DNAJB3

This study aimed to evaluate the effect of hCG injection on Day 3, 4 or 5 post-induction of ovulation on corpus luteum (CL) function in llamas and then, to evaluate its effect on pregnant animals. After induction of ovulation with buserelin (Day 0), llamas were randomly assigned to one of four groups: hCG3 (n = 5), hCG4 (n = 5), hCG5 (n = 5) or control (n = 5), receiving an injection of 750 IU of hCG on Day 3, 4 or 5 or 1.5 ml of saline solution, respectively. All females were examined by transrectal doppler ultrasonography, every other day from Day 6 until Day 12. Blood samples for P4 determination were collected daily from Day 2 to Day 8 and every other day until Day 12. Llamas with hCG4 showed higher plasma P4 concentration on Day 10, higher AUC and plasma P4 remained above 1 ng ml-1 for more days than the control group. Based on these results, Study 2 was performed. Llamas were mated and randomly divided in "Treated" (n = 10) and "Control" (n = 10) group, receiving an injection of 750 IU of hCG or saline solution on Day 4 post-induction of ovulation, respectively. Doppler ultrasonography and blood collection for P4 evaluation were also performed daily, from Day 6 until Day 16 post mating. Plasma P4 concentration post-mating tended to be greater in pregnant treated llamas than in non-treated pregnant females. These results suggest that hCG administration on Day 4 has a luteotropic effect.

HSP40/DNAJ family of proteins is the most diverse chaperone family, comprising about 49 isoforms in humans. Several reports have demonstrated the functional role of a few of these isoforms in the pathogenesis of various viruses, including HIV‐1. Our earlier study has shown that several isoforms of HSP40 get significantly modulated at the mRNA level during HIV‐1 infection in T cells. To explore the biological role of these significantly modulated isoforms, we analyzed their effect on HIV‐1 gene expression and virus production using knockdown and overexpression studies. Among these isoforms, DNAJA3, DNAJB1, DNAJB7, DNAJC4, DNAJC5B, DNAJC5G, DNAJC6, DNAJC22, and DNAJC30 seem to positively regulate virus replication, whereas DNAJB3, DNAJB6, DNAJB8, and DNAJC5 negatively regulate virus replication. Further investigation on the infectivity of the progeny virion demonstrated that only DNAJB8 negatively regulates the progeny virion infectivity. It was further identified that DNAJB8 protein is involved in the downregulation of Vif protein, required for the infectivity of HIV‐1 virions. DNAJB8 seems to direct Vif protein for autophagic‐lysosomal degradation, leading to rescue of the cellular restriction factor APOBEC3G from Vif‐mediated proteasomal degradation, resulting in enhanced packaging of APOBEC3G in budding virions and release of less infective progeny virion particles. Finally, our results also indicate that during the early stage of HIV‐1 infection, enhanced expression of DNAJB8 promotes the production of less infective progeny virions, but at the later stage or at the peak of infection, reduced expression of DNJAB8 protein allows the HIV‐1 to replicate and produce more infective progeny virion particles.

Metabolic stress involved in several dysregulation disorders such as type 2 diabetes mellitus (T2DM) results in down regulation of several heat shock proteins (HSPs) including DNAJB3. This down regulation of HSPs is associated with insulin resistance (IR) and interventions which induce the heat shock response (HSR) help to increase the insulin sensitivity. Metabolic stress leads to changes in signaling pathways through increased activation of both c-jun N-terminal kinase-1 (JNK1) and the inhibitor of κB inflammatory kinase (IKKβ) which in turn leads to inactivation of insulin receptor substrates 1 and 2 (IRS-1 and IRS-2). DNAJB3 interacts with both JNK1 and IKKβ kinases to mitigate metabolic stress. In addition DNAJB3 also activates the PI3K-PKB/AKT pathway through increased phosphorylation of AKT1 and its substrate AS160, a Rab GTPase-activating protein, which results in mobilization of GLUT4 transporter protein and improved glucose uptake. We show through pull down that AK T1 is an interacting partner of DNAJB3, further confirmed by isothermal titration calorimetry (ITC) which quantified the avidity of AKT1 for DNAJB3. The binding interface was identified by combining protein modelling with docking of the AKT1-DNAJB3 complex. DNAJB3 is localized in the cytoplasm and ER, where it interacts directly with AKT1 and mobilizes AS160 for glucose transport. Inhibition of AKT1 resulted in loss of GLUT4 translocation activity mediated by DNAJB3 and also abolished the protective effect of DNAJB3 on tunicamycin-induced ER stress. Taken together, our findings provide evidence for a direct protein-protein interaction between DNAJB3 and AKT1 upon which DNAJB3 alleviates ER stress and promotes GLUT4 translocation.