Identification And Expression Analysis Of Suppressors Of Cytokine Signaling (SOCS) From Soiny Mullet (Liza Haematocheila)

Suppressor of cytokine signaling(SOCS)is a key physiological regulator of the immune system and plays a key regulatory role in innate and adaptive immunity.The mullet(Liza haematocheila)belongs to the Mugliliformes Mugilidae fish.It is one of the main economic fishes in China.Because of the strong response to the external of mullet,it is easy to be scratched,bruised and descaled during breeding,fishing,transportation and releasing,resulting in decreased immunity,resulting in pathogenic bacteria infection and diseases.However,the immune system of the mugilidae,including the mullet,is poorly understood,and the research on its disease resistance mechanism is lacking.In this study,the full-length sequences of ten SOCS family members(SOCS1,SOCS2,SOCS3 a,SOCS3b,SOCS4,SOCS5 a,SOCS5b,SOCS6,SOCS7 and SOCS8)of mullet were cloned by SMART-RACE method,The full length of their cDNA sequences are 1568 bp,2155 bp,1991 bp,2997 bp,2390 bp,2600 bp,2133 bp,5287 bp,3476 bp and 2165 bp;The open reading frame(ORF)nucleotide sequences of their cDNA sequences are 636 bp,609 bp,618 bp,687 bp,1188 bp,1638 bp,1695 bp,1611 bp,2553 bp and 642 bp respectively;inferring to encode 211 aa,202 aa,205 aa,228 aa,395 aa,564 aa,545 aa,536 aa,850 aa and 213 aa respectively.The theoretical protein molecular weights of SOCS family members are 24.03 kDa,22.63 kDa,23.42 kDa,25.51 kDa,44.37 kDa,62.29 kDa,60.65 kDa,91.66 kDa,88.69 kD and23.96 kDa,and the isoelectric point(PI)of SOCS family members are 9.01,8.83,8.80,8.44,8.69,8.95,6.63,6.51,7.06and8.52.Multiple sequence alignment results indicates that the mullet SOCS molecule shares highly conserved functional domains with other vertebrate species,including the SRC homology 2 domain(SH2 domain)and the SOCS-box domain.This study found that there are two major branches which including the type I subfamily(SOCS4,SOCS5 a,SOCS6,SOCS7,and SOCS5b)and the type Π sub-family(SOCS1,SOCS2,SOCS3 a,SOCS3b)through phylogenetic analysis of the SOCS family genes of mammals,reptiles,avians and teleost fish.The former SOCS4,SOCS5 a and SOCS5 b are clustered into one small branch,SOCS6 and SOCS7 are clustered into another small branch;the latter SOCS1,SOCS3 a and SOCS3 b are clustered into one small branch,and SOCS2 and SOCS8 are clustered into another small branch;The expression of SOCS family genes was detected in 8 tissues(gill,skin,muscle,liver,spleen,head kidney,intestine and brain)in normal physiological conditions.All mullet SOCS genes were constitutively expressed in the examined tissues examined,but their expression patterns were differeddifferent.Further,following Streptococcus dysgalactiae infection,all mullet SOCS genes exhibited distinctly different expression patterns in a time-and tissues-dependent manner.These results indicatesuggest thatd the important roles of SOCSs are involved in in immune response to bacterial infections and provided the basis for understanding the complex cytokine regulatory network of teleosts.In summary,10 members of the SOCS family were first identified in mullet and their expression profiles were analyzed after S.dysgalactia infection.The results suggest that SOCSs may have different roles in regulating tissue homeostasis and immune responses to bacterial infections.