지구성 운동 시 NT-PGC-1α가 흰쥐 골격근 내 미토콘드리아 생합성에 미치는 영향

김상현 ( S. H Kim ),정수련 ( S. R Jung ),김기진 ( K. J Kim ) 한국운동생리학회(구 한국운동과학회) 2012 운동과학 Vol.21 No.4

본 연구의 목적은 PGC-1α의 짧은 형태인 NT-PGC-1α가 골격근 내 미토콘드리아 생합성에 어떠한 영향을 미치는가를 알아보는 것이다. 지구성 운동에 따른 골격근 내 PGC-1α, NT-PGC-1α 그리고 미토콘드리아 생합성 정도를 알아보기 위해 18마리의 흰쥐를 각각 6마리씩 3그룹(sedentary; Sed, 1 day exercise; 1d Ex, 3 day exercise; 3d Ex)으로 분류한 다음 수영을 실시(6 h/day)하였다. 골격근은 마지막 운동훈련 18시간후 적출하였다. 그 결과 지구성 운동에 따른 골격근 내 PGC-1α의 발현은 1일 운동 후에는 Sed 그룹에 비해 유의하게 증가 하였으나, 3일 운동 후에는 1일 운동에 의해 증가된 정도가 Sed 그룹 수준으로 감소하였다. NT-PGC-1α는 1일 운동 후에는Sed 그룹과 비교해 차이가 없었으나, 3일 운동 후 유의하게 증가하였다. 그리고 지구성 운동에 따른 골격근 내 COXⅠ과NADH-UO는 1일과 3일 트레이닝 후 모두 유의하게 증가하였다. 또한 NT-PGC-1α가 미토콘드리아 생합성에 어떠한 영향을 미치는지 알아보기 위해 C2C12 골격근 세포에 NT-PGC-1α adenovirus를 처치하여 NT-PGC-1α를 과발현 시킨 후 미토콘드리아 효소의 발현정도를 분석한 결과 미토콘드리아 효소인 cytochrome c, COXⅠ, ATP synthase, citrate synthase 모두 유의하게 증가하였다. 이러한 결과를 종합해 볼 때, PGC-1α는 미토콘드리아 생합성 초기에 관여하고, NT-PGC-1α는 PGC-1α에 의해증가된 미토콘드리아 생합성을 계속 유지하거나 약간 더 증가시키는데 중요한 역할을 할 것이다. N-truncated peroxisome proliferator-activated receptor γ coactivator-1α splice variant (NT-PGC-1 α) has similar biological effects to peroxisome proliferator-activated receptor γ coactivator-1α(PGC-1α) in brown adipose t issue. But, t he e ffect of NT-PGC-1α on mitochondrial biogenesis in skeletal muscles has not been clearly identified. The purpose of this study is to verify that NT-PGC1 induce the mitocondrial biogenesis in skeletal muscle. Eighteen rats were randomly assigned into 3 groups (Sedentary, Sed; 1 day exercise, 1d Ex; 3 day exercise, 3d Ex). Exercise groups were trained by using a 6 h/day swimming program. Muscle samples for PGC-1α, NT-PGC-1α and mitochondrial enzymes were harvested 18 hours after the last bout of exercise. The expression of PGC-1α was increased in the 1d Ex compared with Sed group, but 3d Ex group was not changed compared with Sed group. NT-PGC-1α was increased in the 3d Ex group from the Sed group. The expressions of cytochrome oxidase subunit I (COXⅠ)and NADH-ubiquinone oxidoreductase (NADH-UO) were increased in the 1d Ex and 3d Ex group from the Sed group. Three day overexpressed NT-PGC-1α C2C12 myotubes were harvested for mitochondrial enzymes. The expressions of mitochondrial enzymes, cytochrome c, COXⅠ, ATP synthase and citrate synthase were increased in the NT-PGC-1α overexpressed C2C12 from the Sed group. These findings suggest that PGC-1α protein is responsible for initial increase in mitochondrial biogenesis. While NT-PGC-1α is important for chronic exercise induced increase in mitochondrial proteins.

PGC-1α와 NT-PGC-1α가 4주간의 지구성 운동 유발 미토콘드리아 생합성에 미치는 영향

정수련(SuRyunJung),김기진(KiJinKim,김상현(SangHyunKim) 한국체육학회 2013 한국체육학회지 Vol.52 No.5

본 연구의 목적은 4주간의 지구성 운동시 PGC-1α와 NT-PGC-1α의 변화양상이 골격근 내 미토콘드리아 생합성에 어떠한 역할을 하는지 알아보는 것이다. 75 g의 수컷 Wistar rat 20마리를 대상으로 2집단(좌업, 운동집단)으로 무선배정한 뒤 4주간 트레드밀 달리기(경사도 8%, 23 m/min, 120분, 주당 5일)를 실시하였다. 4주간의 처치 후 족척근을 적출하여 미토콘드리아 단백질을 정량 분석한 결과 PGC-1α와 NT-PGC-1α protein 수준의 변화는 나타나지 않았으나, 미토콘드리아 내 전자전달계 효소(ATPsynthase, Core2)와 TCA cycle 효소(Citrate synthase)의 수준은 유의하게 증가한 것으로 나타났다. 요약하면 장기간의 지구성운동은 PGC-1α의 양적 증가와 관계가 없이 다른 요소에 의한 PGC-1α의 활성화가 미토콘드리아 생합성에 영향을 미칠 것으로 생각된다. The purpose of this study was to examine the effects of long-term endurance exercise training on NT-PGC-1α and mitochondrial biogenesis of skeletal muscle. 20 male Wistar rats were randomly assigned to two group (sedentary or exercise training group) and exercise group were trained with treadmill (slop 8%, 23 m/min, 120 min, 5 day/week) for 4 weeks. After 4 weeks, rats were anesthesized and dissect skeletal muscle to quantify protein level. PGC-1α and NT-PGC-1α protein level were not increased after long-term endurance exercise training in rat skeletal muscle, but mitochondrial protein was significantly increased. Therefore PGC-1α activation, not expression will increase mitochondrial biogenesis after long-term endurance exercise.

운동 중 골격근 내 PGC-1α 농도는 PPARβ/δ를 통한 후전사 기전에 의하여 조절된다: PPARβ/δ silence가 ubiquitin을 통한 PGC-1α 안정성에 미치는 영향

정수련 ( Su Ryun Jung ),김기진 ( Ki Jin Kim ),고진호 ( Jin Ho Koh ) 한국운동생리학회 2015 운동과학 Vol.24 No.3

PURPOSE: The aim of this study was to identified which PPARβ/δ control PGC-1α protein stability in rat skeletal muscle by long-term endurance exercise. METHODS: shPPARβ/δ was over-expressed in rat epitrochlearis (Epi) muscle using electrical pulse-mediated gen transfer (electroporation; EPO) method. Then animal underwent 2 wk long swimming exercise. To evaluate PPARβ/δ, PGC-1α ubiquitination, PGC-1α and mitochondrial enzyme expression in rat skeletal muscle, Epi muscles were dissected 18 h post final bout of swimming exercise. RESULTS: PPARβ/δ, PGC-1α, COX I and NADH protein expression in shPPARβ/δ over-expression sedentary (Sed) skeletal muscle were significantly decreased over 55%, but PGC-1α ubiquitination was significantly increased 2.6 fold when compared to scramble (Scr) treated Sed muscle. PPARβ/δ, PGC-1α, COX I and NADH protein expression in 2 wks swimming exercise with Scr gene treated muscle were significantly increased over 2 fold, but PGC-1α ubiquitination was significantly decreased 66% when compared to Scr gene treated Sed muscle. PPARβ/δ, PGC-1α, COX I and NADH protein expression in 2 wks swimming exercise with shPPARβ/δ gene treated muscle were not increased, but PGC-1α ubiquitination was significantly increased 1.96 fold when compared to Scr gene treated Sed muscle. CONCLUSIONS: Our results indicate that PPARβ/δ controls PGC-1α protein stability in rat skeletal muscle following long-term endurance exercise.

원문 : PGC-1α단백질이 생쥐 근육세포의 글리코겐 분해 및 해당효소의 발현을 조절한다

고진호 ( Jin Ho Koh ),김기진 ( Ki Jin Kim ),김상현 ( Sang Hyun Kim ),정수련 ( Su Ryun Jung ) 한국운동생리학회(구 한국운동과학회) 2014 운동과학 Vol.23 No.4

본 연구는 골격근 세포인 C2C12 myotube에 ppargc1a(PGC-1α 유전자) mRNA를 silence시키는 기법으로 PGC-1α의 발현을 부분적으로 억제하여 글리코겐 분해 및 해당 효소의 발현에 어떠한 영향을 미치는지 확인하는 것이다. C2C12골격근 세포에 PGC-1α의 과발현을 유도하기 위하여 Ad-PGC-1α adenovirus를 처치하였으며, PGC-1α의 발현을 억제하기 위하여ppargc1a mRNA를 silence 시키는 기법을 이용하였다. 골격근 세포에 PGC-1α의 과발현을 유도한 결과, PFK의 발현이 empty vector를 처치한 그룹보다 0.4배 감소한 것으로 나타났다. 골격근 세포에 PGC-1α의 발현을 부분적으로 억제시킨 결과 phosphorylase kinase, glycogen phosphorylase 및 PFK는 empty vector를 처치한 그룹보다 각각 2배, 1.4배, 1.5배 증가한 것으로 나타났다. 본 연구의 결과는 단기간 지구성 운동 후 빠르게 증가하는 PGC-1α가 골격근 세포 내 글리코겐 분해효소 및 해당효소를 간접적으로 조절하여 글리코겐 절약효과를 유도할 수 있음을 증명하였다. The purpose of this study was to evaluate the role of PGC-1α on the expression of glycolytic and glycogenolytic enzyme in C2C12 mouse skeletal muscle cell. PGC-1α overexpression in C2C12 myotube was achieved by PGC-1α encoded adenovirus. When PGC-1α was overexpressed, PFK expression was suppressed 0.4 fold compared to control, empty vector treated cell. Contrary to PGC-1α overexpression, silencing ppargc1a mRNA (suppressed PGC-1α protein expression) induced 2, 1.4 and 1.5 fold increase in phosphorylase kinase, glycogen phosphorylase, and PFK protein expression respectively. In summary, down regulation of expression of the glycogenolytic and glycolytic enzymes in muscle that mediates a slowing of muscle glycogen depletion appears to be through the PGC-1α expression.

PPARβ / δ 과발현은 PGC-1α ubiquitination의 감소를 통해 PGC-1α 단백질을 증가시킨다

고진호 ( Jin Ho Koh ),김홍수 ( Hong Soo Kim ),김기진 ( Ki Jin Kim ) 한국운동생리학회 2015 운동과학 Vol.24 No.4

PURPOSE: The aim of this study was to find mechanism with which PPARβ/δ control PGC-1αprotein stability in mouse skeletal muscle. METHODS: Tibialis anterior (TA) muscles of rat were dissected at 18h after 2 weeks swimming exercise. PPARβ/δ was over-expressed in mouse tibialis anterior (TA) muscle using electrical pulse-mediated gen transfer (electroporation; EPO) method. To evaluate, PGC-1α mRNA and protein, PPARβ/δ, ubiquitin and mitochondrial enzyme protein expression in mouse skeletal muscle, TA muscle were dissected at 2wk and 4wk after EPO. To evaluate binding between PGC-1α and ubiquitin, we conducted V5-PGC-1α Immunoprecipitation. RESULTS: PPARβ/δ and PGC-1α in swimming skeletal muscle for 2 weeks were increased 2.1 and 2.5 fold respectively than sedentary muscle. PGC-1α mRNA in PPARβ/δ over-expression skeletal muscle were not different at 2 wk and 4wk when compared to an empty vector (EV) treated group. Endogenous and exogenous PPARβ/δ in PPARβ/δ over-expression skeletal muscle were increased 2.5 and 3.8 fold respectively when compared to an EV treated group. We identified binding between PGC-1α and ubiquitin, and ubiquitin were decreased 60% in PPARβ/δ transfected C2C12 when compared to an EV treated group. PGC-1α were increased 3 fold in muscle that ubiquitin were decreased 60% when compared to an EV treated muscle and COXI and CYTO C were increased 2.27 and 1.75 fold respectively in muscle when compared to an EV treated muscle. CONCLUSIONS: PPARβ/δ overexpression increases PGC-1α protein through the decreased PGC-1α ubiquitination without the increased PGC-1α mRNA in mouse skeletal muscle.

생쥐의 골격근에 PPARβ/δ 과발현이 1회 지구성 운동 후 안정시 PGC-1α mRNA와 단백질 안정성에 미치는 영향

고진호(Jin-hoKoh),정수련(RyunSuJung),김기진(Ki-jinKim) 한국체육학회 2016 한국체육학회지 Vol.55 No.4

본 연구는 지구성 운동 후 안정시 PGC-1α mRNA와 단백질의 안정성이 PPARβ/δ의 영향을 받는지 확인하는 것이다. 전기 자극 유전자 전이법(electroporation; EPO)을 이용하여 PPARβ/δ와 empty vector(EV) 유전자를 각각 생쥐의 왼쪽과 오른쪽 tibialis anterior(TA)근육에 전이하였으며, 처치하지 않은 대조군(control)과 1회 지구성 운동 후 시간에 경과에 따른 mRNA와 단백질을 비교하였다. 생쥐는 5시간 수영 운동을 1회 실시하였으며, 운동 직후(0h), 24시간(24h)및 54시간(h)이 경과한 후 TA근육을 적출하였다. 운동 직후(0h) 대조군, EV 및 PPARβ/δ가 과발현된 근육의 PGC-1α mRNA는 좌업 그룹보다 각각 6.8배(p<.001)배, 6.2배(p<.001) 및 7.1배(p<.001) 증가하였으나, 24h 및 54h에 좌업 그룹수준으로 회복되었다. 운동 후 24h에 EV가 처치된 근육은 PGC-1α 및 PGC-1α ubiquitination이 좌업 그룹보다 각각2.2배 및 1.74배 증가하였으나, 운동 후 54h에 좌업 그룹수준으로 회복되었다. PPARβ/δ 처치 그룹의 PGC-1α는 운동 후 24h와 54h에 좌업 그룹보다 각각 2.5배와 2.2배 증가하였으나 PGC-1α ubiquitination은 증가하지 않았다. 따라서 PPARβ/δ 과발현은 지구성 운동에 의한 PGC-1α mRNA 단백질 안정성에 영향을 미치지 않는다. 그러나 PPARβ/δ 과발현은 지구성 운동으로 증가된 PGC-1α mRNA가 단백질로 전환된 후 PGC-1α의 안정성을 증가시킨다. The purpose of this study is to identify the effects of PPARβ/δ over-expression on PGC-1α mRNA and protein stability after single bout of swimming exercise in mice skeletal muscle. Empty vector (EV) or PPARβ/δ was over-expressed in tibialis anterior(TA) using electroporation(EPO) technique to compare with non-treatment muscle(control; Con). TA muscles were dissected at 0h, 24h or 54h after termination of exercise. PGC-1α mRNA in Con, EV and PPARβ/δ over-expressed muscles were increased 6.8 fold (p<.001), 6.2 fold(p<.001) and 7.1 fold(p<.001), respectively, than sedentary(Sed) group at 0h after exercise and then reverted to Sed group levels at 24h and 54h after termination of exercise. PGC-1α and PGC-1α ubiquitination in EV treated muscles were increased 2.2 fold and 1.74 fold, respectively, than Sed group at 24h after termination of exercise, and then reverted to Sed group levels at 54h after termination of exercise. PGC-1α in PPARβ/δ over-expressed muscles at 24h and 54h after termination of exercise were increased 2.5 fold and 2.2 fold, respectively, than Sed group, but PGC-1α ubiquitination was not increased at 24h and 54h after termination of exercise. Our results indicate that PPARβ/δ over-expression does not increase PGC-1α mRNA stability, but increase PGC-1α protein stability through post-translation mechanism after termination of exercise.

생쥐의 지구성 운동에 의한 Tfam 발현이 AMPK, PPARβ/δ 및 PGC-1α의 발현에 미치는 영향

고진호(KohJin-ho),김기진(KimKi-jin) 한국체육학회 2017 한국체육학회지 Vol.56 No.2

Mitocondrial transcription factor A (Tfam)의 과발현이 미토콘드리아 생합성 및 호흡 기능을 증가시키는 것으로 보고되었으나 지구성 운동에 의한 Tfam의 발현이 어떠한 기전으로 핵으로 신호를 보내며 근 적응의 주요 인자들과 상호작용하는지 확인되지 않았다. 본 연구는 지구성 운동에 의한 Tfam의 발현이 어떠한 기전으로 골격근 적응의 주요 요인인 AMP-activated protein kinase (AMPK), Peroxisome proliferator-activated receptor (PPARβ/δ) 및 Peroxisome proliferator activated receptor gamma coactivator-1α (PGC-1α) 발현에 영향을 미치는지 확인하는 것이다. 생쥐들은 2주간 수영 운동을 실시하거나, Tfam이 골격근에 과발현되도록 유전자 전이를 실시하였다. 또한 PPARβ/δ와 Tfam의 관련성을 확인하기 위하여 PGC-1α knockout 생쥐의 골격근에 PPARβ/δ를 EPO 하였다. 2주간 지구성 운동을 실시한 생쥐의 근육에서 Tfam, PPARβ/δ 및 PGC-1α의 발현이 증가하였다. Tfam이 과발현 된 근육의 AMP:ATP 비율, pAMPK, PPARβ/δ 및 PGC-1α가 증가하였다. PGC-1α knokout 생쥐의 근육에 PPARβ/δ의 과발현은 Tfam의 발현을 증가시키는 것으로 나타났다. 본 연구는 지구성 운동에 의한 Tfam의 발현 증가가 세포내 AMP:ATP 비율 증가를 유도하여 AMPK의 활성을 증가시키며, AMPK의 활성은 PPARβ/δ와 PGC-1α의 발현을 증가시킨다는 것을 확인하였다. 이는 Tfam이 AMPK-PPARβ/δ 및 PGC-1α를 통하여 자신의 발현도 조절할 수 있음을 나타낸다. Tfam overexpression has been shown to increase mitochondrial biogenesis and respiratory function, but there is not clear how Tfam signals to the nucleus, and that a key factors associated with muscle adaptation are involved in Tfam overexpression by endurance exercise. The aim of this study was to identify the effects of Tfam expression by endurance exercise on AMPK, PPARβ/δ and PGC-1α that are associated with skeletal muscle adaptive response. Mice were subjected to forced swimming for 2 wk or Tfam was electroporated in tibialis anterior (TA) muscle. To identify PPARβ/δ effect on Tfam, PPARβ/δ was electroporated in PGC-1α knockout mouse muscle. Mice Swimming for 2 wk resulted in an increase Tfam, PPARβ/δ and PGC-1α in TA muscle. Tfam overexpression in mouse TA muscle resulted in an increase AMP:ATP ratio, AMPK phosphorylation, PPARβ/δ and PGC-1α expression. PPARβ/δ overexpression in PGC-1 α knockout muscle in mouse resulted in an increase Tfam expression. Our finding indicate that an increased Tfam expression by endurance exercise increases AMPK activation through controled AMP:ATP ratio that result in an increase PPARβ/δ and PGC-1α expression. These results indicate that Tfam can increase itself through AMPK-PPARβ/δ and/or PGC-1α axis.

자연과학편 : 운동강도가 고지방식이와 Streptozotocin 유도된 T2DM 흰쥐 골격근내 AMPK, PGC-1α와 GLUT4의 발현

희뢰(LeiJi),하태균(TaeGyunHa),윤정수(ChungSuYoon) 한국체육학회 2014 한국체육학회지 Vol.53 No.5

이 연구는 고지방식이와 streptozotosine 유도된 T2DM흰쥐가 운동강도에 따른 골격근내 AMPK, PGC-1α와 GLUT4의 발현에 미치는 영향을 알아보기 위한 것이다. 먼저 고지방식이와 streptozotosine(STZ; 40 mg/kg)로 쥐 제2형 당뇨를 유발하였다. 다음에 8 주간의 트레드밀 운동을 저강도(V˙O₂max 40%), 중강도(V˙O₂max 60%)과 고강도(V˙O₂max 80%)로 실시한 후 가자미근과 장지신근 적출하였다. Western blotting로 AMPK, p-AMPK, PGC-1α와 GLUT4 단백질을 분석하여 다음과 같은 결과를 얻었다. 첫째, 운동을 통해서 모두 당뇨운동군이 당뇨대조군에 비해 단백질 발현이 높게 나타났다. 둘째, 장지신근내 AMPK, p-AMPK와 PGC-1α의 발현이 고강도 운동군에 더 많은 영향을 미친 것으로 나타났지만, GLUT4의 발현이 중강도 운동군에 더 많은 영향을 미친 것으로 나타났다. 셋째, 가자미근내 AMPK, p-AMPK와 PGC-1α의 발현이 중강도 운동군에 더 많은 영향을 미친 것으로 나타났지만, GLUT4의 발현이 고강도 운동군에 더 많은 영향을 미친 것으로 나타났다. 이러한 결과로 운동강도와 근섬유의 유형에 따라 AMPK, PGC-1α와 GLUT4의 발현이 다르게 나타날 수 있음을 나타낸다. The purpose of this study was to examine the effects of exercise intensity on AMPK, PGC-1α and GLUT4 expression in skeletal muscle of High fat diet and streptozotocin induced T2DM rats. Type 2 diabetes was induced in rats by a combination of low dose streptozotocin(STZ; 40 mg/kg) and feeding of a high fat diet. The rats had trained by low intensity(VO₂max 40%), medium intensity(VO₂max 60%) and high intensity(VO₂max 80%) exercise on the treadmill for 8 weeks then the rat soleus(SOL) and extensor digitorum longus(EDL) were taken out. Western blotting was performed for the expression of AMPK, p-AMPK, PGC-1α, and GLUT4. The results of the analysis was as follow; First, the AMPK, p-AMPK, PGC-1α and GLUT4 expression level of exercise groups was increasd by exercise. Second, expression of AMPK, p-AMPK and PGC-1α of the EDL in the high intensity group was highest in the three intensity groups, but GLUT4 in the medium intensity group was highest. Third, expression of AMPK, p-AMPK and PGC-1α of the soleus in the medium intensity group was highest in the three intensity groups, but GLUT4 in the high intensity group was highest. This study can be concluded that the expression of AMPK, PGC-1α and GLUT4 proteins was differed with exercise intensity and the type of muscle.

운동에 의한 골격근 내 PGC-1α전사 조절 기전

김상현,고진호,김필상,김기진 한국운동생리학회(구 한국운동과학회) 2013 운동과학 Vol.22 No.3

본 연구는 PGC-1α의 promoter에 존재하는 CRE 서열에 결합하여 PGC-1α의 전사를 유도하는 ATF2와 CREB의 활성화를 중심으로 운동 시 골격근 내 PGC-1α의 전사가 어떻게 이루어지는지 알아보았다. 이를 위해 luciferase reporter system을 이용하여 골격근 내 ATF2와 CREB의 인산화 그리고 PGC-1α의 전사를 확인하기 위해 생쥐의 골격근세포에 clenbuterol(β2-adrenergic agonist)과 anisomycin(p38 MAPK activator)을 처치하였다. 또한 흰쥐 12마리를 무작위로 두 그룹(Sedentary와 Exercise)으로 분류한 후 운동 그룹은 30분간 수영(2% weight/body weight, 30 min)을 실시하였으며, 운동직후 CREB과 ATF2의 인산화 정도를 확인하기 위해 골격근을 적출하였다. 그 결과 clenbuterol 처치는 CREB의 인산화를 증가시켰으며, anisomycin의 처치는 ATF2의 인산화를 증가시켰다. 그러나 운동에 의해서는 ATF2만 인산화가 증가하였다. 그리고 PGC-1α의 전사 또한 ATF2의 인산화에 의해서만 유도되었으며, DN-ATF2에 의해서는 PGC-1α의 전사가 완벽히 억제되었다. 이러한 결과는 운동 시 골격근 내 p38 MAPK 기전의 활성에 의한 ATF2 인산화가 PGC-1α의 전사를 유도함을 나타낸다. This study determines which transcriptional factors, activating transcription factor 2 (ATF2) and/or cAMP responsive element binding protein (CREB), bind to and activate cAMP response element (CRE) transcriptional binding site of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) promoter during exercise. C2C12 cells were treated clenbuterol(β2-adrenergic agonist) and anisomycin (p38 MAPK activator) to determine weather p-CREB and/or p-ATF2 can activate PGC-1α promoter transcriptional activities using luciferase reporter system. Twelve rats were randomly assigned into 2 groups (Sedentary and Exercise). Exercise group was trained by using a 30min swimming with tail load equivalent to 2 % of animal`s own body weight. Muscle samples were harvested immediately after exercise. Clenbuterol and anisomycin increased phosphorylation of CREB and ATF2 respectively in C2C12. The ATF2 phosphorylation was increased in the exercise group compared with sedentary group, but CREB phosphorylation was not changed after exercise. PGC-1α transcription activities were enhanced by ATF2 activation, but not in CREB activated condition. Induction of DN-ATF2 completely blocked PGC-1α promoter activity by p-ATF2. These findings suggest that ATF2 phosphorylation by p38 MAPK system induce PGC-1α transcription in exercised muscle.

Hep3B 세포내 PPARγ/PGC-1α/HNF-4α 연쇄작용을 통한 Atorvastin의 FXR과 CYP1A1 활성화 유도

이진 ( Jin Lee ),홍은미 ( Eun Mi Hong ),정장한 ( Jang Han Jung ),박세우 ( Se Woo Park ),이상표 ( Sang Pyo Lee ),고동희 ( Dong Hee Koh ),장현주 ( Hyun Joo Jang ),계세협 ( Sea Hyub Kae ) 대한소화기학회 2021 대한소화기학회지 Vol.77 No.3

Background/Aims: PPARγ, farnesoid X receptor (FXR) and CYP7A1 are associated with solubility of bile. This study was performed to understand a mechanism and interactions of statin-induced PPARγ, PGC-1α and HNF-4α related to the statin-induced activation of FXR and CYP7A1, and verify whether the mevalonate pathway is involved in the mechanism. Methods: MTT assays were performed using cultured human Hep3B cells to determine the effect of atorvastatin on the cell proliferation. Expression levels of indicated proteins were measured using Western blotting assays by inhibiting the protein expression or not. Results: Atorvastatin increased expression of PPARγ, PGC-1α, HNF-4α, FXR, and CYP7A1 in Hep3B cells. PPARγ ligand of troglitazone upregulated the expression of PGC-1α, HNF-4α, FXR, and CYP7A1 in Hep3B cells. Silencing of PPARγ, PGC1α, and HNF4α using respective siRNA demonstrated that atorvastatin-induced FXR and CYP7A1 activation required sequential action of PPARγ/PGC-1α/HNF-4α. The silencing of PPARγ completely inhibited atorvastatin-induced PGC-1α expression, and the PGC1α silencing partially inhibited atorvastatin-induced PPARγ expression. The inhibition of HNF4α did not affect atorvastatin-induced PPARγ expression, but partially inhibited atorvastatin-induced PGC-1α expression. Besides, mevalonate completely reversed the effect of atorvastatin on PPARγ, PGC-1α, HNF-4α, FXR, and CYP7A1. Conclusions: Atorvastatin induces FXR and CYP7A1 activation as a result of sequential action of PPARγ/PGC-1α/HNF-4α in human hepatocytes. We propose that atorvastatin enhances solubility of cholesterol in bile by simultaneously activating of FXR and CYP7A1. (Korean J Gastroenterol 2021;77:123-131)