Rabbit Anti-Human SUN1 (a.a. 4-257) Polyclonal antibody

New genes (or lineage-specific genes) can facilitate functional innovations. MALE STERILITY 5 (MS5) in Brassica napus is a fertility-related new gene, which has two wild-type alleles (BnMS5(a) and BnMS5(C)) and two mutant alleles (BnMS5(b) and BnMS5(d)) that could induce male sterility. Here, we studied the history and functional evolution of MS5 homologs in plants by phylogenetic analysis and molecular genetic experiments. We identified 727 MS5 homologs and found that they define a Brassicaceae-specific gene family that has expanded partly via multiple tandem gene duplications and also probably transpositions. The MS5 in B. napus is inherited from a basic diploid ancestor of B. rapa. Molecular genetic experiments indicate that BnMS5(a) and BnMS5(C) are functionally distinct in B. napus and that BnMS5(d) can inhibit BnMS5(a) in B. napus in a dosage-dependent manner. The BnMS5(a) protein can move in coordination with meiotic telomeres and interact with the nuclear envelope protein SUN1, with a possible crucial role in meiotic chromosome behavior. In summary, BnMS5 belongs to a Brassicaceae-specific new gene family, and has gained a novel function that is essential for male fertility in B. napus through neofunctionalization that has likely occurred since the origin of B. rapa.

The nuclear envelope (NE) LINC complex, in mammals comprised of SUN domain and nesprin proteins, provides a direct connection between the nuclear lamina and the cytoskeleton, which contributes to nuclear positioning and cellular rigidity. SUN1 and SUN2 interact with lamin A, but lamin A is only required for NE localization of SUN2, and it remains unclear how SUN1 is anchored. Here, we identify emerin and short nesprin-2 isoforms as novel nucleoplasmic binding partners of SUN1/2. These have overlapping binding sites distinct from the lamin A binding site. However, we demonstrate that tight association of SUN1 with the nuclear lamina depends upon a short motif within residues 209-228, a region that does not interact significantly with known SUN1 binding partners. Moreover, SUN1 localizes correctly in cells lacking emerin. Importantly then, the major determinant of SUN1 NE localization has yet to be identified. We further find that a subset of lamin A mutations, associated with laminopathies Emery-Dreifuss muscular dystrophy (EDMD) and Hutchinson-Gilford progeria syndrome (HGPS), disrupt lamin A interaction with SUN1 and SUN2. Despite this, NE localization of SUN1 and SUN2 is not impaired in cell lines from either class of patients. Intriguingly, SUN1 expression at the NE is instead enhanced in a significant proportion of HGPS but not EDMD cells and strongly correlates with pre-lamin A accumulation due to preferential interaction of SUN1 with pre-lamin A. We propose that these different perturbations in lamin A-SUN protein interactions may underlie the opposing effects of EDMD and HGPS mutations on nuclear and cellular mechanics.