Mashandiro anoita insulin receptors
Insulin ihormone yepeptide inoita basa rakakosha mukuchengetedza huwandu hweshuga muropa hwakaenzana uye kudzora metabolism yemacarbohydrate, mafuta, uye mapuroteni. Kuti insulin ishande, inoda "portal" pamusoro pesero inoziva uye inoshandura masaini einsulin kuita mhinduro yemuviri. Iyi port of entry ndiyo insulin receptor. Kunzwisisa mashandiro ekushanda kwe insulin receptor kunobatsira kutsanangura kuti masero anotora sei glucose mushure mekudya, nei huwandu hweshuga muropa huchigona kukwira muchirwere cheshuga, uye kuti insulin resistance inogona kukura sei mumamiriro akasiyana-siyana emetabolism.
Maumbirwo uye Nzvimbo yeInsulin Receptors
Chinotora insulin ndechemhuri ye receptor tyrosine kinase (RTK), inova ma membrane receptors ane tyrosine kinase activity. Chinotora ichi chine mapeya maviri ema subunits: ma subunits maviri e alpha (α) uye ma beta (β) subunits maviri anoumba α2β2 complex. Ma α subunits ari kunze kwesero (extracellular) uye anoshanda kusunga insulin, nepo ma β subunits achipinda mu cell membrane uye aine intracellular domain ine tyrosine kinase activity.
Ma-receptor e-insulin anowanikwa akawanda mumatishu anogamuchira insulin akadai semhasuru dzemapfupa, mafuta, nechiropa. Kuvapo kwema-receptor aya pamusoro pemasero kunoita kuti muviri ugone kupindura huwandu hweinsulin hwakawedzera, semuenzaniso mushure mekudya chikafu chine makabhohaidhiretsi akawanda.
Danho 1: Kusunga Insulin kuReceptor
Maitiro acho anotanga kana insulin inotenderera ichibatana nenzvimbo inosunga insulin ye α subunit. Kusunga uku kwakanangana, zvichireva kuti insulin receptor yakagadzirirwa kuziva insulin ine hukama hwakanyanya. Kana insulin yabatana, receptor inochinja chimiro (conformation). Kuchinja uku kwechimiro "kunomutsa" nzvimbo yemukati yereceptor, iyo β subunit, kuitira kuti receptor igadzirire kutanga kuyerera kwezviratidzo mukati mesero.
Kusunga insulin hakungoshandi se "kiyi" yekuvhura chiratidzo chete, asiwo kunosarudza kusimba kwechiratidzo: kana insulin yakawanda ichisungwa, kusimba kwereceptor, kunyangwe pasi pemamwe mamiriro ezvinhu mhinduro yemasero inogona kuderedzwa nekuda kwekusagona insulin.
Danho rechipiri: Autophosphorylation uye Tyrosine Kinase Activation
Mushure mekunge insulin yabatana, tyrosine kinase domain iri pa β subunit inotanga kushanda. Kushanda uku kunotanga maitiro akakosha anonzi autophosphorylation, umo receptor inozviputira pachayo pa tyrosine amino acid residue. Autophosphorylation inowedzera enzyme ye receptor uye inogadzira "docking site" yemamwe mapuroteni anozotumira chiratidzo.
Kuumbwa kwemasero emuviri (autophosphorylation) kunogona kufungidzirwa sedanho rekuwedzera chiratidzo: receptor, iyo pakutanga yaingogamuchira mameseji kubva ku insulin chete, ikozvino yava puratifomu inoshanda inogona kuunganidza mapuroteni akawanda mukati memasero.
Danho rechitatu: Kutsvaga Varidzi veIRS uye Phosphorylation
Rimwe remapoka makuru emapuroteni anotorwa iInsulin Receptor Substrate (IRS), kunyanya IRS-1 neIRS-2. Mapuroteni eIRS anosunga kune phosphorylated receptor, iyo inobva yaisa phosphorylate IRS pane tyrosine residues. Kana IRS yaiswa phosphorylated, inoshanda seadapta inovhura nzira dzekutumira masaini mukati mesero.
Danho iri rakakosha nekuti mhedzisiro yakawanda yeinsulin—kubva pakutora glucose kusvika pakugadzirwa kweglycogen—inoenderana nekushanda kwenzira dzinoshandiswa neIRS. Kukanganiswa kweIRS phosphorylation imwe yenzira dzinowanzobatanidzwa nekuramba insulin.
Danho rechina: Kushanda kwePI3K–Akt Pathway (Metabolic Pathway)
Nzira inozivikanwa zvikuru yekutumira insulin kumasero iPI3K–Akt. Kana IRS yangoiswa phosphorylated, inotora PI3K (phosphoinositide 3-kinase). PI3K inobva yashandura zvikamu zve membrane lipid (PIP2 kuita PIP3), iyo inoshanda sechiratidzo chekuunganidza mamwe mapuroteni akadai sePDK1 neAkt (protein kinase B).
Akt ndiyo nzvimbo huru inomutsa mhinduro dzakasiyana dzemetabolism, dzinosanganisira:
1. Kutamiswa kweGLUT4
Mutsandanyama dzemapfupa nemafuta, insulin inowedzera kutorwa kweglucose nekufambisa GLUT4 inotakura shuga kubva muma vesicles ari mukati mesero kuenda ku membrane yesero. Kana GLUT4 yakawanda pamusoro, shuga yeropa inopinda nyore nyore musero kuti ishandiswe sesimba kana kuchengetwa.
2. Kugadzirwa kweGlycogen
Mutsandanyama nechiropa, Akt inodzivisa enzyme inodzivisa kuumbwa kweglycogen (kuburikidza neGSK3), nokudaro ichiwedzera basa re glycogen synthase. Nekuda kweizvozvo, glucose inochengetwa se glycogen.
3. Kudziviswa kwegluconeogenesis (kunyanya muchiropa)
Insulin inodzivisa kugadzirwa kweshuga itsva muchiropa nekutonga zvimwe zvinhu zvinoita kuti shuga yeropa isakwire zvakanyanya. Izvi zvinobatsira kudzivirira shuga yeropa kuti isakwire zvakanyanya.
4. Kudzora kushandiswa kwemafuta mumuviri
Insulin inosimudzira kuchengetwa kwemafuta uye inodzivirira kuputsika kwemafuta (lipolysis) mumafuta, zvichibatsira kuderedza kuburitswa kwemafuta emahara muropa.
Danho rechishanu: Kushanda kweRas–MAPK Pathway (Growth Pathway)
Pamusoro pemhedzisiro yayo yemetabolism, insulin receptor inomutsawo nzira dzine chekuita nekukura kwemasero uye kusiyanisa, dzinoti Ras–MAPK. Nzira iyi inowanzobatanidzwa zvakanyanya ne:
- kukura kwemasero,
- kupatsanurana,
- kuratidzwa kwemajini mamwe,
- migumisiro yenguva refu ye insulin pamatishu.
Munzira iyi, IRS kana mamwe mapuroteni eadaptor akadai seShc anogona kumutsa Ras → Raf → MEK → ERK (MAPK) cascade. Kushanda kweERK kunokanganisa nucleus yesero, kuchichinja magene uye mhinduro dzemasero kwenguva refu.
Kuenzana pakati penzira dzePI3K–Akt neRas–MAPK kwakakosha kuti insulin isangodzora huwandu hweglucose chete, asiwo inotsigira mashandiro emasero akajairwa.
Kugumiswa kweChiratidzo: Endocytosis uye Kusanzwa Kwepfungwa
Chiratidzo cheinsulin hachigone kuramba chichishandiswa. Mushure mekunge insulin yabatana uye receptor yashandiswa, insulin-receptor complex inogona kupinda mu endocytosis, iyo iri kudhonzwa musero kuburikidza ne vesicle. Mukati mesero, insulin inogona kusunungurwa uye kuparadzwa, nepo receptor ichigona:
– inodzokororwazve pamusoro pesero, kana
– kuparadzwa kana zvichidikanwa.
Pamusoro pezvo, kune nzira dzinodzivirira zviratidzo kuburikidza ne phosphatases dzinobvisa phosphate kubva ku receptor kana IRS. Mune mamwe mamiriro ezvinhu, IRS phosphorylation pane serine/threonine residues (pane tyrosine) inogona kuderedza kugona kweIRS kutumira zviratidzo, inova imwe yezvikonzero zvikuru zvekusada insulin.
Kuramba kweInsulin muMagariro eReceptors neSignaling
Kusakwanisa kwe insulin kunoitika kana masero asinganyatso teerera insulin, zvichireva kuti inoda insulin yakawanda kuti iite zvakafanana. Maitiro acho anogona kusanganisira:
- huwandu hwema insulin receptors hunoderera (kudzikira kwehuwandu hwe insulin receptors),
- matambudziko e autophosphorylation ye receptor,
- kukanganiswa kweIRS phosphorylation pa tyrosine,
- kuwedzera kwezviratidzo zvekuzvimba uye kushushikana kwe oxidative kunodzivisa nzira yePI3K-Akt,
– kuunganidzwa kwemafuta (lipotoxicity) izvo zvinokanganisa kufambiswa kwemashoko.
Nekuda kweizvozvo, GLUT4 haikwanise kufamba zvakanaka nepakati peganda, kutorwa kweglucose kunodzikira, uye shuga yeropa inowanzo kukwira. Rwatata rinozobhadhara nekugadzira insulin yakawanda, asi nekufamba kwenguva iyi inogona kutadza uye kukura kuita chirwere cheshuga cherudzi rwechipiri.
Mhedziso
Maitiro e insulin receptor anotanga nekusunga insulin ku alpha subunit, zvichiteverwa ne activation ye tyrosine kinase pa beta subunit kuburikidza ne autophosphorylation, uyezve kuunganidzwa kwemapuroteni e IRS anotumira masaini kunzira dzakakosha dzakadai se PI3K–Akt na Ras–MAPK. Nzira ye PI3K–Akt inotonga mhedzisiro ye metabolic ye insulin, kusanganisira GLUT4 translocation uye kuwedzera kuchengetwa kweglucose, nepo nzira ye Ras–MAPK ichiita basa mukukura uye kutonga majini. Chiratidzo che insulin chinozogumiswa kuburikidza ne endocytosis uye desensit mechanisms. Kukanganiswa mune chero chezvikamu izvi kunogona kutungamira mukusagadzikana kwe insulin, inova hwaro hwakakosha hwezvirwere zvakasiyana-siyana zve metabolic zvakaita se type 2 diabetes.
Kana muchida, ndinogona kuwedzera chati iri nyore, pfupiso yepfungwa huru, kana kuibatanidza nemaitiro emishonga yekurwisa chirwere cheshuga inoshanda munzira ye insulin.
