Hypertrophic Cardiomyopathy β-Cardiac Myosin Mutation (P710R) Leads to Hypercontractility by Disrupting Super Relaxed State

Hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, associated with over 1,000 mutations, many in β-cardiac myosin (MYH7). Molecular studies of myosin with different HCM mutations have revealed a diversity of effects on ATPase and load-sensitive rate of detachment from actin. It has been difficult to predict how such diverse molecular effects combine to influence forces at the cellular level and further influence cellular phenotypes. This study focused on the P710R mutation that dramatically decreased in vitro motility velocity and actin-activated ATPase, in contrast to other MYH7 mutations. Optical trap measurements of single myosin molecules revealed that this mutation reduced the step size of the myosin motor and the load sensitivity of the actin detachment rate. Conversely, this mutation destabilized the super relaxed state in longer, two-headed myosin constructs, freeing more heads to generate force. Micropatterned human induced pluripotent derived stem cell (hiPSC)–cardiomyocytes CRISPR-edited with the P710R mutation produced significantly increased force (measured by traction force microscopy) compared with isogenic control cells. The P710R mutation also caused cardiomyocyte hypertrophy and cytoskeletal remodeling as measured by immunostaining and electron microscopy. Cellular hypertrophy was prevented in the P710R cells by inhibition of ERK or Akt. Finally, we used a computational model that integrated the measured molecular changes to predict the measured traction forces. These results confirm a key role for regulation of the super relaxed state in driving hypercontractility in HCM with the P710R mutation and demonstrate the value of a multiscale approach in revealing key mechanisms of disease

ANTIPHOSPHOCHOLINE ANTIBODIES FOUND IN NORMAL MOUSE SERUM ARE PROTECTIVE AGAINST INTRAVENOUS INFECTION WITH TYPE 3 \u3ci\u3eSTREPTOCOCCUS PNEUMONIAE\u3c/i\u3e

Although it has been clearly demonstrated that antibodies to pneumococcal capsules are protective in both mice and men (1, 2), the protective properties of antibodies to other pneumococcal constituents have been less well investigated. In the present report we describe results indicating that naturally occurring antibodies binding with the phosphocholine (PC) determinant of the pneumococcal cell wall C-carbohydrate (3) are important in the protection of mice from experimental pneumococcal infections

Antiphosphocholine antibodies found in normal mouse serum are protective against intravenous infection with type 3 Streptococcuspneumoniae.J. Exlx Med

Although it has been clearly demonstrated that antibodies to pneumococcal capsules are protective in both mice and men (1, 2), the protective properties of antibodies to other pneumococcal constituents have been less well investigated. In the present report we describe results indicating that naturally occurring antibodies binding with the phosphocholine (PC)1 determinant of the pneumococcal cell wall C-carbohydrate (3) are important in the protection of mice from experimental pneumococcal infections. We made this observation while investigating what effects the immune deficiency of the CBA/N mouse might have on its susceptibility to pneumoeoccal infection. This strain carries an X-linked inability (xid) to produce normal humoral antibody responses to a group of thymus independent (TI-2), predominantly carbohydrate antigens (4), including type 3 pneumococcal capsular polysaccharide (5), trinitrophenyl-Fieoll (6), PC (7, 8), dextran (9), levan (8), and group A streptococcal carbohydrate (10). The CBA/N mouse is probably unable to make high levels of anticarbohydrate antibodies in general because the bulk of mouse anticarbohydrate antibodies is either IgM or IgGa (11), and CBA/N mice produce low levels of Ig

Study of the idiotypy of lipopolysaccharide‐specific polyclonal and monoclonal antibodies

The monoclonal antibodies produced by a variety of hybridomas making antibody specific for E. coli 0113 lipopolysaccharide (LPS) were purified by affinity chromatography and their fine specificity studied. All reacted specifically with the polysaccharide moiety of LPS from E. coli 0113 and from Neisseria lactamica; two reacted with LPS from Pseudomonas aeruginosa and one reacted with LPS from Klebsiella pneumoniae. Polyclonal and monoclonal syngeneic and semi‐syngeneic anti‐idiotypic antisera were produced to study the idiotypy of LPS‐specific monoclonal antibodies which express a complex cross‐reactive idiotype (IdX) as well as individual idiotypes. E. coli 0113 LPS‐specific antibodies produced by B ALB/c mice express this IdX and the kinetics for its expression was examined using mice either primed or hyperim‐munized with LPS; idiotypic maturation was observed, but we were unable to detect an auto‐anti‐idiotypic antibody response. This IdX was expressed on E. coli 0113 LPS‐specific antibodies from all strains of mice examined, indicating that its expression is not restricted by genes linked to the IgCH locus. Copyright © 1982 WILEY‐VCH Verlag GmbH & Co. KGaASCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Mouse IgG3 antibodies are highly protective against infection with Streptococcus pneumoniae

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62976/1/294088a0.pd

Hypertrophic cardiomyopathy β-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super relaxed state.

Hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, associated with over 1,000 mutations, many in β-cardiac myosin (MYH7). Molecular studies of myosin with different HCM mutations have revealed a diversity of effects on ATPase and load-sensitive rate of detachment from actin. It has been difficult to predict how such diverse molecular effects combine to influence forces at the cellular level and further influence cellular phenotypes. This study focused on the P710R mutation that dramatically decreased in vitro motility velocity and actin-activated ATPase, in contrast to other MYH7 mutations. Optical trap measurements of single myosin molecules revealed that this mutation reduced the step size of the myosin motor and the load sensitivity of the actin detachment rate. Conversely, this mutation destabilized the super relaxed state in longer, two-headed myosin constructs, freeing more heads to generate force. Micropatterned human induced pluripotent derived stem cell (hiPSC)-cardiomyocytes CRISPR-edited with the P710R mutation produced significantly increased force (measured by traction force microscopy) compared with isogenic control cells. The P710R mutation also caused cardiomyocyte hypertrophy and cytoskeletal remodeling as measured by immunostaining and electron microscopy. Cellular hypertrophy was prevented in the P710R cells by inhibition of ERK or Akt. Finally, we used a computational model that integrated the measured molecular changes to predict the measured traction forces. These results confirm a key role for regulation of the super relaxed state in driving hypercontractility in HCM with the P710R mutation and demonstrate the value of a multiscale approach in revealing key mechanisms of disease