Review Papers Against Their Own Results

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 Long Explanation

Core findings and their evidentiary weight

The paper uses lentiviral shRNA to deplete each of the three striatin family scaffolds (STRN, SG2NA, zinedin) in primary mouse keratinocytes and fibroblasts, with RNA-seq (3 biological replicates), qPCR validation, western blotting, mass spectrometry, MG132 proteasome inhibition, and wound-healing assays Striatin family study methods. The knockdown efficiency was markedly better in keratinocytes than fibroblasts (mRNA fold changes of −4.24, −4.18, and −4.35 for STRN, SG2NA, and zinedin in keratinocytes versus −2.67, −2.78, and −3.03 in fibroblasts), which the authors themselves use to explain why keratinocytes showed more robust downstream transcriptional effects.

The central novel observation is that all three knockdowns reduce pYAP(S127) and pYAP(S397) without changing total YAP, and MG132 rescues both pYAP forms — leading the authors to propose striatins protect phosphorylated YAP from proteasomal degradation. However, YAP ubiquitination was not altered, forcing the authors into a ubiquitin-independent degradation hypothesis (c-degrons, lysosomal IKKε-mediated degradation) that remains speculative. The mass-spectrometry finding that 14-3-3 protein levels drop after STRN/SG2NA depletion offers a partial mechanistic bridge for pYAP(127) loss, but no direct binding data between striatins and pYAP or the proteasome are presented. This is consistent with canonical Hippo logic — LATS-mediated phosphorylation drives YAP degradation and 14-3-3 retention Hippo-YAP pathway foundational review — but here it is inverted: striatin loss appears to increase pYAP turnover without changing upstream LATS/SAV1, an under-explained inconsistency the authors acknowledge.

Cell-type specificity is the real story

RNA-seq revealed strikingly non-overlapping transcriptional responses: SG2NA depletion yielded 159 unique DEGs out of 319 in fibroblasts, while zinedin depletion produced 224 unique DEGs in keratinocytes; almost no DEGs were shared between cell types after striatin depletion DEG overlap analysis. Only ENDOU and KRT16 were upregulated across all three keratinocyte knockdowns — both previously unlinked to striatins, and KRT16 ties mechanistically to migration (KRT16 overexpression reduces keratinocyte migration). Wound-healing assays showed migration impairment 3–9 h after wounding for all three KDs, with a minor Ki-67 proliferation reduction (notably zinedin).

The Wnt connection is weak: APCDD1 mRNA rose substantially in RNA-seq (up to 10.1-fold for zinedin) but only 1.5–2.5-fold by qPCR and less than 1.5-fold at the protein level — a classic magnitude discrepancy the authors candidly attribute to sensitivity, normalization, and primary-cell variability. Active β-catenin changed only modestly. The authors' therapeutic framing (striatins as dual Hippo/Wnt anti-cancer targets) is not supported by the modest, indirect Wnt data presented.

Critical limitations and blind spots

• Correlative mechanism: The pYAP-stabilization model rests on MG132 pharmacology; no rescue experiment (e.g., re-expressing shRNA-resistant striatin) or direct physical evidence is provided.
• shRNA off-targets: 14 shRNAs were screened, but single shRNAs per gene were carried forward; no independent siRNA/CRISPR validation or rescue is described.
• In vitro only: Primary mouse cells and HaCaT overexpression; no in vivo confirmation, and cell-type extrapolation to tissue physiology is uncertain — a well-known limitation of Hippo pathway context-dependence Hippo context-dependence caution.
• Unresolved contradiction: If striatins normally inhibit Hippo by dephosphorylating MST (per STRIPAK literature), their loss should raise pYAP — yet pYAP fell. The authors do not reconcile this tension explicitly.
• Compensation ambiguity: No compensatory upregulation of sibling striatins was observed, but the authors acknowledge functional redundancy may occur via pathway rewiring rather than expression changes — leaving the single-KD interpretation open.

Verdict

A solid, honest exploratory study whose strongest contribution is the cell-type–resolved transcriptomic resource and the provocative pYAP-stabilization hypothesis. Confidence in the pYAP mechanism is moderate at best; the migration and KRT16 findings are the most reproducible, directly measured effects. The Hippo–STRIPAK axis itself is well established; what would disconfirm this paper's specific claim is a demonstration that pYAP loss upon striatin depletion persists with simultaneous proteasome and lysosome inhibition, or that re-expression of striatin fails to restore pYAP levels.

Deepen this review: Best Evidence: pYAP–Striatin BindingDesign Rescue ExperimentsMeta-analysis: STRIPAK–Hippo

Author reviews: Rina Rosin-ArbesfeldDavid C PallasChen LuxenburgMichal CaspiMetsada Pasmanik-ChorArad SofferYarden Shor-NareznoyYan LenderAmnon WittensteinHanin EliasNatalie ZeliksonRana MasriRose Jbara

 BGPT Paper Review

Study Novelty

The per-member dissection of striatin family function and the pYAP-stabilization claim are new; the STRIPAK–Hippo connection itself is established, so novelty is contextual rather than paradigm-shifting.

Scientific Quality

Multiple orthogonal methods (RNA-seq, qPCR, MS, MG132, functional assays) with 3–4 biological replicates and candid discussion of RNA-seq/qPCR discrepancies. Weaknesses: single shRNA per gene carried forward, no rescue experiments, no in vivo validation, and an unreconciled contradiction with the established STRIPAK-dephosphorylates-MST model.

Study Generality

Findings are strongly cell-type specific (near-zero DEG overlap between fibroblasts and keratinocytes), limiting generalizability, though the Hippo/Wnt hub concept has broad relevance to epithelial biology and cancer.

Study Usefulness

Provides a cell-type-resolved transcriptomic resource, identifies ENDOU/KRT16 as novel striatin-responsive genes, and frames testable cancer-therapy hypotheses around striatin-targeted Hippo/Wnt modulation.

Study Reproducibility

Detailed methods, commercial reagents, and planned GEO deposition support replication, but full raw data availability is not yet confirmed and some key data (e.g., some KD westerns) are described only in supplements or 'not shown'.

Explanatory Depth

Offers a mechanistic model (14-3-3 loss → pYAP degradation; ubiquitin-independent route via c-degrons or lysosomes) but relies on indirect pharmacology without direct binding, ubiquitination, or rescue data.