NUANCE, a giant protein connecting the nucleus and actin cytoskeleton

Abstract

NUANCE (NUcleus and ActiN Connecting Element) was identified as a novel protein with an α-actinin-like actin-binding domain. A human 21.8 kb cDNA of NUANCE spreads over 373 kb on chromosome 14q22.1-q22.3. The cDNA sequence predicts a 796 kDa protein with an N-terminal actin-binding domain, a central coiled-coil rod domain and a predicted C-terminal transmembrane domain. High levels of NUANCE mRNA were detected in the kidney, liver,stomach, placenta, spleen, lymphatic nodes and peripheral blood lymphocytes. At the subcellular level NUANCE is present predominantly at the outer nuclear membrane and in the nucleoplasm. Domain analysis shows that the actin-binding domain binds to Factin in vitro and colocalizes with the actin cytoskeleton in vivo as a GFP-fusion protein. The C-terminal transmembrane domain is responsible for the targeting the nuclear envelope. Thus, NUANCE is the firstα-actinin-related protein that has the potential to link the microfilament system with the nucleus.

The Role of Emerin in Cancer Progression and Metastasis

“…The LINC complex physically connects the cytoskeleton to the nucleus and transmits mechanical forces from the cytoskeleton across the NE to the nucleoskeleton (Figure 3) [132,133]. The LINC complex has been implicated in cell division [134], cytoskeletal organization [135], and organelle positioning [136], showing its importance for basic cellular functions. The ONM components of the LINC complex are the nesprins, a large family of spectrin-repeat transmembrane proteins [135,137], which bind to the cytoskeleton via actin or microtubules [135,138].…”

Biallelic SYNE2 Missense Mutations Leading to Nesprin-2 Giant Hypo-Expression Are Associated with Intellectual Disability and Autism

“…In comparison to parental control LCLs, the analyses of the patient indicated that the p.(E788K) and p.(V828G) mutations do not affect the nuclear targeting of mutant proteins. This is not surprising based on the consideration that the mutations reside within the nesprin-2 giant N-terminal half (SR5) and not in the C-terminal KASH domain, which mediates nuclear envelope targeting [1,2,6]. Although SYNE2 transcript expression in the patient LCLs is unaffected, the amount of nesprin-2 giant protein is significantly reduced.…”

“…Primary antibodies used: affinity-purified nesprin-2 CT (pAbK1, [14]), dilution 1:500 (IF) and 1:1500 (WB); mouse anti-nesprin-2 giant (clone K20-478, [6]), undiluted (IF); and mouse anti-GAPDH (Proteintech, Manchester, UK), dilution 1:10,000 (WB). Indirect IF analysis involved secondary chicken anti-Rabbit IgG conjugated Alexa Fluor 488, goat anti-Rabbit Alexa Fluor 568, and donkey anti-mouse Alexa Fluor 488 antibodies (ThermoFisher Scientific, Loughborough, UK, diluted 1:1000).…”

“…These direct associations enable the mechanical linkage of cytoskeletal filaments and associated structures, including the plasma membrane with the nuclear interior. Nesprins are members of the spectrin family of proteins, which exhibit a variable number of spectrin repeats, conserved cytoskeleton-binding domains and a C-terminal KASH-domain that integrates the proteins to the nuclear membrane [1][2][3][4][5][6][7][8]. The human genome contains four genes, termed SYNE (spectrin repeat-containing nuclear envelope protein) 1, 2, 3, and 4 which encode for nesprins (nuclear envelope spectrin repeat proteins) [5,[9][10][11].…”

“…The largest isoforms expressed by SYNE1 and SYNE2 are termed as giant, due to their massive molecular weight ranging from 0.8 (nesprin-2 giant) to 1 MDa (nesprin-1 giant). Besides their size, the main hallmark of the giant isoforms is the presence of an N-terminal actinbinding domain (ABD) which is composed of two calponin homology (CH) domains and the presence of a bulky spectrin repeat (SR)-containing segment which spatially separates the ABD from the C-terminal KASH-domain [6,7,13].…”