (PKA) but not casein kinase II. Phosphorylated USF1 by either PKC or PKA had increased DNA binding activity to the HME. PKC-mediated phosphorylation also leads to the formation of USF1 multimers as assessed by gel shift assay. Analysis of in vivo phosphorylated nuclear proteins from cultured ventricular myocytes showed that USF1 was phosphorylated, and resolution by two-dimensional gel electrophoresis identified at least two distinct phosphorylated USF1 molecules. These results suggest that endogenous kinases can covalently modify USF1 and provide a potential molecular mechanism by which the contractile stimulus mediates changes in myocyte gene transcription.

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In Situ Interleukin-6 Transcription in Embryonic Nonmuscle Myosin Heavy Chain Expressing Immature Mesenchyme Cells of Cardiac Myxoma

Cardiovascular Pathology ◽

10.1016/s1054-8807(99)00031-9 ◽

2000 ◽

Vol 9 (1) ◽

pp. 33-37 ◽

Cited By ~ 7

Author(s):

Jun-ichi Suzuki ◽

Kei Takayama ◽

Fujio Mitsui ◽

Tetsuya Kono ◽

Yoshikazu Yazaki ◽

...

Keyword(s):

Myosin Heavy Chain ◽

Heavy Chain ◽

Interleukin 6 ◽

Cardiac Myxoma ◽

Nonmuscle Myosin ◽

Mesenchyme Cells

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Many chronic lymphocytic leukemia antibodies recognize apoptotic cells with exposed nonmuscle myosin heavy chain IIA: implications for patient outcome and cell of origin

Blood ◽

10.1182/blood-2009-09-244251 ◽

2010 ◽

Vol 115 (19) ◽

pp. 3907-3915 ◽

Cited By ~ 117

Author(s):

Charles C. Chu ◽

Rosa Catera ◽

Lu Zhang ◽

Sebastien Didier ◽

Briana M. Agagnina ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Myosin Heavy Chain ◽

Heavy Chain ◽

Lymphocytic Leukemia ◽

Apoptotic Cells ◽

Nonmuscle Myosin ◽

Cell Of Origin ◽

Poor Clinical Outcome ◽

Mutation Status ◽

Poor Patient Survival

Abstract Many B-cell chronic lymphocytic leukemia (CLL) monoclonal antibodies (mAbs) can be grouped into subsets based on nearly identical stereotyped sequences. Subset 6 CLL mAbs recognize nonmuscle myosin heavy chain IIA (MYHIIA). Herein, we report that during apoptosis, MYHIIA becomes exposed on the cell surface of a subgroup of apoptotic cells, allowing subset 6 CLL mAbs to bind with it. Because other non–subset 6 CLL mAbs interact with apoptotic cells, 26 CLL mAbs, including 24 not belonging to subset 6, were tested for reactivity with MYHIIA-exposed apoptotic cells (MEACs). More than 60% of CLL mAbs bound MEACs well; most of these mAbs expressed unmutated IGHV (15 of 16) and belonged to a stereotyped subset (14 of 16). Binding to MEACs inversely correlated with the degree of IGHV mutation. Interestingly, high binding to MEACs significantly correlated with poor patient survival, suggesting that the basis of IGHV mutation status as a CLL prognostic factor reflects antigen binding. Finally, natural antibodies from human serum also reacted with MEACs. Taken together, our data indicate that a large proportion of CLL clones emerge from natural antibody-producing cells expressing immunoglobulins that recognize MEACs, and that this reactivity is associated with poor clinical outcome.

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Function of the Neuron-specific Alternatively Spliced Isoforms of Nonmuscle Myosin II-B during Mouse Brain Development

Molecular Biology of the Cell ◽

10.1091/mbc.e05-10-0997 ◽

2006 ◽

Vol 17 (5) ◽

pp. 2138-2149 ◽

Cited By ~ 33

Author(s):

Xuefei Ma ◽

Sachiyo Kawamoto ◽

Jorge Uribe ◽

Robert S. Adelstein

Keyword(s):

Amino Acids ◽

Myosin Heavy Chain ◽

Purkinje Cells ◽

Heavy Chain ◽

Myosin Ii ◽

Nonmuscle Myosin ◽

Binding Region ◽

Alternatively Spliced ◽

Cerebellar Purkinje Cells ◽

Mouse Brain Development

We report that the alternatively spliced isoforms of nonmuscle myosin heavy chain II-B (NHMC II-B) play distinct roles during mouse brain development. The B1-inserted isoform of NMHC II-B, which contains an insert of 10 amino acids near the ATP-binding region (loop 1) of the myosin heavy chain, is involved in normal migration of facial neurons. In contrast, the B2-inserted isoform, which contains an insert of 21 amino acids near the actin-binding region (loop 2), is important for postnatal development of cerebellar Purkinje cells. Deletion of the B1 alternative exon, together with reduced expression of myosin II-B, results in abnormal migration and consequent protrusion of facial neurons into the fourth ventricle. This protrusion is associated with the development of hydrocephalus. Restoring the amount of myosin II-B expression to wild-type levels prevents these defects, showing the importance of total myosin activity in facial neuron migration. In contrast, deletion of the B2 alternative exon results in abnormal development of cerebellar Purkinje cells. Cells lacking the B2-inserted isoform show reduced numbers of dendritic spines and branches. Some of the B2-ablated Purkinje cells are misplaced in the cerebellar molecular layer. All of the B2-ablated mice demonstrated impaired motor coordination.

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