TDRD7

TDRD7 is a Tudor/LOTUS-domain RNA-binding scaffold protein that assembles into cytoplasmic RNA granules to exert posttranscriptional control over specific target mRNAs during cell differentiation (PMID:21436445). In lens fiber cells it localizes to distinct TDRD7-containing RNA granules, associates with STAU1-ribonucleoproteins, and directly binds and regulates target transcripts including Hspb1, whose proper expression is needed for normal F-actin organization and fiber cell morphology (PMID:21436445, PMID:32420594). TDRD7 also governs autophagosome maturation by directly binding Tbc1d20 mRNA and suppressing TBC1D20, thereby permitting autophagosome–lysosome fusion; loss of this control blocks autophagic flux and is required for both lens transparency and acrosome biogenesis (PMID:33618632). In the germline, TDRD7 localizes to nuage/chromatoid bodies in a Tudor-domain- and MVH/DDX4-dependent manner, where it drives dynamic remodeling and fusion of these RNP granules and suppresses LINE1 retrotransposons through a pathway distinct from the TDRD1/TDRD9 piRNA route (PMID:21670278, PMID:17141210). Separately, TDRD7 acts as an interferon-stimulated antiviral effector that physically interacts with AMPK through a defined AMPK-binding domain and inhibits its activation, restricting paramyxovirus replication via blockade of autophagy and restricting HSV-1 replication through an autophagy-independent requirement for AMPK (PMID:29381763, PMID:32273341, PMID:37712680).

1. 2006 High

   Establishing where TDRD7 acts and what builds the complex: TDRD7 was shown to occupy germ-cell nuage as part of a Tudor-domain RNP, defining its subcellular platform and its dependence on the RNA helicase MVH/DDX4.

   Evidence Immunofluorescence co-localization, co-IP, dominant-negative truncations, and analysis in Mvh/Ddx4 mutant mice

   PMID:17141210

   Open questions at the time

   • Did not identify the RNA cargo bound in nuage
   • Did not connect nuage localization to a specific posttranscriptional outcome
2. 2008 Low

   An early survey placed TDRD7 in complexes linked to cytoskeleton, mRNA transport, and translation machinery, hinting at a scaffolding role before specific partners were defined.

   Evidence Immunoprecipitation and monoclonal antibody characterization to identify associated protein complexes

   PMID:18582216

   Open questions at the time

   • Single IP method without reciprocal validation
   • Named complex members not mechanistically followed up
   • No functional consequence established
3. 2011 High

   TDRD7 was defined as an RNA-granule scaffold controlling specific mRNAs in lens development, linking its molecular activity to a clear loss-of-function phenotype and human disease.

   Evidence Co-IP of TDRD7 with STAU1-RNPs and lens mRNAs, Tdrd7-null mouse with cataract and spermatogenesis arrest, immunofluorescence

   PMID:21436445

   Open questions at the time

   • Did not resolve which individual mRNAs drive the cataract phenotype
   • Mechanism of granule assembly not defined
4. 2011 High

   Genetic dissection showed TDRD7 remodels chromatoid-body RNPs and restrains LINE1 retrotransposons through a pathway separate from the piRNA-producing TDRDs, distinguishing its germline role.

   Evidence Single and double Tdrd7/Tdrd6 knockout mice, epistasis with Tdrd1/Tdrd6/Tdrd9, retrotransposon expression assays

   PMID:21670278

   Open questions at the time

   • Molecular mechanism of LINE1 suppression independent of piRNA not defined
   • Direct RNA targets in chromatoid bodies not identified
5. 2014 Medium

   The Drosophila ortholog Tapas tied TDRD7 to piRNA-pathway components at the nuage, providing a comparative framework for its transposon-related germline function.

   Evidence Co-IP of Tap with Aub, Ago3, Spindle-E, Vasa; single and double mutants with Tej; piRNA sequencing and transposon assays

   PMID:25287931

   Open questions at the time

   • Ortholog couples to piRNA pathway, whereas mouse TDRD7 acts piRNA-independently — reconciliation unresolved
   • Direct RNA targets of Tap not mapped
6. 2018 High

   An ISG screen reframed TDRD7 as an antiviral effector, showing it blocks paramyxovirus replication by interfering with AMPK-dependent autophagy.

   Evidence shRNA ISG screen, knockdown/knockout and overexpression across cell types, AMPK activity assays, AMPK ablation and chemical inhibition

   PMID:29381763

   Open questions at the time

   • Did not establish whether TDRD7 contacts AMPK directly
   • Did not separate autophagy-dependent from autophagy-independent effects
7. 2020 High

   TDRD7 was shown to restrict HSV-1 via AMPK inhibition independent of autophagy, demonstrating the antiviral effect operates through AMPK itself rather than solely through autophagy.

   Evidence Knockdown/knockout/ectopic expression in human and mouse lines, AMPK genetic ablation, chemical inhibition, epistasis

   PMID:32273341

   Open questions at the time

   • Did not define the physical basis of AMPK inhibition
   • Step in viral life cycle requiring AMPK not fully resolved
8. 2020 High

   TDRD7's direct mRNA target in lens was pinned to Hspb1, connecting its granule-localized binding to cytoskeletal and morphological control preceding cataract.

   Evidence RIP of TDRD7 with Hspb1 mRNA, single-molecule RNA imaging, RNA-seq/proteomics, SEM, phalloidin staining, Hspb1 knockdown in Xenopus

   PMID:32420594

   Open questions at the time

   • Whether TDRD7 stabilizes, transports, or translationally regulates Hspb1 mRNA not resolved
   • Full target mRNA repertoire not defined
9. 2021 Medium

   TDRD7 was linked to autophagosome maturation by binding Tbc1d20 mRNA and suppressing TBC1D20, explaining how it clears organelles for lens transparency and acrosome biogenesis.

   Evidence Transcriptome analysis, TDRD7–Tbc1d20 mRNA binding assays, autophagosome-lysosome fusion and LC3/LAMP1 flux assays, TEM, CTSD processing in tdrd7-deficient MEFs

   PMID:33618632

   Open questions at the time

   • Mechanism of TDRD7-mediated TBC1D20 mRNA downregulation not defined
   • Relationship between this autophagy role and AMPK-mediated antiviral autophagy control unclear
10. 2021 Medium

    In zebrafish, TDRD7 was shown to relocalize germ plasm and reconfigure chromatin accessibility to elaborate germ-cell fate, separating its role in fate from migration.

    Evidence Zebrafish loss-of-function with ATAC-seq, RNA-seq, and live imaging of germ plasm

    PMID:33651978

    Open questions at the time

    • Mechanism linking a cytoplasmic RNA-granule protein to chromatin accessibility unresolved
    • Direct molecular targets in PGCs not identified
11. 2023 High

    The antiviral mechanism was resolved to a direct TDRD7–AMPK interaction via a defined domain, with in vivo confirmation that loss of TDRD7 raises AMPK activity and viral susceptibility.

    Evidence Co-IP of TDRD7 with AMPK, domain deletion mutagenesis, TDRD7-KO primary cells and mice, in vivo respiratory virus infection

    PMID:37712680

    Open questions at the time

    • Structural basis of the TDRD7–AMPK contact not determined
    • Whether the AMPK-binding domain overlaps with RNA-binding domains unclear

• How TDRD7's RNA-binding/scaffold activity and its AMPK-inhibitory activity are mechanistically integrated within one protein — and whether they operate in the same or distinct cellular pools — remains unresolved.
• No structure of full-length TDRD7 or its complexes
• Domain map linking RNA binding, granule assembly, and AMPK inhibition not established
• Comprehensive target mRNA set not defined