Journal: bioRxiv
Article Title: BASP1 Couples Ca 2+ Signaling and Actin Polymerization to Mitochondrial Fission Essential for Neurite Outgrowth
doi: 10.1101/2025.09.05.674494
Figure Lengend Snippet: (A) Representative Western blot of GFP immunoprecipitates (IP) from HeLa cells transfected with GFP alone or BASP1-GFP constructs: wild-type (WT), phosphoablative (S40A/S170A; A,A), and phosphomimetic (S40D/S170D; D,D) double mutants. Blots were probed with anti-GFP and anti-prohibitin 1 (Phb1). (B) MS quantification of prohibitin 1 (Phb1) co-immunoprecipitated using anti-GFP beads from primary embryonic rat cortical neurons transduced with GFP alone or BASP1-GFP constructs: WT, phosphoablative (S40A/S170A; A,A), and phosphomimetic (S40D/S170D; D,D) double mutants. One-Way Anova followed by multiple comparisons with two-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli, *q<0.05. (C) Representative Western blot of BASP1 from HeLa cells co-transfected with GFP alone or BASP1-GFP constructs: BASP1 WT, phosphoablative (S40A/S170A; A,A), and phosphomimetic (S40D/S170D; D,D) double mutants, along with either a 3’UTR-targeting siRNA against human BASP1 or non-targeting control siRNA. (D) Quantification of BASP1 signal normalized to GAPDH (loading control) from (C), with values further normalized to the non-targeting siRNA control within each experiment. N=3. One-way Anova with post hoc Dunnett’s test, * P <0.05. (E-G) Mitochondrial length (E) and number (G) analyzed in HeLa cells from (C) using MitoTracker Deep Red-assisted confocal microscopy (F). Scale bar = 10 µm. N>20. One-way Anova with post hoc Tukey’s test, * P <0.05, ** P <0.01, *** P <0.001, **** P <0.0001. (H) MS quantification of actin co-immunoprecipitated using anti-GFP beads from primary embryonic rat cortical neurons cultured under the conditions described in (B). One-Way Anova followed by multiple comparisons with two-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli, *q<0.05. (I) Representative Western blot of GFP co-immunoprecipitates from HeLa cells cultured under the conditions described in (A). Blots were probed with anti-GFP and anti-actin. (J) Representative confocal pictures of mitochodnira and actin from HeLa cells cultured under the conditions described in (C) and co-transfected with LifeAct-mScarlet to visualize actin. Time-lapse imaging was performed at 150-second intervals to monitor actin localization at mitochondria following 4 µM ionomycin stimulation. Scale bar = 10 µm. (K) Quantification of actin fluorescence intensity from (J) over time following 4 µM ionomycin treatment. (L) Representative confocal pictures of HeLa cells cultured in conditions described in (C) under 4 µM Ionomycin treatment. Actin was visualized by transient expression of LifeAct-mScarlet and mitochondria were labeled with MitoTracker Deep Red. Time-lapse imaging was performed at 15-second intervals. Arrows indicate actin recruitment to mitochondria with BASP1-GFP WT, phosphoablative (S40A/S170A; A,A), and phosphomimetic (S40D/S170D; D,D) double mutants followed by fission events only in BASP1 WT and D,D. Scale bar = 2 µm.
Article Snippet: Primary embryonic rat cortical neurons were isolated from euthanized pregnant Sprague–Dawley rats at embryonic day 18 as described elsewhere ( ).
Techniques: Western Blot, Transfection, Construct, Immunoprecipitation, Transduction, Control, Confocal Microscopy, Cell Culture, Imaging, Fluorescence, Expressing, Labeling