The effect of HSPB8 gene mutation on cell viability in Charcot-Marie-Tooth disease type 2L / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the effect of Charcot-Marie-Tooth 2L disease causing gene K141N mutation in heat shock protein B8 gene (HSPB8) on cell viability.</p><p><b>METHODS</b>By using liposome transfection technique, (wt)HSPB8, (K141N)HSPB8 eukaryotic expression vector and green fluorescent protein (GFP) vector were transfected into SHSY-5Y cell, respectively. Twenty-four hours later, the cells were treated with 44 degree centigrade lethal heat shock for 40 minutes. The relative viability of SHSY-5Y cells in each group was tested by using tetrazole blue colorimetric method (methyl thiazolyl tetrazolium, MTT).</p><p><b>RESULTS</b>There were significant differences among the light absorption value of GFP, pEGFP-(wt)HSPB8 and pEGFP-(K141N)HSPB8 transfected groups after heat shock (P<0.05), indicating that the relative viability of cells overexpressed with (wt)HSPB8 and (K141N)HSPB8 was different from that of control cells. The viability of cells overexpressing (wt)HSPB8 was highest, followed by cells overexpressed with (K141N)HSPB8. The viability of cells tranfected with GFP only was the lowest.</p><p><b>CONCLUSION</b>HSPB8 may play an important role in the protection of cells under lethal heat shock treatment, and the K141N mutation can impair the protective effect.</p>

The clinical characteristics of a pedigree with incompletely penetrated autosomal dominant hereditary spastic paraplegia and its exclusion analysis of genetic loci / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To describe the clinical features of a big family with incompletely penetrated autosomal dominant hereditary spastic paraplegia (SPG) and perform the exclusion analysis of genetic loci.</p><p><b>METHODS</b>The clinical information of this SPG family was analyzed retrospectively. Exclusion analysis of the known autosomal dominant SPG loci was performed by using multiplex fluorescence PCR, capillary electrophoresis and Linkage package.</p><p><b>RESULTS</b>There were eleven affected members available in this SPG family and the age at onset ranged from 2 to 10 years. The first symptoms were a bilateral, symmetrical, progressive lower limb weakness and spasticity. Patients presented with spasticity and hyperreflexia, positive Babinski sign and scissors gait, and the upper limbs were involved more severely than the lower limbs. No urinary inconsistence, sensory impairment, nystagmus and dementia were found. Genetic analysis showed that this family was consistent with autosomal dominant inheritance. The linkage analysis and mutation analysis revealed this family was not linked to the known autosomal dominant loci.</p><p><b>CONCLUSION</b>This SPG family had typical "pure" clinical symptoms. The age at onset was early and the signs in the upper limbs were more obvious than those in the lower limbs. The result of linkage analysis shows that this family represents a new SPG subtype.</p>

Study on aggregate formation mechanism of HSPB8 gene mutation resulting in CMT2L / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the possible mechanism of the intracellular aggregate formation of small heat shock protein HSPB8 (HSPB8)(K141N) mutation resulting in axonal Charcot-Marie-Tooth disease type 2L(CMT2L).</p><p><b>METHODS</b>The cell models which transiently expressed pEGFPN1-HSPB8 and pEGFPN1-(K141N)HSPB8 were established. The immunofluorescent co-location study of EGFP-(K141N)HSPB8 and HSPB1, EGFP-(K141N)HSPB8 and neurofilament light chain (NEFL) was carried out in the SHSY5Y cell models. The aggregate formation of EGFP-(K141N)HSPB8 in cell models was investigated and the possible mechanism of cellular aggregate formation was analyzed by t test and analysis of variance between group(ANOVA).</p><p><b>RESULTS</b>EGFP-(K141N)HSPB8 formed large aggregate which predominantly located around the nucleus in cell models. EGFP-(K141N)HSPB8 co-localized perfectly with HSPB1 and NEFL in the SHSY5Y cell models. The aggregate formation was different in different cell types, there were fewer aggregates formed in an sHSPs deficient milieu than in HEK293T cells.</p><p><b>CONCLUSION</b>(K141N)HSPB8 formed aggregates predominantly locate around the nucleus in cells. (K141N)HSPB8 co-localizes perfectly with HSPB1 and NEFL. The aggregate formation may be due to (K141N)HSPB8 conformational change leading to self aggregation and its abnormal interaction with other sHSPs such as HSPB1.</p>