Human ZMPSTE24 disease mutations: residual proteolytic activity correlates with disease severity

Abstract

The zinc metalloprotease ZMPSTE24 plays a critical role in nuclear lamin biology by cleaving the prenylated and carboxylmethylated 15-amino acid tail from the C-terminus of prelamin A to yield mature lamin A. A defect in this proteolytic event, caused by a mutation in the lamin A gene (LMNA) that eliminates the ZMPSTE24 cleavage site, underlies the premature aging disease Hutchinson-Gilford Progeria Syndrome (HGPS). Likewise, mutations in the ZMPSTE24 gene that result in decreased enzyme function cause a spectrum of diseases that share certain features of premature aging. Twenty human ZMPSTE24 alleles have been identified that are associated with three disease categories of increasing severity: mandibuloacral dysplasia type B (MAD-B), severe progeria (atypical 'HGPS') and restrictive dermopathy (RD). To determine whether a correlation exists between decreasing ZMPSTE24 protease activity and increasing disease severity, we expressed mutant alleles of ZMPSTE24 in yeast and optimized in vivo yeast mating assays to directly compare the activity of alleles associated with each disease category. We also measured the activity of yeast crude membranes containing the ZMPSTE24 mutant proteins in vitro. We determined that, in general, the residual activity of ZMPSTE24 patient alleles correlates with disease severity. Complete loss-of-function alleles are associated with RD, whereas retention of partial, measureable activity results in MAD-B or severe progeria. Importantly, our assays can discriminate small differences in activity among the mutants, confirming that the methods presented here will be useful for characterizing any new ZMPSTE24 mutations that are discovered.

AIM2 inflammasome is activated by pharmacological disruption of nuclear envelope integrity

“…Each filter paper was lodged into the neck of a vial containing 10 mL of scintillation fluid (RPI), capped, and allowed to diffuse at room temperature for 3 h. The base-releasable [ 14 C]-methanol was quantified by liquid scintillation counting. Background counts from ste24Δ rce1Δ yeast with empty vector (77) were subtracted from each sample. IC 50 determinations were performed in triplicate and calculated by using GraphPad 4.0.…”

New ZMPSTE24 (FACE1) mutations in patients affected with restrictive dermopathy or related progeroid syndromes and mutation update

“…Furthermore, a reduced enzymatic activity for this variant was confirmed by an in vitro essay. 37 It is still not clear if this mutation is acting per se or in combination with other unknown predisposing factors. It would be interesting to clinically investigate the prevalence of metabolic syndrome in heterozygous carriers of other ZMPSTE24 missense mutations.…”

“…This was observed in MAD or 'HGPS' patients carrying compound heterozygous loss-of-function and null ZMPSTE24 mutations and recently confirmed with in vitro studies in which enzymatic analyses performed on a series of ZMPSTE24 variants showed that residual proteolytic activity can be correlated with disease severity. 37 A patient carrying a homozygous loss-offunction ZMPSTE24 mutation (c.281C4T, Leu94Pro) belongs to the clinical continuum of this phenotypic group, as the milder phenotype associated with ZMSPTE24 mutations, which correlated to slight prelamin A accumulation. 24 Finally, progeroid disorders caused by ZMPSTE24 recessive mutations are always severe disorders.…”

Mice with reduced expression of the telomere‐associated protein Ft1 develop p53‐sensitive progeroid traits

“…For example, restrictive dermopathy patients carry recessive mutations in the ZMPSTE24 gene, which encodes the proteolytic enzyme involved in lamin A maturation (Barrowman, Wiley, Hudon‐Miller, Hrycyna & Michaelis, 2012). Also, in this case, a mouse model replicates the progeroid phenotype of the disease (Osorio, Ugalde, et al., 2011).…”