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Biomedical subjects

K Willison

Publications and source records attributed to K Willison.

At least 19 recordsLinked to original sources
PubMed2003

Caregiving and its impact on families of the terminally ill.

Changes in the health care system have meant that increasing numbers of the terminally ill receive the majority of their care at home. The purpose of this paper was to document patterns of informal and formal care provided to the terminally ill and assess the impact caregiving has on family members. One hundred and fifty-one family caregivers were recruited for interviews from two community-nursing agencies in an urban region of the province of Ontario, Canada. The majority of respondents 119 (79%) were the female spouses of the patient. The numbers of caregivers providing assistance in specific functional activities were: bathing, 133 (88%); mobility, 123 (81%); dressing and undressing, 114 (76%); toileting, 101(67%), and assistance at night 97 (64%). Sixty-two (41%) respondents reported that they had been providing some form of caregiving for over one year. They also reported that physical demands in caregiving increased substantially during the last three months of the care recipient's life. As family caregivers provided more assistance in activities of daily living they were at greater risk of reporting high caregiver burden. The results of this paper identify the types of care provided by family caregivers of the terminally ill and the impact these demands have on the family caregiver.

Activities of Daily Living↗
PubMed2001

Perceived support needs of family caregivers and implications for a telephone support service.

The purposes of this study were: to identify the perceived support needs of family caregivers of persons living with chronic illness (physical or cognitive) and receiving home-care services, and to describe the types of telephone services that would meet the expressed needs of caregivers. The qualitative design used semi-structured interviews. A total of 34 caregivers (mean age 62 years) participated in the study. The care recipients (mean age 78 years) were primarily the husband/wife or parent of the caregiver. The most commonly expressed caregiver needs were: a social life, instrumental support (e.g., respite, assistance with physical care, financial compensation), informational support, and emotional support. Most caregivers said they would use a telephone support service provided by a professional (71%) or a fellow caregiver (59%) if available. The results of this study support a pilot study and evaluation of a telephone support service for family caregivers.

Adult↗
PubMed1995

The chaperonin containing t-complex polypeptide 1 (TCP-1). Multisubunit machinery assisting in protein folding and assembly in the eukaryotic cytosol.

Many proteins in the cell require assistance from molecular chaperones at stages in their life cycles in order to attain correctly folded states and functional conformations during protein synthesis or during recovery from denatured states. A recently discovered molecular chaperone, which is abundant in the eukaryotic cytosol and is called the chaperonin containing TCP-1 (CCT), has been shown to assist the folding of some proteins in cytosol. This chaperone is a member of the chaperonin family which includes GroEL, 60-kDa heat shock protein (Hsp60), Rubisco subunit binding protein (RBP) and thermophilic factor 55 (TF55), but is distinct from the other members in several respects. Presently the most intriguing feature is the hetero-oligomeric nature of the CCT; at least eight subunit species which are encoded by independent and highly diverged genes are known. These genes are calculated to have diverged around the starting point of the eukaryotic lineage and they are maintained in all eukaryotes investigated, suggesting a specific function for each subunit species. The amino acid sequences of these subunits share approximately 30% identity and have some highly conserved motifs probably responsible for ATPase function, suggesting this function is common to all subunits. Thus, each subunit is thought to have both specific and common functions. These observations, in conjunction with biochemical and genetic analysis, suggest that CCT functions as a very complex machinery for protein folding in the eukaryotic cell and that its chaperone activity may be essential for the folding and assembly of various newly synthesized polypeptides. This complex behaviour of CCT may have evolved to cope with the folding and assembly of certain highly evolved proteins in eukaryotic cells.

Amino Acid Sequence↗
PubMed1995

The eighth Cct gene, Cctq, encoding the theta subunit of the cytosolic chaperonin containing TCP-1.

The chaperonin containing t-complex polypeptide 1 (TCP-1), as one of its subunits, CCT, is a cytosolic heterooligomeric molecular chaperone assisting in the folding of proteins in eukaryotic cytosol. We have isolated a Tcp-1-related 119-bp cDNA fragment from a human cDNA library by polymerase chain reaction, and cloned full-length mouse cDNAs orthologous to the human cDNA by hybridization. The nucleotide (nt) sequence of the longest mouse clone (1844 bp) shows an open reading frame (ORF) encoding a TCP-1-related polypeptide of 548 amino acids (aa) (59,562 Da). This gene is different from Tcp-1 and the six Tcp-1-related genes reported previously, Tcp-1 (Ccta), Cctb, Cctg, Cctd, Ccte, Cctz and Ccth, which encode subunits of CCT. The product of the novel gene was analysed using an antibody raised against the C terminus of the polypeptide deduced from the nt sequence. We found that this gene encodes a subunit of CCT (polypeptide S1; 62 kDa and pI 6.25 by two-dimensional gel analysis). We have named it Cctq, encoding the theta subunit of CCT (CCT theta). The aa sequence of CCT theta shows 23-29% identity to the other CCT subunits, alpha, beta, gamma, delta, epsilon, zeta and eta, and 29% identity to the archaebacterial chaperonin TF55. CCT theta also contains the motifs common to all the other subunits of CCT which are postulated to be involved in ATPase activity.

Amino Acid Sequence↗
PubMed1995

Tctex2: a sperm tail surface protein mapping to the t-complex.

Transmission ratio distortion (TRD) in mouse t-haplotypes remains the most significant example of meiotic drive in vertebrates. While the underlying mechanism that fuels it is still mysterious, TRD is clearly a complex multigene phenomenon. The characterization of Tctex2 (t-complex testis expressed 2) shows it to be one of several candidates for involvement in TRD. Tctex2 maps to the t-complex and encodes a membrane-associated protein found exclusively on the sperm tail. The t-haplotype form of Tctex2 is aberrant in both the level of its expression and its primary amino acid sequence, but is nonetheless translated and transported to its normal location. The multiple amino acid changes in the t-form make it extremely unlikely that it can function normally and, since it is found on sperm tails, suggest that it may actively interfere with the development of normal gamete function in males. The possible role of Tctex2 in t-complex transmission ratio distortion and sterility is discussed.

Amino Acid Sequence↗
PubMed1994

Identification of the major chromaffin granule-binding protein, chromobindin A, as the cytosolic chaperonin CCT (chaperonin containing TCP-1).

Chromobindin A is a multisubunit complex ATPase that binds to chromaffin granule membranes in a calcium-dependent manner and requires ATP for release from the membrane (Martin, W. H., and Creutz, C. E. (1987) J. Biol. Chem. 262, 2803-2810). Here we report that the seven previously characterized subunits of chromobindin A cross react with antisera specific to subunits of CCT, the chaperonin containing TCP-1 (Kubota, H., Hynes, G., Carne, A., Ashworth, A., and Willison, K. (1994) Curr. Biol. 4, 89-99). The chromobindin A subunits previously called chromobindins 12, 13, 14, 15, 16, 18, and 19 cross-react specifically with subunits beta, delta, theta, alpha, zeta, xi, and gamma, respectively, of CCT. Additional similarities in subunit molecular weights, isoelectric points, and the morphologies of the two protein complexes as determined by electron microscopy support identification of chromobindin A as an adrenal medullary form of CCT. The chromobindin A/CCT complex was found to bind at least 7-fold more efficiently to affinity columns of chromaffin granule membranes than of adrenal medullary cytosol proteins, suggesting a specific interaction occurs between the complex and membrane components. The results indicate that the previously described characteristics of chromobindin A are likely to be relevant to the functions of CCT and suggest that the adrenal medullary form of CCT may play a role in the activities of secretory vesicle membranes.

Animals↗
PubMed1994

Identification of six Tcp-1-related genes encoding divergent subunits of the TCP-1-containing chaperonin.

BACKGROUND: TCP-1 is a 60 kD subunit of a cytosolic hetero-oligomeric chaperone that is known to be involved in the folding of actin and tubulin. This protein is a member of the chaperonin family, which includes Escherichia coli GroEL, the mitochondrial heat-shock protein Hsp60, the plastid Rubisco-subunit-binding protein and the archaebacterial protein TF55. These chaperonins assist the folding of proteins upon ATP hydrolysis. RESULTS: Using two-dimensional gel analysis, we have identified nine different subunits of TCP-1-containing chaperonin complexes from mammalian testis and seven different subunits of such complexes from mouse F9 cells. We have isolated full-length mouse cDNAs encoding six novel TCP-1-related polypeptides and show that these cDNAs encode subunits of the TCP-1-containing cytosolic chaperonin. These subunits are between 531 and 545 residues in length. Their sequences are 25-36% identical to one another, 27-35% identical to that of TCP-1 and 32-39% identical to that of the archaebacterial chaperonin, TF55. We have named these genes, Cctb, Cctg, Cctd, Ccte, Cctz and Ccth, which encode the CCT beta, CCT gamma, CCT delta, CCT epsilon, CCT zeta and CCT eta subunits, respectively, of the 'Chaperonin Containing TCP-1' (CCT). All the CCT subunits contain motifs that are also shared by all other known chaperonins of prokaryotes and eukaryotic organelles, and that probably relate to their common ATPase function. CONCLUSION: It is likely that each CCT subunit has a specific, independent function, as they are highly diverged from each other but conserved from mammals to yeast. We suggest that the expansion in the number of types of CCT subunit, compared with other chaperonins, has allowed CCT to carry out the more complex functions that are required for the folding and assembly of highly evolved eukaryotic proteins.

Actins↗
PubMed1993

The t-complex polypeptide 1 complex is a chaperonin for tubulin and actin in vivo.

A role in folding newly translated cytoskeletal proteins in the cytosol of eukaryotes has been proposed for t-complex polypeptide 1 (TCP1). In this study, we investigated tubulin and actin biogenesis in Chinese hamster ovary (CHO) cells. When extracts of pulse-labeled cells were analyzed by anion-exchange and size-exclusion chromatography, newly synthesized alpha-tubulin, beta-tubulin, and actin were observed to enter a large molecular mass complex (approximately 900 kDa). These proteins were released from this complex capable, in the case of tubulin, of forming heterodimers. The large molecular mass complexes coeluted with TCP1 and could be immunoprecipitated by using an anti-TCP1 antibody. These findings demonstrate that there is a cytosolic pathway for folding tubulin and actin in vivo that involves the TCP1 complex.

Actins↗
PubMed1992

Structure and expression of the gene encoding mouse t-complex polypeptide (Tcp-1).

The nucleotide (nt) sequence of the structural gene (Tcp-1) encoding mouse t-complex polypeptide 1 (TCP-1) has been determined. The nt sequence extending to 10,043 bp shows that the Tcp-1 gene is divided into 12 exons, 11 introns and 5'- and 3'-flanking regions. The Tcp-1 gene has a tight cluster of major transcription start points (tsp). Two GC boxes, one CCAAT box and some other possible regulatory elements are located in the region upstream from the tsp, but no TATA box was found. Extending from the 5'-flanking region to the first intron, a CpG dinucleotide-rich cluster is located. In addition, Tcp-1 gene transcripts in mouse organs, embryos and cultured cells were analyzed by Northern blotting. The Tcp-1 mRNA is enriched not only in testes, but also in early post-implantation embryos and some cultured cell lines, as compared with mouse organs other than the testis. The amount of Tcp-1 mRNA in embryos decreases during development. These results suggest that the expression of the Tcp-1 gene may be regulated spatially and temporally in embryonic and adult mice by transcriptional control or by mRNA stability.

Amino Acid Sequence↗
PubMed1992

Evolution of the mouse t haplotype: recent and worldwide introgression to Mus musculus.

Mouse t haplotypes are variants of chromosome 17, consisting of four inversions. Despite the homozygous lethality and pleiotropic effect on embryonic development, sperm production, and recombination, they have widely spread in natural populations of the house mouse (10-40% in frequency) because of the meiotic drive advantage. We sequenced 14 Tcp-1 (t-complex polypeptide 1) genes from four t haplotypes, nine wild mice, and a rat as a reference. From a comparison of intron sequences of 610 base pairs, we dated the origin of t haplotypes to 2.9 +/- 0.7 million years ago, which predates the splitting of Mus musculus subspecies (approximately 1 million years ago). However, the Tcp-1 intron sequences of t haplotypes from different M. musculus subspecies from various parts of the world show no divergence, indicating the recent introgression (no earlier than 0.8 million years ago) of a single ancestral type. Nucleotide changes in coding regions are also consistent with this conclusion. Hence, polymorphisms among t haplotypes including lethality factors have accumulated during this short time period independently in each M. musculus subspecies.

Animals↗
PubMed1992

T-complex polypeptide-1 is a subunit of a heteromeric particle in the eukaryotic cytosol.

The murine t-complex encodes t-complex polypeptide-1 (TCP1), which is constitutively expressed in almost all cells, and upregulated during spermatogenesis. Mammalian sequences have greater than 96% identity with each other, and greater than 60% identity with Drosophila melanogaster and yeast orthologues. TCP1 is essential in yeast, and is postulated to be the cytosolic mammalian equivalent of groEL. We report here that, in the native state, murine and human TCP1 is distributed throughout the cytosol as an 800K-950K hetero-oligomeric particle in association with four to six unidentified proteins and two Hsp70 heat-shock proteins. Negative-stain electron microscopy indicates that the structure is two stacked rings, 12-16 nm in diameter. Therefore, despite similarities with the chaperonin 60 proteins, these data indicate that TCP1 is biochemically and structurally unique. We suggest that TCP1 may represent one of a family of molecules in the eukaryotic cytosol involved in protein folding and regulated in part by their heteromeric associations.

Amino Acid Sequence↗
PubMed1991

Nuclear factor 1 activates the feline leukemia virus long terminal repeat but is posttranscriptionally down-regulated in leukemia cell lines.

A recombinant feline leukemia virus (FeLV) proviral clone (T17T-22) with a long terminal repeat (LTR) which differs from prototype FeLV by a point mutation within a conserved nuclear factor 1 (NF1)-binding motif in the LTR enhancer domain was found to be poorly expressed after DNA transfection. The NF1 point mutation reduced in vitro protein binding as assessed by gel shift analysis and reduced promoter activity significantly (2- to 10-fold). However, the degree of promoter impairment due to the NF1 site mutation varied according to cell type and was least severe in a feline leukemia cell line (T3) which had low levels of nuclear NF1 DNA-binding activity. Low NF1 DNA-binding activity was observed in three FeLV-induced leukemia cell lines (T3, T17, and FL74) and in murine F9 embryonal carcinoma cells. While similar levels of NF1 gene mRNA transcripts were detected in all cell lines, Western immunoblot analysis of F9, T17, and FL74 but not T3 nuclear extracts revealed very low levels of nuclear NF1 protein. These results indicate that NF1 activity is down-regulated in FeLV-induced leukemia cells by diverse posttranscriptional mechanisms. We suggest that NF1 down-regulation may be an important characteristic of target cells susceptible to FeLV transformation in vivo and may provide the selective pressure which favors duplication of the LTR core enhancer sequence in T-cell leukemogenic FeLV variants.

Animals↗
PubMed1990

Absence of the type I IFN system in EC cells: transcriptional activator (IRF-1) and repressor (IRF-2) genes are developmentally regulated.

Interferons (IFNs) are a heterogeneous family of cytokines that exhibits multiple biological activities. Upon viral infection, expression of type I IFNs (i.e., IFN-alpha and IFN-beta) is induced in a variety of differentiated cells but not in cells of embryonal origin. IRF-1 and IRF-2, which bind to the same cis-elements within the promoters of type I IFN and IFN-inducible MHC class I genes, were identified previously. Here we demonstrate that the expression of both IRF and IFN genes is developmentally regulated in mouse EC cells; these genes become functional only after cell differentiation. Furthermore, cDNA-directed IRF-1 produced in undifferentiated but not differentiated EC cells efficiently activates the transfected IFN-alpha and IFN-beta and endogenous IFN-alpha genes, whereas IRF-2 represses the IRF-1 effects. These findings emphasize the dual function of the IRF-responsive cis-elements as positive and negative regulators, since they can be occupied by transcriptionally active or inactive IRF molecules. This type of regulatory mechanism might operate in other cytokine systems.

Animals↗