SUN proteins and nuclear envelope spacing

NE Cain, DA Starr - Nucleus, 2015 - Taylor & Francis
NE Cain, DA Starr
Nucleus, 2015Taylor & Francis
The nuclear envelope consists of 2 membranes separated by 30–50 nm, but how the 2
membranes are evenly spaced has been an open question in the field. Nuclear envelope
bridges composed of inner nuclear membrane SUN proteins and outer nuclear membrane
KASH proteins have been proposed to set and regulate nuclear envelope spacing. We
tested this hypothesis directly by examining nuclear envelope spacing in Caenorhabditis
elegans animals lacking UNC-84, the sole somatic SUN protein. SUN/KASH bridges are not …
The nuclear envelope consists of 2 membranes separated by 30–50 nm, but how the 2 membranes are evenly spaced has been an open question in the field. Nuclear envelope bridges composed of inner nuclear membrane SUN proteins and outer nuclear membrane KASH proteins have been proposed to set and regulate nuclear envelope spacing. We tested this hypothesis directly by examining nuclear envelope spacing in Caenorhabditis elegans animals lacking UNC-84, the sole somatic SUN protein. SUN/KASH bridges are not required to maintain even nuclear envelope spacing in most tissues. However, UNC-84 is required for even spacing in body wall muscle nuclei. Shortening UNC-84 by 300 amino acids did not narrow the nuclear envelope space. While SUN proteins may play a role in maintaining nuclear envelope spacing in cells experiencing forces, our data suggest they are dispensable in most cells.
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