extracted_captions/he2015src.json

{"CAPTION FIG1.png": "\"FIGURE 1: Src2 and cortactin increase the length of lamellipodia. (A\u2013E) DIC live-cell images of _Aplyxia_ growth cones in control condition (CTL; A) and expressing CASrc2 (B), MDSrc2 (C), cortactin (D), or CortF (E). (F) Quantification of lamellipodial length, measured as the distance between the T zone and the leading edge (double-headed arrow in A\u2013E). Mean values +- SEM. Numbers in parentheses are number of growth cones selected from at least three experiments. One-way ANOVA with Dunnett's post hoc test separately performed for Src2 and cortactin groups; **p < 0.01, ***p < 0.001. Scale bar as indicated.\\n\\n\"", "CAPTION FIG2.png": "'Figure 2: Src2 and cortactin positively regulate lamellipodial protrusion persistence. (A) DIC montages of 5-min time-lapse recordings at 10-s intervals showing lamellipodial leading-edge dynamics (red dashed line) in control growth cones or after expression of CASrc2, MDSrc2, cortactin, or CortF. Scale bar as indicated. (B, B\u2019) Respective protrusion and retraction frequencies of lamellipodia. (C, C\u2019) Respective average percentages of time lamellipodia spent in protrusion and retraction phases. (D, D\u2019) Respective average lamellipodial protrusion and retraction rates. Mean values +- SEM. Numbers in parentheses are number of growth cones selected from at least three experiments. One-way ANOVA with Dunnett\u2019s post hoc test was separately performed for Src2 and cortactin conditions; *_p_ < 0.05, **_p_ < 0.01, ***_p_ < 0.001.\\n\\n'", "CAPTION FIG3.png": "'Figure 3: Src2 and cortactin regulate filipodial density and stability. (A\u2013E) DIC images depicting the P domain of control (A) and CASrc2- (B), MDSrc2- (C), cortactin- (D), and CortF-expressing (E) growth cones. (F, G) DIC montages of a region of interest in the periphery of CASrc2- and CortF-expressing growth cones showing small-scale (F) and large-scale (G) lateral movements of filopodia traced with yellow, red, and green lines. Time interval between each image is 20 s; total time, 220 s. Scale bars as indicated. (H\u2013J) Quantifications of filipodial density (H) along growth cone perimeter, as well as small-scale (I) and large-scale (J) filopodial lateral movements, respectively. Small-scale lateral movements were defined as filopodia that moved sideways no further than two adjacent filopodia. Large-scale lateral movements were defined as filopodia that moved sideways further than two adjacent filopodia. Mean values \u00b1 SEM; numbers are numbers of growth cones selected from at least three experiments. One-way ANOVA with Dunnett\u2019s post hoc test was separately performed for Src2 and cortactin conditions; **_p_ < 0.01, ***_p_ < 0.001.\\n\\n'", "CAPTION FIG4.png": "'Figure 4: Src2 and cortactin facilitate protrusion of filopodia. (A) One representative filopodium is shown for each experimental condition. Filopodial length was measured from the T zone (red line) to tip of the filopodium (red dot). The position of leading edge is marked with a white line. Scale bar as indicated. (B) Quantification of average filopodial length after Src2 and cortactin up- and down-regulation, respectively. (C) Distance vs. time plots of five representative filopodial tips for each experimental condition. (D, D) Filopodial protrusion and retraction frequencies were determined as the frequency of entering into protrusion and retraction phase, respectively, from any other phases. (E, E) Percentage of time filopodia spent in protrusion or retraction phase, respectively. (F, F) Filopodial protrusion and retraction rates, respectively. Mean values +- SEM; numbers in parentheses are number of growth cones selected from at least three experiments; one-way ANOVA with Dunnett\u2019s post hoc test was separately performed for Src2 and cortactin conditions; *p < 0.05, **p < 0.01, ***p < 0.001.\\n\\n'", "CAPTION FIG5.png": "'Figure 5: CortF abolishes CASrc2-induced lamellipodial and filopodial effects. (A) DIC live-cell image of Aplysia growth cone expressing CASrc2 and CortF; (B) Average lamellipodial length, (C) average filopodial length, (D) filopodial density, (E) fraction of filopodia undergoing small-scale lateral movement (cross two or fewer filopodia), and (F) fraction of filopodia undergoing large-scale lateral movement (cross more than two filopodia) in Aplysia growth cones expressing CASrc2, CortF, or both together compared with control (CTL) growth cones. Data are means \u00b1 SEM; numbers in parentheses are number of growth cones selected from at least three experiments. The \\\\(p\\\\) values are determined by one-way ANOVA with Dunnett\u2019s post hoc test, comparing each experimental group against a pooled control group. **p < 0.01, ***p < 0.001.\\n\\n'", "CAPTION FIG6.png": "'Figure 6: Actin dynamics in filopodia. (A) Processed actin FSM image of an _Aplysia_ neuronal growth cone. (B) Representative time-lapse montage of a single filopodial actin bundle labeled with Alexa 568\u2013G-actin. Internal speckles (dashed line) are tracked to calculate the retrograde flow rate. Similarly, the positions of newly added speckles (arrowhead) are determined to calculate the actin assembly rate. (C\u2013C\u201d) Actin assembly rates in filopodial tips in protrusion (C), retraction (C\u201d), or pausing (C\u201d) phases. (D\u2013D\u201d) Actin retrograde flow rates near filopodial tips in protrusion (D), retraction (D\u201d), or pausing (D\u201d) phases. Mean values \\\\(\\\\pm\\\\) SEM; numbers in parentheses are number of growth cones selected from at least three experiments. One-way ANOVA with Dunnett\u2019s post hoc test was separately performed for _Src2_ and cortactin conditions. No significant differences were determined between the different conditions.\\n\\n'", "CAPTION FIG7.png": "\"Figure 7: Src2 and cortactin increase the density of actin networks. (A) SEM image of control and (B) CortF-expressing growth cone. Control growth cones had regularly spaced filopodia with dense actin networks in between, whereas CortF-expressing growth cones showed fewer and curved filopodia, as well as lamellipodia that were retracted and contained disorganized actin networks of reduced density. (C) Quantification of actin filament occupancy as indicator of network density in lamellipodia with different Src and cortactin activity levels. _CASrc2_ and cortactin expression increased network density, whereas MDSrc2 and CortF expression had opposite effects. Mean values +- SEM; numbers in parentheses are number of growth cones selected from at least three experiments. One-way ANOVA with Dunnett\u2019s post hoc test separately performed for Src2 and cortactin groups; ***_p_ < 0.001. (D-H) High- magnification SEM images of actin meshwork and F-actin bundles from control and _CASrc2-_, MDSrc2-_, cortactin-, and CortF-expressing growth cones. (D'-H) Higher-magnification SEM images of actin network in the lamellipodia leading edge of control and _CASrc2-_, MDSrc2-_, cortactin-, and CortF-expressing growth cones. (I-K) Low-magnification SEM images of _CASrc2-_, CortF-, and _CASrc2_+CortF-expressing growth cones. Lamellipodial and filopodial orientation phenotypes induced by CortF were restored by _CASrc2_ coexpression. Scale bars as indicated.\\n\\n\"", "CAPTION FIG8.png": "'Figure 8: STORM imaging reveals partial colocalization of cortactin with activated Src2 and Arp2/3 complex. (A) STORM image depicting localization of activated Src2 (pSrc2; red) and cortactin (green) in an Aplysia growth cone. (B) Higher-magnification STORM image of activated Src2 and cortactin showing colocalization along filopodia and leading edge (arrowheads). (C) Clusters of cortactin labels were detected at regular intervals along a growth cone filopodia. (D) Another example of filopodium with double labeling of cortactin and activated Src2. Periodic pattern was detected in both channels, and stronger colocalization can be seen toward the tip of filopodium (right). (E) Partial colocalization of Arp3 (red) and cortactin (green) in growth cone lamellipodia and along filopodia (arrowheads). (F) Colocalization quantification of cortactin, activated Src2, or Arp2/3 complex in growth cone lamellipodia or along filopodia. Data are presented as Manders coefficient (mean values \\\\(\\\\pm\\\\) SEM). Numbers in parentheses refer to the number of growth cones analyzed in the case of lamellipodia and to the number of filopodia analyzed (13 cells). Cortactin/pSrc2 represents the ratio of cortactin signal overlapping with activated Src2 signal. pSrc2/cortactin represents the ratio of activated Src2 labeling overlapping with cortactin labeling. See Materials and Methods for details. Scale bars as indicated.\\n\\n'", "CAPTION FIG9.png": "'Figure 9: Model for Src/cortactin-mediated regulation of dynamics and morphology of growth cone lamellipodia and filopodia. Schematic depicting leading edge of lamellipodia and filopodia of neuronal growth cone in control condition (left), with up-regulated Src activation and cortactin levels (middle), and with down-regulated Src activation and cortactin tyrosine phosphorylation levels (right). 1) In lamellipodia, Src phosphorylation of cortactin facilitates Arp2/3 complex-dependent actin nucleation and branching, which results in lamellipodial protrusion. 2) Src and cortactin contribute to filopodia formation and positioning within the actin network by facilitating Arp2/3-mediated actin branch formation and stabilization. 3) In filopodia, Src phosphorylation of cortactin stabilizes bundles of actin filaments, resulting in straight filopodia. 4) Src and cortactin regulate the transition between different states of actin assembly at the plus end of filaments, thereby controlling persistence of protrusions. High rates of assembly occur during protrusion, whereas low rates of assembly occur during retraction. Up-regulation of Src activation and cortactin levels results in longer filopodia and lamellipodia, higher density of filopodia and actin network in lamellipodia, and more persistent actin-driven protrusions (middle). Down-regulation of Src activation and cortactin phosphorylation results in shorter filopodia and lamellipodia, reduced density of filopodia and actin network in lamellipodia, less persistent protrusions, and increased lateral movements of filopodia (right).\\n\\n'"}