The crosstalk between megakaryocytic lineage cells and the skeletal system has just begun to be explored but remains largely elusive.Using conditional gene knockout mouse models,we demonstrated that loss of Beclin 1(B...The crosstalk between megakaryocytic lineage cells and the skeletal system has just begun to be explored but remains largely elusive.Using conditional gene knockout mouse models,we demonstrated that loss of Beclin 1(Becn1),a major regulator of mammalian autophagy,exclusively in the megakaryocytic lineage disrupted autophagy in platelets but did not compromise megakaryopoiesis or the formation and function of platelets.Unexpectedly,conditional Becn1 deletion in male mice led to a remarkable increase in bone mass with improved bone quality,in association with a decrease in sex hormone binding globulin(SHBG)and an increase in free testosterone(FT).In vivo Becn1 overexpression in megakaryocytic lineage-specific cells reduced bone mass and quality,along with an increase in SHBG and a decrease in FT.Transplantation of wild-type bone marrow cells into megakaryocytic lineage Becn1-deficient male mice restored bone mass and normalized SHBG and FT.Furthermore,bilateral orchiectomy of Becn1^(f/f);Pf4-iCre mice,which are crippled with the production of testosterone,resulted in a reduction in bone mass and quality,whereas in vivo overexpression of SHBG,specifically in the liver of Becn1^(f/f);Pf4-iCre mice,decreased FT and reduced bone mass and quality.In addition,metformin treatment,which induces SHBG expression,reduced FT and normalized bone mass in Becn1^(f/f);Pf4-iCre mice.We thus concluded that Becn1 of the megakaryocytic lineage is dispensable locally for platelet hemostasis but limits bone mass by increasing SHBG,which in turn reduces the FT of male mice.Our findings highlight a mechanism by which Becn1 from megakaryocytic lineage cells distally balances bone growth.展开更多
Emerging evidence suggests that priming intestinal stem cells(ISCs)towards secretory progenitor cells is beneficial for maintaining gut homeostasis against inflammatory bowel disease(IBD).However,the mechanism driving...Emerging evidence suggests that priming intestinal stem cells(ISCs)towards secretory progenitor cells is beneficial for maintaining gut homeostasis against inflammatory bowel disease(IBD).However,the mechanism driving such biased lineage commitment remains elusive.Here we show that MG53,also named as TRIM72,prompts ISCs to secretory lineages via upregulating peroxisome proliferator-activated receptorα(PPARα),thus maintaining intestinal epithelium integrity against noxious insults.Using genetic mouse models,we found that MG53 deficiency leads to exacerbated intestinal damage caused by various injuries in mice,whereas MG53 overexpression in ISCs is sufficient to ameliorate such damage.Mechanistically,MG53 promoted asymmetric division of ISCs to generate more progenitor cells of secretory lineages via activating PPARαsignaling.Specifically,MG53 overexpression induced PPARαexpression at transcriptional level and concomitantly increased PPARαactivity by elevating the contents of a panel of unsaturated fatty acids in the intestine that serve as potent endogenous agonists of PPARα.Furthermore,genetic ablation or pharmacological inhibition of PPARαabolished the protective effects of MG53.These findings reveal a crucial role of MG53-PPARαaxis in driving the secretory lineage commitment of ISCs,especially during injury response,highlighting the important therapeutic potential of targeting MG53-PPARαsignaling for IBD treatment and marking PPARαagonists as novel therapies for IBD caused by various etiologies.展开更多
基金supported in part by grants from the National Natural Science Foundation of China(No.81673093,No.82170227,No.91649113,No.82470165,No.82000121,No.31771640)the Jiangsu Science and Technology Department(No.SBK20200191)+1 种基金the State Key Laboratory of Radiation Medicine and Protection of Soochow University(No.GZC00201)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The crosstalk between megakaryocytic lineage cells and the skeletal system has just begun to be explored but remains largely elusive.Using conditional gene knockout mouse models,we demonstrated that loss of Beclin 1(Becn1),a major regulator of mammalian autophagy,exclusively in the megakaryocytic lineage disrupted autophagy in platelets but did not compromise megakaryopoiesis or the formation and function of platelets.Unexpectedly,conditional Becn1 deletion in male mice led to a remarkable increase in bone mass with improved bone quality,in association with a decrease in sex hormone binding globulin(SHBG)and an increase in free testosterone(FT).In vivo Becn1 overexpression in megakaryocytic lineage-specific cells reduced bone mass and quality,along with an increase in SHBG and a decrease in FT.Transplantation of wild-type bone marrow cells into megakaryocytic lineage Becn1-deficient male mice restored bone mass and normalized SHBG and FT.Furthermore,bilateral orchiectomy of Becn1^(f/f);Pf4-iCre mice,which are crippled with the production of testosterone,resulted in a reduction in bone mass and quality,whereas in vivo overexpression of SHBG,specifically in the liver of Becn1^(f/f);Pf4-iCre mice,decreased FT and reduced bone mass and quality.In addition,metformin treatment,which induces SHBG expression,reduced FT and normalized bone mass in Becn1^(f/f);Pf4-iCre mice.We thus concluded that Becn1 of the megakaryocytic lineage is dispensable locally for platelet hemostasis but limits bone mass by increasing SHBG,which in turn reduces the FT of male mice.Our findings highlight a mechanism by which Becn1 from megakaryocytic lineage cells distally balances bone growth.
基金funded by National Key R&D Program of China(2022YFA1303003,2018YFA0800701,2018YFA0507603,and 2018YFA0800501)National Natural Science Foundation of China(81770376,81630008,81790621,31521062,31671177,and 81370234).
文摘Emerging evidence suggests that priming intestinal stem cells(ISCs)towards secretory progenitor cells is beneficial for maintaining gut homeostasis against inflammatory bowel disease(IBD).However,the mechanism driving such biased lineage commitment remains elusive.Here we show that MG53,also named as TRIM72,prompts ISCs to secretory lineages via upregulating peroxisome proliferator-activated receptorα(PPARα),thus maintaining intestinal epithelium integrity against noxious insults.Using genetic mouse models,we found that MG53 deficiency leads to exacerbated intestinal damage caused by various injuries in mice,whereas MG53 overexpression in ISCs is sufficient to ameliorate such damage.Mechanistically,MG53 promoted asymmetric division of ISCs to generate more progenitor cells of secretory lineages via activating PPARαsignaling.Specifically,MG53 overexpression induced PPARαexpression at transcriptional level and concomitantly increased PPARαactivity by elevating the contents of a panel of unsaturated fatty acids in the intestine that serve as potent endogenous agonists of PPARα.Furthermore,genetic ablation or pharmacological inhibition of PPARαabolished the protective effects of MG53.These findings reveal a crucial role of MG53-PPARαaxis in driving the secretory lineage commitment of ISCs,especially during injury response,highlighting the important therapeutic potential of targeting MG53-PPARαsignaling for IBD treatment and marking PPARαagonists as novel therapies for IBD caused by various etiologies.
