XI. STRATEGIES FOR IMPROVING DIABETES CARE D iabetes is a chronic illness that requires continuing medical care and patient self-management education to prevent acute complications and to reduce the risk of long-term complications. Diabetes care is complex and requires that many issues, beyond glycemic control, be addressed. A large body of evidence exists that supports a range of interventions to improve diabetes outcomes. These standards of care are intended to provide clinicians, patients, researchers, payors, and other interested individuals with the components of diabetes care, treatment goals, and tools to evaluate the quality of care. While individual preferences, comorbidities, and other patient factors may require modification of goals, targets that are desirable for most patients with diabetes are provided. These standards are not intended to preclude more extensive evaluation and management of the patient by other specialists as needed. For more detailed information, refer to Bode (Ed.): Medical Management of Type 1 Diabetes (1), Burant (Ed): Medical Management of Type 2 Diabetes (2), and Klingensmith (Ed): Intensive Diabetes Management (3). The recommendations included are diagnostic and therapeutic actions that are known or believed to favorably affect health outcomes of patients with diabetes. A grading system (Table 1), developed by the American Diabetes Association (ADA) and modeled after existing methods, was utilized to clarify and codify the evidence that forms the basis for the recommendations. The level of evidence that supports each recommendation is listed after each recommendation using the letters A, B, C, or E.

Standards of Medical Care in Diabetes

The probability that a residue in a protein is part of a coiled-coil structure was assessed by comparison of its flanking sequences with sequences of known coiled-coil proteins. This method was used to delineate coiled-coil domains in otherwise globular proteins, such as the leucine zipper domains in transcriptional regulators, and to predict regions of discontinuity within coiled-coil structures, such as the hinge region in myosin. More than 200 proteins that probably have coiled-coil domains were identified in GenBank, including alpha- and beta-tubulins, flagellins, G protein beta subunits, some bacterial transfer RNA synthetases, and members of the heat shock protein (Hsp70) family.

https://science.sciencemag.org/content/sci/252/5009/1162.full.pdf

Predicting coiled coils from protein sequences

Stimulation of adipogenesis in fibroblasts by PPAR gamma 2, a lipid-activated transcription factor.

The role of Jun, Fos and the AP-1 complex in cell-proliferation and transformation.

A 30-amino-acid segment of C/EBP, a newly discovered enhancer binding protein, shares notable sequence similarity with a segment of the cellular Myc transforming protein. Display of these respective amino acid sequences on an idealized alpha helix revealed a periodic repetition of leucine residues at every seventh position over a distance covering eight helical turns. The periodic array of at least four leucines was also noted in the sequences of the Fos and Jun transforming proteins, as well as that of the yeast gene regulatory protein, GCN4. The polypeptide segments containing these periodic arrays of leucine residues are proposed to exist in an alpha-helical conformation, and the leucine side chains extending from one alpha helix interdigitate with those displayed from a similar alpha helix of a second polypeptide, facilitating dimerization. This hypothetical structure is referred to as the "leucine zipper," and it may represent a characteristic property of a new category of DNA binding proteins.

https://science.sciencemag.org/content/sci/240/4860/1759.full.pdf

The leucine zipper: a hypothetical structure common to a new class of DNA binding proteins

In two previous studies we described the properties of a heat-stable DNA-binding protein present in rat liver nuclei. This protein, hereafter termed C/EBP, is capable of selective binding to the CCAAT homology of several viral promoters (Graves et al. 1986), as well as the core homology common to many viral enhancers (Johnson et al. 1987). We now report the isolation of a recombinant clone of the gene that encodes C/EBP. Expression of the clone in bacterial cells yields a protein that binds in vitro to both the CCAAT homology and the enhancer core homology, providing conclusive evidence that a single gene product accounts for both binding activities. By examining the properties of protease-derived fragments of C/EBP, we have localized its DNA-binding domain to a 14-kD fragment. A 60-amino-acid segment located within the DNA-binding domain of C/EBP bears sequence similarity to the products of the myc and fos oncogenes.

/pdf/isolation-of-a-recombinant-copy-of-the-gene-encoding-c-ebp-cki7gbdfrg.pdf

Isolation of a recombinant copy of the gene encoding C/EBP.

C/EBP is a rat liver nuclear protein capable of sequence-specific interaction with DNA. The DNA sequences to which C/EBP binds in vitro have been implicated in the control of messenger RNA synthesis. It has therefore been predicted that C/EBP will play a role in regulating gene expression in mammalian cells. The region of the C/EBP polypeptide required for direct interaction with DNA has been identified and shown to bear amino acid sequence relatedness with the product of the myc, fos, and jun proto-oncogenes. The arrangement of these related amino acid sequences led to the prediction of a new structural motif, termed the "leucine zipper," that plays a role in facilitating sequence-specific interaction between protein and DNA. Experimental tests now provide support for the leucine zipper hypothesis.

https://science.sciencemag.org/content/sci/243/4899/1681.full.pdf

The DNA binding domain of the rat liver nuclear protein, C/EBP, is bipartite

This paper presents the results of experiments that determine the chromosomal location of the mouse gene encoding CCAAT/enhancer binding protein (C/EBP) and measure its expression as a function of tissue type and temporal period of development in mice and rats Three alleles of the C/EBP gene were identified according to restriction fragment length polymorphisms The strain distribution pattern of the three alleles was determined in recombinant inbred mouse strains and compared to that of other mouse genes These results mapped the gene to a position within 25 centimorgans (cM) of the structural gene encoding glucose phosphate isomerase on chromosome 7 of the mouse The expression pattern of the C/EBP gene was studied by a combination of nucleic acid hybridization and antibody staining assays High levels of C/EBP mRNA were observed in tissues known to metabolize lipid and cholesterol-related compounds at uncommonly high rates These included liver, fat, intestine, lung, adrenal gland, and placenta More detailed analysis of two of these tissues, liver and fat, showed that C/EBP expression was limited to fully differentiated cells Moreover, analysis of the temporal pattern of expression of C/EBP mRNA in two tissues, liver and intestine, revealed a coordinated induction just prior to birth These observations raise the possibility that the synthesis of C/EBP may be responsive to humoral factors and that modulation in C/EBP expression might mediate coordinated changes in gene expression that facilitate adaptive challenges met during development or during the fluctuating physiological states of adult life

/pdf/tissue-specific-expression-developmental-regulation-and-10yvwdetl2.pdf

Tissue-specific expression, developmental regulation, and genetic mapping of the gene encoding CCAAT/enhancer binding protein.

Previous studies have shown that differentiation of 3T3-L1 preadipocytes leads to the transcriptional activation of a group of adipose-specific genes. As an approach to defining the mechanism responsible for activating the expression of these genes, we investigated the binding of nuclear factors to the promoters of two differentiation-induced genes, the 422(aP2) and stearoyl-CoA desaturase 1 (SCD1) genes. DNase I footprinting and gel retardation analysis identified two binding regions within the promoters of each gene that interact with nuclear factors present in differentiated 3T3-L1 adipocytes. One differentiation-induced nuclear factor interacts specifically with a single binding site in the promoter of each gene. Competition experiments showed that the interaction of this nuclear factor with the SCD1 promoter was prevented specifically by a synthetic oligonucleotide corresponding to the site footprinted in the 422(aP2) promoter. Several lines of evidence indicate that the differentiation-induced nuclear factor is CCAAT/enhancer binding protein (C/EBP), a DNA-binding protein first isolated from rat liver. Bacterially expressed recombinant C/EBP binds to the same site at which the differentiation-specific nuclear factor interacts within the promoter of each gene. Northern analysis with RNA from 3T3-L1 cells shows that C/EBP mRNA abundance increases markedly during differentiation. Transient cotransfection studies using a C/EBP expression vector demonstrate that C/EBP can function as a trans-activator of both the 422(aP2) and SCD1 gene promoters.

/pdf/differentiation-induced-gene-expression-in-3t3-l1-2j45mz0u9q.pdf

Differentiation-induced gene expression in 3T3-L1 preadipocytes: CCAAT/enhancer binding protein interacts with and activates the promoters of two adipocyte-specific genes.

William H. Landschulz

Papers

The leucine zipper: a hypothetical structure common to a new class of DNA binding proteins

Isolation of a recombinant copy of the gene encoding C/EBP.

The DNA binding domain of the rat liver nuclear protein, C/EBP, is bipartite

Tissue-specific expression, developmental regulation, and genetic mapping of the gene encoding CCAAT/enhancer binding protein.

Differentiation-induced gene expression in 3T3-L1 preadipocytes: CCAAT/enhancer binding protein interacts with and activates the promoters of two adipocyte-specific genes.