Elucidation of the regulatory basis for alternative splicing towards controlling HIV-1 replication

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K08860
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Virology
• Research Institution: The University of Tokushima
• Principal Investigator: NOMAGUCHI Masako 徳島大学, 大学院医歯薬学研究部(医学域), 教授 (80452647)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: HIV-1 / 同義1塩基置換 / 適応 / Vif / 選択的スプライシング

Outline of Final Research Achievements

Vif is essential for HIV-1 replication by antagonizing host restriction factor APOBEC3. Understanding regulatory bases for Vif expression certainly serves to establish a new anti-HIV-1 strategy. HIV-1 mRNAs are produced by alternative splicing via splicing donors (SD1-SD4) and acceptors (SA1-SA7). We demonstrated by adaptation studies that the nucleotide sequence around SA1 and SD2 (SA1D2prox) is involved in modulating vif mRNA expression. Sequence containing the SA1 site forms a stem loop structure (SLSA1). Mutational analysis showed that the SLSA1 stability and the vif mRNA expression level are inversely correlated, indicating the regulatory association of SLSA1 with vif mRNA production. Furthermore, our virological analysis using different HIV-1 subtypes showed that the region around SA2 and SD3, in addition to SA1D2prox, also determines the vif mRNA expression level. Collectively, we newly identified the genomic region and RNA secondary structure critical for vif mRNA production.

Free Research Field

ウイルス学

Academic Significance and Societal Importance of the Research Achievements

HIV-1 Vifタンパク質は、宿主細胞のウイルス抑制因子APOBEC3タンパク質群と拮抗するため、ウイルス複製に必須である。Vifの発現量や活性の変化は、ウイルス複製を変動させる主な要因の一つである。したがって、Vifの発現量調節機構の解明は極めて重要であるが、様々なHIV-1ゲノム配列や宿主因子群などが関与するため、その機構は非常に複雑である。本研究における詳細なウイルス学的研究により、Vif発現量調節に関与するゲノム領域と構造を明らかすることができた。今後、Vifの発現量調節機構の全貌解明を尚一層進展させ、Vif発現量を介したHIV-1複製制御手法の確立を目指す。