Vpliv somatotropina in inzulinu podobnega rastnega dejavnika-1 na signalno pot JAK-STAT v primarnih človeških skeletnomišičnih celicah

Tretjak, Maja (author), Pirkmajer, Sergej (mentor), Srpčič, Anja (comentor)

Os somatotropina (STH) in inzulinu podobnega rastnega dejavnika-1 (IGF-1) ima ključno vlogo pri uravnavanju rasti, diferenciacije in preživetja skeletnih mišic. Kljub številnim raziskavam signalni mehanizmi osi STH/IGF-1 v človeških skeletnomišičnih celicah še vedno niso popolnoma pojasnjeni, kar otežuje razvoj ciljanih terapevtskih strategij. Skeletne mišice delujejo tudi kot endokrini in presnovni organ, kjer se signalne poti STH/IGF-1 prekrivajo s signalizacijo inzulina in interlevkina-6 (IL-6). Ta preplet signalnih poti vpliva na delovanje mišic ter odpira vprašanja o možnih interferencah v delovanju STH/IGF-1, inzulina in IL-6. Razumevanje razlik v teh signalnih poteh bi lahko omogočilo bolj ciljno usmerjene terapevtske pristope pri boleznih mišic. V okviru magistrske naloge smo preučili učinke STH in IGF-1 na signalno pot JAK/STAT v primarnih človeških skeletnomišičnih celicah ter ocenili vpliv inzulina na signalizacijo IGF-1. Poskuse smo izvedli na primarnih človeških skeletnomišičnih celicah, ki smo jih gojili ter nato diferencirali v večjedrne mišične cevčice. Celice smo s STH ali IGF-1 tretirali različna časovna obdobja. Signalizacijo v celicah smo spremljali z metodo prenos western, s katero smo analizirali fosforilacijo proteinov STAT3, STAT1, Akt in p38 MAPK. Izražanje IGF1 in IGF1R smo določili z metodo kvantitativne verižne reakcije s polimerazo. Rezultate smo predstavili kot povprečje s standardnim odklonom. Naši rezultati niso potrdili vpliva STH/IGF-1 na aktivacijo STAT3 in STAT1 v človeških skeletnomišičnih celicah, kljub temu pa nakazujejo, da so izooblike proteinov STAT različne glede na vrsto organizma in celični tip. Prav tako nismo zaznali vpliva STH na izražanje IGF-1 in njegovega receptorja. Po drugi strani pa rezultati kažejo, da prisotnost inzulina v mediju vpliva na signalne poti, ki jih aktivira IGF-1, kar poudarja pomen skrbne izbire eksperimentalnih pogojev za natančno oceno učinkov IGF-1 na celično signalizacijo. Ugotovitve dodatno potrjujejo, da je za razvoj učinkovitih ciljnih terapij ključnega pomena sočasno upoštevanje učinkov tako inzulina kot IGF-1.

• Language: Slovenian
• Keywords: somatotropin, inzulinu podobni rastni dejavnik-1, skeletne mišice, proteini STAT, interference
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2025
• PID: 20.500.12556/RUL-170122
• Publication date in RUL: 02.07.2025

Secondary language

• Language: English
• Title: Effect of somatotropin and insulin-like growth factor-1 on JAK-STAT signaling pathway in primary human skeletal muscle cells

Abstract

The growth hormone (GH) and insulin-like growth factor-1 (IGF-1) axis plays a pivotal role in regulating skeletal muscle growth, differentiation, and survival. Despite extensive research, the precise signaling mechanisms of GH/IGF-1 in human skeletal muscle cells remain incompletely elucidated, posing challenges for the development of targeted therapeutic strategies. Skeletal muscles also function as an endocrine and metabolic organ, where GH/IGF-1 signaling pathways intersect with those of insulin and interleukin-6 (IL-6). This complex interplay of signaling networks influences muscle function and raises questions regarding potential interferences in the actions of GH/IGF-1, insulin, and IL-6. Understanding the differences in these signaling pathways could enable more precisely targeted therapeutic approaches for muscle diseases. Within the scope of the master's thesis, we investigated the effects of STH and IGF-1 on the JAK/STAT signaling pathway in primary human skeletal muscle cells and assessed the influence of insulin on IGF-1-mediated signaling. The experiments were conducted on primary human skeletal muscle cells, which were cultured and subsequently differentiated into multinucleated myotubes. Cells were treated with STH or IGF-1 for various time periods. Signaling in the cells was monitored using western blotting, through which we analyzed the phosphorylation of STAT3, STAT1, Akt, and p38 MAPK proteins. The expression levels of IGF1 and IGF1R were determined using quantitative polymerase chain reaction. Results were presented as means with standard deviation. Our findings did not confirm the effect of the GH/IGF-1 on STAT3 and STAT1 activation. Nevertheless, they suggest that the isoforms of STAT proteins vary depending on the organism and cell type. Additionally, GH did not influence the expression of IGF-1 and its receptor in skeletal muscle cells. Conversely, our results indicate that the presence of insulin in the culture medium modulates IGF-1-activated signaling pathways, emphasizing the necessity of carefully selecting experimental conditions to accurately assess the effects of IGF-1 on cellular signaling. The findings further support that, for the development of effective targeted therapies, it is essential to simultaneously consider the effects of both insulin and IGF-1.

• Keywords: growth hormone, insulin-like growth factor-1, skeletal muscle, STAT proteins, signaling interference