| Diabetes is a metabolic disease caused by interactions between genes and environment,which characterized by hyperglycemia,insulin resistance and insulin secretion.Known risk factors including genetic mutations,family history,body fat,diet and stress.Diabetes is divided into four categories:(1)Type1 diabetes mellitus,insulin-dependent diabetes mellitus,which refers to the cell damage caused by the autoimmunity of islet cells;(2)Type 2 diabetes mellitus,adult onset diabetes,the patient’s ability to produce insulin has not been completely lost,or even too much,but the effect of insulin is poor;(3)Special types of diabetes mellitus,caused by environmental factors and genetic factors and the reasons are relatively defined;(4)Gestational diabetes mellitus.the diagnosis of diabetes during pregnancy.Maturity-Onset Diabetes of the Young(MODY)first found by Fajns in the 1960 s.Now it has been clear that MODY is a diabete characterized by early onset,a family history,and non-obese.In Europe,MODY diabetes account for 1%-2% of the total population.However,MODY and type 1 or type 2 diabetes will overlap on the onset age and clinical manifestations,therefore the actual morbidity was underestimated by misdiagnosed at a great degree.According to statistics,in the UK,80% of MODY patients were misdiagnosed as type 1 or type 2 diabetes,however,it need an average of 13 years to make final diagnosis from the beginning.The research on the MODY started relatively late in our country.The results showed that MODY account for 2%-10% of the Chinese with early onset diabetes or multiple diabetes.Although the diagnostic rate of MODY is not high,and the diagnosis is difficult,the research of the disease is of great significance.First,the correct diagnosis of MODY helps to guide the treatment of patients,both at home and abroad,according to the research on MODY2,the most common subtype MODY caused by GCK gene mutation.Second,the correct diagnosis is helpful to the later treatment,for through diet and exercise MODY patients can control blood sugar levels,which will greatly reduce the patient’s psychological burden.Third,MODY2 isan autosomal dominant genetic disease,specific molecular diagnosis can provide patients and families with genetic counseling as reference.Finally,the establish of MODY model provides a proper model for diabetes research,and helps to study the pathogenic mechanism and drug screening of diabetes.Now it’s clear that GCK is the virulence gene of MODY2.GCK mainly expresses in liver cells and islet beta cells.GCK locates on the chromosome of 7p15 ~p13,and the total length is about 27 kb,containing 12 exons.GCK consists of 448 amino acid residues and folds into two structural domain with different size.With the development into the understanding of human diseases,research shows that most diseases were associated with genetic mutations.Therefore,research on establishing proper animal models to simulate human diseases and select effective target drugs for treatment is a challenge task.In this study,the GCK gene was modified by CRISPR/Cas9.system.We successfully built GCK gene targeting vector and acquired GCK gene knockout rabbits through the microinjection of Cas9/sg RNA m RNA.The results showed that compared with the normal rabbits,GCK gene knockout rabbits showed typical MODY2 clinical symptoms including long-term elevated in blood sugar,impaired glucose tolerance,and decrease in insulin secretion..In addition,we screened a variety of clinical drug for MODY2,including Glimepiride,Repaglinide,Sitagliptin,Metformin and insulin.In view of the different treatment effects,we chose Glimepiride for long-term treatment.The results showed that Glimepiride significantly improved the symptoms of MODY2.In conclusion,we successfully established the GCK gene knockout rabbit model through CRISPR/Cas9 system,it may provide a reliable model for MODY2 clinical treatment and drug screening. |
