Figure 8. CHM7 is required to maintain the integrity of the nuclear membranes in the context of nucleoporin-associated herniations.

(A) Nucleoporins are found at the bases of nuclear envelope herniations in apq12Δ cells. Immunogold labelling of thin sections of apq12Δ cells with 5 nm gold-conjugated secondary antibodies that detect MAb414 labeled nups at bases of herniations. (B) Left: Plot of the diameter of herniation necks in the indicated genetic backgrounds and fenestrations within the intranuclear membrane network associated with chm7_OPEN. Middle: Plot of the percentage of nuclei of the indicated strains where nuclear envelope herniations are observed. Right: Plot of the percentage of nuclei in the indicated strains where nuclear envelope ruptures (NER) are observed. At least 100 cells from each genotype were quantified. P-values are from Student’s t-test, where **p≤0.01, ***p≤0.001. (C) Electron tomograph of 300 nm thick section of apq12Δ cells grown at 37°C for 2 hr. Note the electron density within the herniations. Perspective views of 3D model shown (membranes/nuclear envelope-ER lumen colored pink with electron density within herniation blue). Arrowheads point to herniation necks and stars are nuclear pores. Scale bars are 250 nm. (D) Nuclear envelope herniations associated with nups persist in the absence of CHM7. Representative electron micrographs of the apq12Δ and chm7Δapq12Δ strains grown for 2 hr at 37°C. Asterisks denote herniation lumen. N is nucleus. (E) Nuclear envelope ruptures (NER) are observed in chm7Δapq12Δ cells. Electron micrographs of chm7Δapq12Δ depicting nuclear envelope ruptures (NER). Nucleus is indicated with ‘N’. Scale bars are 250 nm.

Figure 8—figure supplement 1. CHM7 is required to maintain the integrity of the nuclear membranes in the context of nucleoporin-associated herniations.

(A) Tomographic slices from 300 nm sections of nup116Δ cell nuclear envelope herniations. i-iii, Tomographic slice with boxed regions magnified in ii and iii. iv-ix. Different persepectives of 3D model with nuclear envelope and ER membranes in red and herniation densities (marked by asterisks in i-iii) are colored purple. White arrowheads point out the bases of the herniations and stars are nuclear pores. Scale bars are 250 nm.

Figure 8—figure supplement 2. CHM7 is required to maintain the integrity of the nuclear membranes in the context of nucleoporin-associated herniations.

(A) Electron micrographs (from thin sections) showing nuclear envelope ruptures (NER) in apq12Δchm7Δ cells after 2 hr at 37°C. Asterisks indicate herniations. Scale bars are 250 nm.

Figure 8—figure supplement 3. CHM7 is required to maintain the integrity of the nuclear membranes in the context of nucleoporin-associated herniations.

(A) Electron micrographs (from thin sections) showing nuclear envelope ruptures (NER) and herniations (asterisks) in apq12Δsnf7Δ cells after 2 hr at 37°C. Scale bars are 250 nm.