Localized translation and sarcomere maintenance requires ribosomal protein SA in mice
Rami Haddad, Omer Sadeh, Tamar Ziv, Itai Erlich, Lilac Haimovich-Caspi, Ariel Shemesh, Jolanda van der Velden, Izhak Kehat
Rami Haddad, Omer Sadeh, Tamar Ziv, Itai Erlich, Lilac Haimovich-Caspi, Ariel Shemesh, Jolanda van der Velden, Izhak Kehat
View: Text | PDF
Research Article Cardiology

Localized translation and sarcomere maintenance requires ribosomal protein SA in mice

Abstract

Cardiomyocyte sarcomeres contain localized ribosomes, but the factors responsible for their localization and the significance of localized translation are unknown. Using proximity labeling, we identified ribosomal protein SA (RPSA) as a Z-line protein. In cultured cardiomyocytes, the loss of RPSA led to impaired local protein translation and reduced sarcomere integrity. By employing CAS9-expressing mice, along with adeno-associated viruses expressing CRE recombinase and single-guide RNAs targeting Rpsa, we knocked out Rpsa in vivo and observed mislocalization of ribosomes and diminished local translation. These genetic mosaic mice with Rpsa knockout in a subset of cardiomyocytes developed dilated cardiomyopathy, featuring atrophy of RPSA-deficient cardiomyocytes, compensatory hypertrophy of unaffected cardiomyocytes, left ventricular dilation, and impaired contractile function. We demonstrated that RPSA C-terminal domain is sufficient for localization to the Z-lines and that if the microtubule network is disrupted RPSA loses its sarcomeric localization. These findings highlight RPSA as a ribosomal factor essential for ribosome localization to the Z-line, facilitating local translation and sarcomere maintenance.

Authors

Rami Haddad, Omer Sadeh, Tamar Ziv, Itai Erlich, Lilac Haimovich-Caspi, Ariel Shemesh, Jolanda van der Velden, Izhak Kehat

×

Figure 4

Knockout of Rpsa in vivo results in cardiac dysfunction.

Options: View larger image (or click on image) Download as PowerPoint
Knockout of Rpsa in vivo results in cardiac dysfunction. (A–F) Echocardi...
(A–F) Echocardiographic assessment of mice with unconditional CAS9 expression transduced with AAVs encoding for sgRNAs targeting Rpsa or control sgRNAs. Analysis shows Rpsa-knockout results in cardiac dilation with increased left ventricular internal diameter at end diastole (LVIDd), wall thinning with decreased interventricular septal and left ventricular posterior wall diameters at end diastole (IVSd and LVPWd), decreased contractile function with increased left ventricular internal diameter at end systole (LVIDs), and decreased fractional shortening (FS%). Heart rate (HR) was unchanged. n = 11 and 12 mice per group, and a mean of 3 measurements for each mouse. (G) Gravimetric analysis showing increased heart weight normalized to body weight (HW/BW) after Rpsa knockout. n = 11 and 12 mice per group. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001, by unpaired Student’s t test. Data are presented as individual values with box plot displaying the median with 25th and 75th percentiles.