TASK DEFINITION: In this task, you're given a paragraph and title from the research paper. Your task is to classify whether the given title is suitable or not for the research paper based on the given paragraph. Return "True" if title is proper according to paragraph else "False".
PROBLEM: Paragraph: Apelin is an inotropic and cardioprotective peptide that exhibits beneficial effects through activation of the APJ receptor in the pathology of cardiovascular diseases. Apelin induces the expression of angiotensin-converting enzyme 2 (ACE2) in failing hearts, thereby improving heart function in an angiotensin 1-7-dependent manner. Whether apelin antagonizes the over-activation of the renin-angiotensin system in the heart remains elusive. In this study we show that the detrimental effects of angiotensin II (Ang II) were exacerbated in the hearts of aged apelin-gene-deficient mice. Ang II-mediated cardiac dysfunction and hypertrophy were augmented in apelin knockout mice. The loss of apelin increased the ratio of angiotensin-converting enzyme (ACE) to ACE2 expression in the Ang II-stressed hearts, and Ang II-induced cardiac fibrosis was markedly enhanced in apelin knockout mice. mRNA expression of pro-fibrotic genes, such as transforming growth-factor beta (TGF-β) signaling, were significantly upregulated in apelin knockout hearts. Consistently, treatment with the ACE-inhibitor Captopril decreased cardiac contractility in apelin knockout mice. In vitro, apelin ameliorated Ang II-induced TGF-β expression in primary cardiomyocytes, accompanied with reduced hypertrophy. These results provide direct evidence that endogenous apelin plays a crucial role in suppressing Ang II-induced cardiac dysfunction and pathological remodeling. Int. J. Mol. Sci. 2019, 20, 239 2 of 12 dysfunctions [8, 10, 11] . By contrast, APJ was identified as a dual receptor to mediate cardiac hypertrophy [12, 13] via β-arrestin signaling [14, 15] . Thus, the precise role of endogenous apelin signaling in heart function remains elusive. Cardiac hypertrophy is an adaptive response to maintain cardiac function in the event of an increased workload, although prolonged cardiac hypertrophy can lead to heart failure via the ischemia of cardiomyocytes [16, 17] . In addition, cardiac fibrosis adversely increases tissue stiffness and impairs ventricular function. Consistently, cardiac hypertrophy and the development of fibrosis correlate with the deterioration of myocardial function in heart failure [18] [19] [20] . Thus, cardiac hypertrophy and fibrosis are key features of heart failure, and apelin's inotropic and protective roles in the heart are attractive as a potential therapeutic candidate for treating heart failure. Apelin has also been identified as a substrate for angiotensin-converting enzyme 2 (ACE2), which cleaves apelin with similar efficiency as its primary substrate angiotensin II (Ang II) [21] [22] [23] . ACE2 is a negative regulator of the renin-angiotensin system (RAS) that inactivates Ang II by converting it to angiotensin 1-7 (Ang 1-7) [21] [22] [23] , whereas angiotensin-converting enzyme 1 (or ACE1) activates RAS by converting Ang I to Ang II. ACE2 was also identified as a regulator of heart failure [24-26], diabetic nephropathy [27, 28] , acute lung failure [29, 30] , and the SARS (severe acute respiratory syndrome) coronavirus receptor [31, 32] . Apelin-APJ signaling has been shown to counteract the effects of Ang II on AT1R in defined physiological and pathophysiological settings. For instance, in hypertensive rat models, the continuous infusion of Ang II downregulates apelin and APJ expression [33] . We have shown that Apelin upregulates ACE2 expression. Apelin-induced ACE2 downregulates Ang II signaling while enhancing Ang 1-7-Mas receptor signaling in aged or failing hearts [34] . On the other hand, it has been suggested that the counter-balancing effects of the apelin-APJ axis on Ang II-AT1R signaling are mediated by receptor dimerization. The APJ receptor physically interacts with AT1 receptors, and exogenous apelin negatively regulates Ang II-AT1R signaling in in vitro cell culture systems and in an in vivo atherosclerosis model [35] . However, whether endogenous apelin counteracts the over-activation of RAS in the heart remains unexplored. In this study, we aimed to determine the effects of endogenous apelin on Ang II-induced pathology in the heart. We showed that Ang II-mediated cardiac dysfunction, hypertrophy, and fibrosis were augmented in apelin knockout (Apelin KO) mice. 
 Title: Loss of Apelin Augments Angiotensin II-Induced Cardiac Dysfunction and Pathological Remodeling

SOLUTION: True

PROBLEM: Paragraph: The tertiary structures of the S1 and S2 domains of the spike protein of the coronavirus which is responsible of the severe acute respiratory syndrome (SARS) have been recently predicted. Here a molecular assembly of SARS coronavirus peplomer which accounts for the available functional data is suggested. The interaction between S1 and S2 appears to be stabilised by a large hydrophobic network of aromatic side chains present in both domains. This feature results to be common to all coronaviruses, suggesting potential targeting for drugs preventing coronavirus-related infections. 
 Title: Prediction of quaternary assembly of SARS coronavirus peplomer

SOLUTION: False

PROBLEM: Paragraph: The presentation of viral peptide epitopes to host cytotoxic T lymphocytes (CTLs) is crucial for adaptive cellular immunity to clear the virus infection, especially for some chronic viral infections. Indeed, hosts have developed effective strategies to achieve this goal. The ideal scenario would be that the peptide epitopes stimulate a broad spectrum of CTL responses with diversified T-cell receptor (TCR) usage (the TCR repertoire). It is believed that a diversified TCR repertoire requires a "featured" peptide to be presented by the host major histocompatibility complex (MHC). A featured peptide can be processed and presented in a number of ways. Here, using the X-ray diffraction method, the crystal structures of an antigenic peptide derived from rinderpest virus presented by bovine MHC class I N*01801 (BoLA-A11) have been solved, and two distinct conformations of the presented peptide are clearly displayed. A detailed analysis of the structure and comparative sequences revealed that the polymorphic amino acid isoleucine 73 (Ile73) is extremely flexible, allowing the MHC groove to adopt different conformations to accommodate the rinderpest virus peptide. This makes the peptide more featured by exposing different amino acids for T-cell recognition. The crystal structures also demonstrated that the N*01801 molecule has an unusually large A pocket, resulting in the special conformation of the P1 residue at the N terminus of the peptide. We propose that this strategy of host peptide presentation might be beneficial for creating a diversified TCR repertoire, which is important for a moreeffective CTL response. Viral diseases and other infections caused by intracellular pathogens of cattle result in large global economic losses every year. In the past several decades, rinderpest virus (RPV) (23, 40), foot-and-mouth disease virus (FMDV) (7), and bovine tuberculosis infection (62) have brought disastrous consequences, including social panic and even a threat to human health. Nearly 6 decades ago, most countries were committed to developing more-effective vaccines (46), and remarkable achievements were made in controlling threatening bovine viral infectious diseases and other zoonoses (23, 46). In the 1960s, British virologist Walter Plowright developed a live attenuated vaccine against rinderpest virus, which was widely used in rinderpest eradication efforts (40). However, it still remains extremely challenging for humans to completely eradicate a virus. The questions of how the bovine attenuated vaccine induces immune responses and how the viral peptides are presented and recognized by host immune molecules are still largely unanswered. Therefore, studies on bovine immunity against the rinderpest virus may provide clues for our battle against other viral infections. Generally speaking, effective vaccines have common characteristics: they are rich in T-cell and B-cell epitopes and can induce the immune system to generate protective immune responses (3, 36, 54) . During this process, major histocompatibility complex (MHC) molecules play a pivotal role in the host. MHC class I (MHC I) molecules form a heterotrimer complex composed of the heavy chain of MHC, the antigenic peptide, and ␤ 2 -microglobulin (␤ 2 m). Generally, MHC I loads endogenous peptides, including the virus-derived peptides. Briefly, at the initial stage of virus infection, antigenic proteins are processed in a proteasome-dependent or -independent manner. The resultant short peptides are then transported to the endoplasmic reticulum and are loaded onto the peptidebinding grooves of MHC I molecules. Consequently, the peptide-loading MHC I complexes are translocated to the cell surface and are recognized by cytotoxic T lymphocytes (CTLs) with specific T-cell receptors (TCRs) (49, 63). This immune recognition induces an MHC-restricted CD8 ϩ T-cell response that is characterized by the killing and elimination of the infected cells by effector T cells. The majority of virus-derived peptides are processed and presented through this pathway 
 Title: Two Distinct Conformations of a Rinderpest Virus Epitope Presented by Bovine Major Histocompatibility Complex Class I N*01801: a Host Strategy To Present Featured Peptides ᰔ †

SOLUTION:
False