Association of GH, STAT5A, MYF5 gene polymorphisms with milk somatic cell count, EC and pH levels of Holstein dairy cattle

Candidate genes for mastitis resistance in dairy cattle: a data integration approach

BACKGROUND

Inflammation of the mammary tissue (mastitis) is one of the most detrimental health conditions in dairy ruminants and is considered the most economically important infectious disease of the dairy sector. Improving mastitis resistance is becoming an important goal in dairy ruminant breeding programmes. However, mastitis resistance is a complex trait and identification of mastitis-associated alleles in livestock is difficult. Currently, the only applicable approach to identify candidate loci for complex traits in large farm animals is to combine different information that supports the functionality of the identified genomic regions with respect to a complex trait.

METHODS

To identify the most promising candidate loci for mastitis resistance we integrated heterogeneous data from multiple sources and compiled the information into a comprehensive database of mastitis-associated candidate loci. Mastitis-associated candidate genes reported in association, expression, and mouse model studies were collected by searching the relevant literature and databases. The collected data were integrated into a single database, screened for overlaps, and used for gene set enrichment analysis.

RESULTS

The database contains candidate genes from association and expression studies and relevant transgenic mouse models. The 2448 collected candidate loci are evenly distributed across bovine chromosomes. Data integration and analysis revealed overlaps between different studies and/or with mastitis-associated QTL, revealing promising candidate genes for mastitis resistance.

CONCLUSION

Mastitis resistance is a complex trait influenced by numerous alleles. Based on the number of independent studies, we were able to prioritise candidate genes and propose a list of the 22 most promising. To our knowledge this is the most comprehensive database of mastitis associated candidate genes and could be helpful in selecting genes for functional validation studies.

Study of milk production genes and their association with production traits in Rathi cattle

The study aimed to identify polymorphism of LEP, and STAT5A milk-producing genes and their association with production traits in Rathi cattle. An overall 160 animals were selected from a population of Rathi cattle from Livestock Research Station, Rajasthan University of Veterinary and Animals Sciences, Bikaner (Rajasthan). The phenotypic information on total milk yield, peak yield and lactation length were recorded from the years 2012- 2018. Each animal’s milk sample (100 ml) was analysed for milk composition parameters. Genomic DNA was extracted from the whole blood sample through the spin column method and association analysis was done. The polymorphism have been observed in exon-3 (454 bp) of LEP gene, intron 9-10 (224 bp) and intron-15-exon-16 (379 bp) of STAT5A genes by PCR-SSCP and revealed two types of genotypic pattern. The STAT5A exon-7 (215 bp) also showed polymorphism with three genotypic patterns. The AB pattern of LEP exon-3 and AA pattern of intron 9-10 and intron-15-exon-16 of STAT5A genes showed a significant effect on total milk yield. The BB genotypic pattern of the STAT5A exon-7 gene showed a significant impact on peak yield. The AB pattern of LEP and STAT5A genes were associated with more milk fat % in the studied population of Rathi cattle. All these genes showed a significant effect on total solids. The association analysis of LEP and STAT5A genes with different milk production and milk composition traits illustrated the worth of these genes for marker-assisted selection of dairy cattle. Thus, the present study was designed to unmask the relevant genetic factors responsible for variation in milk performance traits.

Role of the JAK-STAT Pathway in Bovine Mastitis and Milk Production

Simple Summary

The cytokine-activated Janus kinase (JAK)—signal transducer and activator of transcription (STAT) pathway has an important role in the regulation of immunity and inflammation. In addition, the signaling of this pathway has been reported to be associated with mammary gland development and milk production. Because of such important functions, the JAK-STAT pathway has been widely targeted in both human and animal diseases as a therapeutic agent. Recently, the JAK2, STATs, and inhibitors of the JAK-STAT pathway, especially cytokine signaling suppressors (SOCSs), have been reported to be associated with milk production and mastitis-resistance phenotypic traits in dairy cattle. Thus, in the current review, we attempt to overview the development of the JAK-STAT pathway role in bovine mastitis and milk production.

Abstract

The cytokine-activated Janus kinase (JAK)—signal transducer and activator of transcription (STAT) pathway is a sequence of communications between proteins in a cell, and it is associated with various processes such as cell division, apoptosis, mammary gland development, lactation, anti-inflammation, and immunity. The pathway is involved in transferring information from receptors on the cell surface to the cell nucleus, resulting in the regulation of genes through transcription. The Janus kinase 2 (JAK2), signal transducer and activator of transcription A and B (STAT5 A & B), STAT1, and cytokine signaling suppressor 3 (SOCS3) are the key members of the JAK-STAT pathway. Interestingly, prolactin (Prl) also uses the JAK-STAT pathway to regulate milk production traits in dairy cattle. The activation of JAK2 and STATs genes has a critical role in milk production and mastitis resistance. The upregulation of SOCS3 in bovine mammary epithelial cells inhibits the activation of JAK2 and STATs genes, which promotes mastitis development and reduces the lactational performance of dairy cattle. In the current review, we highlight the recent development in the knowledge of JAK-STAT, which will enhance our ability to devise therapeutic strategies for bovine mastitis control. Furthermore, the review also explores the role of the JAK-STAT pathway in the regulation of milk production in dairy cattle.