Conserved cysteine residues in the mammalian lamin A tail are essential for cellular responses to ROS generation

Abstract

SummaryPre-lamin A and progerin have been implicated in normal aging, and the pathogenesis of age-related degenerative diseases is termed 'laminopathies'. Here, we show that mature lamin A has an essential role in cellular fitness and that oxidative damage to lamin A is involved in cellular senescence. Primary human dermal fibroblasts (HDFs) aged replicatively or by pro-oxidants acquire a range of dysmorphic nuclear shapes. We observed that conserved cysteine residues in the lamin A tail domain become hyperoxidized in senescent fibroblasts, which inhibits the formation of lamin A inter-and intramolecular disulfide bonds. Both in the absence of lamin A and in the presence of a lamin A cysteine-toalanine mutant, which eliminates these cysteine residues (522, 588, and 591), mild oxidative stress induced nuclear disorganization and led to premature senescence as a result of decreased tolerance to ROS stimulators. Human dermal fibroblasts lacking lamin A or expressing the lamin A cysteine-to-alanine mutant displayed a gene expression profile of ROS-responsive genes characteristic of chronic ROS stimulation. Our findings suggest that the conserved C-terminal cysteine residues are essential for lamin A function and that loss or oxidative damage to these cysteine residues promotes cellular senescence.

Lamin aggregation is an early sensor of porphyria-induced liver injury

“…These findings are consistent with recent observations showing that oxidant exposure to lamin A thiols, as occurs during exposure to ROS or during cell senescence, results in lamin oxidation at conserved cysteines (Pekovic et al, 2011). Conversely, patients with LMNA mutations exhibit increased sensitivity to oxidative stress and show elevated ROS levels (Malhas et al, 2009;Pekovic et al, 2011;Richards et al, 2011;Sieprath et al, 2012). Lamin B1 also plays a role in oxidative stress; for example, lamin B1 expression decreases under conditions of chronic oxidative stress and this decrease alters the anti-oxidant protein expression through regulation of p53 or Oct-1 (Malhas et al, 2009).…”

“…Therefore, the presence of lamin aggregates in drug and geneticinduced liver injury models is likely related to the oxidative stress caused by accumulated PPIX. These findings are consistent with recent observations showing that oxidant exposure to lamin A thiols, as occurs during exposure to ROS or during cell senescence, results in lamin oxidation at conserved cysteines (Pekovic et al, 2011). Conversely, patients with LMNA mutations exhibit increased sensitivity to oxidative stress and show elevated ROS levels (Malhas et al, 2009;Pekovic et al, 2011;Richards et al, 2011;Sieprath et al, 2012).…”

“…MDB formation requires several cellular events including crosslinking of keratins by transglutaminase-2 (TG2) and site-specific keratin phosphorylation Strnad and Omary, 2009;Kwan et al, 2012). Lamins are also known to undergo aggregation in various laminopathies, such as in Hutchinson-Gilford progeria syndrome (Dechat et al, 2008), and become oxidized via conserved C-terminal cysteine residues in response to cell senescence (Pekovic et al, 2011). However, the effect of oxidative liver injury on lamins, and whether lamins aggregate independent of lamin mutation are unknown.…”

Oxydative stress alters nuclear shape through lamins dysregulation

“…In agreement with this model, it has recently been reported that the tail domain of lamin A is a target of oxidative damage, and its irreversible oxidation led to a loss of lamin A function and entry into senescence. 54 Oxidative stress is known to affect telomeres 55 and cause DNA damage; the increase in oxidative stress could therefore also be accountable Figure 1. Interplay between oxidative stress, telomere shortening, and DNA damage for the induction of senescence.…”

Intermolecular disulfide bonds among nucleoporins regulate karyopherin-dependent nuclear transport

“…Reactive oxygen species (ROS) directly or indirectly oxidize the thiol group in cysteine residues, and thereby alter enzymatic functions (Kobayashi et al, 2006;Motohashi and Yamamoto, 2004;Pekovic et al, 2011;Rhee et al, 2005;Spickett et al, 2006;Winterbourn, 2008). The cytoplasm is normally maintained in a reducing state due to ubiquitous reducing reagents such as glutathione.…”