Inhibiting farnesylation reverses the nuclear morphology defect in a HeLa cell model for Hutchinson-Gilford progeria syndrome

Mallampalli, Monica P.; Huyer, Gregory; Bendale, Pravin; Gelb, Michael H.; Michaelis, Susan

doi:10.1073/pnas.0503712102

Cited by 186 publications

(170 citation statements)

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“…Thus, processing mutants, but not R527H, act in a dominant fashion to interfere with pRB function. Our data correspond with recent findings suggesting that unprocessed lamin A acts dominantly in laminopathy-based premature aging and that MAD is an autosomal-recessive disorder (37,40,48).…”

Section: Vol 26 2006supporting

confidence: 80%

Stabilization of the Retinoblastoma Protein by A-Type Nuclear Lamins Is Required for INK4A-Mediated Cell Cycle Arrest

Nitta¹,

Jameson²,

Kudlow

et al. 2006

Molecular and Cellular Biology

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Mutations in the LMNA gene, which encodes all A-type lamins, including lamin A and lamin C, cause a variety of tissue-specific degenerative diseases termed laminopathies. Little is known about the pathogenesis of these disorders. Previous studies have indicated that A-type lamins interact with the retinoblastoma protein (pRB). Here we probe the functional consequences of this association and further examine links between nuclear structure and cell cycle control. Since pRB is required for cell cycle arrest by p16 ink4a , we tested the responsiveness of multiple lamin A/C-depleted cell lines to overexpression of this CDK inhibitor and tumor suppressor. We find that the loss of A-type lamin expression results in marked destabilization of pRB. This reduction in pRB renders cells resistant to p16 ink4a -mediated G 1 arrest. Reintroduction of lamin A, lamin C, or pRB restores p16 ink4a -responsiveness to Lmna ؊/؊ cells. An array of lamin A mutants, representing a variety of pathologies as well as lamin A processing mutants, was introduced into Lmna ؊/؊ cells. Of these, a mutant associated with mandibuloacral dysplasia (MAD R527H), as well as two lamin A processing mutants, but not other disease-associated mutants, failed to restore p16 ink4a responsiveness. Although our findings do not rule out links between altered pRB function and laminopathies, they fail to support such an assertion. These findings do link lamin A/C to the functional activation of a critical tumor suppressor pathway and further the possibility that somatic mutations in LMNA contribute to tumor progression.A-type lamins are intermediate filament proteins that have been linked to the organization and maintenance of nuclear structure. In most differentiated tissues, A-type lamins (predominantly lamins A and C), along with lamin B, comprise the meshwork underlying the inner nuclear membrane known as the nuclear lamina (63). Unlike lamin C, lamin A contains a carboxy-terminal CaaX motif and must undergo a series of posttranslational modifications to form the mature lamin A (77). In particular, the cysteine of the CaaX motif in lamin A is isoprenylated, followed by cleavage of the aaX and carboxymethylation of the C-terminal cysteine (72). Lastly, a second cleavage event by Zmpste24 removes the last 15 amino acids to yield the mature lamin A (3, 13, 74).Mutations within the LMNA gene cause a variety of human disorders collectively known as laminopathies. These include progeria syndromes and dystrophies associated with skeletal muscle and adipose tissue (5,10,15,19,45,58). Mice lacking A-type lamins or deficient in processing lamin A develop skeletal and cardiac muscular dystrophies, thus confirming the importance of A-type lamins for muscle differentiation and/or maintenance (52, 65). The mechanism by which mutations in A-type lamins generate tissue-specific disorders is unknown. However, one model posits that lamin A/C regulates gene expression in differentiated tissue by coordinating the activity of key transcription factors.A-type lamins localize to p...

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Section: Vol 26 2006supporting

confidence: 80%

Stabilization of the Retinoblastoma Protein by A-Type Nuclear Lamins Is Required for INK4A-Mediated Cell Cycle Arrest

Nitta¹,

Jameson²,

Kudlow

et al. 2006

Molecular and Cellular Biology

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“…In all of these cells, the FTI treatment significantly reduced nuclear shape abnormalities. Other laboratories [82][83][84] also reported that FTIs improved nuclear shape in human HGPS fibroblasts and/or cells that had been transfected with a progerin cDNA.…”

Section: Fti Treatment Inhibits Lamin a Biogenesis In Cultured Cells-mentioning

confidence: 96%

Mouse models of the laminopathies

Stewart

Kozlov

Fong

et al. 2007

Experimental Cell Research

107

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The A and B type lamins are nuclear intermediate filament proteins that comprise the bulk of the nuclear lamina, a thin proteinaceous structure underlying the inner nuclear membrane. The A-type lamins are encoded by the lamin A gene (LMNA). Mutations in this gene have been linked to at least nine diseases, including the progeroid diseases Hutchinson-Gilford progeria and atypical Werner's syndromes, striated muscle diseases including muscular dystrophies and dilated cardiomyopathies, lipodystrophies affecting adipose tissue deposition, diseases affecting skeletal development, and a peripheral neuropathy. To understand how different diseases arise from different mutations in the same gene, mouse lines carrying some of the same mutations found in the human diseases have been established. We, and others have generated mice with different mutations that result in progeria, muscular dystrophy, and dilated cardiomyopathy. To further our understanding of the functions of the lamins, we also created mice lacking lamin B1, as well as mice expressing only one of the Atype lamins. These mouse lines are providing insights into the functions of the lamina and how changes to the lamina affect the mechanical integrity of the nucleus as well as signaling pathways that, when disrupted, may contribute to the disease.

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“…On induction (on), a nucleoplasmic and rim localization typical for lamin A is observed. When induced in the presence of farnesyltransferase inhibition (FTI), GFP-prelamin A accumulates within the nucleus in bright foci, as has also been documented by us and others (Capell et al, 2005;Glynn and Glover, 2005;Mallampalli et al, 2005;Toth et al, 2005;Yang et al, 2006). Bar, 50 m. (B) Cycloheximide-chase analysis of preaccumulated nuclear prelamin A upon release from FTI block.…”

Section: The C-terminus Of Zmpste24 Which Contains a Dilysinelike Momentioning

confidence: 99%

“…Such large intranuclear foci have previously been observed under conditions of FTI treatment in several cell types, yet the nature and potential function of these prelamin A-containing foci remains unknown (Capell et al, 2005;Glynn and Glover, 2005;Mallampalli et al, 2005;Toth et al, 2005;Yang et al, 2005). Our data suggest that these foci represent an intermediate in biogenesis rather than dead-end aggregates, because lamin A chases from the foci to the nuclear rim over time in the absence of new protein synthesis ( Figure 2B), but fails to chase to the rim when CaaX processing is blocked ( Figure 2C).…”

Section: Gfp-prelamin a Can Be Processed Within The Nucleusmentioning

confidence: 99%

Analysis of Prelamin A Biogenesis Reveals the Nucleus to be a CaaX Processing Compartment

Barrowman¹,

Hamblet²,

George³

et al. 2008

MBoC

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Proteins establish and maintain a distinct intracellular localization by means of targeting, retention, and retrieval signals, ensuring most proteins reside predominantly in one cellular location. The enzymes involved in the maturation of lamin A present a challenge to this paradigm. Lamin A is first synthesized as a 74-kDa precursor, prelamin A, with a C-terminal CaaX motif and undergoes a series of posttranslational modifications including CaaX processing (farnesylation, aaX cleavage and carboxylmethylation), followed by endoproteolytic cleavage by Zmpste24. Failure to cleave prelamin A results in progeria and related premature aging disorders. Evidence suggests prelamin A is imported directly into the nucleus where it is processed. Paradoxically, the processing enzymes have been shown to reside in the cytosol (farnesyltransferase), or are ER membrane proteins (Zmpste24, Rce1, and Icmt) with their active sites facing the cytosol. Here we have reexamined the cellular site of prelamin A processing, and show that the mammalian and yeast processing enzymes Zmpste24 and Icmt exhibit a dual localization to the inner nuclear membrane, as well as the ER membrane. Our findings reveal the nucleus to be a physiologically relevant location for CaaX processing, and provide insight into the biology of a protein at the center of devastating progeroid diseases. INTRODUCTIONThe nuclear envelope consists of an inner and outer membrane. The outer nuclear membrane (ONM) is continuous with the endoplasmic reticulum (ER) and connects with the inner nuclear membrane (INM) at the nuclear pore membrane (POM; Lusk et al., 2007). Integral membrane proteins that reside in the INM are initially inserted into the endoplasmic reticulum (ER) membrane and move via the POM to the INM where they maintain a concentrated localization by binding to chromatin or tethering to the nuclear lamina (Powell and Burke, 1990;Soullam and Worman, 1993;Holmer and Worman, 2001;Ohba et al., 2004;Lusk et al., 2007;Schirmer and Foisner, 2007). Until recently, conventional wisdom held that the localization of proteins to either the ER membrane or the INM is mutually exclusive. For example, proteins that are found within the INM, such as LAP1, are not generally found throughout the ER/ONM; likewise, ER proteins such as HMG-CoA reductase are strictly localized to the ER (Wright et al., 1988;Powell and Burke, 1990;Deng and Hochstrasser, 2006). It was recently shown that a notable exception to this paradigm is the yeast E3 ubiquitin ligase, Doa10p. Doa10p was long known to reside in the ER membrane (Swanson et al., 2001;Kreft et al., 2006). However, recent data indicate that Doa10p exhibits dual steady-state localizations, residing and functioning in both the ER membrane where it mediates ER-associated degradation of membrane and secretory proteins, and in the INM where it mediates degradation of the nuclear transcription factor MAT␣2 (Deng and Hochstrasser, 2006).The present study documents another exception to the mutual exclusivity of ER membrane and INM localizati...

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Inhibiting farnesylation reverses the nuclear morphology defect in a HeLa cell model for Hutchinson-Gilford progeria syndrome

Cited by 186 publications

References 35 publications

Stabilization of the Retinoblastoma Protein by A-Type Nuclear Lamins Is Required for INK4A-Mediated Cell Cycle Arrest

Stabilization of the Retinoblastoma Protein by A-Type Nuclear Lamins Is Required for INK4A-Mediated Cell Cycle Arrest

Mouse models of the laminopathies

Analysis of Prelamin A Biogenesis Reveals the Nucleus to be a CaaX Processing Compartment

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