Mice that express farnesylated versions of prelamin A in neurons develop achalasia.

Neurons in the brain produce lamin C but almost no lamin A, a consequence of the removal of prelamin A transcripts by miR-9, a brain-specific microRNA. We have proposed that miR-9-mediated regulation of prelamin A in the brain could explain the absence of primary neurological disease in Hutchinson-Gilford progeria syndrome, a genetic disease caused by the synthesis of an internally truncated form of farnesyl-prelamin A (progerin). This explanation makes sense, but it is not entirely satisfying because it is unclear whether progerin-even if were expressed in neurons-would be capable of eliciting neuropathology. To address that issue, we created a new Lmna knock-in allele, Lmna(HG-C), which produces progerin transcripts lacking an miR-9 binding site. Mice harboring the Lmna(HG-C) allele produced progerin in neurons, but they had no pathology in the central nervous system. However, these mice invariably developed esophageal achalasia, and the enteric neurons and nerve fibers in gastrointestinal tract were markedly abnormal. The same disorder, achalasia, was observed in genetically modified mice that express full-length farnesyl-prelamin A in neurons (Zmpste24-deficient mice carrying two copies of a Lmna knock-in allele yielding full-length prelamin A transcripts lacking a miR-9 binding site). Our findings indicate that progerin and full-length farnesyl-prelamin A are toxic to neurons of the enteric nervous system.

New Lmna knock-in mice provide a molecular mechanism for the 'segmental aging' in Hutchinson-Gilford progeria syndrome.

Lamins A and C (products of the LMNA gene) are found in roughly equal amounts in peripheral tissues, but the brain produces mainly lamin C and little lamin A. In HeLa cells and fibroblasts, the expression of prelamin A (the precursor to lamin A) can be reduced by miR-9, but the relevance of those cell culture studies to lamin A regulation in the brain was unclear. To address this issue, we created two new Lmna knock-in alleles, one (Lmna(PLAO-5NT)) with a 5-bp mutation in a predicted miR-9 binding site in prelamin A's 3' UTR, and a second (Lmna(PLAO-UTR)) in which prelamin A's 3' UTR was replaced with lamin C's 3' UTR. Neither allele had significant effects on lamin A levels in peripheral tissues; however, both substantially increased prelamin A transcript levels and lamin A protein levels in the cerebral cortex and the cerebellum. The increase in lamin A expression in the brain was more pronounced with the Lmna(PLAO-UTR) allele than with the Lmna(PLAO-5NT) allele. With both alleles, the increased expression of prelamin A transcripts and lamin A protein was greater in the cerebral cortex than in the cerebellum. Our studies demonstrate the in vivo importance of prelamin A's 3' UTR and its miR-9 binding site in regulating lamin A expression in the brain. The reduced expression of prelamin A in the brain likely explains why children with Hutchinson-Gilford progeria syndrome (a progeroid syndrome caused by a mutant form of prelamin A) are spared from neurodegenerative disease.

Regulation of prelamin A but not lamin C by miR-9, a brain-specific microRNA.

Lamins A and C, alternatively spliced products of the LMNA gene, are key components of the nuclear lamina. The two isoforms are found in similar amounts in most tissues, but we observed an unexpected pattern of expression in the brain. Western blot and immunohistochemistry studies showed that lamin C is abundant in the mouse brain, whereas lamin A and its precursor prelamin A are restricted to endothelial cells and meningeal cells and are absent in neurons and glia. Prelamin A transcript levels were low in the brain, but this finding could not be explained by alternative splicing. In lamin A-only knockin mice, where alternative splicing is absent and all the output of the gene is channeled into prelamin A transcripts, large amounts of lamin A were found in peripheral tissues, but there was very little lamin A in the brain. Also, in knockin mice expressing exclusively progerin (a toxic form of prelamin A found in Hutchinson-Gilford progeria syndrome), the levels of progerin in the brain were extremely low. Further studies showed that prelamin A expression, but not lamin C expression, is down-regulated by a brain-specific microRNA, miR-9. Expression of miR-9 in cultured cells reduced lamin A expression, and this effect was abolished when the miR-9-binding site in the prelamin A 3' UTR was mutated. The down-regulation of prelamin A expression in the brain could explain why mouse models of Hutchinson-Gilford progeria syndrome are free of central nervous system pathology.

Absence of progeria-like disease phenotypes in knock-in mice expressing a non-farnesylated version of progerin.

Hutchinson-Gilford progeria syndrome (HGPS) is caused by a mutant prelamin A, progerin, that terminates with a farnesylcysteine. HGPS knock-in mice (Lmna(HG/+)) develop severe progeria-like disease phenotypes. These phenotypes can be ameliorated with a protein farnesyltransferase inhibitor (FTI), suggesting that progerin's farnesyl lipid is important for disease pathogenesis and raising the possibility that FTIs could be useful for treating humans with HGPS. Subsequent studies showed that mice expressing non-farnesylated progerin (Lmna(nHG/+) mice, in which progerin's carboxyl-terminal -CSIM motif was changed to -SSIM) also develop severe progeria, raising doubts about whether any treatment targeting protein prenylation would be particularly effective. We suspected that those doubts might be premature and hypothesized that the persistent disease in Lmna(nHG/+) mice could be an unanticipated consequence of the cysteine-to-serine substitution that was used to eliminate farnesylation. To test this hypothesis, we generated a second knock-in allele yielding non-farnesylated progerin (Lmna(csmHG)) in which the carboxyl-terminal -CSIM motif was changed to -CSM. We then compared disease phenotypes in mice harboring the Lmna(nHG) or Lmna(csmHG) allele. As expected, Lmna(nHG/+) and Lmna(nHG/nHG) mice developed severe progeria-like disease phenotypes, including osteolytic lesions and rib fractures, osteoporosis, slow growth and reduced survival. In contrast, Lmna(csmHG/+) and Lmna(csmHG/csmHG) mice exhibited no bone disease and displayed entirely normal body weights and survival. The frequencies of misshapen cell nuclei were lower in Lmna(csmHG/+) and Lmna(csmHG/csmHG) fibroblasts. These studies show that the ability of non-farnesylated progerin to elicit disease depends on the carboxyl-terminal mutation used to eliminate protein prenylation.

An absence of both lamin B1 and lamin B2 in keratinocytes has no effect on cell proliferation or the development of skin and hair.

Nuclear lamins are usually classified as A-type (lamins A and C) or B-type (lamins B1 and B2). A-type lamins have been implicated in multiple genetic diseases but are not required for cell growth or development. In contrast, B-type lamins have been considered essential in eukaryotic cells, with crucial roles in DNA replication and in the formation of the mitotic spindle. Knocking down the genes for B-type lamins (LMNB1, LMNB2) in HeLa cells has been reported to cause apoptosis. In the current study, we created conditional knockout alleles for mouse Lmnb1 and Lmnb2, with the goal of testing the hypothesis that B-type lamins are crucial for the growth and viability of mammalian cells in vivo. Using the keratin 14-Cre transgene, we bred mice lacking the expression of both Lmnb1 and Lmnb2 in skin keratinocytes (Lmnb1(Δ/Δ)Lmnb2(Δ/Δ)). Lmnb1 and Lmnb2 transcripts were absent in keratinocytes of Lmnb1(Δ/Δ)Lmnb2(Δ/Δ) mice, and lamin B1 and lamin B2 proteins were undetectable. But despite an absence of B-type lamins in keratinocytes, the skin and hair of Lmnb1(Δ/Δ)Lmnb2(Δ/Δ) mice developed normally and were free of histological abnormalities, even in 2-year-old mice. After an intraperitoneal injection of bromodeoxyuridine (BrdU), similar numbers of BrdU-positive keratinocytes were observed in the skin of wild-type and Lmnb1(Δ/Δ)Lmnb2(Δ/Δ) mice. Lmnb1(Δ/Δ)Lmnb2(Δ/Δ) keratinocytes did not exhibit aneuploidy, and their growth rate was normal in culture. These studies challenge the concept that B-type lamins are essential for proliferation and vitality of eukaryotic cells.

Targeting the protein prenyltransferases efficiently reduces tumor development in mice with K-RAS-induced lung cancer.

RAS and RHO proteins, which contribute to tumorigenesis and metastasis, undergo posttranslational modification with an isoprenyl lipid by protein farnesyltransferase (FTase) or protein geranylgeranyltransferase-I (GGTase-I). Inhibitors of FTase and GGTase-I were developed to block RAS-induced malignancies, but their utility has been difficult to evaluate because of off-target effects, drug resistance, and toxicity. Moreover, the impact of FTase deficiency and combined FTase/GGTase-I deficiency has not been evaluated with genetic approaches. We found that inactivation of FTase eliminated farnesylation of HDJ2 and H-RAS, prevented H-RAS targeting to the plasma membrane, and blocked proliferation of primary and K-RAS(G12D)-expressing fibroblasts. FTase inactivation in mice with K-RAS-induced lung cancer reduced tumor growth and improved survival, similar to results obtained previously with inactivation of GGTase-I. Simultaneous inactivation of FTase and GGTase-I markedly reduced lung tumors and improved survival without apparent pulmonary toxicity. These data shed light on the biochemical and therapeutic importance of FTase and suggest that simultaneous inhibition of FTase and GGTase-I could be useful in cancer therapeutics.

Severe hepatocellular disease in mice lacking one or both CaaX prenyltransferases.

Protein farnesyltransferase (FTase) and protein geranylgeranyltransferase-I (GGTase-I) add 15- or 20-carbon lipids, respectively, to proteins that terminate with a CaaX motif. These posttranslational modifications of proteins with lipids promote protein interactions with membrane surfaces in cells, but the in vivo importance of the CaaX prenyltransferases and the protein lipidation reactions they catalyze remain incompletely defined. One study concluded that a deficiency of FTase was inconsequential in adult mice and led to little or no tissue pathology. To assess the physiologic importance of the CaaX prenyltransferases, we used conditional knockout alleles and an albumin-Cre transgene to produce mice lacking FTase, GGTase-I, or both enzymes in hepatocytes. The hepatocyte-specific FTase knockout mice survived but exhibited hepatocellular disease and elevated transaminases. Mice lacking GGTase-I not only had elevated transaminases but also had dilated bile cannaliculi, hyperbilirubinemia, hepatosplenomegaly, and reduced survival. Of note, GGTase-I-deficient hepatocytes had a rounded shape and markedly reduced numbers of actin stress fibers. Hepatocyte-specific FTase/GGTase-I double-knockout mice closely resembled mice lacking GGTase-I alone, but the disease was slightly more severe. Our studies refute the notion that FTase is dispensable and demonstrate that GGTase-I is crucial for the vitality of hepatocytes.

Inhibitors of protein geranylgeranyltransferase-I lead to prelamin A accumulation in cells by inhibiting ZMPSTE24.

Protein farnesyltransferase (FTase) inhibitors, generally called "FTIs," block the farnesylation of prelamin A, inhibiting the biogenesis of mature lamin A and leading to an accumulation of prelamin A within cells. A recent report found that a GGTI, an inhibitor of protein geranylgeranyltransferase-I (GGTase-I), caused an exaggerated accumulation of prelamin A in the presence of low amounts of an FTI. This finding was interpreted as indicating that prelamin A can be alternately prenylated by GGTase-I and that inhibiting both protein prenyltransferases leads to more prelamin A accumulation than blocking FTase alone. Here, we tested an alternative hypothesis-GGTIs are not specific for GGTase-I, and they lead to prelamin A accumulation by inhibiting ZMPSTE24 (a zinc metalloprotease that converts farnesyl-prelamin A to mature lamin A). In our studies, commonly used GGTIs caused prelamin A accumulation in human fibroblasts, but the prelamin A in GGTI-treated cells exhibited a more rapid electrophoretic mobility than prelamin A from FTI-treated cells. The latter finding suggested that the prelamin A in GGTI-treated cells might be farnesylated (which would be consistent with the notion that GGTIs inhibit ZMPSTE24). Indeed, metabolic labeling studies revealed that the prelamin A in GGTI-treated fibroblasts is farnesylated. Moreover, biochemical assays of ZMPSTE24 activity showed that ZMPSTE24 is potently inhibited by a GGTI. Our studies show that GGTIs inhibit ZMPSTE24, leading to an accumulation of farnesyl-prelamin A. Thus, caution is required when interpreting the effects of GGTIs on prelamin A processing.

The posttranslational processing of prelamin A and disease.

Human geneticists have shown that some progeroid syndromes are caused by mutations that interfere with the conversion of farnesyl-prelamin A to mature lamin A. For example, Hutchinson-Gilford progeria syndrome is caused by LMNA mutations that lead to the accumulation of a farnesylated version of prelamin A. In this review, we discuss the posttranslational modifications of prelamin A and their relevance to the pathogenesis and treatment of progeroid syndromes.

Direct synthesis of lamin A, bypassing prelamin a processing, causes misshapen nuclei in fibroblasts but no detectable pathology in mice.

Lamin A, a key component of the nuclear lamina, is generated from prelamin A by four post-translational processing steps: farnesylation, endoproteolytic release of the last three amino acids of the protein, methylation of the C-terminal farnesylcysteine, and finally, endoproteolytic release of the last 15 amino acids of the protein (including the farnesylcysteine methyl ester). The last cleavage step, mediated by ZMPSTE24, releases mature lamin A. This processing scheme has been conserved through vertebrate evolution and is widely assumed to be crucial for targeting lamin A to the nuclear envelope. However, its physiologic importance has never been tested. To address this issue, we created mice with a "mature lamin A-only" allele (Lmna(LAO)), which contains a stop codon immediately after the last codon of mature lamin A. Thus, Lmna(LAO/LAO) mice synthesize mature lamin A directly, bypassing prelamin A synthesis and processing. The levels of mature lamin A in Lmna(LAO/LAO) mice were indistinguishable from those in "prelamin A-only" mice (Lmna(PLAO/PLAO)), where all of the lamin A is produced from prelamin A. Lmna(LAO/LAO) exhibited normal body weights and had no detectable disease phenotypes. A higher frequency of nuclear blebs was observed in Lmna(LAO/LAO) embryonic fibroblasts; however, the mature lamin A in the tissues of Lmna(LAO/LAO) mice was positioned normally at the nuclear rim. We conclude that prelamin A processing is dispensable in mice and that direct synthesis of mature lamin A has little if any effect on the targeting of lamin A to the nuclear rim in mouse tissues.

Activating the synthesis of progerin, the mutant prelamin A in Hutchinson-Gilford progeria syndrome, with antisense oligonucleotides.

Hutchinson-Gilford progeria syndrome (HGPS) is caused by point mutations that increase utilization of an alternate splice donor site in exon 11 of LMNA (the gene encoding lamin C and prelamin A). The alternate splicing reduces transcripts for wild-type prelamin A and increases transcripts for a truncated prelamin A (progerin). Here, we show that antisense oligonucleotides (ASOs) against exon 11 sequences downstream from the exon 11 splice donor site promote alternate splicing in both wild-type and HGPS fibroblasts, increasing the synthesis of progerin. Indeed, wild-type fibroblasts transfected with these ASOs exhibit progerin levels similar to (or greater than) those in fibroblasts from HGPS patients. This progerin was farnesylated, as judged by metabolic labeling studies. The synthesis of progerin in wild-type fibroblasts was accompanied by the same nuclear shape and gene-expression perturbations observed in HGPS fibroblasts. An ASO corresponding to the 5' portion of intron 11 also promoted alternate splicing. In contrast, an ASO against exon 11 sequences 5' to the alternate splice site reduced alternate splicing in HGPS cells and modestly lowered progerin levels. Thus, different ASOs can be used to increase or decrease 'HGPS splicing'. ASOs represent a new and powerful tool for recreating HGPS pathophysiology in wild-type cells.

Progerin elicits disease phenotypes of progeria in mice whether or not it is farnesylated.

Hutchinson-Gilford progeria syndrome (HGPS), a rare disease that results in what appears to be premature aging, is caused by the production of a mutant form of prelamin A known as progerin. Progerin retains a farnesyl lipid anchor at its carboxyl terminus, a modification that is thought to be important in disease pathogenesis. Inhibition of protein farnesylation improves the hallmark nuclear shape abnormalities in HGPS cells and ameliorates disease phenotypes in mice harboring a knockin HGPS mutation (LmnaHG/+). The amelioration of disease, however, is incomplete, leading us to hypothesize that nonfarnesylated progerin also might be capable of eliciting disease. To test this hypothesis, we created knockin mice expressing nonfarnesylated progerin (LmnanHG/+). LmnanHG/+ mice developed the same disease phenotypes observed in LmnaHG/+ mice, although the phenotypes were milder, and mouse embryonic fibroblasts (MEFs) derived from these mice contained fewer misshapen nuclei. The steady-state levels of progerin in LmnanHG/+ MEFs and tissues were lower, suggesting a possible explanation for the milder phenotypes. These data support the concept that inhibition of protein farnesylation in progeria could be therapeutically useful but also suggest that this approach may be limited, as progerin elicits disease phenotypes whether or not it is farnesylated.

Assessing the efficacy of protein farnesyltransferase inhibitors in mouse models of progeria.

Hutchinson-Gilford progeria syndrome (HGPS) is caused by the accumulation of a farnesylated form of prelamin A (progerin). Previously, we showed that blocking protein farnesylation with a farnesyltransferase inhibitor (FTI) ameliorates the disease phenotypes in mouse model of HGPS (Lmna(HG/+)). However, the interpretation of the FTI treatment studies is open to question in light of recent studies showing that mice expressing a nonfarnesylated version of progerin (Lmna(nHG/+)) develop progeria-like disease phenotypes. The fact that Lmna(nHG/+) mice manifest disease raised the possibility that the beneficial effects of an FTI in Lmna(HG/+) mice were not due to the effects of the drug on the farnesylation of progerin, but may have been due to unanticipated secondary effects of the drug on other farnesylated proteins. To address this issue, we compared the ability of an FTI to improve progeria-like disease phenotypes in both Lmna(HG/+) and Lmna(nHG/+) mice. In Lmna(HG/+) mice, the FTI reduced disease phenotypes in a highly significant manner, but the drug had no effect in Lmna(nHG/+) mice. The failure of the FTI to ameliorate disease in Lmna(nHG/+) mice supports the idea that the beneficial effects of an FTI in Lmna(HG/+) mice are due to the effect of drug on the farnesylation of progerin.

Treatment with a farnesyltransferase inhibitor improves survival in mice with a Hutchinson-Gilford progeria syndrome mutation.

Hutchinson-Gilford progeria syndrome (HGPS) is a progeroid syndrome characterized by multiple aging-like disease phenotypes. We recently reported that a protein farnesyltransferase inhibitor (FTI) improved several disease phenotypes in mice with a HGPS mutation (Lmna(HG/+)). Here, we investigated the impact of an FTI on the survival of Lmna(HG/+) mice. The FTI significantly improved the survival of both male and female Lmna(HG/+) mice. Treatment with the FTI also improved body weight curves and reduced the number of spontaneous rib fractures. This study provides further evidence for a beneficial effect of an FTI in HGPS.

A farnesyltransferase inhibitor improves disease phenotypes in mice with a Hutchinson-Gilford progeria syndrome mutation.

Hutchinson-Gilford progeria syndrome (HGPS) is caused by the production of a truncated prelamin A, called progerin, which is farnesylated at its carboxyl terminus. Progerin is targeted to the nuclear envelope and causes misshapen nuclei. Protein farnesyltransferase inhibitors (FTI) mislocalize progerin away from the nuclear envelope and reduce the frequency of misshapen nuclei. To determine whether an FTI would ameliorate disease phenotypes in vivo, we created gene-targeted mice with an HGPS mutation (LmnaHG/+) and then examined the effect of an FTI on disease phenotypes. LmnaHG/+ mice exhibited phenotypes similar to those in human HGPS patients, including retarded growth, reduced amounts of adipose tissue, micrognathia, osteoporosis, and osteolytic lesions in bone. Osteolytic lesions in the ribs led to spontaneous bone fractures. Treatment with an FTI increased adipose tissue mass, improved body weight curves, reduced the number of rib fractures, and improved bone mineralization and bone cortical thickness. These studies suggest that FTIs could be useful for treating humans with HGPS.

Prelamin A and lamin A appear to be dispensable in the nuclear lamina.

Lamin A and lamin C, both products of Lmna, are key components of the nuclear lamina. In the mouse, a deficiency in both lamin A and lamin C leads to slow growth, muscle weakness, and death by 6 weeks of age. Fibroblasts deficient in lamins A and C contain misshapen and structurally weakened nuclei, and emerin is mislocalized away from the nuclear envelope. The physiologic rationale for the existence of the 2 different Lmna products lamin A and lamin C is unclear, although several reports have suggested that lamin A may have particularly important functions, for example in the targeting of emerin and lamin C to the nuclear envelope. Here we report the development of lamin C-only mice (Lmna(LCO/LCO)), which produce lamin C but no lamin A or prelamin A (the precursor to lamin A). Lmna(LCO/LCO) mice were entirely healthy, and Lmna(LCO/LCO) cells displayed normal emerin targeting and exhibited only very minimal alterations in nuclear shape and nuclear deformability. Thus, at least in the mouse, prelamin A and lamin A appear to be dispensable. Nevertheless, an accumulation of farnesyl-prelamin A (as occurs with a deficiency in the prelamin A processing enzyme Zmpste24) caused dramatically misshapen nuclei and progeria-like disease phenotypes. The apparent dispensability of prelamin A suggested that lamin A-related progeroid syndromes might be treated with impunity by reducing prelamin A synthesis. Remarkably, the presence of a single Lmna(LCO) allele eliminated the nuclear shape abnormalities and progeria-like disease phenotypes in Zmpste24-/- mice. Moreover, treating Zmpste24-/- cells with a prelamin A-specific antisense oligonucleotide reduced prelamin A levels and significantly reduced the frequency of misshapen nuclei. These studies suggest a new therapeutic strategy for treating progeria and other lamin A diseases.

Caution! Analyze transcripts from conditional knockout alleles.

A common strategy for conditional knockout alleles is to "flox" (flank with loxP sites) a 5' exon within the target gene. Typically, the floxed exon does not contain a unit number of codons so that the Cre-mediated recombination event yields a frameshift and a null allele. Documenting recombination within the genomic DNA is often regarded as sufficient proof of a frameshift, and the analysis of transcripts is neglected. We evaluated a previously reported conditional knockout allele for the beta-subunit of protein farnesyltransferase. The recombination event in that allele-the excision of exon 3-was predicted to yield a frameshift. However, following the excision of exon 3, exon 4 was skipped by the mRNA splicing machinery, and the predominant transcript from the mutant allele lacked exon 3 and exon 4 sequences. The "Deltaexon 3-4 transcript" does not contain a frameshift but rather is predicted to encode a protein with a short in-frame deletion. This represents a significant concern when studying an enzyme, since an enzyme with partial function could lead to erroneous conclusions. With thousands of new conditional knockout alleles under construction within mouse mutagenesis consortiums, the protein farnesyltransferase allele holds an important lesson-to characterize knockout alleles at both the DNA and RNA levels.

Protein farnesyltransferase inhibitors and progeria.

Genetic mutations that lead to an accumulation of farnesyl-prelamin A cause progeroid syndromes, including Hutchinson-Gilford progeria syndrome. It seemed possible that the farnesylated form of prelamin A might be toxic to mammalian cells, accounting for all the disease phenotypes that are characteristic of progeria. This concept led to the hypothesis that protein farnesyltransferase inhibitors (FTIs) might ameliorate the disease phenotypes of progeria in mouse models. Thus far, two different mouse models of progeria have been examined. In both models, FTIs improved progeria-like disease phenotypes. Here, prelamin A post-translational processing is discussed and several mutations underlying human progeroid syndromes are described. In addition, recent data showing that FTIs ameliorate disease phenotypes in a pair of mouse models of progeria are discussed.

Modulation of LMNA splicing as a strategy to treat prelamin A diseases.

The alternatively spliced products of LMNA, lamin C and prelamin A (the precursor to lamin A), are produced in similar amounts in most tissues and have largely redundant functions. This redundancy suggests that diseases, such as Hutchinson-Gilford progeria syndrome (HGPS), that are caused by prelamin A-specific mutations could be treated by shifting the output of LMNA more toward lamin C. Here, we investigated mechanisms that regulate LMNA mRNA alternative splicing and assessed the feasibility of reducing prelamin A expression in vivo. We identified an exon 11 antisense oligonucleotide (ASO) that increased lamin C production at the expense of prelamin A when transfected into mouse and human fibroblasts. The same ASO also reduced the expression of progerin, the mutant prelamin A protein in HGPS, in fibroblasts derived from patients with HGPS. Mechanistic studies revealed that the exon 11 sequences contain binding sites for serine/arginine-rich splicing factor 2 (SRSF2), and SRSF2 knockdown lowered lamin A production in cells and in murine tissues. Moreover, administration of the exon 11 ASO reduced lamin A expression in wild-type mice and progerin expression in an HGPS mouse model. Together, these studies identify ASO-mediated reduction of prelamin A as a potential strategy to treat prelamin A-specific diseases.

Estradiol protects against cerebellar damage and motor deficit in ethanol-withdrawn rats.

On the basis of findings obtained from this study, we hypothesize that the female sex steroid 17beta-estradiol (E(2)) protects against cerebellar neuronal damage and behavioral deficit in rats withdrawn from chronic ethanol exposure. Ovariectomized rats implanted with E(2) or an oil pellet received liquid ethanol (7.5% [wt./vol.]) or dextrin diet for 5 weeks, followed by 2 weeks of ethanol withdrawal. On termination of diet administration, rats were tested for both overt withdrawal signs and latency (seconds) to fall from an accelerating rotarod in six consecutive sessions (the longer the latency, the better the performance). The initial latency was measured separately to assess motoric capacity before learning occurred. Rats were then killed, and cerebella were prepared for accessing of Purkinje cell damage. The study revealed three specific findings. (1) In the absence of E(2), the ethanol withdrawal group showed higher total ethanol withdrawal sign scores than those for the dextrin group, whereas the score for the ethanol withdrawal group was lower in the presence of E(2). (2) In the absence of E(2), the ethanol withdrawal group showed shorter rotarod latency than that for the dextrin group, whereas the latency for the ethanol withdrawal group increased in the E(2)-treated group. In ethanol withdrawal groups, E(2) treatment also resulted in a longer latency than that observed with oil treatment in the initial session and in subsequent sessions. (3) Purkinje cell numbers in the ethanol withdrawal group without E(2) were lower than those in dextrin groups and in the ethanol withdrawal group with E(2) treatment. These findings support the suggestion that E(2) exerts protective effects against withdrawal signs, cerebellar neuronal damage, and motoric impairment in subjects exposed to, and withdrawn from, chronic ethanol exposure.