Question

Sam68 protein

•Member of STAR family of RNA binding proteins

•STAR= signal transduction and activation of RNA

•STAR proteins regulate mRNA stability, export, splicing and translation

Mice were bred for 5 mo with wild-type females of proven fertility and # of litters and pups tallied. Pronuclei (indicated by arrowheads in B) in the fertilized eggs were used to score fertilization. A graph showing the results of three independent mating experiments is shown in C.

(B) Quantitative real-time PCR analysis of Spag16, Nedd1, Spdya, Tpn2, and Prm2 mRNA levels in the polysomal and ribonucleoprotein (RNP) fractions of spermatogonial cells.(C) Western blot analysis of Sam68, SPAG16, NEDD1, and SPDYA proteins in germ cells isolated from Sam68+/+ or Sam68?/? testes. ERK2 was used as a loading control.

I couldnt get the images but they can be found here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2700383/

Any help is greatly appreciated and I will provide positive feedback!!!

1)Summarize the analysis of the male fertility phenotype of Sam68-/- mice.

2)Which genes demonstrate altered expression in the Sam68-/- germ cells?

4)Do these data overall make sense given the known functions of STAR proteins?

Answer 1

1) Sam 68-/- mice are shown to be infertile, since SAM 68 is a part of the STAR family whic are involved in mRNA export, splicing and translation. The paper mentions that SAM 68 is expressed in meiotic and post meitoic Testes cells. It has also been shown that SAM 68-/- mice have fewer spermatozoa, have motility defects in sperm and are unable to fertilize. Hence the SAm 68 -/- phenotype mice are infertile

2) In the qPCR analysis the following genes showed altered expression KLK1, NEDD1, Park 2, Spag 16, Kcnip4, Lrcc1, PP1r1c, Zymnd 12, Spdya, Mbd5, Prm2 and R1k4931428L18.

4) The data does make limited sense since the paper proves that SAM 68 is involved in differentioninto mature spermatazoa and is responsible for causing the infertility. More studies have to be conducted to see how the altered expression of the genes due to Sam 68 ablation have this effect from a molecular perspective.