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61.
Novel proteins with binding specificity for DNA CTG repeats and RNA CUG repeats: implications for myotonic dystrophy 总被引:7,自引:6,他引:7
While an unstable CTG triplet repeat expansion is responsible for myotonic
dystrophy, the mechanism whereby this genetic defect induces the disease
remains unknown. To detect proteins binding to CTG triplet repeats, we
performed bandshift analysis using as probes double- stranded DNA fragments
having CTG repeats [ds(CTG)6-10] and single- stranded oligonucleotides
having CTG repeats ss(CTG)8 or RNA CUG triplet repeats (CUG)8. The source
of protein was nuclear and cytoplasmic extracts of HeLa cells, fibroblasts
and myotubes. Proteins binding to the double-stranded DNA repeat
[ds(CTG)6-10], were inhibited by nonlabeled ds(CTG)6-10, but not by a
non-specific DNA fragment (USF/AD-ML). Another protein binding to ssCTG
probe and RNA CUG probe was inhibited by nonlabeled (CTG)8 and (CUG)8.
Nonlabeled oligos with different triplet repeat sequences, ss(CAG)8 or
ss(CGG)8, did not inhibit binding to the ss(CTG)8 probe. However, when
labeled as probes, the (CAG)8 and (CGG)8 bound to proteins distinct from
the CTG proteins and binding was inhibited by nonlabeled (CAG)8 or (CGG)8
respectively. The protein binding only to the RNA repeat (CUG)8 was
inhibited by nonlabeled (CUG)8 but not by nonlabeled single- or
double-stranded CTG repeats. Furthermore, the CUG-BP exhibited no binding
to an RNA oligonucleotide of triplet repeats of the same length but having
a different sequence, CGG. The CUG binding protein was localized to the
cytoplasm, whereas dsDNA binding proteins were localized to the nuclear
extract. Thus, several trinucleotide binding proteins exist and their
specificity is determined by the triplet sequence. The novel protein,
CUG-BP, is particularly interesting since it binds to triplet repeats known
to be present in myotonin protein kinase mRNA which is responsible for
myotonic dystrophy.
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62.
The assembly and function of respiratory-competent mitochondria in
eukaryotic cells depends on collaboration between the nuclear and
mitochondrial genomes, but the molecular mechanisms underlying such
cross-talk are poorly understood. Microcell-mediated chromosome transfer
has been used to transfer intact chromosomes from one mammalian cell to
another, helping to map loci implicated in different diseases and in the
senescence process. In the present work, we show that microcells have a
significant number of mitochondria which can be transferred to another cell
simultaneously with a limited number of chromosomes. By fusing microcells
from a colon carcinoma cell line with a mitochondrial DNA (mtDNA)-less
osteosarcoma cell line, we were able to isolate transmitochondrial hybrids
containing only one of three selectable chromosomes and mtDNA from the
donor cell. The proportion of transmitochondrial hybrids containing one
chromosomal marker with respect to the total transmitochondrial hybrids and
cybrids was approximately 1% and no hybrids were isolated containing more
than one nuclear marker. The genetic data correlated well with the
composition and structure of the microcell preparations, which showed the
presence of cytoplast-like structures and microcells containing
mitochondria surrounding the micronuclei. Microcell-mediated mtDNA and
chromosome transfer can be used to identify nuclear factors implicated in
mtDNA maintenance and gene expression, as well as to investigate nuclear
factors which modulate clinical phenotypes in mitochondrial disorders.
相似文献
63.
64.
Impact of reclassifying noninvasive follicular variant of papillary thyroid carcinoma on the risk of malignancy in The Bethesda System for Reporting Thyroid Cytopathology 下载免费PDF全文
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66.
Going beyond “Basaloid neoplasm”: Fine needle aspiration cytology of epithelial‐myoepithelial carcinoma of the parotid gland 下载免费PDF全文
Stacy L. Molnar BS SCT CT Matthew A. Zarka MD Luis E. De Las Casas MD FASCP 《Diagnostic cytopathology》2016,44(5):422-425
Epithelial‐myoepithelial carcinoma (EMC) is a rare salivary gland malignancy with variable cytologic findings. Its rarity, variable morphologic findings, and similarities with more common salivary gland entities make it a difficult cytologic diagnosis. As the name signifies, the key feature of this tumor is presence of an epithelial and myoepithelial component. However, when one of these two components is scant on the fine needle aspiration (FNA) smears, it may be overlooked. We present a case from a 62 year‐old female who presented to the clinic with a parotid nodule and episodes of sharp, throbbing pain. A fine needle aspiration was performed which revealed a highly cellular specimen comprised primarily of aggregates of cells with small, round nuclei and scant to absent cytoplasm. Abundant hyaline stromal material was also noted. The case was signed out as basaloid neoplasm with a recommendation for surgical resection. The subsequent resection specimen revealed EMC. By reviewing the FNA specimen following the surgical resection of the tumor, we were able to utilize the benefit of hindsight to more clearly identify the subtle, biphasic components of the tumor. Diagn. Cytopathol. 2016;44:422–425. © 2016 Wiley Periodicals, Inc. 相似文献
67.
68.
Relapsed infant MLL‐rearranged acute lymphoblastic leukemia with additional genetic alterations 下载免费PDF全文
69.
80例临床疑垂体肿瘤的高催乳素血症患者进行了直接增强鞍区冠状扫描。本文着重介绍检查方法及CT表现,并探讨高催乳素血症与垂体病变的关系,影响病灶显示的因素及临床意义。 相似文献
70.