Glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) has been identified in multiple genome-wide association studies (GWAS) as a contributor to obesity, and GIPR knockout mice are protected against diet-induced obesity (DIO). On the basis of this genetic evidence, we developed anti-GIPR antagonistic antibodies as a potential therapeutic strategy for the treatment of obesity and observed that a mouse anti-murine GIPR antibody (muGIPR-Ab) protected against body weight gain, improved multiple metabolic parameters, and was associated with reduced food intake and resting respiratory exchange ratio (RER) in DIO mice. We replicated these results in obese nonhuman primates (NHPs) using an anti-human GIPR antibody (hGIPR-Ab) and found that weight loss was more pronounced than in mice. In addition, we observed enhanced weight loss in DIO mice and NHPs when anti-GIPR antibodies were codosed with glucagon-like peptide-1 receptor (GLP-1R) agonists. Mechanistic and crystallographic studies demonstrated that hGIPR-Ab displaced GIP and bound to GIPR using the same conserved hydrophobic residues as GIP. Further, using a conditional knockout mouse model, we excluded the role of GIPR in pancreatic β-cells in the regulation of body weight and response to GIPR antagonism. In conclusion, these data provide preclinical validation of a therapeutic approach to treat obesity with anti-GIPR antibodies.

Phosphorylation of the cAMP response element binding protein (CREB) at Ser-133 in response to hormonal stimuli triggers cellular gene expression via the recruitment of the histone acetylase coactivator paralogs CREB binding protein (CBP) and p300 to the promoter. The NMR structure of the CREB:CBP complex, using relevant interaction domains called KID and KIX, respectively, reveals a shallow hydrophobic groove on the surface of KIX that accommodates an amphipathic helix in phospho (Ser-133) KID. Using an NMR-based screening approach on a preselected smallmolecule library, we identified several compounds that bind to different surfaces on KIX. One of these, KG-501 (2-naphthol-AS-Ephosphate), targeted a surface distal to the CREB binding groove that includes Arg-600, a residue that is required for the CREB:CBP interaction. When added to live cells, KG-501 disrupted the CREB: CBP complex and attenuated target gene induction in response to cAMP agonist. These results demonstrate the ability of small molecules to interfere with second-messenger signaling cascades by inhibiting specific protein-protein interactions in the nucleus.cAMP response element binding protein ͉ transcription P rotein-protein interactions often serve as key regulatory points for signal propagation in response to extracellular stimuli. The formation of protein-protein complexes is of particular interest in the field of transcriptional regulation, where multiple low-affinity interactions appear to contribute to the recruitment of the transcriptional apparatus to the promoter (1). Initially thought to result from low energy interactions between unstructured regions, the recognition of an activator by its coactivator cognate often involves discrete surface contacts between well-folded protein domains. Moreover, the interaction surfaces between such protein pairs often are modulated by covalent modifications at residues near the protein-protein interface.Phosphorylation of the cAMP response element binding protein (CREB) at Ser-133 stimulates its association with the coactivator paralogs CREB binding protein (CBP) and p300 via a direct mechanism (2); the Ser-133 phosphate forms a hydrogen bond with Tyr-658 and an ion pair with Lys-662 in the KIX domain (3). Binding of CREB to CBP͞p300 is further stabilized by a random coil-to-helix transition in KID that provides the majority of hydrophobic surface contacts with residues lining a shallow groove in KIX (4, 5). The KIX domain folds into a three-helix structure with helices ␣1 and ␣3 aligned in nearly parallel fashion to form a groove that accommodates hydrophobic residues in KID. Helix ␣2 does not participate directly in surface contacts with KID but appears to stabilize KIX structure.The CREB binding site in KIX also recognizes other activators, most notably the protooncogene c-Myb (6). Similar to phospho (Ser-133) KID, c-Myb binds to KIX via an amphipathic helix that forms numerous surface contacts with residues lining the shallow hydrophobic groove in KIX (7). Notably, surfaces distal to the CREB-bi...

p53 target promoters are structurally diverse and display pronounced differences in RNA polymerase II (RNAP II) occupancy even in unstressed cells, with higher levels observed on cell cycle arrest genes (p21) compared with apoptotic genes (Fas/APO1). This occupancy correlates well with their ability to undergo rapid or delayed stress induction. To understand the basis for such distinct temporal assembly of transcription complexes, we examined the role of core promoter structures in this process. We find that the p21 core promoter directs rapid, TATA box-dependent assembly of RNAP II preinitiation complexes (PICs), but permits few rounds of RNAP II reinitiation. In contrast, PIC formation at the Fas/APO1 core promoter is very inefficient but supports multiple rounds of transcription. We define a downstream element within the Fas/APO1 core promoter that is essential for its activation, and identify nuclear transcription factor Y (NF-Y) as its binding partner. NF-Y acts as a bifunctional transcription factor that regulates basal expression of Fas/APO1 in vivo. Thus, two critical parameters of the stress-induced p53 transcriptional response are the kinetics of gene induction and duration of expression through frequent reinitiation. These features are intrinsic, DNA-encoded properties of diverse core promoters that may be fundamental to anticipatory programming of p53 response genes upon stress.

Cell division in animals must be regulated; during development, for example, proliferation often occurs in spatially and temporally restricted patterns, and loss of mitotic control underlies cancer. The epidermal growth factor receptor (EGFR) has been implicated extensively in the control of cell proliferation in metazoans; in addition, hyperactivity of the EGFR and its three relatives, ErbB2-ErbB4, are implicated in many cancers. But little is known about how these receptor tyrosine kinases regulate the cell cycle. In the developing Drosophila melanogaster imaginal eye disc, there is a single patterned mitosis that sweeps across the eye disc epithelium in the third larval instar. This 'second mitotic wave' is triggered by EGFR signalling and depends on expression of String, the Drosophila homologue of Cdc25 phosphatase, the ultimate regulator of mitosis in all eukaryotic cells. Here we show that two antagonistic transcriptional regulators, Pointed, an activator, and Tramtrack69, a repressor, directly regulate the transcription of string. The activity of at least one of these regulators, Pointed, is controlled by EGFR signalling. This establishes a molecular mechanism for how intercellular signalling can control string expression, and thereby cell proliferation.