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Progerin reduces LAP2α-telomere association in Hutchinson-Gilford progeria.

Chojnowski A, Ong PF, Wong ES, Lim JS, Mutalif RA, Navasankari R, Dutta B, Yang H, Liow YY, Sze SK, Boudier T, Wright GD, Colman A, Burke B, Stewart CL, Dreesen O - Elife (2015)

Bottom Line: Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase.However, the mechanism how progerin causes disease remains unclear.These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization.

View Article: PubMed Central - PubMed

Affiliation: Developmental and Regenerative Biology, Institute of Medical Biology, Singapore, Singapore.

ABSTRACT
Hutchinson-Gilford progeria (HGPS) is a premature ageing syndrome caused by a mutation in LMNA, resulting in a truncated form of lamin A called progerin. Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase. However, the mechanism how progerin causes disease remains unclear. Here, we describe an inducible cellular system to model HGPS and find that LAP2α (lamina-associated polypeptide-α) interacts with lamin A, while its interaction with progerin is significantly reduced. Super-resolution microscopy revealed that over 50% of telomeres localize to the lamina and that LAP2α association with telomeres is impaired in HGPS. This impaired interaction is central to HGPS since increasing LAP2α levels rescues progerin-induced proliferation defects and loss of H3K27me3, whereas lowering LAP2 levels exacerbates progerin-induced defects. These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization.

No MeSH data available.


Related in: MedlinePlus

Expression of hTERT or LAP2α does not alleviate nuclear abnormalities in HGPS cells.(A) Percentage of cells with nuclear abnormalities before and after transduction with hTERT. P16 control (ctrl), HGPS AG11498 and HGPS AG11513 were transduced with hTERT and propagated for an additional 20 to 28 passages. (B) Percentage of cells with nuclear abnormalities in the presence or absence of ectopic LAP2α. HGPS AG11513 were transduced with hTERT and pTRIPZ-LAP2α. Nuclear abnormalities were scored by immunofluorescence microscopy, numbers of scored cells are indicated within each bar. Error bars represent standard deviation.DOI:http://dx.doi.org/10.7554/eLife.07759.005
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fig1s2: Expression of hTERT or LAP2α does not alleviate nuclear abnormalities in HGPS cells.(A) Percentage of cells with nuclear abnormalities before and after transduction with hTERT. P16 control (ctrl), HGPS AG11498 and HGPS AG11513 were transduced with hTERT and propagated for an additional 20 to 28 passages. (B) Percentage of cells with nuclear abnormalities in the presence or absence of ectopic LAP2α. HGPS AG11513 were transduced with hTERT and pTRIPZ-LAP2α. Nuclear abnormalities were scored by immunofluorescence microscopy, numbers of scored cells are indicated within each bar. Error bars represent standard deviation.DOI:http://dx.doi.org/10.7554/eLife.07759.005

Mentions: Progerin expression leads to misshapen nuclei (Figure 1—figure supplement 1B), inhibition of cell proliferation (Figure 1C, Figure 1—figure supplement 1C), premature senescence (as measured by expression of senescence-associated β-galactosidase, [SA-β-gal]), a reduction in lamin B1 levels, (Figure 1—figure supplement 1A,D,G) and the induction of 53BP-1 DNA-damage foci (Figure 1D). In addition, western blot analysis from three independent experiments demonstrated that expression of TERT did not reduce progerin levels (Figure 1B,E and Figure 1—figure supplement 1E). All of these changes are consistent with previous findings from HGPS and senescent fibroblasts (Scaffidi and Misteli, 2005; Taimen et al., 2009; Shimi et al., 2011; Freund et al., 2012; Dreesen et al., 2013). The expression of exogenous TERT prevented progerin-induced proliferative defects, loss of lamin B1, and reduced the number of SA-β-gal positive cells to background levels (Figure 1B,D; Figure 1—figure supplement 1A,C,D,G). Consistent with these results, expression of TERT in HGPS patient derived fibroblasts increased telomere length, restored their proliferative capacity and reduced the number of cells with DNA damage foci (Figure 1—figure supplement 1H–J). In contrast, expression of TERT did not ameliorate the nuclear abnormalities of HGPS cells (Figure 1—figure supplement 2A). Lastly, expression of normal lamin A did not significantly affect the proliferation rates of primary- or TERT+ human fibroblasts (Figure 1—figure supplement 1F).


Progerin reduces LAP2α-telomere association in Hutchinson-Gilford progeria.

Chojnowski A, Ong PF, Wong ES, Lim JS, Mutalif RA, Navasankari R, Dutta B, Yang H, Liow YY, Sze SK, Boudier T, Wright GD, Colman A, Burke B, Stewart CL, Dreesen O - Elife (2015)

Expression of hTERT or LAP2α does not alleviate nuclear abnormalities in HGPS cells.(A) Percentage of cells with nuclear abnormalities before and after transduction with hTERT. P16 control (ctrl), HGPS AG11498 and HGPS AG11513 were transduced with hTERT and propagated for an additional 20 to 28 passages. (B) Percentage of cells with nuclear abnormalities in the presence or absence of ectopic LAP2α. HGPS AG11513 were transduced with hTERT and pTRIPZ-LAP2α. Nuclear abnormalities were scored by immunofluorescence microscopy, numbers of scored cells are indicated within each bar. Error bars represent standard deviation.DOI:http://dx.doi.org/10.7554/eLife.07759.005
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4565980&req=5

fig1s2: Expression of hTERT or LAP2α does not alleviate nuclear abnormalities in HGPS cells.(A) Percentage of cells with nuclear abnormalities before and after transduction with hTERT. P16 control (ctrl), HGPS AG11498 and HGPS AG11513 were transduced with hTERT and propagated for an additional 20 to 28 passages. (B) Percentage of cells with nuclear abnormalities in the presence or absence of ectopic LAP2α. HGPS AG11513 were transduced with hTERT and pTRIPZ-LAP2α. Nuclear abnormalities were scored by immunofluorescence microscopy, numbers of scored cells are indicated within each bar. Error bars represent standard deviation.DOI:http://dx.doi.org/10.7554/eLife.07759.005
Mentions: Progerin expression leads to misshapen nuclei (Figure 1—figure supplement 1B), inhibition of cell proliferation (Figure 1C, Figure 1—figure supplement 1C), premature senescence (as measured by expression of senescence-associated β-galactosidase, [SA-β-gal]), a reduction in lamin B1 levels, (Figure 1—figure supplement 1A,D,G) and the induction of 53BP-1 DNA-damage foci (Figure 1D). In addition, western blot analysis from three independent experiments demonstrated that expression of TERT did not reduce progerin levels (Figure 1B,E and Figure 1—figure supplement 1E). All of these changes are consistent with previous findings from HGPS and senescent fibroblasts (Scaffidi and Misteli, 2005; Taimen et al., 2009; Shimi et al., 2011; Freund et al., 2012; Dreesen et al., 2013). The expression of exogenous TERT prevented progerin-induced proliferative defects, loss of lamin B1, and reduced the number of SA-β-gal positive cells to background levels (Figure 1B,D; Figure 1—figure supplement 1A,C,D,G). Consistent with these results, expression of TERT in HGPS patient derived fibroblasts increased telomere length, restored their proliferative capacity and reduced the number of cells with DNA damage foci (Figure 1—figure supplement 1H–J). In contrast, expression of TERT did not ameliorate the nuclear abnormalities of HGPS cells (Figure 1—figure supplement 2A). Lastly, expression of normal lamin A did not significantly affect the proliferation rates of primary- or TERT+ human fibroblasts (Figure 1—figure supplement 1F).

Bottom Line: Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase.However, the mechanism how progerin causes disease remains unclear.These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization.

View Article: PubMed Central - PubMed

Affiliation: Developmental and Regenerative Biology, Institute of Medical Biology, Singapore, Singapore.

ABSTRACT
Hutchinson-Gilford progeria (HGPS) is a premature ageing syndrome caused by a mutation in LMNA, resulting in a truncated form of lamin A called progerin. Progerin triggers loss of the heterochromatic marker H3K27me3, and premature senescence, which is prevented by telomerase. However, the mechanism how progerin causes disease remains unclear. Here, we describe an inducible cellular system to model HGPS and find that LAP2α (lamina-associated polypeptide-α) interacts with lamin A, while its interaction with progerin is significantly reduced. Super-resolution microscopy revealed that over 50% of telomeres localize to the lamina and that LAP2α association with telomeres is impaired in HGPS. This impaired interaction is central to HGPS since increasing LAP2α levels rescues progerin-induced proliferation defects and loss of H3K27me3, whereas lowering LAP2 levels exacerbates progerin-induced defects. These findings provide novel insights into the pathophysiology underlying HGPS, and how the nuclear lamina regulates proliferation and chromatin organization.

No MeSH data available.


Related in: MedlinePlus