Biomedical subjects

Jianfeng Xiao

Publications and source records attributed to Jianfeng Xiao.

7 recordsLinked to original sources

PubMed2006

Murine central and peripheral nervous system transcriptomes: comparative gene expression.

The central and peripheral nervous systems exhibit significant embryological, morphological, and functional differences. Moreover, the pathology of most acquired and hereditary neurological diseases preferentially targets specific components of the nervous system. In order to test the hypothesis that central and peripheral neural transcriptomes show fundamental quantitative differences, Affymetrix GeneChip expression arrays were used to compare murine lumbar spinal cord (SC) and dorsal root ganglion (DRG) gene expression. As the crucial component of a novel technique to preserve RNA integrity, mice were perfusion-fixed with RNAlater before the SC and DRG were harvested. As per Affymetrix terminology, a total of 111 transcripts were present (P) on all DRG arrays, absent (A) on all SC arrays, and demonstrated at least 10-fold greater expression in DRG than in SC. Conversely, a total of 112 transcripts were present on all SC arrays, absent on all DRG arrays, and showed at least 10-fold greater expression in SC than in DRG. For a subset of transcripts, quantitative real-time RT-PCR was used to corroborate and validate microarray results. Among those genes enriched in DRG, many belonged to a few distinct functional classes: G-protein coupled receptor-protein signaling pathways, potassium transport, sodium transport, sensory perception, and cell-surface receptor-linked signal transduction. In contrast, genes associated with synaptic transmission, organic acid transport, neurotransmitter transport, and circulation were enriched in SC. Notably, the majority of genes causally associated with hereditary neuropathies were highly enriched in DRG. These differential neural gene expression profiles provide a robust framework for future molecular and genetic studies of neuropathy and SC diseases.

Animals↗

PubMed2005

Caytaxin deficiency causes generalized dystonia in rats.

The genetically dystonic rat (SD-dt:JFL) is an autosomal recessive model of generalized dystonia. Without cerebellectomy, the dt rat dies prior to Postnatal Day 40. The dt locus was mapped to a 4.2 Mb region on Chr 7q11 and candidate genes were screened with semi-quantitative RT-PCR. Then, Southern blotting and genomic DNA sequencing identified the 3'-long terminal repeat portion of an intracisternal A particle element inserted into Intron 1 of Atcay, the gene which encodes caytaxin. Northern and Western blotting and quantitative real-time RT-PCR defined the Atcay allele in dt rats (Atcay(dt)) as hypomorphic. To establish a framework for functional studies of caytaxin, the developmental expression of rat Atcay transcript was analyzed with Northern blotting, relative quantitative multiplex real-time RT-PCR (QRT-PCR) and in situ hybridization. With a multiple tissue Northern blot, three Atcay transcripts were identified in brain but none were present in heart, spleen, lung, liver, muscle, kidney or testis. With a multiple time-point Northern blot, the same three transcripts were present in cerebellum at Embryonic Day (E15), Postnatal Day 1 (P1), P7, P14, P36 and 8 months. During early development (E15 to P14), the relative proportion of the smallest transcript was increased. QRT-PCR was performed with total RNA from cerebral cortex, striatum, thalamus, hippocampus and cerebellum. Transcript levels peaked at P7 in hippocampus, increased linearly from P1 to P36 in cerebellum, and showed minimal developmental regulation in cerebral cortex. Radioactive in situ hybridization localized Atcay transcript to seemingly all neuronal populations in brain. In cerebellum, Atcay transcript was present in the molecular, Purkinje and granular layers; transcript density in the molecular layer peaked at P14. In the background of previous biochemical, behavioral and electrophysiological studies in the dt rat, our data are compatible with a vital role for caytaxin in the development and neurophysiology of cerebellar cortex.

Amino Acid Sequence↗

PubMed2004

Developmental expression of rat torsinA transcript and protein.

A GAG deletion in the gene (TOR1A) for torsinA is associated with childhood-onset generalized dystonia (DYT1). Environmental factors may contribute to development of the phenotype since mutations in TOR1A are clinically penetrant in less than 40% of cases. Median age of onset is 10 and appearance of dystonia after 28 is rare. As a step towards understanding the temporal window of DYT1 disease penetrance, we have examined torsinA transcript and protein expression in rats from the embryonic period through adulthood. With relative quantitative multiplex real-time RT-PCR, we detected torsinA transcript in both neural (cerebellar cortex, striatum, cerebral cortex, thalamus and hippocampus) and non-neural (liver, kidney and heart) tissues at each developmental time point tested (embryonic day 20 [E20], postnatal day 1 [P1], P7, P14, P36, 6 months, 1.5 years). Levels of torsinA transcript were highest at E20 or P1 in all tissues examined except for the cerebellum where transcript levels peaked at P14. Early postnatal levels of torsinA transcript were over three times higher than those seen in adult rats. With quantitative radioactive in situ hybridization, torsinA transcript was widely distributed in brain at all ages with levels peaking at P14 in both cerebellum and striatum. TorsinA-immunoreactivity (IR) was present in neurons throughout the brain. TorsinA-IR was detected in perikarya, dendrites and axons but not nuclei. At P14, prominent expression of torsinA was noted in both striatal cholinergic interneurons and cerebellar Purkinje cells. Our results suggest that torsinA may contribute to postnatal maturational events in the brain such as dendritic arborization and synaptogenesis. Furthermore, the time course of torsinA expression in discrete components of motor networks is compatible with the temporal window of clinical penetrance in DYT1 mutation carriers.

Animals↗

PubMed2003

Cloning, developmental regulation and neural localization of rat epsilon-sarcoglycan.

Mutations in the gene for epsilon sarcoglycan (epsilon-SG) are associated with a disorder of the central nervous system, the myoclonus-dystonia syndrome (MDS; DYT11). In contrast, mutations of other sarcoglycan family members lead to limb-girdle muscular dystrophies. To establish the framework for functional studies of epsilon-SG, we cloned rat epsilon-SG cDNA, quantified epsilon-SG mRNA levels in neural and non-neural tissues at different developmental time points with relative quantitative multiplex real-time reverse transcriptase PCR (RT-PCR), and characterized the distribution of epsilon-SG mRNA in brain with in situ hybridization. Rat epsilon-SG cDNA contains an open reading frame (ORF) of 1311 bp that encodes a 437-amino acid (aa) protein with 95.9% and 98.2% identity to human and mouse epsilon-SG amino acid sequences, respectively. Using real-time RT-PCR, epsilon-SG was detected in both neural (cerebellar cortex, striatum, cerebral cortex, thalamus, hippocampus) and non-neural (muscle, liver, kidney, heart) tissues at each developmental time point tested [Embryonic Day 20 (E20), Postnatal Day 1 (P1), P7, P14, P36, 6 months, 1.5 years). Levels of epsilon-SG mRNA were highest at E20 in all tissues. The developmental regulation of epsilon-SG mRNA expression was most striking in muscle with E20 and early postnatal epsilon-SG mRNA levels over 10 times higher than those seen in adult rats. In adult rats, epsilon-SG mRNA levels were several-fold higher in brain, particularly cerebellar cortex, than in muscle. Radioactive in situ hybridization showed that epsilon-SG mRNA was widely distributed in rat brain. Robust hybridization signal was obtained from regions with dense neuronal packing such as the hippocampus, cerebellar molecular layer, and cerebral cortex. Our results suggest that epsilon-SG participates in the development of both neural and non-neural tissues and contributes to neuronal structure in the adult central nervous system.

Animals↗

PubMed2003

[Mutation analysis of neurofilament-light gene in Chinese Charcot-Marie-Tooth disease].

OBJECTIVE: To study the characteristic of the mutation of neurofilament-light (NF-L) gene in Chinese Charcot-Marie-Tooth disease (CMT) patients. METHODS: Mutation analysis of NF-L gene was made by use of polymerase chain reaction-single strand conformation polymorphsim combined with DNA direct sequencing in 32 CMT probands from the Hans of five provinces in China who had been diagnosed by clinical feature and electromyography and/or biopsy of sural nerve. RESULTS: In 32 CMT probands, only one sporadic case was found to display variant banding pattern, and this case was confirmed as 1329C to T (Tyr443Tyr) single nucleotide polymorphism by sequencing. CONCLUSION: Mutation of NF-L gene may be rare in Chinese CMT patients.

Adolescent↗

PubMed2002

[A new mutation in the connexin 32 gene of a Chinese family with Charcot-Marie-Tooth disease associated with central conduction slowing].

OBJECTIVE: To report a Chinese Charcot-Marie-Tooth disease (CMT) family whose proband had abnormal brainstem auditory evoked potentials (BAEPs) and to study its relationship with connexin 32 (Cx32) gene mutation. METHODS: All family members were studied through clinical examinations, out of them, the proband was subjected to electromyography and BAEPs examination. Mutation analysis of Cx32 was screened by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) combined with DNA direct sequencing in the proband, 8 family members and 50 unrelated normal individuals. RESULTS: The proband had highly decreased nerve conduction velocities and delayed BAEPs. Leu131Pro mutation was found in the proband and 3 family members, not found in 50 normal controls. CONCLUSION: This mutation has not been reported previously. Central nervous system can be affected in CMT patients.

Asian People↗

PubMed2002

[The clinical and pathologic features of Charcot-Marie-Tooth disease].

OBJECTIVE: To study the clinical and pathological features of Charcot-Marie-Tooth disease (CMT). METHODS: The general clinical data, the changes of neuroelectrophysiology and the pathological features of neural and muscular biopsy of 20 CMT patients were comprehensively analyzed. RESULTS: The clinical manifestations in the two types of CMT were nearly the same, but the changes of neuroelectrophysiology and the pathological characteristics of the neural and muscular biopsy in the two types were obviously different. 16 cases of CMT type 1 were characterized by decreased sensory nerve conduction velocity (SNCV < 30 m/s) and are associated with demyelinating hypertrophic neuropathy. 4 cases of CMT tylpe 2 were characterized by normal SNCV and associated with axonopathy. CONCLUSION: Neuroelectrophysiology and neural and muscular biopsy are important for the diagnosis of CMT.

Adolescent↗