I-amino acids zizinto ezisisiseko zeeprotheni kunye neengxenye ezibalulekileyo zezicubu zomntu, zidlala indima yokutshintshwa kwesignali yeseli, ukulawulwa komsebenzi we-enzyme, umsebenzi wokuzivikela komzimba kunye neminye imisebenzi yomzimba.

Ubuninzi bee-amino acids kwiiseli zihlala zitshintsha kwiimeko ezahlukeneyo ze-physiological and pathological. Ke ngoko, indlela umzimba oluva ngayo utshintsho lwenqanaba le-amino acid kwaye wenze impendulo eguquguqukayo yingxaki ebalulekileyo yesayensi yoxinzelelo lwe-metabolic kunye nekamva leseli.

Ukuziva okungaqhelekanga kwe-amino acid kuhambelana ngokusondeleyo nomhlaza, isifo seswekile, izifo ze-neurodeergenerative kunye nenkqubo yokuguga. Ke ngoko, ukuphonononga indlela yeemolekyuli zokungeniswa kwe-amino acid engaqhelekanga kunokubonelela ngethagethi entsha yokuthintela okanye unyango lwezifo ze-metabolic kunye nomhlaza. I-Valine, njenge-amino acid eyimfuneko ye-branched-chain, idlala indima ebalulekileyo kwi-protein synthesis, neurobehavior, kunye ne-leukemia progression. Nangona kunjalo, indlela kunye nomsebenzi we-cell sensing ye-valine ihlala ingacacanga.

Ngomhla wama-20 kaNovemba ka-2024, iqela likaWang Ping elisuka kwiYunivesithi yaseTongji yeSibhedlele sezoNyango / iSibhedlele se-10 esiManyeneyo saBantu sapapasha iphepha lophando elinesihloko esithi "Umntu HDAC6 uva ubuninzi bevaline yokulawula umonakalo weDNA" kwiphephancwadi leNdalo.

Olu phononongo luchonge i-valine-specific sensor, i-deacetylase ye-HDAC6 yabantu, kwaye iveze indlela ethile apho uthintelo lwe-valine lukhokelela ekufudusweni kwe-nuclear ye-HDAC6, ngaloo ndlela iphucula umsebenzi we-TET2 kunye nokubangela umonakalo we-DNA.

Okubangela umdla kukuba, le ndlela yokuziva yodwa kwiiprimates, kwaye olunye uhlalutyo lwendlela lubonise ukuba iprimate HDAC6 iqulethe i-serine-rich glutamate-tetranectide (SE14) ephinda isizinda kunye neemvakalelo zobuninzi be-valine ngalo mmandla. Ngokumalunga nonyango lwe-tumor, uthintelo oluphakathi lwe-valine okanye indibaniselwano ye-PARP inhibitors inokuthintela ngokufanelekileyo ukukhula kwethumba.

Olu phononongo lubonisa indlela inoveli apho uxinzelelo lwesondlo lulawula umonakalo we-DNA ngokuguqulwa kwe-epigenetic, kwaye iphakamisa isicwangciso esinoveli sonyango lwe-tumor kunye nokutya okuthintelweyo kwe-valine kudityaniswe ne-PARP inhibitors.

Izinzwa ze-amino acid ngokuqhelekileyo kufuneka zidibanise i-amino acids ukuze ziqaphele kwaye ziphendule utshintsho kwi-amino acid concentration ngaphakathi nangaphandle kweseli, ukuze zenze umsebenzi wazo wokuva.

Ukuze kuchongwe ngokucwangcisiweyo iiprotheni ezibopha i-valine, i-biotinylated valine probes yasetyenziselwa iimvavanyo ze-immunocoprecipitate ezidityaniswe ne-mass spectrometry, kunye nokuhlolwa okungakhethiyo kweeprotheni ezibophezelayo ze-valine zenziwa nge-biology yekhemikhali.

Ababhali bafumanisa ukuba ngaphezu kwe-valyl tRNA synthetases (VARS) eyaziwayo, i-deacetylase HDAC6 ibonise amandla anamandla okubopha i-D-valine xa kuthelekiswa ne-VARS. Ababhali baqinisekisa ngakumbi ukuba i-HDAC6 inokubopha ngokuthe ngqo i-valine kunye ne-affinity ye-Kd ≈ 2μM ngokusebenzisa imifuniselo yokubopha isotopu, imifuniselo ye-isothermal titration calorimetry (ITC) kunye nemifuniselo ye-thermal drift. Uhlalutyo lweempawu zesakhiwo se-amino acids eziqatshelwe ngokuva iiprotheni kunceda ukuqonda ngakumbi indlela yeemolekyuli zokutshintsha kobuninzi be-amino acid eyenziwa ziiseli. Ngokuhlalutya iimvavanyo ezibophelelayo ze-analogues ze-valine, ababhali bafumanisa ukuba i-HDAC6 iyayibona i-carboxyl terminal kunye nekhonkco yecala le-valine kwaye inokunyamezela ukuguqulwa kwe-amino terminal. Ukongeza, kwiiseli ze-HDAC6 zokunkqonkqoza, ukulawulwa kwendlela yokubonisa i-mTOR ngokuthintelwa kwe-valine kwakungahlukanga kakhulu kwiqela lolawulo, ebonisa ukuba oku kubopha kwakuhluke kwindlela yokubonakalisa i-amino acid yendabuko.

Ukuze uhlolisise i-domain ebalulekileyo kunye nomsebenzi we-valine yokuva i-HDAC6. Ababhali baye bafumanisa ukuba i-HDAC6 ibophelela i-valine nge-domain yayo ye-SE14 nge-HDAC6 yovavanyo lokubopha umzimba oluncitshisiweyo. Okumangalisayo kukuba, ababhali bafumene ngokuthelekisa i-homology ukuba isizinda se-SE14 sikhona kuphela kwi-HDAC6 kwiiprimates. Ngokungafaniyo neprimate (umntu kunye nenkawu) HDAC6, imouse HDAC6 ayibopheleli kwi-valine. Oku kufunyaniswayo kubonakalisa ukungafani phakathi kweentlobo ezahlukeneyo kwi-valine induction, ebonisa ukuba ukuguquka kweentlobo kudlala indima ebalulekileyo kwi-amino acid induction.

Ngokusekelwe kwisigqibo sokuba i-HDAC6 ibophelela ngokuthe ngqo i-valine nge-domain yayo ye-SE14, ababhali bacinge ukuba utshintsho kumandla okubopha i-HDAC6 kunye ne-valine inokuchaphazela isakhiwo kunye nomsebenzi wayo xa ubuninzi be-valine kwiiseli zitshintsha. Ngokusebenzisa uchungechunge lwezilingo kunye nokudibanisa noncwadi kwindima ebalulekileyo ye-SE14 domain kwi-cytoplasmic retention ye-HDAC6, ababhali bafumanisa ukuba ukusilela kwe-valine ye-intracellular kunokubangela ukudluliselwa kwe-HDAC6 kwi-nucleus. Ummandla osebenzayo we-enzyme (i-DAC1 kunye ne-DAC2) ibophelela kummandla osebenzayo (i-CD domain) ye-DNA hydroxymethylase TET2, ukukhuthaza ukuchithwa kwe-TET2, kwaye emva koko isebenze umsebenzi wayo we-enzyme. Ukusebenzisa iindlela ze-methylomics ezifana ne-WGBS, i-ACE-Seq kunye ne-MAB-Seq, saphinda saqinisekisa ukuba indlala ye-valine ye-intracellular inokukhuthaza i-demethylation esebenzayo ye-DNA ngokusebenzisa i-axis ye-HDAC6-TET2 yesignali. Ngaphambili, iqela lika-Andre Nussenzweig lifumene ukuba i-thymine DNA glycosylase (TDG) -ixhomekeke kwi-DNA demethylation esebenzayo yabangela ukuba i-DNA i-single-strand umonakalo kwi-neuronal enhancer. Ngokudibanisa i-TET2 ChIP-Seq kunye ne-high-throughput sequencing technology END-Seq kunye ne-ddC S1 END-Seq, sinqume ukuba ukusilela kwe-valine kukhuthaza umonakalo we-DNA. Umonakalo we-DNA obangelwa kukunqongophala kwe-valine kwakhona kuxhomekeke kumonakalo we-strand eyodwa obangelwa yi-TDG yokukhutshwa kwe-oxymethylcytosine (5fC / 5caC).

Kuthatyathwe kunye, ababhali bafumene i-novel sensors ze-valine kwaye ngokokuqala ngqa bacacisa indlela ye-molecular apho i-valine inqanda ukungeniswa komonakalo we-DNA nge-HDAC6-TET2-TDG yokubonisa i-axis, yongeza ubungakanani obutsha ekuqondeni umsebenzi woxinzelelo lwe-amino acid kwi-cell fate determination.

Ukuthintelwa kokutya okanye ukujoliswa kwe-amino acid metabolism kunye nokuziva kuye kwaba sisicwangciso sokuncedisa ukwandiswa kobomi kunye nokunyangwa kwezifo ezininzi, kuquka umhlaza. Ngenxa yokuba ukuvinjwa kwe-valine kunokubangela umonakalo we-DNA, ababhali baqhubela phambili baphanda ukuba isithintelo se-valine sidlala indima kunyango lomhlaza. Kwimodeli yethumba lomhlaza we-colorectal xenograft, i-valine-restricted diet efanelekileyo (0.41% valine, w/w) ithintele kakhulu ukukhula kwethumba kunye neziphumo ebezingalindelekanga ezimbalwa. Kuwo omabini amaqela othintelo kunye nonyango, ababhali babonisa ngakumbi ukuba ukutya okuthintelweyo kwe-valine kuthintele i-tumorigenesis kunye nokuqhubela phambili kusetyenziswa imodeli yomhlaza we-colorectal PDX. Kwiisampulu ze-tumor, amanqanaba anciphileyo e-valine aye anxulunyaniswa ngokufanelekileyo kunye nokunyuka kwe-HDAC6 yokudluliselwa kwenyukliya, amanqanaba e-5hmC, kunye nomonakalo we-DNA. Ekubeni ukubangela umonakalo we-DNA kunyango lwe-antiticancer, kunokwenzeka ngokweklinikhi ukuvimba ukulungiswa kwe-DNA ngokusebenzisa i-PARP inhibitors. Ababhali bafumanise ukuba indibaniselwano ye-valine-restricted diet kunye ne-PARP inhibitor talazoparib iphucule kakhulu i-antitumor effect, inika ubungqina obuqinileyo kunyango lokunyanga umhlaza ngokubangela umonakalo we-DNA.

Ukuqukumbela, uphononongo lufumene ukuba i-HDAC6 kwiiprimates iyinoveli yeprotein yevaline ezimeleyo kwi-sensing zemveli, iveza umahluko kwi-valine sensing phakathi kweentlobo ezahlukeneyo, ebonisa indima ebalulekileyo ye-biological evolution kwi-amino acid sensing.

Ukongeza, olu phononongo lucacisa indlela entsha yolawulo olusebenzayo loxinzelelo lwe-metabolic yesondlo, ukulawulwa kwe-epigenetic kunye nomonakalo we-DNA, yandisa ukubaluleka koxinzelelo lwezondlo kwi-biology yoxinzelelo, kwaye ifumanisa ukuba indibaniselwano yokutya okuthintelweyo kwe-valine kunye ne-PARP inhibitors ingasetyenziswa njengesicwangciso esitsha sonyango lomhlaza.