Work in the authors' laboratory is supported by a grant from the National Institute of General Medical Sciences (GM41628) and by a grant to the Stowers Institute for Medical Research from the Helen Nelson Medical Research Fund at the Greater Kansas City Community Foundation.

מבחני Remodeling הנוקלאוזום .1 תלוי ATP כדי למדוד ATP תלוי פעילויות הנוקלאוזום שיפוץ, immunopurified INO80 או subcomplexes INO80 מודגרת עם ATP ומצע mononucleosomal, המכיל הנוקלאוזום יחיד ממוקם בקצה אחד של קטע DNA 216-BP, שכותרתו-P 32. תוצרי התגובה לאחר מכן נתון לאלקטרופורזה בג&#39;ל פולי-acrylamide ילידים. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> על מנת ליצור את, בר 32 שכותרתו P &#39;601&#39; DNA, להגביר מpGEM-3Z-601 4 שבר 216 נ&quot;ב DNA המכיל 601 רצף מיצוב הנוקלאוזום מיקום סוף, באמצעות oligonucleotides 5&#39;-ACAGGATGTATATATCTGACACGTGCCTGG ו5&#39;-AATACTCAAGCTTGGATGCCTGCAG כ קדימה ולאחור פריימרים. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> הגדר את תגובת PCR 100 μl כפי שמתואר בטבלה 1. </li><li style=";text-align:right;direction:rtl"> לבצע PCR התגובות בCycler תרמית באמצעות התכנית הבאה: 1 דקות ב96 מעלות צלזיוס, followeד על ידי 45 שניות על 94 מעלות צלזיוס, 30 שניות ב57 ° C, 60 שניות ב72 מעלות צלזיוס במשך 30 מחזורים; כלה ב7 דקות ב72 מעלות צלזיוס. </li><li style=";text-align:right;direction:rtl"> לאחר תגובת PCR נגמרה, להסיר את נוקלאוטידים מאוגדים על ידי העברת תוצרי התגובה פעמיים באמצעות עמודות ספין nuclease חינם. </li><li style=";text-align:right;direction:rtl"> לרוץ 5 μl של מוצר PCR המטוהר בagarose ג&#39;ל 1.2% כדי לאשר שתגובת PCR שנוצרה קטע DNA נ&quot;ב הרצוי ~ 216. </li><li style=";text-align:right;direction:rtl"> לדלל 5 μl של מוצר PCR המטוהר פי 20, ולמדוד את ריכוז DNA באמצעות ספקטרופוטומטר UV. התשואה הממוצעת היא ~ 40 ng / μl. </li><li style=";text-align:right;direction:rtl"> מדוד את הרדיואקטיביות של 1 μl של מוצר PCR המטוהר במונה נצנץ. להעריך את יעילות התיוג על ידי חישוב עותקים לדקה / ng. תגובת תיוג מוצלחת צפויה להניב ~ 15,000 עותקים לדקה / ng של 601 קטע DNA. </li></ol></li><li style=";text-align:right;direction:rtl"> העבר את nucleosomes תא הלה על DNA 601 שכותרתו באמצעות שיטת דילול סדרתי 5. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> לערבב 2 pmol של32 קטע DNA 601 עם כותרת P 6 מיקרוגרם של nucleosomes הלה (שהוכן כמתואר 5) ב50 μl של מאגר המכיל 1.0 M NaCl, 10 מ&quot;מ טריס-HCl, pH 8.0, 1 mM EDTA, 0.1 מ&quot;מ PMSF, ו1 מ&quot;מ DTT ולדגור על 30 מעלות צלזיוס במשך 30 דקות. </li><li style=";text-align:right;direction:rtl"> רצף לדלל את התערובת ל0.8 M, 0.6 M, ו0.4 M NaCl על ידי דילול עם 12.5 μl, 20.8 μl, ו41.6 μl, בהתאמה, של 10 מ&quot;מ טריס-HCl (pH 8.0), 1 mM EDTA, 0.1 מ&quot;מ PMSF, ו 1 מ&quot;מ DTT, עם דגירה 30 דקות ב30 מעלות צלזיוס לאחר כל דילול. </li><li style=";text-align:right;direction:rtl"> יתר על כן לדלל את התערובת ל0.2 M ולאחר מכן ל0.1 M NaCl על ידי תוספת של 125 μl ולאחר מכן 250 μl מאותו המאגר המכיל 0.1% Nonidet P-40, גליצרול 20%, ו200 מיקרוגרם / מ&quot;ל ​​BSA, עם דגירה 30 דקות ב30 מעלות צלזיוס בין שני דילולים הסופיים. אחסן את מצע mononucleosome ב 4 מעלות צלזיוס למשך עד 3 חודשים. </li></ol></li><li style=";text-align:right;direction:rtl"> לבצע תגובות הנוקלאוזום הזזה ATP תלויות בנפח כולל של 10 μl. המחשבהרכיבי ction מפורטים בטבלה 2. מאז ריכוז NaCl האופטימלי לפעילות שיפוץ הנוקלאוזום INO80 הוא ~ 50 mM NaCl (תוצאות לא פורסמו), להתאים את הריכוז הכולל של NaCl בכל תגובה ל50 מ&quot;מ, תוך לקיחה בחשבון את כמות NaCl הכלולה ב הכנות של nucleosomes ואנזים. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> לפני שיתחיל בלהגדיר את מבחני, להטיל ג&#39;לי פולי-acrylamide ילידים (18 x 16 סנטימטר). כדי להכין ג&#39;ל יחיד המכיל 5% acrylamide (acrylamide: bisacrylamide 37.5: 1), TBE 0.5x (45 borate מ&quot;מ טריס, 1 mM EDTA), 0.01% persulfate אמוניום (APS), ו0.001% N, N, N&#39;, -tetramethylethylenediamine N&#39;(TEMED), לערבב את החומרים המפורטים בטבלה 3. אפשר ג&#39;ל לפלמר לפחות שעה 2 ב RT. </li><li style=";text-align:right;direction:rtl"> בינתיים, לכל תגובה שיש לבצע, לשלב בצינור 1.5 מ&quot;ל microcentrifuge מראש צונן siliconized ~ 20 ננומטר INO80 או subcomplex INO80 (שהוכן כמתואר 3) עם סכום של חיץ EB100 ( <strאונג&gt; לוח 4) מספיק כדי לתת נפח של 4.75 μl. מייד מחדש להקפיא כל שברים המכיל INO80 שנותרו בקרח יבש אבקה או חנקן נוזלי. </li><li style=";text-align:right;direction:rtl"> הגדר את קוקטייל הורים עם שאר החומרים, גמלון בפקטור של &quot;X&quot; (כאשר X = מספר כולל של תגובות +3). הסכום של כל מרכיב הנחוץ לתגובת 10 μl בודדת מופיע בטבלה 5; המתכון צריך להיות בקנה מידה גדול בהתאם למספר של תגובות שיש לבצע. מערבבים היטב על ידי הקשה על הצינור או על ידי pipetting למעלה ולמטה עם Pipetman ולסובב את הצינור לכמה שניות בmicrocentrifuge המעבדתיים. </li><li style=";text-align:right;direction:rtl"> לוותר 5.25 μl של קוקטייל האדון לכל אחד מצינורות התגובה הוקמו בצעד 1.3.2. מערבבים היטב על ידי pipetting למעלה ולמטה. התחל את התגובות על ידי העברת צינורות תגובה לאמבטית גוש חום C 30 מעלות או מים ודגירה עבור שעה 2. </li><li style=";text-align:right;direction:rtl"> בינתיים, להכין את &#39;הסרת לערבב&#39; קוקטייל המכיל DNA מתחרהוnucleosomes, גמלון בפקטור של X (X = מספר הכולל של תגובות + 4). הסכום של כל מרכיב הדרוש כדי להכין 1.5 μl הסרת תערובת לתגובה יחידה מופיע בלוח 6; המתכון צריך להיות בקנה מידה גדול בהתאם למספר מבחני שיש לבצע. </li><li style=";text-align:right;direction:rtl"> לסיים תגובות על ידי הוספת 1.5 μl של תמהיל הסרת. מערבבים היטב, ספין למטה, ולדגור על 30 מעלות צלזיוס במשך 30 דקות נוספות. </li><li style=";text-align:right;direction:rtl"> בינתיים, לפני לרוץ ג&#39;ל polyacrylamide הילידים ביחידת אלקטרופורזה אנכית ב100 V ל30 דקות ב 4 ° C, באמצעות TBE 0.5x כחיץ פועל עם בר ומערבב מגנטי בתוך החדר התחתון כדי לשמור על זרימת דם למאגר קבועה. </li><li style=";text-align:right;direction:rtl"> כדי לטעון את המדגם, להוסיף 2.5 μl של טעינת צבע המכיל 3x TBE, גליצרול 30%, 0.25% כחול bromophenol, ו0.25% Cyanol FF קסילן. מערבבים היטב, ספין בקצרה הדגימות, ולהעמיס אותו על ג&#39;ל באמצעות עצות לטעינה. </li><li style=";text-align:right;direction:rtl"> הפעל את הג&#39;ל על 200 V ל4.5 שעות על 4 מעלות צלזיוס עם זרימת חיץ.</li><li style=";text-align:right;direction:rtl"> כדי לזהות את האות, להעביר את הג&#39;ל לערימה של שני גיליונות של נייר סינון. לעטוף את נייר הסינון עם ג&#39;ל על גבי באמצעות ניילון נצמד ברור, ולאחר מכן לחשוף אותו למסך זרחן האחסון ב 4 מעלות צלזיוס למשך הזמן הרצוי. </li><li style=";text-align:right;direction:rtl"> סרוק את המסך עם מערכת סורק הדמיה איזוטופ ולנתח את הנתונים באמצעות תוכנה מתאימה. </li></ol></li></ol> 2 מבחני כריכת Mononucleosome לassay הזיקה המחייבת של מורכב INO80 ניתנו לmononucleosomes, לבצע Shift electrophoretic ניידות Assay (Emsa) באמצעות מצע mononucleosomal שנוצר בשלב 1.2. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> הגדר את תגובת תערובות לכריכה מבחני כפי שתואר עבור מבחני שיפוץ הנוקלאוזום אבל להשמיט ATP ותמהיל הסרת מהתגובות; לדגור על 30 מעלות צלזיוס במשך 30 דקות. </li><li style=";text-align:right;direction:rtl"> הוסף 2.5 μl של טעינת צבע לכל תערובת תגובה, ותחול על ג&#39;ל polyacrylamide ילידים המכיל 3.5 acrylamide% (acrylamide: bis 31), 1% גליצרול, TBE 0.5x, APS 0.01%, ו0.001% TEMED: 7.5. </li><li style=";text-align:right;direction:rtl"> באמצעות TBE 0.5x כחיץ פועל, הפעל את הג&#39;ל על 200 V ל2.5 שעה על 4 מעלות צלזיוס עם זרימת חיץ ולחשוף למסך זרחן האחסון. </li></ol> .3 דנ&quot;א והנוקלאוזום תלוי מבחני ATPase לבצע מבחני ATPase בתערובות תגובת 5 μl מכילות 20 מ&quot;מ טריס-HCl (pH 7.5), 60 mM NaCl, 6.6 מ&quot;מ MgCl 2, 0.8 mM EDTA, 0.015% Nonidet P-40, גליצרול 2.5%, 0.1 מ&quot;ג / מ&quot;ל BSA, 1 מ&quot;מ DTT, 0.1 מ&quot;מ PMSF, 2 מ&quot;מ ATP, 2 μCi של [P 32 α-] ATP (3,000 Ci / mmol). עבור כל מורכב INO80 או כמות מורכבת INO80 להיות assayed הקים שלוש תגובות מקבילות, חיץ EB100 מכיל אחד למדוד דנ&quot;א או הנוקלאוזום עצמאי ATPase, אחד מכיל סגורות פלסמיד דנ&quot;א העגול (נ&quot;ב 5,000, ~ 30 ננומטר) כדי למדוד דנ&quot;א ATPase תלוי, ואחד המכיל oligonucleosomes הלה (~ 185 ננומטר) כדי למדוד ATPase הנוקלאוזום תלוי. הגדר את כל התגובות על קרח. <ol&gt; <li style=";text-align:right;direction:rtl"> עבור כל תגובה, לשלב 10-50 ננומטר של subcomplexes INO80 או INO80 immunopurified עם סכום של חיץ EB100 מספיק כדי לתת נפח של 2.2 μl ב1.5 מ&quot;ל צינורות microcentrifuge משומן מראש צונן. מייד מחדש להקפיא כל שברים המכיל INO80 בקרח יבש אבקה או חנקן נוזלי. </li><li style=";text-align:right;direction:rtl"> הגדר את הקוקטייל שני. הסכום של כל מרכיב הנחוץ לתגובה יחידה מופיע בלוח 7. בהיקף של עד המתכון לפי קנה מידה על ידי גורם של 3 (X + 2) +1, כאשר X = מספר הכנות INO80 להיות assayed. </li><li style=";text-align:right;direction:rtl"> כדי להכין מאגר המכיל &#39;משנה הקוקטיילים&#39; בלבד, DNA, או nucleosomes, לוותר 2.5 (X + 2) μl של קוקטייל האב לשלושה צינורות נפרדים. הוספת 0.3 (X + 2) μl של שתי EB100, DNA הסגור המעגלי פלסמיד (1.5 מיקרוגרם / μl), או (1.5 מיקרוגרם / μl) oligonucleosomes הלה ומערבבים היטב. </li><li style=";text-align:right;direction:rtl"> לוותר 2.8 μl של תת הקוקטייל המתאים לצינורות תגובה המכיל אנזים שהוקמו בstep 3.1. פיפטה בעדינות מעלה ומטה כדי לערבב; למנוע החדרת בועות. </li><li style=";text-align:right;direction:rtl"> כדי להתחיל את תגובות, להעביר את צינורות תגובה לגוש חום C 30 מעלות. </li><li style=";text-align:right;direction:rtl"> לאחר 5, 15, 30, ו60 דקות של דגירה, לזהות 0.5 μl של כל תערובת תגובה על כרומטוגרפיה שכבה דקה polyethyleneimine תאית צלחת (TLC) (20 x 10 סנטימטר) בקו ישר לפחות 1.5 ס&quot;מ מהקצה התחתון . מייד לחזור צינורות תגובה לגוש חום C 30 מעלות ניתן לקחת נקודות זמן כל כך רבות מצינור אחד. אחרי שהבחנתי ב, לייבש את צלחות TLC באמצעות מכת מייבש. </li><li style=";text-align:right;direction:rtl"> העבר את צלחות TLC לתא זכוכית המכיל מספיק פוספט 0.375 M אשלגן (pH 3.5) כדי לאפשר 0.5 סנטימטר תחתית צלחת TLC להיות שקוע בפתרון. </li><li style=";text-align:right;direction:rtl"> כסה את התא, ולפתח עד החלק הקדמי של השלב הנוזלי מגיע העליון של צלחות TLC. מיידי לייבש את הצלחות באמצעות מכת מייבש ביסודיות. </li><li style=";text-align:right;direction:rtl"> לחשוף את צלחות TLC המיובשים למסך זרחני אחסון ב RT.סרוק את המסך עם מערכת סורק הדמיה איזוטופ ולקבוע את סכום מצע ATP רדיואקטיבי לבין מוצר ADP. </li><li style=";text-align:right;direction:rtl"> כדי לחשב את הסכום של ATP הידרוליזה, להכפיל את ATP% הידרוליזה על ידי הכמות של הווה ATP בתערובת התגובה החל שימוש בנוסחה הבאה: ATP pmol הידרוליזה ATP pmol = 10 במתחילים x תגובה [ADP / (ATP + ADP)] </li></ol>

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D., Thastrom, A., Widom, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+access+of+proteins+to+buried+nucleosomal+DNA+target+sites+occurs+via+a+mechanism+that+is+distinct+from+nucleosome+translocation,+Mol.Cell+Biol.">Spontaneous access of proteins to buried nucleosomal DNA target sites occurs via a mechanism that is distinct from nucleosome translocation, Mol.Cell Biol.</a> 22 (20), 7147-7157 (2002).</li><li>Saha, A., Wittmeyer, J., Cairns, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+remodeling+through+directional+DNA+translocation+from+an+internal+nucleosomal+site.">Chromatin remodeling through directional DNA translocation from an internal nucleosomal site.</a> Nature Structural and Molecular Biology. 12 (9), 747-755 (2005).</li><li>Gottschalk, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(ADP-ribosyl)ation+directs+recruitment+and+activation+of+an+ATP-dependent+chromatin+remodeler,+Proc.Natl.Acad.Sci.U.S.A.">Poly(ADP-ribosyl)ation directs recruitment and activation of an ATP-dependent chromatin remodeler, Proc.Natl.Acad.Sci.U.S.A.</a> 106 (33), 13770-13774 (2009).</li><li>Clapier, C. R., Cairns, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+ISWI+involves+inhibitory+modules+antagonized+by+nucleosomal+epitopes.">Regulation of ISWI involves inhibitory modules antagonized by nucleosomal epitopes.</a> Nature. 492 (7428), 280-284 (2012).</li><li>Brune, M., Hunter, J. L., Corrie, J. E. T., Direct Webb, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-Time+Measurement+of+Rapid+Inorganic+Phosphate+Release+Using+a+Novel+Fluorescent+Probe+and+Its+Application+to+Actomyosin+Subfragment+1+ATPase,+Biochemistry.">Real-Time Measurement of Rapid Inorganic Phosphate Release Using a Novel Fluorescent Probe and Its Application to Actomyosin Subfragment 1 ATPase, Biochemistry.</a> 33 (27), 8262-8271 (1994).</li><li>Luk, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stepwise+histone+replacement+by+SWR1+requires+dual+activation+with+histone+H2A.Z+and+canonical+nucleosome.">Stepwise histone replacement by SWR1 requires dual activation with histone H2A.Z and canonical nucleosome.</a> Cell. 143 (5), 725-736 (2010).</li></ol>

The authors declare that they have no competing financial interests.

כדי להבטיח ששיפוץ הנוקלאוזום ופעילויות ATPase שאנו רואים במבחנים תלויים בפעילות הקטליטית של מתחמי INO80, ולא על זיהום ו / או אנזימי ATPase שיפוץ, אנו הנוקלאוזום באופן שגרתי assay שיפוץ ופעילות ATPase של גרסאות כקטליזאטור פעילים של מתחמי INO80, מטוהר ב במקביל עם הסוג בר INO80 תוך שימוש ב?...

מתחמי שיפוץ הכרומטין משפחת SNF2 כוללים מקטע ATPase מרכזי כמו SNF2-1,2. פונקציה מסוימת כמו SNF2-ATPases כאנזימים למקטע אחד, בעוד שאחרים לתפקד כמקטע קטליטי של מתחמים רב למקטע גדולים יותר. הבהרת המנגנונים המולקולריים שבאמצעותו כל אחד מיחידות המשנה של הכרומטין מתחמי שיפוץ לתרום לפעילויות שלהם דורש את היכולת לבצע מבחני ביוכימיים שלנתח את תהליך שיפוץ. שיפוץ הנוקלאוזום תלוי ATP על ידי מורכב INO80 האנושי ואנזימי הכרומטין שיפוץ אחרים יכול להיות שחזה כתהליך רב שלבים שמתחיל בכריכה של אנזים שיפוץ לnucleosomes, ואחרי הפעלה של דנ&quot;א ו / או ATPase הנוקלאוזום תלוי, טרנסלוקציה של אנזים שיפוץ על DNA nucleosomal, ומיצוב מחדש סופו של הדבר nucleosomes 1,2. הבנת הפרטים המולקולריים של r תהליך שיפוץ הכרומטין תלוי ATPequires נתיחה של תגובת שיפוץ לשלבים הבודדים שלה והגדרתה של תרומתם של יחידות משנה נפרדות של מתחם שיפוץ הכרומטין לכל צעד של התגובה. ניתוח מסוג זה דורש היכולת לנתח שיפוץ הנוקלאוזום ופעילויות אחרות באמצעות מצעים מולקולריים מוגדרים במבחנה. בפרוטוקול יופיטר קודם, שתארנו תהליכים המשמשים ליצירת מתחמי INO80 שיפוץ הכרומטין וsubcomplexes עם יצירות למקטע מוגדרים 3. כאן, אנו מציגים שלושה מבחני ביוכימיים שיאפשר ניתוח כמותי של הנוקלאוזום המחייב, דנ&quot;א וATPase מופעל הנוקלאוזום, ופעילויות שיפוץ הנוקלאוזום הקשורים למתחמים כאלה.

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biochemical assays for analyzing activities of atp-dependent chromatin remodeling enzymes

Members of the SNF2 family of ATPases often function as components of multi-subunit chromatin remodeling complexes that regulate nucleosome dynamics and DNA accessibility by catalyzing ATP-dependent nucleosome remodeling. Biochemically dissecting the contributions of individual subunits of such complexes to the multi-step ATP-dependent chromatin remodeling reaction requires the use of assays that monitor the production of reaction products and measure the formation of reaction intermediates. This JOVE protocol describes assays that allow one to measure the biochemical activities of chromatin remodeling complexes or subcomplexes containing various combinations of subunits. Chromatin remodeling is measured using an ATP-dependent nucleosome sliding assay, which monitors the movement of a nucleosome on a DNA molecule using an electrophoretic mobility shift assay (EMSA)-based method. Nucleosome binding activity is measured by monitoring the formation of remodeling complex-bound mononucleosomes using a similar EMSA-based method, and DNA- or nucleosome-dependent ATPase activity is assayed using thin layer chromatography (TLC) to measure the rate of conversion of ATP to ADP and phosphate in the presence of either DNA or nucleosomes. Using these assays, one can examine the functions of subunits of a chromatin remodeling complex by comparing the activities of the complete complex to those lacking one or more subunits. The human INO80 chromatin remodeling complex is used as an example; however, the methods described here can be adapted to the study of other chromatin remodeling complexes.

הנתונים מראים תוצאות נציג של מבחני ביוכימיים משמשים כדי לאפיין פעילויות INO80, כוללים הנוקלאוזום הזזה (איור 1) ומחייב (איור 2) מבחני ודנ&quot;א או מבחני הנוקלאוזום תלוי ATPase (איור 3). הניסוי שמוצג באיור 1</stro...

Watch this Scientific Journal Video about Biochemical Assays for Analyzing Activities of ATP-dependent Chromatin Remodeling Enzymes at JoVE.com

Biochemical Assays for Analyzing Activities of ATP-dependent Chromatin Remodeling Enzymes

Here we describe biochemical assays that can be used to characterize ATP-dependent chromatin remodeling enzymes for their abilities to 1) catalyze ATP-dependent nucleosome sliding, 2) engage with nucleosome substrates, and 3) hydrolyze ATP in a nucleosome- or DNA-dependent manner.

מבחני ביוכימיים לניתוח פעילויות של ATP תלוי הכרומטין שיפוץ אנזימים

Members of the SNF2 family of ATPases often function as components of multi-subunit chromatin remodeling complexes that regulate nucleosome dynamics and ...

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14.7K Views.  Stowers Institute for Medical Research. Here we describe biochemical assays that can be used to characterize ATP-dependent chromatin remodeling enzymes for their abilities to 1) catalyze ATP-dependent nucleosome sliding, 2) engage with nucleosome substrates, and 3) hydrolyze ATP in a nucleosome- or DNA-dependent manner.

Video: Biochemical Assays for Analyzing Activities of ATP-dependent Chromatin Remodeling Enzymes

A Chromatin Assay for Human Brain Tissue

Chronic neuropsychiatric illnesses such as schizophrenia, bipolar disease and autism are thought to result from a combination of genetic and environmental factors that might result in epigenetic alterations of gene expression and other molecular pathology. Traditionally, however, expression studies in postmortem brain were confined to quantification of mRNA or protein. The limitations encountered in postmortem brain research   such as variabilities in autolysis time and tissue integrities   are also likely to impact any studies of higher order chromatin structures. However, the nucleosomal organization of genomic DNA   including DNA:core histone binding - appears to be largely preserved in representative samples provided by various brain banks. Therefore, it is possible to study the methylation pattern and other covalent modifications of the core histones at defined genomic loci in postmortem brain. Here, we present a simplified native chromatin immunoprecipitation (NChIP) protocol for frozen (never-fixed) human brain specimens. Starting with micrococcal nuclease digestion of brain homogenates, NChIP followed by qPCR can be completed within three days. The methodology presented here should be useful to elucidate epigenetic mechanisms of gene expression in normal and diseased human brain.

Until recently, expression studies on human brain were limited to quantification of RNA or protein. With the chromatin immunoprecipitation techniques described in this paper, it will be possible to map histone methylation and other epigenetic regulators of gene expression in postmortem brain.

Assay הכרומטין של רקמת מוח האדם

Chronic neuropsychiatric illnesses such as schizophrenia, bipolar disease and autism are thought to result from a combination of genetic and environmental ...

Zebrafish Brain Ventricle Injection

Proper brain ventricle formation during embryonic brain development is required for normal brain function.  Brain ventricles are the highly conserved cavities within the brain that are filled with cerebrospinal fluid.  In zebrafish, after neural tube formation, the neuroepithelium undergoes a series of constrictions and folds while it fills with fluid resulting in brain ventricle formation.  In order to understand the process of ventricle formation, and the neuroepithelial shape changes that occur at the same time, we needed a way to visualize the ventricle space in comparison to the brain tissue.  However, the nature of transparent zebrafish embryos makes it difficult to differentiate the tissue from the ventricle space.  Therefore, we developed a brain ventricle injection technique where the ventricle space is filled with a fluorescent dye and imaged by brightfield and fluorescent microscopy.  The brightfield and the fluorescent images are then processed and superimposed in Photoshop.  This technique allows for visualization of the ventricle space with the fluorescent dye, in comparison to the shape of the neuroepithelium in the brightfield image.  Brain ventricle injection in zebrafish can be employed from 18 hours post fertilization through early larval stages.  We have used this technique extensively in our studies of brain ventricle formation and morphogenesis as well as in characterizing brain morphogenesis mutants (1-3).

After neural tube formation, the neuroepithelium constricts and folds while the tube fills with embryonic cerebrospinal fluid (eCSF) to form the embryonic brain ventricles. We developed this ventricle injection technique to better visualize the fluid filled space in contrast to the neuroepithelial shape in a live embryo.

החדר דג הזברה המוח Injection

Proper brain ventricle formation during embryonic brain development is required for normal brain function.  Brain ventricles are the highly conserved ...

Photobleaching Assays (FRAP &amp; FLIP) to Measure Chromatin Protein Dynamics in Living Embryonic Stem Cells

Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Loss In Photobleaching (FLIP) enable the study of protein dynamics in living cells with good spatial and temporal resolution. Here we describe how to perform FRAP and FLIP assays of chromatin proteins, including H1 and HP1, in mouse embryonic stem (ES) cells. In a FRAP experiment, cells are transfected, either transiently or stably, with a protein of interest fused with the green fluorescent protein (GFP) or derivatives thereof (YFP, CFP, Cherry, etc.). In the transfected, fluorescing cells, an intense focused laser beam bleaches a relatively small region of interest (ROI). The laser wavelength is selected according to the fluorescent protein used for fusion. The laser light irreversibly bleaches the fluorescent signal of molecules in the ROI and, immediately following bleaching, the recovery of the fluorescent signal in the bleached area - mediated by the replacement of the bleached molecules with the unbleached molecules - is monitored using time lapse imaging. The generated fluorescence recovery curves provide information on the protein's mobility. If the fluorescent molecules are immobile, no fluorescence recovery will be observed. In a complementary approach, Fluorescence Loss in Photobleaching (FLIP), the laser beam bleaches the same spot repeatedly and the signal intensity is measured elsewhere in the fluorescing cell. FLIP experiments therefore measure signal decay rather than fluorescence recovery and are useful to determine protein mobility as well as protein shuttling between cellular compartments. Transient binding is a common property of chromatin-associated proteins. Although the major fraction of each chromatin protein is bound to chromatin at any given moment at steady state, the binding is transient and most chromatin proteins have a high turnover on chromatin, with a residence time in the order of seconds. These properties are crucial for generating high plasticity in genome expression1. Photobleaching experiments are therefore particularly useful to determine chromatin plasticity using GFP-fusion versions of chromatin structural proteins, especially in ES cells, where the dynamic exchange of chromatin proteins (including heterochromatin protein 1 (HP1), linker histone H1 and core histones) is higher than in differentiated cells2,3.

Photobleaching Assays FRAP &amp; FLIP to Measure Chromatin Protein Dynamics in Living Embryonic Stem Cells

We describe photobleaching methods including Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Loss In Photobleaching (FLIP) to monitor chromatin protein dynamics in embryonic stem (ES) cells. Chromatin protein dynamics, which is considered to be one of the means to study chromatin plasticity, is enhanced in pluripotent cells.

מבחני photobleaching (FRAP &amp; FLIP) כדי למדוד Dynamics חלבון הכרומטין בתוך החיים בתאי גזע עובריים

Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Loss In Photobleaching (FLIP) enable the study of protein dynamics in living cells with ...

Quantitative Comparison of cis-Regulatory Element (CRE) Activities in Transgenic Drosophila melanogaster

Gene expression patterns are specified by cis-regulatory element (CRE) sequences, which are also called enhancers or cis-regulatory modules. A typical CRE possesses an arrangement of binding sites for several transcription factor proteins that confer a regulatory logic specifying when, where, and at what level the regulated gene(s) is expressed. The full set of CREs within an animal genome encodes the organism&prime;s program for development1, and empirical as well as theoretical studies indicate that mutations in CREs played a prominent role in morphological evolution2-4. Moreover, human genome wide association studies indicate that genetic variation in CREs contribute substantially to phenotypic variation5,6. Thus, understanding regulatory logic and how mutations affect such logic is a central goal of genetics. 
Reporter transgenes provide a powerful method to study the in vivo function of CREs. Here a known or suspected CRE sequence is coupled to heterologous promoter and coding sequences for a reporter gene encoding an easily observable protein product. When a reporter transgene is inserted into a host organism, the CRE&prime;s activity becomes visible in the form of the encoded reporter protein. P-element mediated transgenesis in the fruit fly species Drosophila (D.) melanogaster7 has been used for decades to introduce reporter transgenes into this model organism, though the genomic placement of transgenes is random. Hence, reporter gene activity is strongly influenced by the local chromatin and gene environment, limiting CRE comparisons to being qualitative. In recent years, the phiC31 based integration system was adapted for use in D. melanogaster to insert transgenes into specific genome landing sites8-10. This capability has made the quantitative measurement of gene and, relevant here, CRE activity11-13 feasible. The production of transgenic fruit flies can be outsourced, including phiC31-based integration, eliminating the need to purchase expensive equipment and/or have proficiency at specialized transgene injection protocols. 
Here, we present a general protocol to quantitatively evaluate a CRE&prime;s activity, and show how this approach can be used to measure the effects of an introduced mutation on a CRE&prime;s activity and to compare the activities of orthologous CREs. Although the examples given are for a CRE active during fruit fly metamorphosis, the approach can be applied to other developmental stages, fruit fly species, or model organisms. Ultimately, a more widespread use of this approach to study CREs should advance an understanding of regulatory logic and how logic can vary and evolve.

Quantitative Comparison of cis-Regulatory Element CRE Activities in Transgenic Drosophila melanogaster

Phenotypic variation for traits can result from mutations in cis-regulatory element (CRE) sequences that control gene expression patterns. Methods derived for use in Drosophila melanogaster can quantitatively compare the levels of spatial and temporal patterns of gene expression mediated by modified or naturally occurring CRE variants.

השוואה כמותית של Cis-רגולטוריות (Cre) אלמנט פעילות טראנסגנטי תסיסנית melanogaster</em

Gene expression patterns are specified by cis-regulatory element (CRE) sequences, which are also called enhancers or cis-regulatory modules. A typical CRE ...

Blood Collection for Biochemical Analysis in Adult Zebrafish

The zebrafish has been used as an animal model for studies of several human diseases. It can serve as a powerful preclinical platform for studies of molecular events and therapeutic strategies as well as for evaluating the physiological mechanisms of some pathologies1. 
There are relatively few publications related to adult zebrafish physiology of organs and systems2, which may lead researchers to infer that the basic techniques needed to allow the exploration of zebrafish systems are lacking3. Hematologic biochemical values of zebrafish were first reported in 2003 by Murtha and colleagues4 who employed a blood collection technique first described by Jagadeeswaran and colleagues in 1999. Briefly, blood was collected via a micropipette tip through a lateral incision, approximately 0.3 cm in length, in the region of the dorsal aorta5. Because of the minute dimensions involved, this is a high-precision technique requiring a highly skilled practitioner. The same technique was used by the same group in another publication in that same year6. In 2010, Eames and colleagues assessed whole blood glucose levels in zebrafish7. They gained access to the blood by performing decapitations with scissors and then inserting a heparinized microcapillary collection tube into the pectoral articulation. They mention difficulties with hemolysis that were solved with an appropriate storage temperature based on the work Kilpatrick et al.8. When attempting to use Jagadeeswaran's technique in our laboratory, we found that it was difficult to make the incision in precisely the right place as not to allow a significant amount of blood to be lost before collection could be started. 
Recently, Gupta et al.9 described how to dissect adult zebrafish organs, Kinkle et al.10 described how to perform intraperitoneal injections, and Pugach et al.11 described how to perform retro-orbital injections. However, more work is needed to more fully explore basic techniques for research in zebrafish.
The small size of zebrafish presents challenges for researchers using it as an experimental model. Furthermore, given this smallness of scale, it is important that simple techniques are developed to enable researchers to explore the advantages of the zebrafish model.

This paper presents a technique for collection of blood from the dorsal aorta of Zebrafish. It also provides instructions for obtaining serum for use in biochemical analyses, such as tests for determining cholesterol and triglyceride levels.

הדם אוסף של ניתוח ביוכימי דג הזברה למבוגרים בלבד

The zebrafish has been used as an animal model for studies of several human diseases. It can serve as a powerful preclinical platform for studies of ...

Biochemical and High Throughput Microscopic Assessment of Fat Mass in Caenorhabditis Elegans

The nematode C. elegans has emerged as an important model for the study of conserved genetic pathways regulating fat metabolism as it relates to human obesity and its associated pathologies. Several previous methodologies developed for the visualization of C. elegans triglyceride-rich fat stores have proven to be erroneous, highlighting cellular compartments other than lipid droplets. Other methods require specialized equipment, are time-consuming, or yield inconsistent results. We introduce a rapid, reproducible, fixative-based Nile red staining method for the accurate and rapid detection of neutral lipid droplets in C. elegans. A short fixation step in 40% isopropanol makes animals completely permeable to Nile red, which is then used to stain animals. Spectral properties of this lipophilic dye allow it to strongly and selectively fluoresce in the yellow-green spectrum only when in a lipid-rich environment, but not in more polar environments. Thus, lipid droplets can be visualized on a fluorescent microscope equipped with simple GFP imaging capability after only a brief Nile red staining step in isopropanol. The speed, affordability, and reproducibility of this protocol make it ideally suited for high throughput screens. We also demonstrate a paired method for the biochemical determination of triglycerides and phospholipids using gas chromatography mass-spectrometry. This more rigorous protocol should be used as confirmation of results obtained from the Nile red microscopic lipid determination. We anticipate that these techniques will become new standards in the field of C. elegans metabolic research.

Biochemical and High Throughput Microscopic Assessment of Fat Mass in Caenorhabditis Elegans

We present robust biochemical and microscopic methods for studying Caenorhabditis elegans lipid stores. A rapid, simple, fixing-staining procedure for fluorescent lipid droplet imaging leverages the spectral properties of the lipophilic dye Nile red. We then present biochemical measurement of triglycerides and phospholipids using solid phase extraction and gas chromatography-mass spectrometry.

הערכה ביוכימית ותפוקה גבוהה מיקרוסקופית של מסת שומן ב<em&gt; Elegans Caenorhabditis</em

The nematode C. elegans has emerged as an important  model for the study of conserved genetic pathways regulating fat metabolism as  it relates to human ...

Biochemical Titration of Glycogen In vitro

Glycogen is the main energetic polymer of glucose in vertebrate animals and plays a crucial role in whole body metabolism as well as in cellular metabolism. Many methods to detect glycogen already exist but only a few are quantitative. We describe here a method using the Abcam Glycogen assay kit, which is based on specific degradation of glycogen to glucose by glucoamylase. Glucose is then specifically oxidized to a product that reacts with the OxiRed probe to produce fluorescence. Titration is accurate, sensitive and can be achieved on cell extracts or tissue sections. However, in contrast to other techniques, it does not give information about the distribution of glycogen in the cell. As an example of this technique, we describe here the titration of glycogen in two cell lines, Chinese hamster lung fibroblast CCL39 and human colon carcinoma LS174, incubated in normoxia (21% O2) versus hypoxia (1% O2). We hypothesized that hypoxia is a signal that prepares cells to synthesize and store glycogen in order to survive1.

Biochemical Titration of Glycogen In vitro

We describe here an accurate, reproducible and convenient biochemical method for titration of glycogen in vitro. This technique uses the Abcam Glycogen assay kit and is based on successive hydrolysis of glycogen to glucose and glucose titration by fluorescence.

כותרות ביוכימית של גליקוגן<em&gt; במבחנה</em

Glycogen is the main energetic polymer of glucose in vertebrate animals and plays a crucial role in whole body metabolism as well as in cellular ...

Generation and Purification of Human INO80 Chromatin Remodeling Complexes and Subcomplexes

INO80 chromatin remodeling complexes regulate nucleosome dynamics and DNA accessibility by catalyzing ATP-dependent nucleosome remodeling. Human INO80 complexes consist of 14 protein subunits including Ino80, a SNF2-like ATPase, which serves both as the catalytic subunit and the scaffold for assembly of the complexes. Functions of the other subunits and the mechanisms by which they contribute to the INO80 complex&#39;s chromatin remodeling activity remain poorly understood, in part due to the challenge of generating INO80 subassemblies in human cells or heterologous expression systems. This JOVE protocol describes a procedure that allows purification of human INO80 chromatin remodeling subcomplexes that are lacking a subunit or a subset of subunits. N-terminally FLAG epitope tagged Ino80 cDNA are stably introduced into human embryonic kidney (HEK) 293 cell lines using Flp-mediated recombination. In the event that a subset of subunits of the INO80 complex is to be deleted, one expresses instead mutant Ino80 proteins that lack the platform needed for assembly of those subunits. In the event an individual subunit is to be depleted, one transfects siRNAs targeting this subunit into an HEK 293 cell line stably expressing FLAG tagged Ino80 ATPase. Nuclear extracts are prepared, and FLAG immunoprecipitation is performed to enrich protein fractions containing Ino80 derivatives. The compositions of purified INO80 subcomplexes can then be analyzed using methods such as immunoblotting, silver staining, and mass spectrometry. The INO80 and INO80 subcomplexes generated according to this protocol can be further analyzed using various biochemical assays, which are described in the accompanying JOVE protocol. The methods described here can be adapted for studies of the structural and functional properties of any mammalian multi-subunit chromatin remodeling and modifying complexes.

This protocol describes a procedure for generating and purifying wild type and mutant versions of the human INO80 chromatin remodeling complex. Epitope tagged versions of INO80 subunits are stably expressed in HEK293 cells, and complete complexes and complexes lacking specific sets of subunits are purified by immunoaffinity chromatography.

דור וטיהור של מכלולי אדם INO80 הכרומטין שיפוץ וSubcomplexes

INO80 chromatin remodeling complexes regulate nucleosome dynamics and DNA accessibility by catalyzing ATP-dependent nucleosome remodeling. Human INO80 ...

Isolation of Specific Genomic Regions and Identification of Associated Molecules by enChIP

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. To enable the non-biased identification of molecules interacting with a specific genomic region of interest, we recently developed the engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) technique. Here, we describe how to use enChIP to isolate specific genomic regions and identify the associated proteins and RNAs. First, a genomic region of interest is tagged with a transcription activator-like (TAL) protein or a clustered regularly interspaced short palindromic repeats (CRISPR) complex consisting of a catalytically inactive form of Cas9 and a guide RNA. Subsequently, the chromatin is crosslinked and fragmented by sonication. The tagged locus is then immunoprecipitated and the crosslinking is reversed. Finally, the proteins or RNAs that are associated with the isolated chromatin are subjected to mass spectrometric or RNA sequencing analyses, respectively. This approach allows the successful identification of proteins and RNAs associated with a genomic region of interest.

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. This protocol describes procedures to perform engineered DNA-binding molecule-mediated chromatin imunoprecipitation (enChIP) for identification of proteins and RNAs associated with a specific genomic region.

בידוד של אזורים הגנומי ספציפיים וזיהוי של Associated מולקולות על ידי enChIP

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

הגברה, רצף הדור הבא, ואת הגנום מיפוי ה- DNA של אתרי אינטגרצית retroviral

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...