Spinocerebellar ataxia type 7 (SCA7) is a polyglutamine (polyQ) disorder characterized by specific degeneration of cerebellar, brainstem, and retinal neurons. Although they share little sequence homology, proteins implicated in polyQ disorders have common properties beyond their characteristic polyQ tract. These include the production of proteolytic fragments, nuclear accumulation, and processing by caspases. Here we report that ataxin-7 is cleaved by caspase-7, and we map two putative caspase-7 cleavage sites to Asp residues at positions 266 and 344 of the ataxin-7 protein. Site-directed mutagenesis of these two caspase-7 cleavage sites in the polyQ-expanded form of ataxin-7 produces an ataxin-7 D266N/D344N protein that is resistant to caspase cleavage. Although ataxin-7 displays toxicity, forms nuclear aggregates, and represses transcription in human embryonic kidney 293T cells in a polyQ length-dependent manner, expression of the non-cleavable D266N/D344N form of polyQ-expanded ataxin-7 attenuated cell death, aggregate formation, and transcriptional interference. Expression of the caspase-7 truncation product of ataxin-7-69Q or -92Q, which removes the putative nuclear export signal and nuclear localization signals of ataxin-7, showed increased cellular toxicity. We also detected N-terminal polyQ-expanded ataxin-7 cleavage products in SCA7 transgenic mice similar in size to those generated by caspase-7 cleavage. In a SCA7 transgenic mouse model, recruitment of caspase-7 into the nucleus by polyQ-expanded ataxin-7 correlated with its activation. Our results, thus, suggest that proteolytic processing of ataxin-7 by caspase-7 may contribute to SCA7 disease pathogenesis. Spinocerebellar ataxia type 7 (SCA7)4 is an autosomal dominant polyglutamine disorder clinically characterized by progressive ataxia and blindness. In the disease state, highly specific cell death ultimately occurs, most notably in the photoreceptor cells of the retina, Purkinje cells, dentate nuclei, and granule cells of the cerebellum, inferior olivary nuclei, and pontine neurons (1-3). SCA7 is a member of a family of "polyglutamine disorders." The retinal degeneration distinguishes SCA7 from the other polyglutamine diseases, although like many of the other polyQ disease proteins, ataxin-7 is widely expressed throughout the central nervous system. These autosomal dominant neurodegenerative diseases include Huntington disease (4), spinocerebellar ataxias type 1, 2, 3, 6, and 17 (SCA1, SCA2, SCA3 or Machado-Joseph disease, SCA6, SCA17) (5-8), dentatorubropallidoluysian atrophy (9), and spinal bulbar muscular atrophy (Kennedy disease) (10). The resultant increase in polyQ tract length derived from the CAG expansion within the gene product appears to exert direct toxicity on neuronal populations. Common mechanisms of disease pathogenesis include transcriptional dysregulation (11, 12) and proteolysis to produce toxic fragments (13-18). Neurodegeneration of specific neuronal populations found for each disease has been proposed to involve cell-specific...

The autosomal dominant cerebellar ataxias (ADCA) comprise a heterogeneous group of neurologic disorders characterized by degeneration of the cerebellum, spinal cord, and brainstem. Genetic analysis has revealed two loci, SCA1 on chromosome 6p, and SCA2 on chromosome 12q, responsible for some ADCA. We present a four-generation kindred of 42 individuals, 12 of whom were clinically affected with ADCA and an associated cone dystrophy. Early loss of color discrimination with retinal and macular signs is followed by gradual progression of cerebellar dysfunction and development of pyramidal signs. Pathology shows degeneration of cerebellum, basis pontis, inferior olive, and retinal ganglion cells. For genetic analysis, we used polymorphic markers D6S89 and D12S79; linkage analysis gave negative results, excluding linkage to both SCA1 and SCA2. The data strongly support genetic heterogeneity consistent with the unique clinicopathologic features of the form of ADCA displayed in this large family.

A heterogeneous group of neurological disorders known as the spinocerebellar ataxias (SCA) are characterized by degeneration of the cerebellum, spinal cord and brainstem. We describe linkage analysis in four unusual SCA families revealing a distinct disease locus on chromosome 3p14-21.1. The disease in these families is distinguished from other forms of SCA by concomitant retinal degeneration. Initial visual problems leading to blindness, disabling ataxia and anticipation are seen in all kindreds. The anticipation in these families suggests a dynamic mutation at this locus. Eventual molecular characterization of this disease may provide valuable insights into the processes of both neural and retinal degeneration.

Cancer survivors often relapse due to evolving drug-resistant clones and repopulating tumor stem cells. Our preclinical study demonstrated that terminal cancer patient’s lymphocytes can be converted from tolerant bystanders in vivo into effective cytotoxic T-lymphocytes in vitro killing patient’s own tumor cells containing drug-resistant clones and tumor stem cells. We designed a clinical trial combining peginterferon α-2b with imatinib for treatment of stage III/IV gastrointestinal stromal tumor (GIST) with the rational that peginterferon α-2b serves as danger signals to promote antitumor immunity while imatinib’s effective tumor killing undermines tumor-induced tolerance and supply tumor-specific antigens in vivo without leukopenia, thus allowing for proper dendritic cell and cytotoxic T-lymphocyte differentiation toward Th1 response. Interim analysis of eight patients demonstrated significant induction of IFN-γ-producing-CD8+, -CD4+, -NK cell, and IFN-γ-producing-tumor-infiltrating-lymphocytes, signifying significant Th1 response and NK cell activation. After a median follow-up of 3.6 years, complete response (CR) + partial response (PR) = 100%, overall survival = 100%, one patient died of unrelated illness while in remission, six of seven evaluable patients are either in continuing PR/CR (5 patients) or have progression-free survival (PFS, 1 patient) exceeding the upper limit of the 95% confidence level of the genotype-specific-PFS of the phase III imatinib-monotherapy (CALGB150105/SWOGS0033), demonstrating highly promising clinical outcomes. The current trial is closed in preparation for a larger future trial. We conclude that combination of targeted therapy and immunotherapy is safe and induced significant Th1 response and NK cell activation and demonstrated highly promising clinical efficacy in GIST, thus warranting development in other tumor types.